Variation of angle velocity during the pubertal growth peak and its influence on bracing outcome in brace-wearing idiopathic scoliosis patients

English Keywords:Adolescent idiopathic scoliosis  Peak growth velocity  Curve progression  Bracing outcome

English Abstract:

  【Abstract】 Objectives: To analyze the pubertal growth parameters and the variation of angle velocity(AV) during the pubertal growth peak in brace-wearing idiopathic scoliosis(IS) patients, and to analyze the difference in bracing outcome between patients with alleviative and positive AV as well as the difference in pubertal growth parameters between patients with successful and failed bracing outcomes. Methods: 35 physically immature braced IS girls with open triradiate cartilage were evaluated every three to six months through their growth spurt until brace wearing or surgery. Serial measurements of Cobb angle and multi-dimensional maturity indicators involving chorological age, triradiate cartilage, Risser sign, height, spinal length and distal radius and ulnar(DRU) classification were recorded. The timing and magnitude of peak height growth velocity(PHGV) and peak spinal growth velocity(PSGV) were identified and compared between the failed and successful brace group. The AV fluctuated by onset of PSGV was also defined as alleviative if the AV was negative, otherwise it was positive. The bracing outcome was defined as failed if curve progression ≥5° or needing surgical intervention(>40°). Results: The average age and Cobb angle at initial visit were 10.2±1.5 years(8-12.5 years) and 26.5°±5.0°(20°-38°), while the average values changed to 15.3±2.2 years(12-18 years) and 34.0°±12.6°(9°-59°) at last follow-up, respectively. There were 20 and 15 patients undergoing Milwaukee and Boston braces, respectively. The average follow-up period was 5.1±2.1 years(4.0-6.2 years). Bracing treatment through the pubertal growth spurt demonstrated the successful and failure rate of 42.9% and 57.1% respectively. Patients in the failed group had older PHGV and PSGV ages, greater Cobb angle at last follow-up, higher ratio of thoracic curve and AV at PSGV than patients in the successful group(P<0.05). No difference was found in the magnitude of PHGV and PSGV, or initial Cobb angle(P>0.05). Onset of PSGV triggered the occurrence of positive and alleviative AV in 45.7% and 54.3% of the patients. The alleviative AV group had lower incidence of failed brace treatment, surgical rate, AV at PSGV and Cobb angle at last follow-up as compared with the positive AV group(P<0.05). Conclusions: The AV at pubertal spurt is significantly correlated with bracing outcome. Bracing prescribed before pubertal spurt is associated with higher risk of failed brace treatment, especially for those with relatively advanced onset of growth spurt, positive AV by growth peak and curve pattern being major thoracic scoliosis.