Wyatt J. Andersen, ATC

ABSTRACT

Use of mesenchymal stem cells from bone marrow has gained significant popularity. The iliac crest has been determined to be an effective site for harvesting mesenchymal stem cells. Review of the literature reveals that multiple techniques are used to harvest bone marrow aspirate from the iliac crest, but the descriptions are based on the experience of various authors as opposed to studied anatomy. A safe, reliable, and reproducible method for aspiration has yet to be studied and described. We hypothesized that there would be an ideal angle and distance for aspiration that would be the safest, most consistent, and most reliable. Using magnetic resonance imaging (MRI), we reviewed 26 total lumbar spine MRI scans (13 males, 13 females) and found that an angle of 24° should be used when entering the most medial aspect of the posterior superior iliac spine (PSIS) and that this angle did not differ between the sexes. The distance that the trocar can advance after entry before hitting the anterior ilium wall varied significantly between males and females, being 7.53 cm in males and 6.74 cm in females. In addition, the size of the PSIS table was significantly different between males and females (1.20 cm and 0.96 cm, respectively). No other significant differences in the measurements gathered were found. Using the data gleaned from this study, we developed an aspiration technique. This method uses ultrasound to determine the location of the PSIS and the entry point on the PSIS. This contrasts with most techniques that use landmark palpation, which is known to be unreliable and inaccurate. The described technique for aspiration from the PSIS is safe, reliable, reproducible, and substantiated by data.

The iliac crest is an effective site for harvesting bone marrow stem cells. It allows for easy access and is superficial in most individuals, allowing for a relatively quick and simple procedure. Use of mesenchymal stem cells (MSCs) for treatment of orthopedic injuries has grown recently. Whereas overall use has increased, review of the literature reveals very few techniques for iliac crest aspiration,¹ but these are not based on anatomic relationships or studies. Hernigou and colleagues^2,3 attempted to quantitatively evaluate potential “sectors” allowing for safe aspiration using cadaver and computed tomographic reconstruction imaging. We used magnetic resonance imaging (MRI) to analyze aspiration parameters. Owing to the ilium’s anatomy, improper positioning or aspiration technique during aspiration can result in serious injury.^2,4-6 We hypothesized that there is an ideal angle and positioning for bone marrow aspiration from the posterior superior iliac spine (PSIS) that is safe, consistent, and reproducible. Although most aspiration techniques use landmark palpation, this is unreliable and inaccurate, especially when compared with ultrasound-guided injections^7-16 and procedures.^9,12,17-19 We describe our technique using ultrasound to visualize patient anatomy and accurately determine anatomic entry with the trocar.

METHODS

MRI scans of 26 patients (13 males, 13 females) were reviewed to determine average angles and distances. Axial T2-weighted views of the lumbar spine were used in all analyses. The sacroiliac (SI) joint angle was defined as the angle formed between the vector through the midline of the pelvis and the vector that is parallel to the SI joint. The approach angle was defined as the angle formed between the vector of the most medial aspect of the PSIS through the ilium to the anterior wall and the vector through the midline of the pelvis (Figure 1). 

Continue to: For the 13 males, the mean SI joint...

RESULTS

The results are reported in the Table. 

Table. Measurements of Patients Taken on Axial T2-Weighted Views of Lumbosacral MRI Scans^a

^aStatistical significance is denoted as P < .02.

Abbreviations: MRI, magnetic resonance imaging; PSIS, posterior iliac spine; SI, sacroiliac.

For the 13 males, the mean SI joint angle was 31.22° ± 7.18° (range, 20.20° to 48.50°). The mean approach angle was 24.41° ± 4.11° (range, 19.50° to 31.00°). The mean PSIS table width was 1.20 cm ± 0.26 cm (range, 0.84 cm to 1.70 cm). The mean distance from the PSIS to the anterior ilium wall was 7.53 cm ± 0.75 cm (range, 6.43 cm to 8.80 cm). The mean perpendicular distance from the PSIS table to the anterior ilium was 3.40 cm ± 0.56 cm (range, 2.34 cm to 4.16 cm). The mean minimum width of the ilium to the SI joint was 1.16 cm ± 0.26 cm (range, 0.65 cm to 1.56 cm).

For the 13 females, the mean SI joint angle was 29.54° ± 10.84° (range, 17.20° to 48.20°). The mean approach angle was 23.56° ± 6.88° (range, 14.80° to 38.50°). The mean PSIS table width was 0.96 cm ± 0.21 cm (range, 0.61 cm to 1.54 cm). The mean distance from the PSIS to the anterior ilium wall was 6.74 cm ± 0.85 cm (range, 5.33 cm to 8.32 cm). The mean perpendicular distance from the PSIS table to the anterior ilium was 3.00 cm ± 0.48 cm (range, 2.23 cm to 3.76 cm). The mean minimum width of the ilium to the SI joint was 1.04 cm ± 0.25 cm (range, 0.71 cm to 1.42 cm).

For the 26 total patients, the mean SI joint angle was 30.38° ± 9.05° (range, 17.20° to 48.50°). The mean approach angle was 23.98° ± 5.57° (range, 14.80° to 38.50°). The mean PSIS table width was 1.08 cm ± 0.26 cm (range, 0.61 cm to 1.70 cm). The mean distance from the PSIS to the anterior ilium wall was 7.14 cm ± 0.88 cm (range, 5.33 cm to 8.80 cm). The mean perpendicular distance from the PSIS table to the anterior ilium was 3.20 cm ± 0.55 cm (range, 2.23 cm to 4.16 cm). The mean minimum width of the ilium to the SI joint was 1.10 cm ± 0.26 cm (range, 0.65 cm to 1.56 cm).

There was a statistically significant difference between the male and female groups for the maximum distance the trocar can be advanced from the PSIS to the anterior ilium wall (P < .02), and a statistically significant difference for the PSIS table width (P < .02). There were no significant differences between the male and female groups for the approach angle, the SI joint angle, the perpendicular distance from the PSIS to the anterior ilium, and the minimum width of the ilium to the SI joint.

Continue to: The patient is brought to the procedure...

TECHNIQUE: ILIAC CREST (PSIS) BONE MARROW ASPIRATION

The patient is brought to the procedure room and placed in a prone position. The donor site is prepared and draped in the usual sterile manner. Ultrasound is used to identify the median sacral crest in a short-axis view. The probe is then moved laterally to identify the PSIS (Figures 4A, 4B). 

The crosshairs on the ultrasound probe are used to mark the center lines of each plane. The central point marks the location of the PSIS. Alternatively, an in-plane technique can be used to place a spinal needle on the exact entry point on the PSIS. Once the PSIS and entry point are identified, the site is blocked with 10 mL of 0.5% ropivacaine.

Prior to introduction of the trocar, all instrumentation is primed with heparin and syringes are prepped with anticoagulant citrate dextrose solution, solution A. A stab incision is made at the site. The trocar is placed at the entry point, which should be centered in a superior-inferior plane and at the most medial point of the PSIS. Starting with the trocar vertical, the trocar is angled laterally 24° by dropping the hand medially toward the midline. No angulation cephalad or caudad is necessary, but cephalad must be avoided so as not to skive superiorly. This angle, which is recommended for both males and females, allows for the greatest distance the trocar can travel in bone before hitting the anterior ilium wall. A standard deviation of 5.57° is present, which should be considered. Steady pressure should be applied with a slight twisting motion on the PSIS. If advancement of the trocar is too difficult, a mallet or drill can be used to assist in penetration.

With the trocar advanced into the bone 1 cm, the trocar needle is removed while the cannula remains in place. The syringe is attached to the top of the cannula. The syringe plunger is pulled back to aspirate 20 mL of bone marrow. The cannula and syringe assembly are advanced 2 cm farther into the bone to allow for aspiration of a new location within the bone marrow cavity, and 20 mL of bone marrow are again aspirated. This is done a final time, advancing the trocar another 2 cm and aspirating a final 20 mL of bone marrow. The entire process should yield roughly 60 mL of bone marrow from one side. If desired, the same process can be repeated for the contralateral PSIS to yield a total of 120 mL of bone marrow from the 2 sites.

Based on our data, the average distance to the anterior ilium wall was 7 cm, but the shortest distance noted in this study was 5 cm. On the basis of the data presented, this technique allows for safe advancement based on even the shortest measured distance, without fear of puncturing the anterior ilium wall. Perforation could damage the femoral nerve and the internal or external iliac artery or vein that lie anterior to the ilium.

Continue to: We hypothesized that there...

DISCUSSION

We hypothesized that there would be an optimal angle of entry and maximal safe distance the trocar could advance through the ilium when aspirating. Because male and female pelvic anatomy differs, we also hypothesized that there would be differences in distance and size measurements for males and females. Our results supported our hypothesis that there is an ideal approach angle. The results also showed that the maximum distance the trocar can advance and the width of the PSIS table differ significantly between males and females.

Although pelvic anatomy differs between males and females, there should be an ideal entry angle that would allow maximum advancement into the ilium without perforating the anterior wall, which we defined as the approach angle. In our comparison of 26 MRI scans, we found that the approach angle did not differ significantly between the 2 groups (13 males, 13 females). This allows clinicians to enter the PSIS at roughly 24° medial to the parasagittal line, maximizing the space before puncturing into the anterior pelvis in either males or females.

If clinicians were to enter perpendicular to the patient’s PSIS, they would, on average, be able to advance only 3.20 cm before encountering the SI joint. When entering at 24° as we recommend, the average distance increases to 7.14 cm. Although the angle did not differ significantly, there was a significant difference between males and females in the length from the PSIS to the anterior wall, with males having 7.53 cm distance and females 6.74 cm. This is an important measurement because if the anterior ilium wall is punctured, the femoral nerve and the common, internal and external iliac arteries and veins could be damaged, resulting in retroperitoneal hemorrhage.

A fatality in 2001 in the United Kingdom led to a national audit of bone marrow aspiration and biopsies.^4-6 Although these procedures were done primarily for patients with cancer, hemorrhagic events were the most frequent and serious events. This audit led to the identification of many risk factors. Bain^4-6 conducted reviews of bone marrow aspirations and biopsies in the United Kingdom from 2002 to 2004. Of a total of 53,088 procedures conducted during that time frame, 48 (0.09%) adverse events occurred, with 29 (0.05%) being hemorrhagic events. Although infrequent, hemorrhagic adverse events represent significant morbidity. Reviews such as those conducted by Bain^4-6 highlight the importance of a study that helps determine the optimal parameters for aspiration to ensure safety and reliability.

Hernigou and colleagues^2,3 conducted studies analyzing different “sectors” in an attempt to develop a safe aspiration technique. They found that obese patients were at higher risk, and some sites of aspiration (sectors 1, 4, 5) had increased risk for perforation and damage to surrounding structures. Their sector 6, which incorporated the entirety of the PSIS table, was considered the safest, most reliable site for trocar introduction.^2,3 Hernigou and colleagues,² in comparing the bone mass of the sectors, also noted that sector 6 has the greatest bone thickness close to the entry point, making it the most favorable site. The PSIS is not just a point; it is more a “table.” The PSIS can be palpated posteriorly, but this is inaccurate and unreliable, particularly in larger individuals. The PSIS table can be identified on ultrasound before introducing the trocar, which is a more reliable method of landmark identification than palpation guidance, just as in ultrasound-guided injections^7-16 and procedures.^9,12,17-19

Continue to: If the PSIS is not accurately...

MSCs are found as perivascular cells and lie in the cortices of bones.²¹ Following the approach angle and directed line from the PSIS to the anterior ilium wall described in this study (Figures 1 and 2), the trocar would pass through the narrow corridor as it advances farther into the ilium. The minimum width of this corridor was measured in this study and, on average, was 1.10 cm wide from cortex to cortex (Figure 3). As the bone marrow is aspirated from this narrow corridor, the clinician is gathering MSCs from both the lateral and medial cortices of the ilium. By aspirating from a greater surface area of the cortices, it is believed that this will increase the total collection of MSCs.

CONCLUSION

Although there are reports in the literature that describe techniques for bone marrow aspiration from the iliac crest, the techniques are very general and vague regarding the ideal angles and methods. Studies have attempted to quantify the safest entry sites for aspiration but have not detailed ideal parameters for collection. Blind aspiration from the iliac crest can have serious implications if adverse events occur, and thus there is a need for a safe and reliable method of aspiration from the iliac crest. Ultrasound guidance to identify anatomy, as opposed to palpation guidance, ensures anatomic placement of the trocar while minimizing the risk of aspiration. Based on the measurements gathered in this study, an optimal angle of entry and safe distance of penetration have been identified. Using our data and relevant literature, we developed a technique for a safe, consistent, and reliable method of bone marrow aspiration out of the iliac crest.

ABSTRACT

Use of mesenchymal stem cells from bone marrow has gained significant popularity. The iliac crest has been determined to be an effective site for harvesting mesenchymal stem cells. Review of the literature reveals that multiple techniques are used to harvest bone marrow aspirate from the iliac crest, but the descriptions are based on the experience of various authors as opposed to studied anatomy. A safe, reliable, and reproducible method for aspiration has yet to be studied and described. We hypothesized that there would be an ideal angle and distance for aspiration that would be the safest, most consistent, and most reliable. Using magnetic resonance imaging (MRI), we reviewed 26 total lumbar spine MRI scans (13 males, 13 females) and found that an angle of 24° should be used when entering the most medial aspect of the posterior superior iliac spine (PSIS) and that this angle did not differ between the sexes. The distance that the trocar can advance after entry before hitting the anterior ilium wall varied significantly between males and females, being 7.53 cm in males and 6.74 cm in females. In addition, the size of the PSIS table was significantly different between males and females (1.20 cm and 0.96 cm, respectively). No other significant differences in the measurements gathered were found. Using the data gleaned from this study, we developed an aspiration technique. This method uses ultrasound to determine the location of the PSIS and the entry point on the PSIS. This contrasts with most techniques that use landmark palpation, which is known to be unreliable and inaccurate. The described technique for aspiration from the PSIS is safe, reliable, reproducible, and substantiated by data.

The iliac crest is an effective site for harvesting bone marrow stem cells. It allows for easy access and is superficial in most individuals, allowing for a relatively quick and simple procedure. Use of mesenchymal stem cells (MSCs) for treatment of orthopedic injuries has grown recently. Whereas overall use has increased, review of the literature reveals very few techniques for iliac crest aspiration,¹ but these are not based on anatomic relationships or studies. Hernigou and colleagues^2,3 attempted to quantitatively evaluate potential “sectors” allowing for safe aspiration using cadaver and computed tomographic reconstruction imaging. We used magnetic resonance imaging (MRI) to analyze aspiration parameters. Owing to the ilium’s anatomy, improper positioning or aspiration technique during aspiration can result in serious injury.^2,4-6 We hypothesized that there is an ideal angle and positioning for bone marrow aspiration from the posterior superior iliac spine (PSIS) that is safe, consistent, and reproducible. Although most aspiration techniques use landmark palpation, this is unreliable and inaccurate, especially when compared with ultrasound-guided injections^7-16 and procedures.^9,12,17-19 We describe our technique using ultrasound to visualize patient anatomy and accurately determine anatomic entry with the trocar.

METHODS

MRI scans of 26 patients (13 males, 13 females) were reviewed to determine average angles and distances. Axial T2-weighted views of the lumbar spine were used in all analyses. The sacroiliac (SI) joint angle was defined as the angle formed between the vector through the midline of the pelvis and the vector that is parallel to the SI joint. The approach angle was defined as the angle formed between the vector of the most medial aspect of the PSIS through the ilium to the anterior wall and the vector through the midline of the pelvis (Figure 1). 

Continue to: For the 13 males, the mean SI joint...

RESULTS

The results are reported in the Table. 

Table. Measurements of Patients Taken on Axial T2-Weighted Views of Lumbosacral MRI Scans^a

^aStatistical significance is denoted as P < .02.

Abbreviations: MRI, magnetic resonance imaging; PSIS, posterior iliac spine; SI, sacroiliac.

For the 13 males, the mean SI joint angle was 31.22° ± 7.18° (range, 20.20° to 48.50°). The mean approach angle was 24.41° ± 4.11° (range, 19.50° to 31.00°). The mean PSIS table width was 1.20 cm ± 0.26 cm (range, 0.84 cm to 1.70 cm). The mean distance from the PSIS to the anterior ilium wall was 7.53 cm ± 0.75 cm (range, 6.43 cm to 8.80 cm). The mean perpendicular distance from the PSIS table to the anterior ilium was 3.40 cm ± 0.56 cm (range, 2.34 cm to 4.16 cm). The mean minimum width of the ilium to the SI joint was 1.16 cm ± 0.26 cm (range, 0.65 cm to 1.56 cm).

For the 13 females, the mean SI joint angle was 29.54° ± 10.84° (range, 17.20° to 48.20°). The mean approach angle was 23.56° ± 6.88° (range, 14.80° to 38.50°). The mean PSIS table width was 0.96 cm ± 0.21 cm (range, 0.61 cm to 1.54 cm). The mean distance from the PSIS to the anterior ilium wall was 6.74 cm ± 0.85 cm (range, 5.33 cm to 8.32 cm). The mean perpendicular distance from the PSIS table to the anterior ilium was 3.00 cm ± 0.48 cm (range, 2.23 cm to 3.76 cm). The mean minimum width of the ilium to the SI joint was 1.04 cm ± 0.25 cm (range, 0.71 cm to 1.42 cm).

For the 26 total patients, the mean SI joint angle was 30.38° ± 9.05° (range, 17.20° to 48.50°). The mean approach angle was 23.98° ± 5.57° (range, 14.80° to 38.50°). The mean PSIS table width was 1.08 cm ± 0.26 cm (range, 0.61 cm to 1.70 cm). The mean distance from the PSIS to the anterior ilium wall was 7.14 cm ± 0.88 cm (range, 5.33 cm to 8.80 cm). The mean perpendicular distance from the PSIS table to the anterior ilium was 3.20 cm ± 0.55 cm (range, 2.23 cm to 4.16 cm). The mean minimum width of the ilium to the SI joint was 1.10 cm ± 0.26 cm (range, 0.65 cm to 1.56 cm).

There was a statistically significant difference between the male and female groups for the maximum distance the trocar can be advanced from the PSIS to the anterior ilium wall (P < .02), and a statistically significant difference for the PSIS table width (P < .02). There were no significant differences between the male and female groups for the approach angle, the SI joint angle, the perpendicular distance from the PSIS to the anterior ilium, and the minimum width of the ilium to the SI joint.

Continue to: The patient is brought to the procedure...

TECHNIQUE: ILIAC CREST (PSIS) BONE MARROW ASPIRATION

The patient is brought to the procedure room and placed in a prone position. The donor site is prepared and draped in the usual sterile manner. Ultrasound is used to identify the median sacral crest in a short-axis view. The probe is then moved laterally to identify the PSIS (Figures 4A, 4B). 

The crosshairs on the ultrasound probe are used to mark the center lines of each plane. The central point marks the location of the PSIS. Alternatively, an in-plane technique can be used to place a spinal needle on the exact entry point on the PSIS. Once the PSIS and entry point are identified, the site is blocked with 10 mL of 0.5% ropivacaine.

Prior to introduction of the trocar, all instrumentation is primed with heparin and syringes are prepped with anticoagulant citrate dextrose solution, solution A. A stab incision is made at the site. The trocar is placed at the entry point, which should be centered in a superior-inferior plane and at the most medial point of the PSIS. Starting with the trocar vertical, the trocar is angled laterally 24° by dropping the hand medially toward the midline. No angulation cephalad or caudad is necessary, but cephalad must be avoided so as not to skive superiorly. This angle, which is recommended for both males and females, allows for the greatest distance the trocar can travel in bone before hitting the anterior ilium wall. A standard deviation of 5.57° is present, which should be considered. Steady pressure should be applied with a slight twisting motion on the PSIS. If advancement of the trocar is too difficult, a mallet or drill can be used to assist in penetration.

With the trocar advanced into the bone 1 cm, the trocar needle is removed while the cannula remains in place. The syringe is attached to the top of the cannula. The syringe plunger is pulled back to aspirate 20 mL of bone marrow. The cannula and syringe assembly are advanced 2 cm farther into the bone to allow for aspiration of a new location within the bone marrow cavity, and 20 mL of bone marrow are again aspirated. This is done a final time, advancing the trocar another 2 cm and aspirating a final 20 mL of bone marrow. The entire process should yield roughly 60 mL of bone marrow from one side. If desired, the same process can be repeated for the contralateral PSIS to yield a total of 120 mL of bone marrow from the 2 sites.

Based on our data, the average distance to the anterior ilium wall was 7 cm, but the shortest distance noted in this study was 5 cm. On the basis of the data presented, this technique allows for safe advancement based on even the shortest measured distance, without fear of puncturing the anterior ilium wall. Perforation could damage the femoral nerve and the internal or external iliac artery or vein that lie anterior to the ilium.

Continue to: We hypothesized that there...

DISCUSSION

We hypothesized that there would be an optimal angle of entry and maximal safe distance the trocar could advance through the ilium when aspirating. Because male and female pelvic anatomy differs, we also hypothesized that there would be differences in distance and size measurements for males and females. Our results supported our hypothesis that there is an ideal approach angle. The results also showed that the maximum distance the trocar can advance and the width of the PSIS table differ significantly between males and females.

Although pelvic anatomy differs between males and females, there should be an ideal entry angle that would allow maximum advancement into the ilium without perforating the anterior wall, which we defined as the approach angle. In our comparison of 26 MRI scans, we found that the approach angle did not differ significantly between the 2 groups (13 males, 13 females). This allows clinicians to enter the PSIS at roughly 24° medial to the parasagittal line, maximizing the space before puncturing into the anterior pelvis in either males or females.

If clinicians were to enter perpendicular to the patient’s PSIS, they would, on average, be able to advance only 3.20 cm before encountering the SI joint. When entering at 24° as we recommend, the average distance increases to 7.14 cm. Although the angle did not differ significantly, there was a significant difference between males and females in the length from the PSIS to the anterior wall, with males having 7.53 cm distance and females 6.74 cm. This is an important measurement because if the anterior ilium wall is punctured, the femoral nerve and the common, internal and external iliac arteries and veins could be damaged, resulting in retroperitoneal hemorrhage.

A fatality in 2001 in the United Kingdom led to a national audit of bone marrow aspiration and biopsies.^4-6 Although these procedures were done primarily for patients with cancer, hemorrhagic events were the most frequent and serious events. This audit led to the identification of many risk factors. Bain^4-6 conducted reviews of bone marrow aspirations and biopsies in the United Kingdom from 2002 to 2004. Of a total of 53,088 procedures conducted during that time frame, 48 (0.09%) adverse events occurred, with 29 (0.05%) being hemorrhagic events. Although infrequent, hemorrhagic adverse events represent significant morbidity. Reviews such as those conducted by Bain^4-6 highlight the importance of a study that helps determine the optimal parameters for aspiration to ensure safety and reliability.

Hernigou and colleagues^2,3 conducted studies analyzing different “sectors” in an attempt to develop a safe aspiration technique. They found that obese patients were at higher risk, and some sites of aspiration (sectors 1, 4, 5) had increased risk for perforation and damage to surrounding structures. Their sector 6, which incorporated the entirety of the PSIS table, was considered the safest, most reliable site for trocar introduction.^2,3 Hernigou and colleagues,² in comparing the bone mass of the sectors, also noted that sector 6 has the greatest bone thickness close to the entry point, making it the most favorable site. The PSIS is not just a point; it is more a “table.” The PSIS can be palpated posteriorly, but this is inaccurate and unreliable, particularly in larger individuals. The PSIS table can be identified on ultrasound before introducing the trocar, which is a more reliable method of landmark identification than palpation guidance, just as in ultrasound-guided injections^7-16 and procedures.^9,12,17-19

Continue to: If the PSIS is not accurately...

MSCs are found as perivascular cells and lie in the cortices of bones.²¹ Following the approach angle and directed line from the PSIS to the anterior ilium wall described in this study (Figures 1 and 2), the trocar would pass through the narrow corridor as it advances farther into the ilium. The minimum width of this corridor was measured in this study and, on average, was 1.10 cm wide from cortex to cortex (Figure 3). As the bone marrow is aspirated from this narrow corridor, the clinician is gathering MSCs from both the lateral and medial cortices of the ilium. By aspirating from a greater surface area of the cortices, it is believed that this will increase the total collection of MSCs.

CONCLUSION

Although there are reports in the literature that describe techniques for bone marrow aspiration from the iliac crest, the techniques are very general and vague regarding the ideal angles and methods. Studies have attempted to quantify the safest entry sites for aspiration but have not detailed ideal parameters for collection. Blind aspiration from the iliac crest can have serious implications if adverse events occur, and thus there is a need for a safe and reliable method of aspiration from the iliac crest. Ultrasound guidance to identify anatomy, as opposed to palpation guidance, ensures anatomic placement of the trocar while minimizing the risk of aspiration. Based on the measurements gathered in this study, an optimal angle of entry and safe distance of penetration have been identified. Using our data and relevant literature, we developed a technique for a safe, consistent, and reliable method of bone marrow aspiration out of the iliac crest.

ABSTRACT

Use of mesenchymal stem cells from bone marrow has gained significant popularity. The iliac crest has been determined to be an effective site for harvesting mesenchymal stem cells. Review of the literature reveals that multiple techniques are used to harvest bone marrow aspirate from the iliac crest, but the descriptions are based on the experience of various authors as opposed to studied anatomy. A safe, reliable, and reproducible method for aspiration has yet to be studied and described. We hypothesized that there would be an ideal angle and distance for aspiration that would be the safest, most consistent, and most reliable. Using magnetic resonance imaging (MRI), we reviewed 26 total lumbar spine MRI scans (13 males, 13 females) and found that an angle of 24° should be used when entering the most medial aspect of the posterior superior iliac spine (PSIS) and that this angle did not differ between the sexes. The distance that the trocar can advance after entry before hitting the anterior ilium wall varied significantly between males and females, being 7.53 cm in males and 6.74 cm in females. In addition, the size of the PSIS table was significantly different between males and females (1.20 cm and 0.96 cm, respectively). No other significant differences in the measurements gathered were found. Using the data gleaned from this study, we developed an aspiration technique. This method uses ultrasound to determine the location of the PSIS and the entry point on the PSIS. This contrasts with most techniques that use landmark palpation, which is known to be unreliable and inaccurate. The described technique for aspiration from the PSIS is safe, reliable, reproducible, and substantiated by data.

The iliac crest is an effective site for harvesting bone marrow stem cells. It allows for easy access and is superficial in most individuals, allowing for a relatively quick and simple procedure. Use of mesenchymal stem cells (MSCs) for treatment of orthopedic injuries has grown recently. Whereas overall use has increased, review of the literature reveals very few techniques for iliac crest aspiration,¹ but these are not based on anatomic relationships or studies. Hernigou and colleagues^2,3 attempted to quantitatively evaluate potential “sectors” allowing for safe aspiration using cadaver and computed tomographic reconstruction imaging. We used magnetic resonance imaging (MRI) to analyze aspiration parameters. Owing to the ilium’s anatomy, improper positioning or aspiration technique during aspiration can result in serious injury.^2,4-6 We hypothesized that there is an ideal angle and positioning for bone marrow aspiration from the posterior superior iliac spine (PSIS) that is safe, consistent, and reproducible. Although most aspiration techniques use landmark palpation, this is unreliable and inaccurate, especially when compared with ultrasound-guided injections^7-16 and procedures.^9,12,17-19 We describe our technique using ultrasound to visualize patient anatomy and accurately determine anatomic entry with the trocar.

METHODS

MRI scans of 26 patients (13 males, 13 females) were reviewed to determine average angles and distances. Axial T2-weighted views of the lumbar spine were used in all analyses. The sacroiliac (SI) joint angle was defined as the angle formed between the vector through the midline of the pelvis and the vector that is parallel to the SI joint. The approach angle was defined as the angle formed between the vector of the most medial aspect of the PSIS through the ilium to the anterior wall and the vector through the midline of the pelvis (Figure 1). 

Continue to: For the 13 males, the mean SI joint...

RESULTS

The results are reported in the Table. 

Table. Measurements of Patients Taken on Axial T2-Weighted Views of Lumbosacral MRI Scans^a

^aStatistical significance is denoted as P < .02.

Abbreviations: MRI, magnetic resonance imaging; PSIS, posterior iliac spine; SI, sacroiliac.

For the 13 males, the mean SI joint angle was 31.22° ± 7.18° (range, 20.20° to 48.50°). The mean approach angle was 24.41° ± 4.11° (range, 19.50° to 31.00°). The mean PSIS table width was 1.20 cm ± 0.26 cm (range, 0.84 cm to 1.70 cm). The mean distance from the PSIS to the anterior ilium wall was 7.53 cm ± 0.75 cm (range, 6.43 cm to 8.80 cm). The mean perpendicular distance from the PSIS table to the anterior ilium was 3.40 cm ± 0.56 cm (range, 2.34 cm to 4.16 cm). The mean minimum width of the ilium to the SI joint was 1.16 cm ± 0.26 cm (range, 0.65 cm to 1.56 cm).

For the 13 females, the mean SI joint angle was 29.54° ± 10.84° (range, 17.20° to 48.20°). The mean approach angle was 23.56° ± 6.88° (range, 14.80° to 38.50°). The mean PSIS table width was 0.96 cm ± 0.21 cm (range, 0.61 cm to 1.54 cm). The mean distance from the PSIS to the anterior ilium wall was 6.74 cm ± 0.85 cm (range, 5.33 cm to 8.32 cm). The mean perpendicular distance from the PSIS table to the anterior ilium was 3.00 cm ± 0.48 cm (range, 2.23 cm to 3.76 cm). The mean minimum width of the ilium to the SI joint was 1.04 cm ± 0.25 cm (range, 0.71 cm to 1.42 cm).

For the 26 total patients, the mean SI joint angle was 30.38° ± 9.05° (range, 17.20° to 48.50°). The mean approach angle was 23.98° ± 5.57° (range, 14.80° to 38.50°). The mean PSIS table width was 1.08 cm ± 0.26 cm (range, 0.61 cm to 1.70 cm). The mean distance from the PSIS to the anterior ilium wall was 7.14 cm ± 0.88 cm (range, 5.33 cm to 8.80 cm). The mean perpendicular distance from the PSIS table to the anterior ilium was 3.20 cm ± 0.55 cm (range, 2.23 cm to 4.16 cm). The mean minimum width of the ilium to the SI joint was 1.10 cm ± 0.26 cm (range, 0.65 cm to 1.56 cm).

There was a statistically significant difference between the male and female groups for the maximum distance the trocar can be advanced from the PSIS to the anterior ilium wall (P < .02), and a statistically significant difference for the PSIS table width (P < .02). There were no significant differences between the male and female groups for the approach angle, the SI joint angle, the perpendicular distance from the PSIS to the anterior ilium, and the minimum width of the ilium to the SI joint.

Continue to: The patient is brought to the procedure...

TECHNIQUE: ILIAC CREST (PSIS) BONE MARROW ASPIRATION

The patient is brought to the procedure room and placed in a prone position. The donor site is prepared and draped in the usual sterile manner. Ultrasound is used to identify the median sacral crest in a short-axis view. The probe is then moved laterally to identify the PSIS (Figures 4A, 4B). 

The crosshairs on the ultrasound probe are used to mark the center lines of each plane. The central point marks the location of the PSIS. Alternatively, an in-plane technique can be used to place a spinal needle on the exact entry point on the PSIS. Once the PSIS and entry point are identified, the site is blocked with 10 mL of 0.5% ropivacaine.

Prior to introduction of the trocar, all instrumentation is primed with heparin and syringes are prepped with anticoagulant citrate dextrose solution, solution A. A stab incision is made at the site. The trocar is placed at the entry point, which should be centered in a superior-inferior plane and at the most medial point of the PSIS. Starting with the trocar vertical, the trocar is angled laterally 24° by dropping the hand medially toward the midline. No angulation cephalad or caudad is necessary, but cephalad must be avoided so as not to skive superiorly. This angle, which is recommended for both males and females, allows for the greatest distance the trocar can travel in bone before hitting the anterior ilium wall. A standard deviation of 5.57° is present, which should be considered. Steady pressure should be applied with a slight twisting motion on the PSIS. If advancement of the trocar is too difficult, a mallet or drill can be used to assist in penetration.

With the trocar advanced into the bone 1 cm, the trocar needle is removed while the cannula remains in place. The syringe is attached to the top of the cannula. The syringe plunger is pulled back to aspirate 20 mL of bone marrow. The cannula and syringe assembly are advanced 2 cm farther into the bone to allow for aspiration of a new location within the bone marrow cavity, and 20 mL of bone marrow are again aspirated. This is done a final time, advancing the trocar another 2 cm and aspirating a final 20 mL of bone marrow. The entire process should yield roughly 60 mL of bone marrow from one side. If desired, the same process can be repeated for the contralateral PSIS to yield a total of 120 mL of bone marrow from the 2 sites.

Based on our data, the average distance to the anterior ilium wall was 7 cm, but the shortest distance noted in this study was 5 cm. On the basis of the data presented, this technique allows for safe advancement based on even the shortest measured distance, without fear of puncturing the anterior ilium wall. Perforation could damage the femoral nerve and the internal or external iliac artery or vein that lie anterior to the ilium.

Continue to: We hypothesized that there...

DISCUSSION

We hypothesized that there would be an optimal angle of entry and maximal safe distance the trocar could advance through the ilium when aspirating. Because male and female pelvic anatomy differs, we also hypothesized that there would be differences in distance and size measurements for males and females. Our results supported our hypothesis that there is an ideal approach angle. The results also showed that the maximum distance the trocar can advance and the width of the PSIS table differ significantly between males and females.

Although pelvic anatomy differs between males and females, there should be an ideal entry angle that would allow maximum advancement into the ilium without perforating the anterior wall, which we defined as the approach angle. In our comparison of 26 MRI scans, we found that the approach angle did not differ significantly between the 2 groups (13 males, 13 females). This allows clinicians to enter the PSIS at roughly 24° medial to the parasagittal line, maximizing the space before puncturing into the anterior pelvis in either males or females.

If clinicians were to enter perpendicular to the patient’s PSIS, they would, on average, be able to advance only 3.20 cm before encountering the SI joint. When entering at 24° as we recommend, the average distance increases to 7.14 cm. Although the angle did not differ significantly, there was a significant difference between males and females in the length from the PSIS to the anterior wall, with males having 7.53 cm distance and females 6.74 cm. This is an important measurement because if the anterior ilium wall is punctured, the femoral nerve and the common, internal and external iliac arteries and veins could be damaged, resulting in retroperitoneal hemorrhage.

A fatality in 2001 in the United Kingdom led to a national audit of bone marrow aspiration and biopsies.^4-6 Although these procedures were done primarily for patients with cancer, hemorrhagic events were the most frequent and serious events. This audit led to the identification of many risk factors. Bain^4-6 conducted reviews of bone marrow aspirations and biopsies in the United Kingdom from 2002 to 2004. Of a total of 53,088 procedures conducted during that time frame, 48 (0.09%) adverse events occurred, with 29 (0.05%) being hemorrhagic events. Although infrequent, hemorrhagic adverse events represent significant morbidity. Reviews such as those conducted by Bain^4-6 highlight the importance of a study that helps determine the optimal parameters for aspiration to ensure safety and reliability.

Hernigou and colleagues^2,3 conducted studies analyzing different “sectors” in an attempt to develop a safe aspiration technique. They found that obese patients were at higher risk, and some sites of aspiration (sectors 1, 4, 5) had increased risk for perforation and damage to surrounding structures. Their sector 6, which incorporated the entirety of the PSIS table, was considered the safest, most reliable site for trocar introduction.^2,3 Hernigou and colleagues,² in comparing the bone mass of the sectors, also noted that sector 6 has the greatest bone thickness close to the entry point, making it the most favorable site. The PSIS is not just a point; it is more a “table.” The PSIS can be palpated posteriorly, but this is inaccurate and unreliable, particularly in larger individuals. The PSIS table can be identified on ultrasound before introducing the trocar, which is a more reliable method of landmark identification than palpation guidance, just as in ultrasound-guided injections^7-16 and procedures.^9,12,17-19

Continue to: If the PSIS is not accurately...

MSCs are found as perivascular cells and lie in the cortices of bones.²¹ Following the approach angle and directed line from the PSIS to the anterior ilium wall described in this study (Figures 1 and 2), the trocar would pass through the narrow corridor as it advances farther into the ilium. The minimum width of this corridor was measured in this study and, on average, was 1.10 cm wide from cortex to cortex (Figure 3). As the bone marrow is aspirated from this narrow corridor, the clinician is gathering MSCs from both the lateral and medial cortices of the ilium. By aspirating from a greater surface area of the cortices, it is believed that this will increase the total collection of MSCs.

CONCLUSION

Although there are reports in the literature that describe techniques for bone marrow aspiration from the iliac crest, the techniques are very general and vague regarding the ideal angles and methods. Studies have attempted to quantify the safest entry sites for aspiration but have not detailed ideal parameters for collection. Blind aspiration from the iliac crest can have serious implications if adverse events occur, and thus there is a need for a safe and reliable method of aspiration from the iliac crest. Ultrasound guidance to identify anatomy, as opposed to palpation guidance, ensures anatomic placement of the trocar while minimizing the risk of aspiration. Based on the measurements gathered in this study, an optimal angle of entry and safe distance of penetration have been identified. Using our data and relevant literature, we developed a technique for a safe, consistent, and reliable method of bone marrow aspiration out of the iliac crest.

Take-Home Points

• The SCR is a viable treatment option for massive, irreparable RCTs.
• Arm position and exact measurement between anchors will help ensure proper graft tensioning.
• Anterior and posterior tension and margin convergence are critical to stabilizing the graft.
• Acromial-humeral distance, ASES, and VAS scores are improved and maintained over long-term follow-up.
• The dermal allograft should be 3.0 mm or thicker.

Conventional treatments for irreparable massive rotator cuff tears (RCTs) have ranged from nonoperative care to débridement and biceps tenotomy,^1,2 partial cuff repair,^3,4 bridging patch grafts,⁵ tendon transfers,^6,7 and reverse total shoulder arthroplasty (RTSA).^8,9 Superior capsular reconstruction (SCR), originally described by Mihata and colleagues,¹⁰ has been developed as an alternative to these interventions. Dr. Hirahara modified the technique to use dermal allograft instead of fascia lata autograft.^10,11

Biomechanical analysis has confirmed the integral role of the superior capsule in shoulder function.^10,12-14 In the presence of a massive RCT, the humeral head migrates superiorly, causing significant pain and functional deficits, such as pseudoparalysis. It is theorized that reestablishing this important stabilizer—centering the humeral head in the glenoid and allowing the larger muscles to move the arm about a proper fulcrum—improves function and decreases pain.

Using ultrasonography (US), radiography, magnetic resonance imaging (MRI), clinical outcome scores, and a visual analog scale (VAS) for pain, we prospectively evaluated minimum 2-year clinical outcomes of performing SCR with dermal allograft for irreparable RCTs.

Methods

Except where noted otherwise, all products mentioned in this section were made by Arthrex.

Surgical Technique

The surgical technique used here was described by Hirahara and Adams.¹¹ ArthroFlex dermal allograft was attached to the greater tuberosity and the glenoid, creating a superior restraint that replaced the anatomical superior capsule (Figures 1A, 1B). Some cases included biceps tenotomy, subscapularis repair, or infraspinatus repair.

Medial fixation was obtained with a PASTA (partial articular supraspinatus tendon avulsion) bridge-type construct¹⁵ that consisted of two 3.0-mm BioComposite SutureTak anchors (placed medially on the glenoid rim, medial to the labrum) and a 3.5-mm BioComposite Vented SwiveLock. In some cases, a significant amount of tissue was present medially, and the third anchor was not used; instead, a double surgeon knot was used to fixate the double pulley medially.

Posterior margin convergence (PMC) was performed in all cases. Anterior margin convergence (AMC) was performed in only 3 cases.

Clinical Evaluation

All patients who underwent SCR were followed prospectively, and all signed an informed consent form. Between 2014 and the time of this study, 9 patients had surgery with a minimum 2-year follow-up. Before surgery, all patients received a diagnosis of full-thickness RCT with decreased acromial-humeral distance (AHD). One patient had RTSA 18 months after surgery, did not reach the 2-year follow-up, and was excluded from the data analysis. Patients were clinically evaluated on the 100-point American Shoulder and Elbow Surgeons (ASES) shoulder index and on a 10-point VAS for pain—before surgery, monthly for the first 6 months after surgery, then every 6 months until 2 years after surgery, and yearly thereafter. These patients were compared with Dr. Hirahara’s historical control patients, who had undergone repair of massive RCTs. Mean graft size was calculated and reported. Cases were separated and analyzed on the basis of whether AMC was performed. Student t tests were used to determine statistical differences between study patients’ preoperative and postoperative scores, between study and historical control patients, and between patients who had AMC performed and those who did not (P < .05).

Imaging

For all SCR patients, preoperative and postoperative radiographs were obtained in 2 planes: anterior-posterior with arm in neutral rotation, and scapular Y. On anteroposterior radiographs, AHD was measured from the most proximal aspect of the humeral head in a vertical line to the most inferior portion of the acromion (Figures 2A, 2B).

Results

The Table provides an overview of the study results. Eight patients (6 men, 2 women) met the final inclusion criteria for postoperative ASES and VAS data analysis.

AHD was measured on a standard anteroposterior radiograph in neutral rotation. The Hamada grading scale16 was used to classify the massive RCTs before and after surgery. Before surgery, 4 were grade 4A, 1 grade 3, 2 grade 2, and 1 grade 1; immediately after surgery, all were grade 1 (AHD, ≥6 mm). Two years after surgery, 1 patient had an AHD of 4.6 mm after a failure caused by a fall. Mean (SD) preoperative AHD was 4.50 (2.25) mm (range, 1.7-7.9 mm). Radiographs obtained immediately (mean, 1.22 months; range, 1 day-2.73 months) after surgery showed AHD was significantly (P < .0008) increased (mean, 8.48 mm; SD, 1.25 mm; range, 6.0-10.0 mm) (Figure 5).

Mean graft size was 2.9 mm medial × 3.6 mm lateral × 5.4 mm anterior × 5.4 mm posterior. Three patients had AMC performed. There was a significant (P < .05) difference in ASES scores between patients who had AMC performed (93) and those who did not (77).

Ultrasonography

Two weeks to 2 months after surgery, all patients had an intact capsular graft and no pulsatile vessels on US. Between 4 months and 10 months, US showed the construct intact laterally in all cases, a pulsatile vessel in the graft at the tuberosity (evidence of blood flow) in 4 of 5 cases, and a pulsatile vessel hypertrophied in 2 cases (Figures 6A, 6B).

Magnetic Resonance Imaging

Before surgery, 4 patients had Goutallier¹⁷ stage 4 rotator cuff muscle degeneration, 2 had stage 3 degeneration, and 2 had stage 2 degeneration. Throughout the follow-up period, US was as effective as MRI in determining graft integrity, graft thickness, and greater tuberosity fixation. Therefore, the SCRs were assessed primarily with US. MRI was ordered only if a failure was suspected or if the patient had some form of trauma. A total of 7 MRIs were ordered for 5 of the 8 patients in the study. The graft was intact in 4 of the 5 (Figures 7A-7C) and ruptured in the fifth.

Discussion

Mihata and colleagues¹⁰ published 2-year data for their reconstructive procedure with fascia lata autograft. In a modification of their procedure, Dr. Hirahara used dermal allograft to recreate the superior capsule.¹¹ The results of the present 2-year study mirror the clinical outcomes reported by Mihata and colleagues¹⁰ and confirm that SCR improves functional outcomes and increases AHD regardless of graft type used.

The outcomes of the SCR patients in our study were significantly better than the outcomes of the historical control patients, who underwent repair of massive RCTs. Although there was no significant difference in the 2 groups’ ASES scores, the control patients had significantly higher postoperative VAS pain scores. We think that, as more patients undergo SCR and the population sample increases, we will see a significant difference in ASES scores as well (our SCR patients already showed a trend toward improved ASES scores).

Compared with RTSA, SCR has fewer risks and fewer complications and does not limit further surgical options.^8,9,18 The 9 patients who had surgery with a minimum 2-year follow-up in our study had 4 complications. Six months after surgery, 1 patient fell and tore the infraspinatus and subscapularis muscles. Outcomes continued to improve, and no issues were reported, despite a decrease in AHD, from 8 mm immediately after surgery to 4.6 mm 2 years after surgery.

Two patients were in motor vehicle accidents. In 1 case, the accident occurred about 2 months after surgery. This patient also sustained a possible injury in a fall after receiving general anesthesia for a dental procedure. After having done very well the preceding months, the patient now reported increasing pain and dysfunction. MRI showed loss of glenoid fixation. Improved ASES and VAS pain scores were maintained throughout the follow-up period. AHD was increased at 13 months and mildly decreased at 2 years. Glenoid fixation was obtained with 2 anchors and a double surgeon knot. When possible, however, it is best to add an anchor and double-row fixation, as 3 anchors and a double-row construct are biomechanically stronger.^19-24

The other motor vehicle accident occurred about 23 months after surgery. Two months later, a graft rupture was found on US and MRI, but the patient was maintaining full range of motion, AHD, and improved strength. The 1.5-mm graft in this patient was thinner than the 3.5-mm grafts in the rest of the study group. This was the only patient who developed a graft rupture rather than loss of fixation.

If only patients with graft thickness >3.0 mm are included in the data analysis, mean ASES score rises to 89.76, and mean VAS pain score drops to 0. Therefore, we argue against using a graft thinner than 3.5 mm. Our excellent study results indicate that larger grafts are unnecessary. Mihata and colleagues¹⁰ used fascia lata grafts of 6 mm to 8 mm. Ultimate load to failure is significantly higher for dermal allograft than for fascia lata graft.²⁵ In SCR, the stronger dermal allograft withstands applied forces and repeated deformations and has excellent clinical outcomes.

Only 1 patient had a failure that required RTSA. VAS pain scores were lower and ASES scores were improved the first year after surgery, but then function deteriorated. The patient said there was no specific precipitating incident. Computed tomography arthrogram, ordered to assess the construct, showed anterior and superior subluxation of the humeral head, even with an intact subscapularis tendon—an indication of underlying instability, which most likely caused the failure. Eighteen months after surgery, the patient was able to undergo RTSA. On further evaluation of this patient’s procedure, it was determined that the graft needed better fixation anteriorly.

Mihata and colleagues^10,12,14 indicated that AMC was unnecessary, and our procedure did not require it. However, data in our prospective evaluation began showing improved outcomes with AMC. As dermal allograft is more elastic than fascia lata autograft,²⁵ we concluded that graft tensioning is key to the success of this procedure. Graft tension depends on many factors, including exact measurement of the distances between the anchors to punch holes in the graft, arm position to set the relationship between the anchor distances, and AMC and PMC. We recommend placing the arm in neutral rotation, neutral flexion, and abduction with the patient at rest, based on the size of the patient’s latissimus dorsi. Too much abduction causes overtensioning, and excess rotation or flexion-extension changes the distance between the glenoid and the greater tuberosity asymmetrically, from anterior to posterior. With the arm in neutral position, distances between anchors are accurately measured, and these measurements are used to determine graft size.

Graft tension is also needed to control the amount of elasticity allowed by the graft and thereby maintain stability, as shown by the Poisson ratio, the ratio of transverse contraction to longitudinal extension on a material in the presence of a stretching force. As applied to SCR, it is the ratio of mediolateral elasticity to anteroposterior deformation or constraint. If the graft is appropriately secured in the anteroposterior direction by way of ACM and PMC, elongation in the medial-lateral direction will be limited—reducing the elasticity of the graft, improving overall stability, and ultimately producing better clinical outcomes. This issue was discussed by Burkhart and colleagues²⁶ with respect to the “rotator cable complex,” which now might be best described as the “rotator-capsule cable complex.” In our study, this phenomenon was evident in the finding that patients who had AMC performed did significantly better than patients who did not have AMC performed. The ability of dermal allograft to deform in these dimensions without failure while allowing excellent range of motion makes dermal allograft an exceptional choice for grafting during SCR. Mihata25 also found dermal allograft had a clear advantage in providing better range of motion, whereas fascia lata autograft resulted in a stiffer construct. 

Dermal allograft can also incorporate into the body and transform into host tissue. The literature has described musculoskeletal US as an effective diagnostic and interventional tool.^27-31 We used it to evaluate graft size, patency, and viability. As can be seen on US, the native rotator cuff does not have any pulsatile vessels and is fed by capillary flow. Dermal allograft has native vasculature built into the tissue. After 4 months to 8 months, presence of pulsatile vessels within the graft at the greater tuberosity indicates clear revascularization and incorporation of the tissue (Figure 6B). Disappearance of pulsatile vessels on US after 1 year indicates transformation to a stabilizing structure analogous to capsule or ligament with capillary flow. US also showed graft hypertrophy after 2 years, supporting a finding of integration and growth.

Conclusion

In the past, patients with irreparable massive RCTs had few good surgical management options, RTSA being the most definitive. SCR is technically challenging and requires use of specific implantation methods but can provide patients with outstanding relief. Our clinical data showed that technically well executed SCR effectively restores the superior restraints in the glenohumeral joint and thereby increases function and decreases pain in patients with irreparable massive RCTs, even after 2 years.

Take-Home Points

• The SCR is a viable treatment option for massive, irreparable RCTs.
• Arm position and exact measurement between anchors will help ensure proper graft tensioning.
• Anterior and posterior tension and margin convergence are critical to stabilizing the graft.
• Acromial-humeral distance, ASES, and VAS scores are improved and maintained over long-term follow-up.
• The dermal allograft should be 3.0 mm or thicker.

Conventional treatments for irreparable massive rotator cuff tears (RCTs) have ranged from nonoperative care to débridement and biceps tenotomy,^1,2 partial cuff repair,^3,4 bridging patch grafts,⁵ tendon transfers,^6,7 and reverse total shoulder arthroplasty (RTSA).^8,9 Superior capsular reconstruction (SCR), originally described by Mihata and colleagues,¹⁰ has been developed as an alternative to these interventions. Dr. Hirahara modified the technique to use dermal allograft instead of fascia lata autograft.^10,11

Biomechanical analysis has confirmed the integral role of the superior capsule in shoulder function.^10,12-14 In the presence of a massive RCT, the humeral head migrates superiorly, causing significant pain and functional deficits, such as pseudoparalysis. It is theorized that reestablishing this important stabilizer—centering the humeral head in the glenoid and allowing the larger muscles to move the arm about a proper fulcrum—improves function and decreases pain.

Using ultrasonography (US), radiography, magnetic resonance imaging (MRI), clinical outcome scores, and a visual analog scale (VAS) for pain, we prospectively evaluated minimum 2-year clinical outcomes of performing SCR with dermal allograft for irreparable RCTs.

Methods

Except where noted otherwise, all products mentioned in this section were made by Arthrex.

Surgical Technique

The surgical technique used here was described by Hirahara and Adams.¹¹ ArthroFlex dermal allograft was attached to the greater tuberosity and the glenoid, creating a superior restraint that replaced the anatomical superior capsule (Figures 1A, 1B). Some cases included biceps tenotomy, subscapularis repair, or infraspinatus repair.

Medial fixation was obtained with a PASTA (partial articular supraspinatus tendon avulsion) bridge-type construct¹⁵ that consisted of two 3.0-mm BioComposite SutureTak anchors (placed medially on the glenoid rim, medial to the labrum) and a 3.5-mm BioComposite Vented SwiveLock. In some cases, a significant amount of tissue was present medially, and the third anchor was not used; instead, a double surgeon knot was used to fixate the double pulley medially.

Posterior margin convergence (PMC) was performed in all cases. Anterior margin convergence (AMC) was performed in only 3 cases.

Clinical Evaluation

All patients who underwent SCR were followed prospectively, and all signed an informed consent form. Between 2014 and the time of this study, 9 patients had surgery with a minimum 2-year follow-up. Before surgery, all patients received a diagnosis of full-thickness RCT with decreased acromial-humeral distance (AHD). One patient had RTSA 18 months after surgery, did not reach the 2-year follow-up, and was excluded from the data analysis. Patients were clinically evaluated on the 100-point American Shoulder and Elbow Surgeons (ASES) shoulder index and on a 10-point VAS for pain—before surgery, monthly for the first 6 months after surgery, then every 6 months until 2 years after surgery, and yearly thereafter. These patients were compared with Dr. Hirahara’s historical control patients, who had undergone repair of massive RCTs. Mean graft size was calculated and reported. Cases were separated and analyzed on the basis of whether AMC was performed. Student t tests were used to determine statistical differences between study patients’ preoperative and postoperative scores, between study and historical control patients, and between patients who had AMC performed and those who did not (P < .05).

Imaging

For all SCR patients, preoperative and postoperative radiographs were obtained in 2 planes: anterior-posterior with arm in neutral rotation, and scapular Y. On anteroposterior radiographs, AHD was measured from the most proximal aspect of the humeral head in a vertical line to the most inferior portion of the acromion (Figures 2A, 2B).

Results

The Table provides an overview of the study results. Eight patients (6 men, 2 women) met the final inclusion criteria for postoperative ASES and VAS data analysis.

AHD was measured on a standard anteroposterior radiograph in neutral rotation. The Hamada grading scale16 was used to classify the massive RCTs before and after surgery. Before surgery, 4 were grade 4A, 1 grade 3, 2 grade 2, and 1 grade 1; immediately after surgery, all were grade 1 (AHD, ≥6 mm). Two years after surgery, 1 patient had an AHD of 4.6 mm after a failure caused by a fall. Mean (SD) preoperative AHD was 4.50 (2.25) mm (range, 1.7-7.9 mm). Radiographs obtained immediately (mean, 1.22 months; range, 1 day-2.73 months) after surgery showed AHD was significantly (P < .0008) increased (mean, 8.48 mm; SD, 1.25 mm; range, 6.0-10.0 mm) (Figure 5).

Mean graft size was 2.9 mm medial × 3.6 mm lateral × 5.4 mm anterior × 5.4 mm posterior. Three patients had AMC performed. There was a significant (P < .05) difference in ASES scores between patients who had AMC performed (93) and those who did not (77).

Ultrasonography

Two weeks to 2 months after surgery, all patients had an intact capsular graft and no pulsatile vessels on US. Between 4 months and 10 months, US showed the construct intact laterally in all cases, a pulsatile vessel in the graft at the tuberosity (evidence of blood flow) in 4 of 5 cases, and a pulsatile vessel hypertrophied in 2 cases (Figures 6A, 6B).

Magnetic Resonance Imaging

Before surgery, 4 patients had Goutallier¹⁷ stage 4 rotator cuff muscle degeneration, 2 had stage 3 degeneration, and 2 had stage 2 degeneration. Throughout the follow-up period, US was as effective as MRI in determining graft integrity, graft thickness, and greater tuberosity fixation. Therefore, the SCRs were assessed primarily with US. MRI was ordered only if a failure was suspected or if the patient had some form of trauma. A total of 7 MRIs were ordered for 5 of the 8 patients in the study. The graft was intact in 4 of the 5 (Figures 7A-7C) and ruptured in the fifth.

Discussion

Mihata and colleagues¹⁰ published 2-year data for their reconstructive procedure with fascia lata autograft. In a modification of their procedure, Dr. Hirahara used dermal allograft to recreate the superior capsule.¹¹ The results of the present 2-year study mirror the clinical outcomes reported by Mihata and colleagues¹⁰ and confirm that SCR improves functional outcomes and increases AHD regardless of graft type used.

The outcomes of the SCR patients in our study were significantly better than the outcomes of the historical control patients, who underwent repair of massive RCTs. Although there was no significant difference in the 2 groups’ ASES scores, the control patients had significantly higher postoperative VAS pain scores. We think that, as more patients undergo SCR and the population sample increases, we will see a significant difference in ASES scores as well (our SCR patients already showed a trend toward improved ASES scores).

Compared with RTSA, SCR has fewer risks and fewer complications and does not limit further surgical options.^8,9,18 The 9 patients who had surgery with a minimum 2-year follow-up in our study had 4 complications. Six months after surgery, 1 patient fell and tore the infraspinatus and subscapularis muscles. Outcomes continued to improve, and no issues were reported, despite a decrease in AHD, from 8 mm immediately after surgery to 4.6 mm 2 years after surgery.

Two patients were in motor vehicle accidents. In 1 case, the accident occurred about 2 months after surgery. This patient also sustained a possible injury in a fall after receiving general anesthesia for a dental procedure. After having done very well the preceding months, the patient now reported increasing pain and dysfunction. MRI showed loss of glenoid fixation. Improved ASES and VAS pain scores were maintained throughout the follow-up period. AHD was increased at 13 months and mildly decreased at 2 years. Glenoid fixation was obtained with 2 anchors and a double surgeon knot. When possible, however, it is best to add an anchor and double-row fixation, as 3 anchors and a double-row construct are biomechanically stronger.^19-24

The other motor vehicle accident occurred about 23 months after surgery. Two months later, a graft rupture was found on US and MRI, but the patient was maintaining full range of motion, AHD, and improved strength. The 1.5-mm graft in this patient was thinner than the 3.5-mm grafts in the rest of the study group. This was the only patient who developed a graft rupture rather than loss of fixation.

If only patients with graft thickness >3.0 mm are included in the data analysis, mean ASES score rises to 89.76, and mean VAS pain score drops to 0. Therefore, we argue against using a graft thinner than 3.5 mm. Our excellent study results indicate that larger grafts are unnecessary. Mihata and colleagues¹⁰ used fascia lata grafts of 6 mm to 8 mm. Ultimate load to failure is significantly higher for dermal allograft than for fascia lata graft.²⁵ In SCR, the stronger dermal allograft withstands applied forces and repeated deformations and has excellent clinical outcomes.

Only 1 patient had a failure that required RTSA. VAS pain scores were lower and ASES scores were improved the first year after surgery, but then function deteriorated. The patient said there was no specific precipitating incident. Computed tomography arthrogram, ordered to assess the construct, showed anterior and superior subluxation of the humeral head, even with an intact subscapularis tendon—an indication of underlying instability, which most likely caused the failure. Eighteen months after surgery, the patient was able to undergo RTSA. On further evaluation of this patient’s procedure, it was determined that the graft needed better fixation anteriorly.

Mihata and colleagues^10,12,14 indicated that AMC was unnecessary, and our procedure did not require it. However, data in our prospective evaluation began showing improved outcomes with AMC. As dermal allograft is more elastic than fascia lata autograft,²⁵ we concluded that graft tensioning is key to the success of this procedure. Graft tension depends on many factors, including exact measurement of the distances between the anchors to punch holes in the graft, arm position to set the relationship between the anchor distances, and AMC and PMC. We recommend placing the arm in neutral rotation, neutral flexion, and abduction with the patient at rest, based on the size of the patient’s latissimus dorsi. Too much abduction causes overtensioning, and excess rotation or flexion-extension changes the distance between the glenoid and the greater tuberosity asymmetrically, from anterior to posterior. With the arm in neutral position, distances between anchors are accurately measured, and these measurements are used to determine graft size.

Graft tension is also needed to control the amount of elasticity allowed by the graft and thereby maintain stability, as shown by the Poisson ratio, the ratio of transverse contraction to longitudinal extension on a material in the presence of a stretching force. As applied to SCR, it is the ratio of mediolateral elasticity to anteroposterior deformation or constraint. If the graft is appropriately secured in the anteroposterior direction by way of ACM and PMC, elongation in the medial-lateral direction will be limited—reducing the elasticity of the graft, improving overall stability, and ultimately producing better clinical outcomes. This issue was discussed by Burkhart and colleagues²⁶ with respect to the “rotator cable complex,” which now might be best described as the “rotator-capsule cable complex.” In our study, this phenomenon was evident in the finding that patients who had AMC performed did significantly better than patients who did not have AMC performed. The ability of dermal allograft to deform in these dimensions without failure while allowing excellent range of motion makes dermal allograft an exceptional choice for grafting during SCR. Mihata25 also found dermal allograft had a clear advantage in providing better range of motion, whereas fascia lata autograft resulted in a stiffer construct. 

Dermal allograft can also incorporate into the body and transform into host tissue. The literature has described musculoskeletal US as an effective diagnostic and interventional tool.^27-31 We used it to evaluate graft size, patency, and viability. As can be seen on US, the native rotator cuff does not have any pulsatile vessels and is fed by capillary flow. Dermal allograft has native vasculature built into the tissue. After 4 months to 8 months, presence of pulsatile vessels within the graft at the greater tuberosity indicates clear revascularization and incorporation of the tissue (Figure 6B). Disappearance of pulsatile vessels on US after 1 year indicates transformation to a stabilizing structure analogous to capsule or ligament with capillary flow. US also showed graft hypertrophy after 2 years, supporting a finding of integration and growth.

Conclusion

In the past, patients with irreparable massive RCTs had few good surgical management options, RTSA being the most definitive. SCR is technically challenging and requires use of specific implantation methods but can provide patients with outstanding relief. Our clinical data showed that technically well executed SCR effectively restores the superior restraints in the glenohumeral joint and thereby increases function and decreases pain in patients with irreparable massive RCTs, even after 2 years.

Take-Home Points

• The SCR is a viable treatment option for massive, irreparable RCTs.
• Arm position and exact measurement between anchors will help ensure proper graft tensioning.
• Anterior and posterior tension and margin convergence are critical to stabilizing the graft.
• Acromial-humeral distance, ASES, and VAS scores are improved and maintained over long-term follow-up.
• The dermal allograft should be 3.0 mm or thicker.

Conventional treatments for irreparable massive rotator cuff tears (RCTs) have ranged from nonoperative care to débridement and biceps tenotomy,^1,2 partial cuff repair,^3,4 bridging patch grafts,⁵ tendon transfers,^6,7 and reverse total shoulder arthroplasty (RTSA).^8,9 Superior capsular reconstruction (SCR), originally described by Mihata and colleagues,¹⁰ has been developed as an alternative to these interventions. Dr. Hirahara modified the technique to use dermal allograft instead of fascia lata autograft.^10,11

Biomechanical analysis has confirmed the integral role of the superior capsule in shoulder function.^10,12-14 In the presence of a massive RCT, the humeral head migrates superiorly, causing significant pain and functional deficits, such as pseudoparalysis. It is theorized that reestablishing this important stabilizer—centering the humeral head in the glenoid and allowing the larger muscles to move the arm about a proper fulcrum—improves function and decreases pain.

Using ultrasonography (US), radiography, magnetic resonance imaging (MRI), clinical outcome scores, and a visual analog scale (VAS) for pain, we prospectively evaluated minimum 2-year clinical outcomes of performing SCR with dermal allograft for irreparable RCTs.

Methods

Except where noted otherwise, all products mentioned in this section were made by Arthrex.

Surgical Technique

The surgical technique used here was described by Hirahara and Adams.¹¹ ArthroFlex dermal allograft was attached to the greater tuberosity and the glenoid, creating a superior restraint that replaced the anatomical superior capsule (Figures 1A, 1B). Some cases included biceps tenotomy, subscapularis repair, or infraspinatus repair.

Medial fixation was obtained with a PASTA (partial articular supraspinatus tendon avulsion) bridge-type construct¹⁵ that consisted of two 3.0-mm BioComposite SutureTak anchors (placed medially on the glenoid rim, medial to the labrum) and a 3.5-mm BioComposite Vented SwiveLock. In some cases, a significant amount of tissue was present medially, and the third anchor was not used; instead, a double surgeon knot was used to fixate the double pulley medially.

Posterior margin convergence (PMC) was performed in all cases. Anterior margin convergence (AMC) was performed in only 3 cases.

Clinical Evaluation

All patients who underwent SCR were followed prospectively, and all signed an informed consent form. Between 2014 and the time of this study, 9 patients had surgery with a minimum 2-year follow-up. Before surgery, all patients received a diagnosis of full-thickness RCT with decreased acromial-humeral distance (AHD). One patient had RTSA 18 months after surgery, did not reach the 2-year follow-up, and was excluded from the data analysis. Patients were clinically evaluated on the 100-point American Shoulder and Elbow Surgeons (ASES) shoulder index and on a 10-point VAS for pain—before surgery, monthly for the first 6 months after surgery, then every 6 months until 2 years after surgery, and yearly thereafter. These patients were compared with Dr. Hirahara’s historical control patients, who had undergone repair of massive RCTs. Mean graft size was calculated and reported. Cases were separated and analyzed on the basis of whether AMC was performed. Student t tests were used to determine statistical differences between study patients’ preoperative and postoperative scores, between study and historical control patients, and between patients who had AMC performed and those who did not (P < .05).

Imaging

For all SCR patients, preoperative and postoperative radiographs were obtained in 2 planes: anterior-posterior with arm in neutral rotation, and scapular Y. On anteroposterior radiographs, AHD was measured from the most proximal aspect of the humeral head in a vertical line to the most inferior portion of the acromion (Figures 2A, 2B).

Results

The Table provides an overview of the study results. Eight patients (6 men, 2 women) met the final inclusion criteria for postoperative ASES and VAS data analysis.

AHD was measured on a standard anteroposterior radiograph in neutral rotation. The Hamada grading scale16 was used to classify the massive RCTs before and after surgery. Before surgery, 4 were grade 4A, 1 grade 3, 2 grade 2, and 1 grade 1; immediately after surgery, all were grade 1 (AHD, ≥6 mm). Two years after surgery, 1 patient had an AHD of 4.6 mm after a failure caused by a fall. Mean (SD) preoperative AHD was 4.50 (2.25) mm (range, 1.7-7.9 mm). Radiographs obtained immediately (mean, 1.22 months; range, 1 day-2.73 months) after surgery showed AHD was significantly (P < .0008) increased (mean, 8.48 mm; SD, 1.25 mm; range, 6.0-10.0 mm) (Figure 5).

Mean graft size was 2.9 mm medial × 3.6 mm lateral × 5.4 mm anterior × 5.4 mm posterior. Three patients had AMC performed. There was a significant (P < .05) difference in ASES scores between patients who had AMC performed (93) and those who did not (77).

Ultrasonography

Two weeks to 2 months after surgery, all patients had an intact capsular graft and no pulsatile vessels on US. Between 4 months and 10 months, US showed the construct intact laterally in all cases, a pulsatile vessel in the graft at the tuberosity (evidence of blood flow) in 4 of 5 cases, and a pulsatile vessel hypertrophied in 2 cases (Figures 6A, 6B).

Magnetic Resonance Imaging

Before surgery, 4 patients had Goutallier¹⁷ stage 4 rotator cuff muscle degeneration, 2 had stage 3 degeneration, and 2 had stage 2 degeneration. Throughout the follow-up period, US was as effective as MRI in determining graft integrity, graft thickness, and greater tuberosity fixation. Therefore, the SCRs were assessed primarily with US. MRI was ordered only if a failure was suspected or if the patient had some form of trauma. A total of 7 MRIs were ordered for 5 of the 8 patients in the study. The graft was intact in 4 of the 5 (Figures 7A-7C) and ruptured in the fifth.

Discussion

Mihata and colleagues¹⁰ published 2-year data for their reconstructive procedure with fascia lata autograft. In a modification of their procedure, Dr. Hirahara used dermal allograft to recreate the superior capsule.¹¹ The results of the present 2-year study mirror the clinical outcomes reported by Mihata and colleagues¹⁰ and confirm that SCR improves functional outcomes and increases AHD regardless of graft type used.

The outcomes of the SCR patients in our study were significantly better than the outcomes of the historical control patients, who underwent repair of massive RCTs. Although there was no significant difference in the 2 groups’ ASES scores, the control patients had significantly higher postoperative VAS pain scores. We think that, as more patients undergo SCR and the population sample increases, we will see a significant difference in ASES scores as well (our SCR patients already showed a trend toward improved ASES scores).

Compared with RTSA, SCR has fewer risks and fewer complications and does not limit further surgical options.^8,9,18 The 9 patients who had surgery with a minimum 2-year follow-up in our study had 4 complications. Six months after surgery, 1 patient fell and tore the infraspinatus and subscapularis muscles. Outcomes continued to improve, and no issues were reported, despite a decrease in AHD, from 8 mm immediately after surgery to 4.6 mm 2 years after surgery.

Two patients were in motor vehicle accidents. In 1 case, the accident occurred about 2 months after surgery. This patient also sustained a possible injury in a fall after receiving general anesthesia for a dental procedure. After having done very well the preceding months, the patient now reported increasing pain and dysfunction. MRI showed loss of glenoid fixation. Improved ASES and VAS pain scores were maintained throughout the follow-up period. AHD was increased at 13 months and mildly decreased at 2 years. Glenoid fixation was obtained with 2 anchors and a double surgeon knot. When possible, however, it is best to add an anchor and double-row fixation, as 3 anchors and a double-row construct are biomechanically stronger.^19-24

The other motor vehicle accident occurred about 23 months after surgery. Two months later, a graft rupture was found on US and MRI, but the patient was maintaining full range of motion, AHD, and improved strength. The 1.5-mm graft in this patient was thinner than the 3.5-mm grafts in the rest of the study group. This was the only patient who developed a graft rupture rather than loss of fixation.

If only patients with graft thickness >3.0 mm are included in the data analysis, mean ASES score rises to 89.76, and mean VAS pain score drops to 0. Therefore, we argue against using a graft thinner than 3.5 mm. Our excellent study results indicate that larger grafts are unnecessary. Mihata and colleagues¹⁰ used fascia lata grafts of 6 mm to 8 mm. Ultimate load to failure is significantly higher for dermal allograft than for fascia lata graft.²⁵ In SCR, the stronger dermal allograft withstands applied forces and repeated deformations and has excellent clinical outcomes.

Only 1 patient had a failure that required RTSA. VAS pain scores were lower and ASES scores were improved the first year after surgery, but then function deteriorated. The patient said there was no specific precipitating incident. Computed tomography arthrogram, ordered to assess the construct, showed anterior and superior subluxation of the humeral head, even with an intact subscapularis tendon—an indication of underlying instability, which most likely caused the failure. Eighteen months after surgery, the patient was able to undergo RTSA. On further evaluation of this patient’s procedure, it was determined that the graft needed better fixation anteriorly.

Mihata and colleagues^10,12,14 indicated that AMC was unnecessary, and our procedure did not require it. However, data in our prospective evaluation began showing improved outcomes with AMC. As dermal allograft is more elastic than fascia lata autograft,²⁵ we concluded that graft tensioning is key to the success of this procedure. Graft tension depends on many factors, including exact measurement of the distances between the anchors to punch holes in the graft, arm position to set the relationship between the anchor distances, and AMC and PMC. We recommend placing the arm in neutral rotation, neutral flexion, and abduction with the patient at rest, based on the size of the patient’s latissimus dorsi. Too much abduction causes overtensioning, and excess rotation or flexion-extension changes the distance between the glenoid and the greater tuberosity asymmetrically, from anterior to posterior. With the arm in neutral position, distances between anchors are accurately measured, and these measurements are used to determine graft size.

Graft tension is also needed to control the amount of elasticity allowed by the graft and thereby maintain stability, as shown by the Poisson ratio, the ratio of transverse contraction to longitudinal extension on a material in the presence of a stretching force. As applied to SCR, it is the ratio of mediolateral elasticity to anteroposterior deformation or constraint. If the graft is appropriately secured in the anteroposterior direction by way of ACM and PMC, elongation in the medial-lateral direction will be limited—reducing the elasticity of the graft, improving overall stability, and ultimately producing better clinical outcomes. This issue was discussed by Burkhart and colleagues²⁶ with respect to the “rotator cable complex,” which now might be best described as the “rotator-capsule cable complex.” In our study, this phenomenon was evident in the finding that patients who had AMC performed did significantly better than patients who did not have AMC performed. The ability of dermal allograft to deform in these dimensions without failure while allowing excellent range of motion makes dermal allograft an exceptional choice for grafting during SCR. Mihata25 also found dermal allograft had a clear advantage in providing better range of motion, whereas fascia lata autograft resulted in a stiffer construct. 

Dermal allograft can also incorporate into the body and transform into host tissue. The literature has described musculoskeletal US as an effective diagnostic and interventional tool.^27-31 We used it to evaluate graft size, patency, and viability. As can be seen on US, the native rotator cuff does not have any pulsatile vessels and is fed by capillary flow. Dermal allograft has native vasculature built into the tissue. After 4 months to 8 months, presence of pulsatile vessels within the graft at the greater tuberosity indicates clear revascularization and incorporation of the tissue (Figure 6B). Disappearance of pulsatile vessels on US after 1 year indicates transformation to a stabilizing structure analogous to capsule or ligament with capillary flow. US also showed graft hypertrophy after 2 years, supporting a finding of integration and growth.

Conclusion

In the past, patients with irreparable massive RCTs had few good surgical management options, RTSA being the most definitive. SCR is technically challenging and requires use of specific implantation methods but can provide patients with outstanding relief. Our clinical data showed that technically well executed SCR effectively restores the superior restraints in the glenohumeral joint and thereby increases function and decreases pain in patients with irreparable massive RCTs, even after 2 years.

Take-Home Points

• Use ultrasound to identify integrity and location of MPFL tear.
• Anatomic repair allows native tissue to reintegrate into bone.
• Repairs done early can prevent complications of recurrent instability.
• Repair maintains biological and proprioceptive qualities of tissue.

• 10Ultrasound-guided percutaneous repair is quick and effective.

The medial patellofemoral ligament (MPFL) is the primary passive restraint to lateral patellar excursion^1-5 and helps control patellar tilt and rotation.^6,7 More than 90% of lateral patellar dislocations cause the MPFL to rupture, and roughly 90% of these detachments involve the femoral insertion.⁴ Ensuing patellar instability often results from MPFL insufficiency. It has been suggested that re-creating the anatomy and functionality of this ligament is of utmost importance in restoring normal patellar biomechanics.^1-5,7,8

Anatomical risk factors for recurrent patellar instability include patella alta, increased tibial tuberosity-trochlear groove (TT-TG) distance, trochlear dysplasia, and torsional abnormalities.^1-4,6 A medial reefing technique with a lateral tissue release traditionally was used to restore proper kinematics, but was shown to have associated postoperative issues.⁹

Methods

Patient Demographics

Dr. Hirahara developed this technique in 2013 and performed it 11 times between 2013 and 2016. Of the 11 patients, 1 was excluded from our retrospective analysis because of trochlear dysplasia, now considered a relative contraindication. Of the remaining 10 patients, 5 (50%) had the repair performed on the right knee. Eight patients (80%) were female. Mean (SD) age was 17.21 (3.53) years. One patient had concurrent femur- and patella-side detachments; otherwise, 6 (60%) of 10 repairs were performed exclusively at the patella. We grade patellar instability according to amount of glide based on patellar width and quadrants. Normal lateral displacement was usually 1 to 2 quadrants of lateral glide relative to the contralateral side. Before surgery, 6 (60%) of the 10 patients presented with lateral glide of 3 quadrants, and 3 (30%) presented with lateral glide of 4 quadrants. All had patellar instability apprehension on physical examination.

Surgical Indications

Before surgery, MPFL integrity is determined by ultrasound evaluation. Repair is considered if the MPFL has a femur- or patella-side tear and is of adequate quantity and quality, and if there are minimal or no arthritic changes (Table 2).

Surgical Technique

The patient is brought to the operating room and placed supine. Patellar stability of the affected knee is assessed and compared with that of the contralateral side with patellar glide. The knee is prepared and draped in usual sterile fashion. With the knee flexed at 90º, a tourniquet is inflated. Diagnostic arthroscopy is performed with standard anteromedial and anterolateral portals, and, if necessary, arthroscopic procedures are performed.

Femoral Attachment Repair

With the leg in extension, ultrasound is used to identify the tear at the femoral attachment (watch part 1 of the video). A spinal needle is placed at the femoral insertion, typically just anterior and distal to the adductor tubercle (Figure 4).¹⁰

Patellar Attachment Repair

With the leg in extension, ultrasound is used to identify where the MPFL is detached from the patella (watch part 2 of the video). A spinal needle is placed at the detachment site (Figure 5). A scalpel is used to make a 1-cm incision down to the patella.

In this description, we showcase knotless and knotted techniques for each repair site. Either method is appropriate for the 2 repair sites. Owing to the superficial nature of the attachment sites—they may have very little fat, particularly at the patella—knot stacks are more prominent, can be felt after surgery, and have the potential to irritate surrounding tissues. Therefore, we prefer knotless fixation for both sites.

Rehabilitation

Rehabilitation after MPFL repair is much like rehabilitation after quadriceps tendon repair. The patient is locked in a brace in full extension when up and moving. Early weight-bearing and minimal use of assistive devices (crutches) are allowed because, when the leg is in full extension, there is no tension at the repair sites. Rehabilitation begins within 1 week, and normal daily function is quickly attained. The protocol emphasizes pain-free motion and suitable patellar mobility, and allows the immobilizing brace to be unlocked for exercise and sitting. During the first 4 weeks, quadriceps activation is limited; progression to full ROM occurs by 4 to 6 weeks. During the strengthening phase, loading the knee in early flexion should be avoided. Return to heavy lifting, physical activity, and sports is delayed until after 6 months in order to allow the construct to mature and integrate. Once the patient has satisfied all the strength, ROM, and functional outcome measurements, a brace is no longer required during sports and normal activity.

Results

Mean tourniquet time for each procedure, which includes diagnostic arthroscopy and ultrasound-guided percutaneous repair, was 26.9 minutes.

Discussion

Conservative management typically is recommended for acute patellar dislocations. In the event of failed conservative management or chronic patellar instability, surgical intervention is indicated. Studies have found that conservative management has recurrent-dislocation rates of 35% at 3-year follow-up and 73% at 6-year follow-up, and recurrent dislocations significantly increase patients’ risk of developing chondral and bony damage.¹³ MPFL repair is designed to restore proper patellar tracking and kinematics while maintaining the anatomical tissue. Lateral patellar dislocations often cause the MPFL to rupture; tears are reported in more than 90% of incidents.⁴ The significant rate indicates that, even after a single patellar dislocation, the MPFL should be evaluated. The MPFL contributes 50% to 60% of the medial stabilizing force during patellar tracking^1,7,14 and is the primary restraint to lateral patellar excursion and excessive patellar tilt and rotation.^1-5 Its absence plays a key role in recurrent lateral patellar instability. With this structure being so important, proper identification and intervention are vital. Studies have established that redislocation rates are significantly higher for nonoperatively (vs operatively) treated primary patellar dislocations.¹³ Simple and accurate percutaneous repair of the MPFL should be performed early to avoid the long-term complications of recurrent instability that could damage the cartilage and bone of the patella and trochlea.

The primary advantage of this technique is its novel use of musculoskeletal ultrasound to accurately identify anatomy and pathology and the placement of anatomical repairs. Accurate preoperative and intraoperative assessment of MPFL anatomy is vital to the success of a procedure. Descriptions of MPFL anatomy suggest discrepancies in the exact locations of the femoral and patellar attachments.^{2,5,7,10,12,15,16} Tanaka⁵ noted that, even within paired knees, there was “marked variability” in the MPFL insertions. McCarthy and colleagues¹⁰ contended the femoral attachment of the MPFL is just anterior and distal to the adductor tubercle, the landmark addressed in this technique. Steensen and colleagues¹⁶ described this attachment site as being statistically the “single most important point affecting isometry” of the MPFL. Sallay and colleagues⁴ asserted that an overwhelming majority of MPFL tears (87%) occur at the adductor tubercle. The variable distribution of tear locations and the importance of re-creating patient anatomy further highlight the need for individualized treatment, which is afforded by ultrasound. Fluoroscopy has been inadequate in identifying MPFL anatomy; this modality is difficult, cumbersome, inaccurate, and inconsistent.^11,12 Conversely, ultrasound provides real-time visualization of anatomy and allows for precise identification of MPFL attachments and accurate placement of suture anchors for repair during surgery (Figures 3, 4).

For femur-side and patella-side tears, repairs can and should be performed. For midsubstance tears, however, repair is not feasible, and reconstruction is appropriate. MPFL repair is superior to reconstruction in several ways. Repair is a simple percutaneous procedure that had a mean tourniquet time of 26.9 minutes in this study. For tissue that is quantitatively and qualitatively adequate, repair allows the structure to reintegrate into bone without total reconstruction. In the event of multiple tears, the percutaneous procedure allows for repair of each attachment. As the MPFL sits between the second and third tissue layers of the medial knee, reconstruction can be difficult and invasive and require establishment of a between-layers plane, which can disrupt adjacent tissue.^4,7,17 Repair also maintains native tissue and its neurovascular and proprioceptive properties.

Reconstruction of the MPFL has become the gold-standard treatment for recurrent lateral patellar instability but has limitations and complications.^3,7,12,17 Reconstruction techniques use either surface anatomy palpation (requiring large incisions) or fluoroscopy to identify tunnel placement locations, and accurate placement has often been difficult and inconsistent. Our repair technique has several advantages over reconstruction. It does not burn any bridges; it allows for subsequent reconstruction. It does not require a graft and, using small suture anchors instead of large sockets and anchors, involves less bone loss. It also allows for early repair of tears—patients can return to activities, sports, and work quicker—and avoids the risk of chondral and bony damage with recurrent dislocations. According to our review of the MPFL repairs performed by Dr. Hirahara starting in 2013, the procedure is quick and successful and has outstanding outcomes.

Another treatment option for recurrent lateral patellar instability combines reefing of the medial patellofemoral tissues with a lateral release. This combination has had several postoperative complications and is no longer indicated.⁹ TT transfer and trochleoplasty procedures have been developed to address different aspects of patellar instability, increased TT-TG distance, and dysplastic trochlea (Table 2). Both types of procedures are highly invasive and difficult to perform, requiring technical expertise. They are best used when warranted by the anatomy, but this is uncommon. The technique we have presented allows for easy and reliable repair of dislocations in the absence of associated pathology that would require larger, more complex surgery. The ease of use and accuracy of musculoskeletal ultrasound make this technique superior to others.

Conclusion

The MPFL is a vital static stabilizer of the patella and as such should be evaluated in the setting of patellar injury. The novel preoperative and intraoperative use of musculoskeletal ultrasound described in this article allows for easy real-time identification of the MPFL and simple and accurate percutaneous repair of torn structures. Nonoperative treatments of acute patellar dislocations have higher rates of recurrent dislocations, which put patella and trochlea at risk for bony and chondral damage. Given appropriate tear location and tissue quality, repairs should be considered early and before reconstruction. To our knowledge, a reliable, easily reproducible MPFL repair was not described until now. We have reported on use of such a technique and on its promising patient outcomes, which should be considered when addressing MPFL injuries.

Am J Orthop. 2017;46(3):152-157. Copyright Frontline Medical Communications Inc. 2017. All rights reserved.

Take-Home Points

• Use ultrasound to identify integrity and location of MPFL tear.
• Anatomic repair allows native tissue to reintegrate into bone.
• Repairs done early can prevent complications of recurrent instability.
• Repair maintains biological and proprioceptive qualities of tissue.

• 10Ultrasound-guided percutaneous repair is quick and effective.

The medial patellofemoral ligament (MPFL) is the primary passive restraint to lateral patellar excursion^1-5 and helps control patellar tilt and rotation.^6,7 More than 90% of lateral patellar dislocations cause the MPFL to rupture, and roughly 90% of these detachments involve the femoral insertion.⁴ Ensuing patellar instability often results from MPFL insufficiency. It has been suggested that re-creating the anatomy and functionality of this ligament is of utmost importance in restoring normal patellar biomechanics.^1-5,7,8

Anatomical risk factors for recurrent patellar instability include patella alta, increased tibial tuberosity-trochlear groove (TT-TG) distance, trochlear dysplasia, and torsional abnormalities.^1-4,6 A medial reefing technique with a lateral tissue release traditionally was used to restore proper kinematics, but was shown to have associated postoperative issues.⁹

Methods

Patient Demographics

Dr. Hirahara developed this technique in 2013 and performed it 11 times between 2013 and 2016. Of the 11 patients, 1 was excluded from our retrospective analysis because of trochlear dysplasia, now considered a relative contraindication. Of the remaining 10 patients, 5 (50%) had the repair performed on the right knee. Eight patients (80%) were female. Mean (SD) age was 17.21 (3.53) years. One patient had concurrent femur- and patella-side detachments; otherwise, 6 (60%) of 10 repairs were performed exclusively at the patella. We grade patellar instability according to amount of glide based on patellar width and quadrants. Normal lateral displacement was usually 1 to 2 quadrants of lateral glide relative to the contralateral side. Before surgery, 6 (60%) of the 10 patients presented with lateral glide of 3 quadrants, and 3 (30%) presented with lateral glide of 4 quadrants. All had patellar instability apprehension on physical examination.

Surgical Indications

Before surgery, MPFL integrity is determined by ultrasound evaluation. Repair is considered if the MPFL has a femur- or patella-side tear and is of adequate quantity and quality, and if there are minimal or no arthritic changes (Table 2).

Surgical Technique

The patient is brought to the operating room and placed supine. Patellar stability of the affected knee is assessed and compared with that of the contralateral side with patellar glide. The knee is prepared and draped in usual sterile fashion. With the knee flexed at 90º, a tourniquet is inflated. Diagnostic arthroscopy is performed with standard anteromedial and anterolateral portals, and, if necessary, arthroscopic procedures are performed.

Femoral Attachment Repair

With the leg in extension, ultrasound is used to identify the tear at the femoral attachment (watch part 1 of the video). A spinal needle is placed at the femoral insertion, typically just anterior and distal to the adductor tubercle (Figure 4).¹⁰

Patellar Attachment Repair

With the leg in extension, ultrasound is used to identify where the MPFL is detached from the patella (watch part 2 of the video). A spinal needle is placed at the detachment site (Figure 5). A scalpel is used to make a 1-cm incision down to the patella.

In this description, we showcase knotless and knotted techniques for each repair site. Either method is appropriate for the 2 repair sites. Owing to the superficial nature of the attachment sites—they may have very little fat, particularly at the patella—knot stacks are more prominent, can be felt after surgery, and have the potential to irritate surrounding tissues. Therefore, we prefer knotless fixation for both sites.

Rehabilitation

Rehabilitation after MPFL repair is much like rehabilitation after quadriceps tendon repair. The patient is locked in a brace in full extension when up and moving. Early weight-bearing and minimal use of assistive devices (crutches) are allowed because, when the leg is in full extension, there is no tension at the repair sites. Rehabilitation begins within 1 week, and normal daily function is quickly attained. The protocol emphasizes pain-free motion and suitable patellar mobility, and allows the immobilizing brace to be unlocked for exercise and sitting. During the first 4 weeks, quadriceps activation is limited; progression to full ROM occurs by 4 to 6 weeks. During the strengthening phase, loading the knee in early flexion should be avoided. Return to heavy lifting, physical activity, and sports is delayed until after 6 months in order to allow the construct to mature and integrate. Once the patient has satisfied all the strength, ROM, and functional outcome measurements, a brace is no longer required during sports and normal activity.

Results

Mean tourniquet time for each procedure, which includes diagnostic arthroscopy and ultrasound-guided percutaneous repair, was 26.9 minutes.

Discussion

Conservative management typically is recommended for acute patellar dislocations. In the event of failed conservative management or chronic patellar instability, surgical intervention is indicated. Studies have found that conservative management has recurrent-dislocation rates of 35% at 3-year follow-up and 73% at 6-year follow-up, and recurrent dislocations significantly increase patients’ risk of developing chondral and bony damage.¹³ MPFL repair is designed to restore proper patellar tracking and kinematics while maintaining the anatomical tissue. Lateral patellar dislocations often cause the MPFL to rupture; tears are reported in more than 90% of incidents.⁴ The significant rate indicates that, even after a single patellar dislocation, the MPFL should be evaluated. The MPFL contributes 50% to 60% of the medial stabilizing force during patellar tracking^1,7,14 and is the primary restraint to lateral patellar excursion and excessive patellar tilt and rotation.^1-5 Its absence plays a key role in recurrent lateral patellar instability. With this structure being so important, proper identification and intervention are vital. Studies have established that redislocation rates are significantly higher for nonoperatively (vs operatively) treated primary patellar dislocations.¹³ Simple and accurate percutaneous repair of the MPFL should be performed early to avoid the long-term complications of recurrent instability that could damage the cartilage and bone of the patella and trochlea.

The primary advantage of this technique is its novel use of musculoskeletal ultrasound to accurately identify anatomy and pathology and the placement of anatomical repairs. Accurate preoperative and intraoperative assessment of MPFL anatomy is vital to the success of a procedure. Descriptions of MPFL anatomy suggest discrepancies in the exact locations of the femoral and patellar attachments.^{2,5,7,10,12,15,16} Tanaka⁵ noted that, even within paired knees, there was “marked variability” in the MPFL insertions. McCarthy and colleagues¹⁰ contended the femoral attachment of the MPFL is just anterior and distal to the adductor tubercle, the landmark addressed in this technique. Steensen and colleagues¹⁶ described this attachment site as being statistically the “single most important point affecting isometry” of the MPFL. Sallay and colleagues⁴ asserted that an overwhelming majority of MPFL tears (87%) occur at the adductor tubercle. The variable distribution of tear locations and the importance of re-creating patient anatomy further highlight the need for individualized treatment, which is afforded by ultrasound. Fluoroscopy has been inadequate in identifying MPFL anatomy; this modality is difficult, cumbersome, inaccurate, and inconsistent.^11,12 Conversely, ultrasound provides real-time visualization of anatomy and allows for precise identification of MPFL attachments and accurate placement of suture anchors for repair during surgery (Figures 3, 4).

For femur-side and patella-side tears, repairs can and should be performed. For midsubstance tears, however, repair is not feasible, and reconstruction is appropriate. MPFL repair is superior to reconstruction in several ways. Repair is a simple percutaneous procedure that had a mean tourniquet time of 26.9 minutes in this study. For tissue that is quantitatively and qualitatively adequate, repair allows the structure to reintegrate into bone without total reconstruction. In the event of multiple tears, the percutaneous procedure allows for repair of each attachment. As the MPFL sits between the second and third tissue layers of the medial knee, reconstruction can be difficult and invasive and require establishment of a between-layers plane, which can disrupt adjacent tissue.^4,7,17 Repair also maintains native tissue and its neurovascular and proprioceptive properties.

Reconstruction of the MPFL has become the gold-standard treatment for recurrent lateral patellar instability but has limitations and complications.^3,7,12,17 Reconstruction techniques use either surface anatomy palpation (requiring large incisions) or fluoroscopy to identify tunnel placement locations, and accurate placement has often been difficult and inconsistent. Our repair technique has several advantages over reconstruction. It does not burn any bridges; it allows for subsequent reconstruction. It does not require a graft and, using small suture anchors instead of large sockets and anchors, involves less bone loss. It also allows for early repair of tears—patients can return to activities, sports, and work quicker—and avoids the risk of chondral and bony damage with recurrent dislocations. According to our review of the MPFL repairs performed by Dr. Hirahara starting in 2013, the procedure is quick and successful and has outstanding outcomes.

Another treatment option for recurrent lateral patellar instability combines reefing of the medial patellofemoral tissues with a lateral release. This combination has had several postoperative complications and is no longer indicated.⁹ TT transfer and trochleoplasty procedures have been developed to address different aspects of patellar instability, increased TT-TG distance, and dysplastic trochlea (Table 2). Both types of procedures are highly invasive and difficult to perform, requiring technical expertise. They are best used when warranted by the anatomy, but this is uncommon. The technique we have presented allows for easy and reliable repair of dislocations in the absence of associated pathology that would require larger, more complex surgery. The ease of use and accuracy of musculoskeletal ultrasound make this technique superior to others.

Conclusion

The MPFL is a vital static stabilizer of the patella and as such should be evaluated in the setting of patellar injury. The novel preoperative and intraoperative use of musculoskeletal ultrasound described in this article allows for easy real-time identification of the MPFL and simple and accurate percutaneous repair of torn structures. Nonoperative treatments of acute patellar dislocations have higher rates of recurrent dislocations, which put patella and trochlea at risk for bony and chondral damage. Given appropriate tear location and tissue quality, repairs should be considered early and before reconstruction. To our knowledge, a reliable, easily reproducible MPFL repair was not described until now. We have reported on use of such a technique and on its promising patient outcomes, which should be considered when addressing MPFL injuries.

Am J Orthop. 2017;46(3):152-157. Copyright Frontline Medical Communications Inc. 2017. All rights reserved.

Take-Home Points

• Use ultrasound to identify integrity and location of MPFL tear.
• Anatomic repair allows native tissue to reintegrate into bone.
• Repairs done early can prevent complications of recurrent instability.
• Repair maintains biological and proprioceptive qualities of tissue.

• 10Ultrasound-guided percutaneous repair is quick and effective.

The medial patellofemoral ligament (MPFL) is the primary passive restraint to lateral patellar excursion^1-5 and helps control patellar tilt and rotation.^6,7 More than 90% of lateral patellar dislocations cause the MPFL to rupture, and roughly 90% of these detachments involve the femoral insertion.⁴ Ensuing patellar instability often results from MPFL insufficiency. It has been suggested that re-creating the anatomy and functionality of this ligament is of utmost importance in restoring normal patellar biomechanics.^1-5,7,8

Anatomical risk factors for recurrent patellar instability include patella alta, increased tibial tuberosity-trochlear groove (TT-TG) distance, trochlear dysplasia, and torsional abnormalities.^1-4,6 A medial reefing technique with a lateral tissue release traditionally was used to restore proper kinematics, but was shown to have associated postoperative issues.⁹

Methods

Patient Demographics

Dr. Hirahara developed this technique in 2013 and performed it 11 times between 2013 and 2016. Of the 11 patients, 1 was excluded from our retrospective analysis because of trochlear dysplasia, now considered a relative contraindication. Of the remaining 10 patients, 5 (50%) had the repair performed on the right knee. Eight patients (80%) were female. Mean (SD) age was 17.21 (3.53) years. One patient had concurrent femur- and patella-side detachments; otherwise, 6 (60%) of 10 repairs were performed exclusively at the patella. We grade patellar instability according to amount of glide based on patellar width and quadrants. Normal lateral displacement was usually 1 to 2 quadrants of lateral glide relative to the contralateral side. Before surgery, 6 (60%) of the 10 patients presented with lateral glide of 3 quadrants, and 3 (30%) presented with lateral glide of 4 quadrants. All had patellar instability apprehension on physical examination.

Surgical Indications

Before surgery, MPFL integrity is determined by ultrasound evaluation. Repair is considered if the MPFL has a femur- or patella-side tear and is of adequate quantity and quality, and if there are minimal or no arthritic changes (Table 2).

Surgical Technique

The patient is brought to the operating room and placed supine. Patellar stability of the affected knee is assessed and compared with that of the contralateral side with patellar glide. The knee is prepared and draped in usual sterile fashion. With the knee flexed at 90º, a tourniquet is inflated. Diagnostic arthroscopy is performed with standard anteromedial and anterolateral portals, and, if necessary, arthroscopic procedures are performed.

Femoral Attachment Repair

With the leg in extension, ultrasound is used to identify the tear at the femoral attachment (watch part 1 of the video). A spinal needle is placed at the femoral insertion, typically just anterior and distal to the adductor tubercle (Figure 4).¹⁰

Patellar Attachment Repair

With the leg in extension, ultrasound is used to identify where the MPFL is detached from the patella (watch part 2 of the video). A spinal needle is placed at the detachment site (Figure 5). A scalpel is used to make a 1-cm incision down to the patella.

In this description, we showcase knotless and knotted techniques for each repair site. Either method is appropriate for the 2 repair sites. Owing to the superficial nature of the attachment sites—they may have very little fat, particularly at the patella—knot stacks are more prominent, can be felt after surgery, and have the potential to irritate surrounding tissues. Therefore, we prefer knotless fixation for both sites.

Rehabilitation

Rehabilitation after MPFL repair is much like rehabilitation after quadriceps tendon repair. The patient is locked in a brace in full extension when up and moving. Early weight-bearing and minimal use of assistive devices (crutches) are allowed because, when the leg is in full extension, there is no tension at the repair sites. Rehabilitation begins within 1 week, and normal daily function is quickly attained. The protocol emphasizes pain-free motion and suitable patellar mobility, and allows the immobilizing brace to be unlocked for exercise and sitting. During the first 4 weeks, quadriceps activation is limited; progression to full ROM occurs by 4 to 6 weeks. During the strengthening phase, loading the knee in early flexion should be avoided. Return to heavy lifting, physical activity, and sports is delayed until after 6 months in order to allow the construct to mature and integrate. Once the patient has satisfied all the strength, ROM, and functional outcome measurements, a brace is no longer required during sports and normal activity.

Results

Mean tourniquet time for each procedure, which includes diagnostic arthroscopy and ultrasound-guided percutaneous repair, was 26.9 minutes.

Discussion

Conservative management typically is recommended for acute patellar dislocations. In the event of failed conservative management or chronic patellar instability, surgical intervention is indicated. Studies have found that conservative management has recurrent-dislocation rates of 35% at 3-year follow-up and 73% at 6-year follow-up, and recurrent dislocations significantly increase patients’ risk of developing chondral and bony damage.¹³ MPFL repair is designed to restore proper patellar tracking and kinematics while maintaining the anatomical tissue. Lateral patellar dislocations often cause the MPFL to rupture; tears are reported in more than 90% of incidents.⁴ The significant rate indicates that, even after a single patellar dislocation, the MPFL should be evaluated. The MPFL contributes 50% to 60% of the medial stabilizing force during patellar tracking^1,7,14 and is the primary restraint to lateral patellar excursion and excessive patellar tilt and rotation.^1-5 Its absence plays a key role in recurrent lateral patellar instability. With this structure being so important, proper identification and intervention are vital. Studies have established that redislocation rates are significantly higher for nonoperatively (vs operatively) treated primary patellar dislocations.¹³ Simple and accurate percutaneous repair of the MPFL should be performed early to avoid the long-term complications of recurrent instability that could damage the cartilage and bone of the patella and trochlea.

The primary advantage of this technique is its novel use of musculoskeletal ultrasound to accurately identify anatomy and pathology and the placement of anatomical repairs. Accurate preoperative and intraoperative assessment of MPFL anatomy is vital to the success of a procedure. Descriptions of MPFL anatomy suggest discrepancies in the exact locations of the femoral and patellar attachments.^{2,5,7,10,12,15,16} Tanaka⁵ noted that, even within paired knees, there was “marked variability” in the MPFL insertions. McCarthy and colleagues¹⁰ contended the femoral attachment of the MPFL is just anterior and distal to the adductor tubercle, the landmark addressed in this technique. Steensen and colleagues¹⁶ described this attachment site as being statistically the “single most important point affecting isometry” of the MPFL. Sallay and colleagues⁴ asserted that an overwhelming majority of MPFL tears (87%) occur at the adductor tubercle. The variable distribution of tear locations and the importance of re-creating patient anatomy further highlight the need for individualized treatment, which is afforded by ultrasound. Fluoroscopy has been inadequate in identifying MPFL anatomy; this modality is difficult, cumbersome, inaccurate, and inconsistent.^11,12 Conversely, ultrasound provides real-time visualization of anatomy and allows for precise identification of MPFL attachments and accurate placement of suture anchors for repair during surgery (Figures 3, 4).

For femur-side and patella-side tears, repairs can and should be performed. For midsubstance tears, however, repair is not feasible, and reconstruction is appropriate. MPFL repair is superior to reconstruction in several ways. Repair is a simple percutaneous procedure that had a mean tourniquet time of 26.9 minutes in this study. For tissue that is quantitatively and qualitatively adequate, repair allows the structure to reintegrate into bone without total reconstruction. In the event of multiple tears, the percutaneous procedure allows for repair of each attachment. As the MPFL sits between the second and third tissue layers of the medial knee, reconstruction can be difficult and invasive and require establishment of a between-layers plane, which can disrupt adjacent tissue.^4,7,17 Repair also maintains native tissue and its neurovascular and proprioceptive properties.

Reconstruction of the MPFL has become the gold-standard treatment for recurrent lateral patellar instability but has limitations and complications.^3,7,12,17 Reconstruction techniques use either surface anatomy palpation (requiring large incisions) or fluoroscopy to identify tunnel placement locations, and accurate placement has often been difficult and inconsistent. Our repair technique has several advantages over reconstruction. It does not burn any bridges; it allows for subsequent reconstruction. It does not require a graft and, using small suture anchors instead of large sockets and anchors, involves less bone loss. It also allows for early repair of tears—patients can return to activities, sports, and work quicker—and avoids the risk of chondral and bony damage with recurrent dislocations. According to our review of the MPFL repairs performed by Dr. Hirahara starting in 2013, the procedure is quick and successful and has outstanding outcomes.

Another treatment option for recurrent lateral patellar instability combines reefing of the medial patellofemoral tissues with a lateral release. This combination has had several postoperative complications and is no longer indicated.⁹ TT transfer and trochleoplasty procedures have been developed to address different aspects of patellar instability, increased TT-TG distance, and dysplastic trochlea (Table 2). Both types of procedures are highly invasive and difficult to perform, requiring technical expertise. They are best used when warranted by the anatomy, but this is uncommon. The technique we have presented allows for easy and reliable repair of dislocations in the absence of associated pathology that would require larger, more complex surgery. The ease of use and accuracy of musculoskeletal ultrasound make this technique superior to others.

Conclusion

The MPFL is a vital static stabilizer of the patella and as such should be evaluated in the setting of patellar injury. The novel preoperative and intraoperative use of musculoskeletal ultrasound described in this article allows for easy real-time identification of the MPFL and simple and accurate percutaneous repair of torn structures. Nonoperative treatments of acute patellar dislocations have higher rates of recurrent dislocations, which put patella and trochlea at risk for bony and chondral damage. Given appropriate tear location and tissue quality, repairs should be considered early and before reconstruction. To our knowledge, a reliable, easily reproducible MPFL repair was not described until now. We have reported on use of such a technique and on its promising patient outcomes, which should be considered when addressing MPFL injuries.

Am J Orthop. 2017;46(3):152-157. Copyright Frontline Medical Communications Inc. 2017. All rights reserved.

Video, Part 1. Femoral Attachment

1. Ultrasound is used to identify femoral and patellar attachments of medial patellofemoral ligament (MPFL).

2. MPFL is followed from patella to its attachment near adductor tubercle.

3. In-plane ultrasound guidance is used to place needle anterior and distal to tubercle.

4. Percutaneous incision is made down to needle tip. Spear is placed at needle tip for anatomical placement of socket.

5. Socket is drilled.

6. 3.0-mm suture anchor (BioComposite Knotless SutureTak; Arthrex) is placed.

7. Leading edge of torn MPFL is identified.

8. Suture passer (Labral FastPass Scorpion; Arthrex) is used to pass sutures through leading edge of torn MPFL to create horizontal mattress.

9. Sutures are tied.

10. Repair is complete.

Video, Part 2. Patellar Attachment

1. Ultrasound is used to scan patella to identify ideal or exact location of tear. In-plane ultrasound guidance is used to place spinal needle at desired socket location.

2. After spinal needle is positioned, in-line percutaneous incision is made, and needle is palpated at patella.

3. Spear is then placed at spinal needle tip for anatomical positioning of socket.

4. Socket is drilled.

5. 3.0-mm suture anchor (BioComposite Knotless SutureTak; Arthrex) is placed in socket.

6. Leading edge of torn medial patellofemoral ligament (MPFL) is identified.

7. Suture passer (Labral Past Pass Scorpion; Arthrex) is used to pass suture from anchor in horizontal mattress fashion through leading edge of torn MPFL.

8. Wire with loop (FiberSnare; Arthrex) is used as part of knotless technology to pull suture back through anchor to create knotless fixation.

9. Suture is pulled for appropriate tensioning of tissue.

10. Ultrasound is used to visualize construct to confirm that MPFL tissue abuts anchor and that repair is complete.

Video, Part 1. Femoral Attachment

1. Ultrasound is used to identify femoral and patellar attachments of medial patellofemoral ligament (MPFL).

2. MPFL is followed from patella to its attachment near adductor tubercle.

3. In-plane ultrasound guidance is used to place needle anterior and distal to tubercle.

4. Percutaneous incision is made down to needle tip. Spear is placed at needle tip for anatomical placement of socket.

5. Socket is drilled.

6. 3.0-mm suture anchor (BioComposite Knotless SutureTak; Arthrex) is placed.

7. Leading edge of torn MPFL is identified.

8. Suture passer (Labral FastPass Scorpion; Arthrex) is used to pass sutures through leading edge of torn MPFL to create horizontal mattress.

9. Sutures are tied.

10. Repair is complete.

Video, Part 2. Patellar Attachment

1. Ultrasound is used to scan patella to identify ideal or exact location of tear. In-plane ultrasound guidance is used to place spinal needle at desired socket location.

2. After spinal needle is positioned, in-line percutaneous incision is made, and needle is palpated at patella.

3. Spear is then placed at spinal needle tip for anatomical positioning of socket.

4. Socket is drilled.

5. 3.0-mm suture anchor (BioComposite Knotless SutureTak; Arthrex) is placed in socket.

6. Leading edge of torn medial patellofemoral ligament (MPFL) is identified.

7. Suture passer (Labral Past Pass Scorpion; Arthrex) is used to pass suture from anchor in horizontal mattress fashion through leading edge of torn MPFL.

8. Wire with loop (FiberSnare; Arthrex) is used as part of knotless technology to pull suture back through anchor to create knotless fixation.

9. Suture is pulled for appropriate tensioning of tissue.

10. Ultrasound is used to visualize construct to confirm that MPFL tissue abuts anchor and that repair is complete.

Video, Part 1. Femoral Attachment

1. Ultrasound is used to identify femoral and patellar attachments of medial patellofemoral ligament (MPFL).

2. MPFL is followed from patella to its attachment near adductor tubercle.

3. In-plane ultrasound guidance is used to place needle anterior and distal to tubercle.

4. Percutaneous incision is made down to needle tip. Spear is placed at needle tip for anatomical placement of socket.

5. Socket is drilled.

6. 3.0-mm suture anchor (BioComposite Knotless SutureTak; Arthrex) is placed.

7. Leading edge of torn MPFL is identified.

8. Suture passer (Labral FastPass Scorpion; Arthrex) is used to pass sutures through leading edge of torn MPFL to create horizontal mattress.

9. Sutures are tied.

10. Repair is complete.

Video, Part 2. Patellar Attachment

1. Ultrasound is used to scan patella to identify ideal or exact location of tear. In-plane ultrasound guidance is used to place spinal needle at desired socket location.

2. After spinal needle is positioned, in-line percutaneous incision is made, and needle is palpated at patella.

3. Spear is then placed at spinal needle tip for anatomical positioning of socket.

4. Socket is drilled.

5. 3.0-mm suture anchor (BioComposite Knotless SutureTak; Arthrex) is placed in socket.

6. Leading edge of torn medial patellofemoral ligament (MPFL) is identified.

7. Suture passer (Labral Past Pass Scorpion; Arthrex) is used to pass suture from anchor in horizontal mattress fashion through leading edge of torn MPFL.

8. Wire with loop (FiberSnare; Arthrex) is used as part of knotless technology to pull suture back through anchor to create knotless fixation.

9. Suture is pulled for appropriate tensioning of tissue.

10. Ultrasound is used to visualize construct to confirm that MPFL tissue abuts anchor and that repair is complete.

Arthrex Synergy MSK Ultrasound by Clarius(http://www.synergy-ultrasound.com/)

Arthrex Synergy MSK Ultrasound by Clarius is a new wireless ultrasound scanner that can connect to any iOS or Android device through a secure WiFi Direct connection. The scanner sets up the connection to an app on the device. Ultrasound and wireless technology have been around for decades, but combinations thereof have produced poor results. The main challenge has been to create and wirelessly transmit high-quality images without latency to a display while maintaining a reasonably sized transducer. Handheld ultrasound transducers scan effectively and process the scanned information in compact form. Recent advances in image processing and proprietary imaging algorithms now allow creation of high-resolution images comparable to those produced by most midrange or high-range machines costing $30,000 to $50,000. This new unit costs about $12,000. Ultrasound use has increased over the past decade. Numerous studies have found improved accuracy, efficacy, and outcomes of injections, and reduced pain, with ultrasound-guided injections over blind injections, and cost savings over magnetic resonance imaging.^1-12

Three scanners are capable of targeting different tissue types and depths. We prefer the Synergy MSK Linear Ultrasound by Clarius, a linear transducer that can evaluate tissue to depths of 7 cm and use frequencies from 4 MHz to 13 MHz. Its battery holds a standby charge for 7 days and can be actively used for 45 minutes. The unit has a magnesium shell; with the battery removed, the unit can be completely immersed in liquid without being damaged, which allows for easy cleaning and, potentially, sterilization with a soak solution. Color Doppler (for blood-flow assessment) and proprietary advanced needle visualization technology will be available in June.

The app is simply controlled with typical smart-device gestures. Depth control requires a finger swipe, and zoom takes a pinch. Other controls, such as optimal gain and frequency settings, are automated. Images and videos can be stored on the device and uploaded either to the Clarius Cloud or to a PACS (picture archiving and communication system) device. New features will allow the device to use a Synergy arthroscopy tower (Arthrex) as its display for surgeons and anesthesiologists in the surgical suite.

This technology finally allows ultrasound to be used in the operating room without the hassles of cumbersome machines and the potential contamination by the sleeves covering the cord that connects the transducer and the base unit (Figure 1).

Arthrex Synergy MSK Ultrasound by Clarius(http://www.synergy-ultrasound.com/)

Arthrex Synergy MSK Ultrasound by Clarius is a new wireless ultrasound scanner that can connect to any iOS or Android device through a secure WiFi Direct connection. The scanner sets up the connection to an app on the device. Ultrasound and wireless technology have been around for decades, but combinations thereof have produced poor results. The main challenge has been to create and wirelessly transmit high-quality images without latency to a display while maintaining a reasonably sized transducer. Handheld ultrasound transducers scan effectively and process the scanned information in compact form. Recent advances in image processing and proprietary imaging algorithms now allow creation of high-resolution images comparable to those produced by most midrange or high-range machines costing $30,000 to $50,000. This new unit costs about $12,000. Ultrasound use has increased over the past decade. Numerous studies have found improved accuracy, efficacy, and outcomes of injections, and reduced pain, with ultrasound-guided injections over blind injections, and cost savings over magnetic resonance imaging.^1-12

Three scanners are capable of targeting different tissue types and depths. We prefer the Synergy MSK Linear Ultrasound by Clarius, a linear transducer that can evaluate tissue to depths of 7 cm and use frequencies from 4 MHz to 13 MHz. Its battery holds a standby charge for 7 days and can be actively used for 45 minutes. The unit has a magnesium shell; with the battery removed, the unit can be completely immersed in liquid without being damaged, which allows for easy cleaning and, potentially, sterilization with a soak solution. Color Doppler (for blood-flow assessment) and proprietary advanced needle visualization technology will be available in June.

The app is simply controlled with typical smart-device gestures. Depth control requires a finger swipe, and zoom takes a pinch. Other controls, such as optimal gain and frequency settings, are automated. Images and videos can be stored on the device and uploaded either to the Clarius Cloud or to a PACS (picture archiving and communication system) device. New features will allow the device to use a Synergy arthroscopy tower (Arthrex) as its display for surgeons and anesthesiologists in the surgical suite.

This technology finally allows ultrasound to be used in the operating room without the hassles of cumbersome machines and the potential contamination by the sleeves covering the cord that connects the transducer and the base unit (Figure 1).

Arthrex Synergy MSK Ultrasound by Clarius(http://www.synergy-ultrasound.com/)

Arthrex Synergy MSK Ultrasound by Clarius is a new wireless ultrasound scanner that can connect to any iOS or Android device through a secure WiFi Direct connection. The scanner sets up the connection to an app on the device. Ultrasound and wireless technology have been around for decades, but combinations thereof have produced poor results. The main challenge has been to create and wirelessly transmit high-quality images without latency to a display while maintaining a reasonably sized transducer. Handheld ultrasound transducers scan effectively and process the scanned information in compact form. Recent advances in image processing and proprietary imaging algorithms now allow creation of high-resolution images comparable to those produced by most midrange or high-range machines costing $30,000 to $50,000. This new unit costs about $12,000. Ultrasound use has increased over the past decade. Numerous studies have found improved accuracy, efficacy, and outcomes of injections, and reduced pain, with ultrasound-guided injections over blind injections, and cost savings over magnetic resonance imaging.^1-12

Three scanners are capable of targeting different tissue types and depths. We prefer the Synergy MSK Linear Ultrasound by Clarius, a linear transducer that can evaluate tissue to depths of 7 cm and use frequencies from 4 MHz to 13 MHz. Its battery holds a standby charge for 7 days and can be actively used for 45 minutes. The unit has a magnesium shell; with the battery removed, the unit can be completely immersed in liquid without being damaged, which allows for easy cleaning and, potentially, sterilization with a soak solution. Color Doppler (for blood-flow assessment) and proprietary advanced needle visualization technology will be available in June.

The app is simply controlled with typical smart-device gestures. Depth control requires a finger swipe, and zoom takes a pinch. Other controls, such as optimal gain and frequency settings, are automated. Images and videos can be stored on the device and uploaded either to the Clarius Cloud or to a PACS (picture archiving and communication system) device. New features will allow the device to use a Synergy arthroscopy tower (Arthrex) as its display for surgeons and anesthesiologists in the surgical suite.

This technology finally allows ultrasound to be used in the operating room without the hassles of cumbersome machines and the potential contamination by the sleeves covering the cord that connects the transducer and the base unit (Figure 1).