Knee OA Symptoms, Metabolism Improved After Bariatric Surgery

In obese patients with knee osteoarthritis, significant weight loss after bariatric surgery reduced pain and stiffness, decreased low-grade inflammation, and changed cartilage turnover, according to a study published in the January issue of Annals of Rheumatic Diseases.

In addition to the well-known relationship between obesity and onset of knee osteoarthritis (OA), several studies have now shown that the association goes beyond the increase in mechanical load on the tibiofemoral cartilage. "Adipose tissue may act as an endocrine organ, releasing several proinflammatory mediators and adipokines in blood that may participate in cartilage alteration in obese patients," according to Dr. Pascal Richette of Hôpital Lariboisière and coauthors. The authors added, "Trials that have assessed the efficacy of surgically induced massive weight loss on knee OA symptoms are scarce and have not specifically included patients with well-defined radiographic evidence of knee OA, as in our study." (Ann. Rheum. Dis. 2011;70:139-44).

The authors studied 44 obese patients (36 women) with a baseline body mass index of 50.7 before surgery and moderate to severe knee OA. The patients underwent laparoscopic Roux-en-Y gastric bypass surgery or laparoscopic adjustable gastric banding. Patient data was collected before and 6 months after the surgery.

At 6 months, patients had a 20% drop from baseline BMIs. Their VAS (visual acuity scores) decreased from 50 mm to 24.5 mm and their scores on the WOMAC (Western Ontario MacMaster) Questionnaire improved. Significant decreases were seen in average serum levels of interleukin-6 (IL-6), which declined by 26%, and of high-sensitivity C-reactive protein (hsCRP), which dropped 46%. Also, weight loss was associated with changes in adipokine levels: Mean serum leptin concentration was decreased by 48% and serum level of adiponectin was increased by 21%, the authors reported.

The average serum level of procollagen type II N-terminal propeptide (PIIANP), a marker of cartilage synthesis, rose 32%, while the serum level of cartilage oligomeric matrix protein (COMP) decreased by 36%. "These results are the first to suggest a benefit of weight loss on both cartilage anabolism and catabolism," the authors wrote.

The researchers found a significant correlation between IL-6 level and WOMAC Questionnaire scores as well as between urinary type II collagen helical peptide (helix-II) and hsCRP. Variation in COMP concentration was significantly correlated with changes in VAS pain scores and WOMAC stiffness score, the authors wrote, adding, "Our findings extend the results of recent work showing a significant association of IL-6 circulating levels and the prevalence and incidence of knee OA."

Since the study was an open exploratory study, it was prone to bias in evaluation of results. Also, the sample size was small. The findings don’t imply causality between variables, "and thus should be carefully interpreted," the researchers wrote. Also, "the effect of changes in insulin resistance related to weight loss on cartilage homoeostasis needs further investigation."

The study was funded by Assistance Publique-Hôpitaux de Paris, Direction of Clinical Research, which promoted and supported the clinical investigation, a grant from the European community, and the Association Rhumatisme et Travail (Hôpital Lariboisière, Paris).

The authors reported no financial conflicts of interest.

In obese patients with knee osteoarthritis, significant weight loss after bariatric surgery reduced pain and stiffness, decreased low-grade inflammation, and changed cartilage turnover, according to a study published in the January issue of Annals of Rheumatic Diseases.

In addition to the well-known relationship between obesity and onset of knee osteoarthritis (OA), several studies have now shown that the association goes beyond the increase in mechanical load on the tibiofemoral cartilage. "Adipose tissue may act as an endocrine organ, releasing several proinflammatory mediators and adipokines in blood that may participate in cartilage alteration in obese patients," according to Dr. Pascal Richette of Hôpital Lariboisière and coauthors. The authors added, "Trials that have assessed the efficacy of surgically induced massive weight loss on knee OA symptoms are scarce and have not specifically included patients with well-defined radiographic evidence of knee OA, as in our study." (Ann. Rheum. Dis. 2011;70:139-44).

The authors studied 44 obese patients (36 women) with a baseline body mass index of 50.7 before surgery and moderate to severe knee OA. The patients underwent laparoscopic Roux-en-Y gastric bypass surgery or laparoscopic adjustable gastric banding. Patient data was collected before and 6 months after the surgery.

At 6 months, patients had a 20% drop from baseline BMIs. Their VAS (visual acuity scores) decreased from 50 mm to 24.5 mm and their scores on the WOMAC (Western Ontario MacMaster) Questionnaire improved. Significant decreases were seen in average serum levels of interleukin-6 (IL-6), which declined by 26%, and of high-sensitivity C-reactive protein (hsCRP), which dropped 46%. Also, weight loss was associated with changes in adipokine levels: Mean serum leptin concentration was decreased by 48% and serum level of adiponectin was increased by 21%, the authors reported.

The average serum level of procollagen type II N-terminal propeptide (PIIANP), a marker of cartilage synthesis, rose 32%, while the serum level of cartilage oligomeric matrix protein (COMP) decreased by 36%. "These results are the first to suggest a benefit of weight loss on both cartilage anabolism and catabolism," the authors wrote.

The researchers found a significant correlation between IL-6 level and WOMAC Questionnaire scores as well as between urinary type II collagen helical peptide (helix-II) and hsCRP. Variation in COMP concentration was significantly correlated with changes in VAS pain scores and WOMAC stiffness score, the authors wrote, adding, "Our findings extend the results of recent work showing a significant association of IL-6 circulating levels and the prevalence and incidence of knee OA."

Since the study was an open exploratory study, it was prone to bias in evaluation of results. Also, the sample size was small. The findings don’t imply causality between variables, "and thus should be carefully interpreted," the researchers wrote. Also, "the effect of changes in insulin resistance related to weight loss on cartilage homoeostasis needs further investigation."

The study was funded by Assistance Publique-Hôpitaux de Paris, Direction of Clinical Research, which promoted and supported the clinical investigation, a grant from the European community, and the Association Rhumatisme et Travail (Hôpital Lariboisière, Paris).

The authors reported no financial conflicts of interest.

In obese patients with knee osteoarthritis, significant weight loss after bariatric surgery reduced pain and stiffness, decreased low-grade inflammation, and changed cartilage turnover, according to a study published in the January issue of Annals of Rheumatic Diseases.

In addition to the well-known relationship between obesity and onset of knee osteoarthritis (OA), several studies have now shown that the association goes beyond the increase in mechanical load on the tibiofemoral cartilage. "Adipose tissue may act as an endocrine organ, releasing several proinflammatory mediators and adipokines in blood that may participate in cartilage alteration in obese patients," according to Dr. Pascal Richette of Hôpital Lariboisière and coauthors. The authors added, "Trials that have assessed the efficacy of surgically induced massive weight loss on knee OA symptoms are scarce and have not specifically included patients with well-defined radiographic evidence of knee OA, as in our study." (Ann. Rheum. Dis. 2011;70:139-44).

The authors studied 44 obese patients (36 women) with a baseline body mass index of 50.7 before surgery and moderate to severe knee OA. The patients underwent laparoscopic Roux-en-Y gastric bypass surgery or laparoscopic adjustable gastric banding. Patient data was collected before and 6 months after the surgery.

At 6 months, patients had a 20% drop from baseline BMIs. Their VAS (visual acuity scores) decreased from 50 mm to 24.5 mm and their scores on the WOMAC (Western Ontario MacMaster) Questionnaire improved. Significant decreases were seen in average serum levels of interleukin-6 (IL-6), which declined by 26%, and of high-sensitivity C-reactive protein (hsCRP), which dropped 46%. Also, weight loss was associated with changes in adipokine levels: Mean serum leptin concentration was decreased by 48% and serum level of adiponectin was increased by 21%, the authors reported.

The average serum level of procollagen type II N-terminal propeptide (PIIANP), a marker of cartilage synthesis, rose 32%, while the serum level of cartilage oligomeric matrix protein (COMP) decreased by 36%. "These results are the first to suggest a benefit of weight loss on both cartilage anabolism and catabolism," the authors wrote.

The researchers found a significant correlation between IL-6 level and WOMAC Questionnaire scores as well as between urinary type II collagen helical peptide (helix-II) and hsCRP. Variation in COMP concentration was significantly correlated with changes in VAS pain scores and WOMAC stiffness score, the authors wrote, adding, "Our findings extend the results of recent work showing a significant association of IL-6 circulating levels and the prevalence and incidence of knee OA."

Since the study was an open exploratory study, it was prone to bias in evaluation of results. Also, the sample size was small. The findings don’t imply causality between variables, "and thus should be carefully interpreted," the researchers wrote. Also, "the effect of changes in insulin resistance related to weight loss on cartilage homoeostasis needs further investigation."

The study was funded by Assistance Publique-Hôpitaux de Paris, Direction of Clinical Research, which promoted and supported the clinical investigation, a grant from the European community, and the Association Rhumatisme et Travail (Hôpital Lariboisière, Paris).

The authors reported no financial conflicts of interest.