The Effect of Night-time versus Full-time Bracing on the Sagittal Profile in Adolescent Idiopathic Scoliosis

Study Design. Retrospective multicenter cohort study Objective. To investigate the impact of night-time bracing (NTB) and full-time bracing (FTB) on the sagittal profile in adolescent idiopathic scoliosis (AIS) patients. Summary of background data. Recent studies have shown that FTB in AIS patients may induce hypokyphosis. Whether this effect differs between NTB and FTB is unknown. Methods. We included skeletally immature AIS patients with main curves ranging from 20-45° treated with either NTB or FTB. The two cohorts were propensity-score matched on Risser stage, age, major curve size, and kyphosis at brace initiation. Coronal and sagittal radiographic parameters were gathered at the initiation and completion of brace treatment. Results. Two-hundred fifty-seven patients were eligible for inclusion. The matched cohorts included 62 patients in each group. During bracing, the thoracic kyphosis increased from 31±11° to 35±13° in the NTB group compared to a decrease from 30±12° to 28±13° in the FTB group ( P =0.011). Eight percent were hypokyphotic (<20°) after bracing in the NTB group compared to 24% in the FTB group ( P =0.015). Pelvic incidence, sacral slope, and pelvic tilt were not significantly different between the groups. In the coronal plane, curve progression >50° was seen in 50% in the NTB group and 31% in FTB ( P =0.028). Conclusion. We saw a small increase in thoracic kyphosis in the NTB group vs. a small decrease in the FTB group. Eight percent in the NTB group vs 24% in the FTB group showed substantial hypokyphosis after bracing. The impact of minor changes in thoracic kyphosis remains uncertain; however, a threefold difference in the occurrence of hypokyphosis is notable and merits further attention.