Decreased orthotic effectiveness in overweight patients with adolescent idiopathic scoliosis

Background: Many studies have demonstrated that orthotic treatment is effective for the prevention of curve progression in patients with adolescent idiopathic scoliosis. However, the effect of being overweight on the outcome of orthotic treatment has not been reported. The purpose of the present study was to determine whether orthotic treatment of adolescent idiopathic scoliosis is less successful for patients who are overweight than it is for those who are not overweight. Methods: A ten-year multicenter retrospective review of patients in whom adolescent idiopathic scoliosis had been treated with a Boston or a custom-molded thoracolumbosacral orthosis was performed. The inclusion criteria were no previous treatment, skeletal immaturity (a Risser sign of 0, 1, or 2), a curve of 25° to 40° at the time of orthotic initiation, and follow-up to skeletal maturity. Patients were divided into two groups according to body habitus, with overweight patients defined as those with a body mass index in the eighty-fifth percentile or greater. Curve progression was compared between the two groups. Successful orthotic treatment was defined as no more than a 5° increase in the primary curve from the start of orthotic wear to skeletal maturity. Absolute curve progression to 45° or greater also was considered to be an adverse outcome. Results: Two hundred and seventy-six consecutive patients from two institutions were analyzed, and thirty-one patients were considered to be overweight. The mean curve progression was 9.6° ± 7.3° for the patients who were overweight, compared with 3.6° ± 9.4° for those who were not overweight (p < 0.01). Overweight patients were 3.1 times more likely to have an unsuccessful result than those who were not overweight. Curve progression to 45° or greater occurred in fourteen (45%) of the thirty-one patients who were overweight, compared with sixty-nine (28%) of the 245 patients who were not overweight. Conclusions: The results of the present study suggest that overweight patients with adolescent idiopathic scoliosis will have greater curve progression and less successful results following orthotic treatment than those who are not overweight. The ability of an orthosis to transmit corrective forces to the spine through the ribs and soft tissue may be compromised in overweight patients. This factor should be taken into consideration when making treatment decisions. Additional study is warranted to determine a threshold effect. Level of Evidence: Therapeutic level III. See Instructions to Authors for a complete description of levels of evidence.