Humeral Head Ossification Growth Prediction: Can This Method Be Reproduced?

Radiographically assessing skeletal maturity is of paramount importance to guide appropriate management for patients with adolescent idiopathic scoliosis. The reported advantages of the Humeral Head Ossification System (HHOS) are an even distribution around peak growth age (PGA), the presence of an optimal view of the humeral head in most scoliosis radiographs, and an interobserver and intraobserver reliability of 0.95 and 0.96, respectively. The goal of this study was to determine whether similar reliability could be achieved at an institution other than the one at which the HHOS was originally described.

Six raters used the HHOS to stage the humeral head on 30 deidentified posteroanterior spine radiographs. This process was repeated 2 weeks later. All raters were provided with a document demonstrating the radiographic parameters of each stage, as well as annotations to aid with classification. Intraclass coefficients were calculated. A secondary analysis was then performed grouping stages 1-2 as "pre-PGA" and 3-5 as "post-PGA."

Fair to moderate interobserver and intraobserver reliability was achieved when determining each individual HHOS stage. This improved to good to excellent when the humeral was classified as pre-PGA or post-PGA. Subanalysis did not show any correlation between intraobserver reliability and level of orthopaedic experience.

We found fair to moderate interobserver and intraobserver reliability with the HHOS and this was independent of level of orthopaedic experience. This is much lower than reported by the authors who developed the system, and suggests that the HHOS might not be as easy to incorporate into a scoliosis management algorithm as previously noted. The improved reliability achieved when staging the humeral head as pre-PGA or post-PGA might be the true benefit of this system.

Level III-diagnostic.