The medial collapse sign is associated with cubitus varus after pediatric supracondylar humeral fracture fixation: a retrospective cohort study.

BACKGROUND

Cubitus varus deformity is a common complication following pediatric supracondylar humeral fractures and rarely remodels spontaneously. However, surgeons lack a reliable intraoperative radiographic sign that directly reflects inadequate medial column reduction. This study aimed to evaluate whether the medial collapse sign (MCS) on immediate postoperative anteroposterior radiographs is associated with postoperative cubitus varus.

METHODS

A retrospective cohort study included pediatric patients who underwent surgical treatment for supracondylar humeral fractures consecutively between January 2016 and March 2024. Fifty-two patients treated with reduction and cross pinning and followed for at least 6 months were included. Patients were categorized according to the presence or absence of cubitus varus at final follow-up (n = 20 and n = 32, respectively), which was radiographically defined as a side-to-side carrying-angle difference ≥5° on standing anteroposterior radiographs. Univariable and multivariable analyses were performed using Firth's penalized logistic regression.

RESULTS

Presence of the MCS was strongly associated with cubitus varus (OR 155.4, 95% CI 24.8-1965.5; Holm-adjusted P < .001). MCS remained associated after adjustment for medial cortical comminution (OR 47.5, 95% CI 6.6-590.4, Holm-adjusted P < .001). The large effect size should be interpreted cautiously because of the limited sample size. Sensitivity and specificity were 90.0% and 96.9%, respectively. Interobserver reliability was almost perfect (κ = 0.919).

CONCLUSION

The medial collapse sign is strongly associated with postoperative cubitus varus and may reflect inadequate medial column reduction. Recognition of the same medial cortical morphology on intraoperative fluoroscopy may prompt reassessment of alignment and reduction.

LEVEL OF EVIDENCE: Level III, Retrospective cohort comparison, prognosis study.