Adolescent idiopathic scoliosis: is there a relationship between Risser staging and the proximal humerus ossification system?

PURPOSE

To evaluate whether there is a mismatch between Risser staging and the proximal humerus ossification system (PHOS); and to analyze the correlation in the skeletal maturity stages between the two humeral epiphyses.

METHODS

Data from patients aged 10 to 18 years with adolescent idiopathic scoliosis (AIS) seen between 2018 to 2021 were analyzed. In an anteroposterior (AP) spine radiograph the ossification process was evaluated using the Risser classification method and bilateral PHOS (if both humeral epiphyses were visualized). A mismatch between methods was defined as a Risser 0-1 (relatively skeletally immature) with a PHOS 4-5 (skeletally mature), or a Risser 2-5 (relatively skeletally mature) with a PHOS 1-3 (skeletally immature). The McNemar test was used to calculate the significance of the mismatch.

RESULTS

A mismatch between Risser and PHOS stages was observed in 28.5% of 105 patients, which was statistically significant (p < 0.001). Of the 49 patients with a Risser 0-1, 55.1% (n = 27) had a PHOS 4-5. None of the patients with a Risser 2-5 had a PHOS 1-3. In the 47 patients in whom both humeri were visualized, the absolute correlation between the left and right PHOS values was 95.7%.

CONCLUSION

Of AIS patients who are relatively skeletally immature according to Risser staging, more than half may be skeletally mature when measured with PHOS. In patients with a Risser 0-1, it is recommended to measure skeletal maturity in an AP spine radiograph using the PHOS method, which may more accurately guide treatment decision-making, without the need to visualize both humeral epiphyses in this radiographic projection.

LEVEL OF EVIDENCE

IV.

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

PURPOSE

The 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.

METHODS

A 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° 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.

RESULTS

After 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°, and 20.0% for curves ≥ 40°. No curve progression occurred when weaning at PHOS Stage 5 with radius grade of 10 for curves ≥ 40°. Factors associated with curve progression were: Months post-menarche (p = 0.021), weaning Cobb angle (p = 0.002), curves < 40° versus ≥ 40° (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).

CONCLUSION

PHOS 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°. For large curves ≥ 40°, PHOS Stage 5 is also effective in indicating the timing of weaning together with radius grade ≥ 10.

Modification and application of the proximal humerus ossification system to adolescent idiopathic scoliosis patients

PURPOSE

We have previously demonstrated that proximal humeral ossification patterns are reliable for assessing peak height velocity in growing patients. Here, we sought to modify the system by including medial physeal closure and evaluate whether this system combined with the Cobb angle correlates with progression to surgery in patients with adolescent idiopathic scoliosis.

METHODS

We reviewed 616 radiographs from 79 children in a historical collection to integrate closure of the medial physis into novel stages 3A and 3B. We then analyzed radiographs from the initial presentation of 202 patients with adolescent idiopathic scoliosis who had either undergone surgery or completed monitoring at skeletal maturity. Summary statistics for the percentage of patients who progressed to the surgical range were calculated for each category of humerus and Cobb angle.

RESULTS

The intra-observer and inter-observer ICC for assessment of the medial physis was 0.6 and 0.8, respectively. Only 3.4% of radiographs were unable to be assessed for medial humerus closure. The medial humerus physis begins to close about 1 year prior to the lateral physis and patients with a closing medial physis, but an open lateral physis were found to be the closest to PHV (0.7 years). Stratifying patients by Cobb angle and modified humerus stage yield categories with low and high risks of progression to the surgical range.

CONCLUSION

The medial humerus can be accurately evaluated and integrated into a new modified proximal humerus ossification system. Patients with humerus stage 3A or below have a higher rate of progression to the surgical range than those with humerus stage 3B or above.