Can the proximal humeral ossification system (PHOS) effectively guide brace weaning in patients with adolescent idiopathic scoliosis?

PurposeThe proximal humeral epiphyses can be conveniently viewed in routine spine radiographs. This study aimed to investigate whether the proximal humeral epiphyseal ossification system (PHOS) can be used to determine the timing of brace weaning in adolescent idiopathic scoliosis (AIS), as assessed by the rate of curve progression after brace weaning.MethodsA total of 107 patients with AIS who had weaned brace-wear at Risser Stage >= 4, no bodily growth and post-menarche >= 2 years between 7/2014 and 2/2016 were studied. Increase in major curve Cobb angle > 5 degrees between weaning and 2-year follow-up was considered curve progression. Skeletal maturity was assessed using the PHOS, distal radius and ulna (DRU) classification, Risser and Sanders staging. Curve progression rate per maturity grading at weaning was examined.ResultsAfter brace-wear weaning, 12.1% of the patients experienced curve progression. Curve progression rate for weaning at PHOS Stage 5 was 0% for curves < 40 degrees, and 20.0% for curves >= 40 degrees. No curve progression occurred when weaning at PHOS Stage 5 with radius grade of 10 for curves >= 40 degrees. Factors associated with curve progression were: Months post-menarche (p = 0.021), weaning Cobb angle (p = 0.002), curves < 40 degrees versus >= 40 degrees (p = 0.009), radius (p = 0.006) and ulna (p = 0.025) grades, and Sanders stages (p = 0.025), but not PHOS stages (p = 0.454).ConclusionPHOS can be a useful maturity indicator for brace-wear weaning in AIS, with PHOS Stage 5 having no post-weaning curve progression in curves < 40 degrees. For large curves >= 40 degrees, PHOS Stage 5 is also effective in indicating the timing of weaning together with radius grade >= 10.

Automated summary

The study aimed to determine whether the proximal humeral epiphyseal ossification system (PHOS) can be used to determine the timing of brace weaning in adolescent idiopathic scoliosis (AIS) by assessing the rate of curve progression after brace weaning. The results showed that patients with PHOS Stage 5 had no curve progression after brace weaning, regardless of whether the curve angle was less than or equal to 40 degrees. For curves greater than or equal to 40 degrees, PHOS Stage 5 and a radius grade of 10 were also effective in indicating the timing of weaning.