Low BMD Predicts Scoliosis Progression in Adolescents

TORONTO — Low bone mineral density in patients with adolescent idiopathic scoliosis is predictive of worsening of the spinal curvature, according to findings from a new Chinese study presented at a world congress on osteoporosis.

Previous studies have shown that adolescent idiopathic scoliosis (AIS) patients have significantly lower bone mass than do age- and sex-matched controls, but it has not previously been determined whether low bone mineral density (BMD) should be added to the list of risk factors for progression, according to Dr. V.W.Y. Hung of the department of orthopedics and traumatology, Prince of Wales Hospital, the Chinese University of Hong Kong.

In order to address this, researchers enrolled 324 girls with AIS and 276 controls aged 11-16 years in a prospective study. On recruitment, all had lumbar spine and bilateral femoral neck BMD measurements using dual energy x-ray absorptiometry (DXA), and age-adjusted z scores were calculated. Patients with scores of −1 or less were considered to have osteopenia, and progression of the spinal curvature was defined as an increase of 6 degrees on any two sequential spinal x-rays.

The hips were defined as concave and convex according to their relation to the convexity of the spine. For example, if the patient had a right thoracic curve, the right hip was defined as the convex-side hip (J. Bone Joint Surg. 2005;87:2709-16). Clinical and radiographic assessments were done every 6 months.

Mean age at diagnosis was 13.5 years, and the average initial Cobb angle was 24 degrees. The prevalence of osteopenia at the spine and hip was 27.5% and 23.1%, respectively.

Study participants were followed for a mean of 3.5 years. Data on hip BMD, which is considered more reliable than spinal BMD in adolescents, were available for 318 patients.

On logistic regression analysis, low bone mass at the concave side of the femoral neck was found to be a significant factor for scoliosis progression, with an odds ratio of 2.3, Dr. Hung said at the meeting, which was sponsored by the International Osteoporosis Foundation.

Other significant predictors were younger age and premenarcheal status at diagnosis, lower Risser grade, and a greater initial Cobb angle.

Follow-up BMD measurements done at the time skeletal maturity was reached found that low BMD persisted in 85% of AIS patients. Persistently low BMD at skeletal maturity may result in lower peak bone mass and increased risk for fractures later in life, Dr. Hung said.

“This is the first study to show that low bone mass plays an important role in predicting curve progression,” she said. While the cause of low BMD in AIS patients is unclear, some studies have suggested that inadequate calcium intake and insufficient exercise may contribute. These findings suggest that DXA screening might serve as an objective measurement to predict curve progression and might also help physicians predict risk.

TORONTO — Low bone mineral density in patients with adolescent idiopathic scoliosis is predictive of worsening of the spinal curvature, according to findings from a new Chinese study presented at a world congress on osteoporosis.

Previous studies have shown that adolescent idiopathic scoliosis (AIS) patients have significantly lower bone mass than do age- and sex-matched controls, but it has not previously been determined whether low bone mineral density (BMD) should be added to the list of risk factors for progression, according to Dr. V.W.Y. Hung of the department of orthopedics and traumatology, Prince of Wales Hospital, the Chinese University of Hong Kong.

In order to address this, researchers enrolled 324 girls with AIS and 276 controls aged 11-16 years in a prospective study. On recruitment, all had lumbar spine and bilateral femoral neck BMD measurements using dual energy x-ray absorptiometry (DXA), and age-adjusted z scores were calculated. Patients with scores of −1 or less were considered to have osteopenia, and progression of the spinal curvature was defined as an increase of 6 degrees on any two sequential spinal x-rays.

The hips were defined as concave and convex according to their relation to the convexity of the spine. For example, if the patient had a right thoracic curve, the right hip was defined as the convex-side hip (J. Bone Joint Surg. 2005;87:2709-16). Clinical and radiographic assessments were done every 6 months.

Mean age at diagnosis was 13.5 years, and the average initial Cobb angle was 24 degrees. The prevalence of osteopenia at the spine and hip was 27.5% and 23.1%, respectively.

Study participants were followed for a mean of 3.5 years. Data on hip BMD, which is considered more reliable than spinal BMD in adolescents, were available for 318 patients.

On logistic regression analysis, low bone mass at the concave side of the femoral neck was found to be a significant factor for scoliosis progression, with an odds ratio of 2.3, Dr. Hung said at the meeting, which was sponsored by the International Osteoporosis Foundation.

Other significant predictors were younger age and premenarcheal status at diagnosis, lower Risser grade, and a greater initial Cobb angle.

Follow-up BMD measurements done at the time skeletal maturity was reached found that low BMD persisted in 85% of AIS patients. Persistently low BMD at skeletal maturity may result in lower peak bone mass and increased risk for fractures later in life, Dr. Hung said.

“This is the first study to show that low bone mass plays an important role in predicting curve progression,” she said. While the cause of low BMD in AIS patients is unclear, some studies have suggested that inadequate calcium intake and insufficient exercise may contribute. These findings suggest that DXA screening might serve as an objective measurement to predict curve progression and might also help physicians predict risk.

TORONTO — Low bone mineral density in patients with adolescent idiopathic scoliosis is predictive of worsening of the spinal curvature, according to findings from a new Chinese study presented at a world congress on osteoporosis.

Previous studies have shown that adolescent idiopathic scoliosis (AIS) patients have significantly lower bone mass than do age- and sex-matched controls, but it has not previously been determined whether low bone mineral density (BMD) should be added to the list of risk factors for progression, according to Dr. V.W.Y. Hung of the department of orthopedics and traumatology, Prince of Wales Hospital, the Chinese University of Hong Kong.

In order to address this, researchers enrolled 324 girls with AIS and 276 controls aged 11-16 years in a prospective study. On recruitment, all had lumbar spine and bilateral femoral neck BMD measurements using dual energy x-ray absorptiometry (DXA), and age-adjusted z scores were calculated. Patients with scores of −1 or less were considered to have osteopenia, and progression of the spinal curvature was defined as an increase of 6 degrees on any two sequential spinal x-rays.

The hips were defined as concave and convex according to their relation to the convexity of the spine. For example, if the patient had a right thoracic curve, the right hip was defined as the convex-side hip (J. Bone Joint Surg. 2005;87:2709-16). Clinical and radiographic assessments were done every 6 months.

Mean age at diagnosis was 13.5 years, and the average initial Cobb angle was 24 degrees. The prevalence of osteopenia at the spine and hip was 27.5% and 23.1%, respectively.

Study participants were followed for a mean of 3.5 years. Data on hip BMD, which is considered more reliable than spinal BMD in adolescents, were available for 318 patients.

On logistic regression analysis, low bone mass at the concave side of the femoral neck was found to be a significant factor for scoliosis progression, with an odds ratio of 2.3, Dr. Hung said at the meeting, which was sponsored by the International Osteoporosis Foundation.

Other significant predictors were younger age and premenarcheal status at diagnosis, lower Risser grade, and a greater initial Cobb angle.

Follow-up BMD measurements done at the time skeletal maturity was reached found that low BMD persisted in 85% of AIS patients. Persistently low BMD at skeletal maturity may result in lower peak bone mass and increased risk for fractures later in life, Dr. Hung said.

“This is the first study to show that low bone mass plays an important role in predicting curve progression,” she said. While the cause of low BMD in AIS patients is unclear, some studies have suggested that inadequate calcium intake and insufficient exercise may contribute. These findings suggest that DXA screening might serve as an objective measurement to predict curve progression and might also help physicians predict risk.