Role of the triradiate cartilage in predicting curve progression in adolescent idiopathic scoliosis.

Braces are commonly used to treat progressive adolescent idiopathic scoliosis. Several previous studies have reported a correlation between the success of brace treatment and skeletal maturity markers. These studies have not focused on the status of the triradiate cartilage (TRC) as it relates to successful brace treatment for adolescent idiopathic scoliosis. The authors retrospectively evaluated all patients at their institution from 1990 to 1997 with a diagnosis of adolescent idiopathic scoliosis who were treated in a Boston brace. Sixty-two patients met inclusion criteria. At presentation, the average age was 12.87 years, the average Risser sign was 0.56, and 45% of patients had an open TRC. The average follow-up was 2.92 years. Greater than 5 degrees of progression at discontinuation of bracing was considered a failure. Curves with a closed TRC failed bracing 21% of the time, whereas those with an open TRC failed 54% of the time (P = 0.0069). Those curves with a closed TRC progressed 3.12 degrees on average, whereas curves with an open TRC progressed 6.86 degrees. Curves associated with a closed TRC at initiation of bracing progressed less frequently and to a lesser degree than those associated with an open TRC (P = 0.027). Although the TRC is not an independent predictor of curve stability, it is an additional indicator of skeletal maturity and may prove most useful in patients with otherwise borderline indications for brace treatment.