Bone mineral accrual in osteopenic and nonosteopenic girls with idiopathic scoliosis during bracing treatment

Study Design. A prospective longitudinal follow-up study. Objectives. To assess the effect of standardized bracing treatment on bone mineral density (BMD) accumulation in girls with adolescent idiopathic scoliosis (AIS) and to analyze the possible influencing factors of BMD accumulation during bracing treatment. Summary of Background Data. The association between osteopenia and AIS has been reported in numerous studies. Although a very recent study argued that bracing did not appear to affect BMD accumulation, the impact of initial bone mineral status on the BMD accrual during the bracing treatment has not been analyzed before. Methods. Using a dual energy radiograph absorptiometer, BMD and BMC measurements were taken initially and with a follow-up after 1 year in the lumbar spine (L2-L4, LS) and femoral neck ( FN) of the non-dominant side on AIS girls who were treated with braces. Differences in bone mineral accrual in initially osteopenic and nonosteopenic AIS girls were analyzed. The BMD accumulation rates were correlated with maturity status at entry, the anthropometric data, and the duration of bracing. Results. Forty-nine patients with AIS were included. At entry, osteopenia was found in 16 and 14 girls at the site of LS and FN, respectively. After an average duration of 1.1 years brace treatment, more than 94% of AIS girls had a positive bone mineral accrual. The annual accumulation rates of LS-BMD and FN-BMD were 0.054 g/(cm(2).yr) and 0.076 g/(cm(2).yr) respectively, and both were similar initially in osteopenic and nonosteopenic patients. Neither the total nor the daily bracing time correlated significantly with the accumulation rates at either site. The annual accumulation rate of LS-BMD was found to be inversely correlated with maturity at entry whereas positively correlated with changes in height and weight. Conclusion. It is concluded that nearly all of AIS girls had positive bone mineral accrual at LS and FN during over-1-year brace treatment. Brace treatment and the initial bone mineral status may not play important roles in the BMD accumulation. Growth potential of AIS patients is one of the key factors influencing bone mineral accrual during brace treatment.