Temporal patterns of redisplacement risk following nonoperative treatment of pediatric supracondylar humeral fractures: A retrospective cohort study

Background: Although risk factors for redisplacement after nonoperative treatment of pediatric supracondylar humeral fractures (SCHFs) are well described, the temporal distribution of this risk remains poorly understood. This study investigated temporal patterns of redisplacement and identified independent predictors using time-to-event analysis. Methods: = 76) SCHFs managed with closed reduction and custom-molded triplanar splinting between September 2020 and August 2023. Type III fractures were included only when fluoroscopic stress testing confirmed post-reduction stability. Redisplacement was assessed radiographically and analyzed using Kaplan-Meier and Cox regression methods. Results: Redisplacement occurred in 39 patients (17.9%). Cumulative incidence demonstrated a nonlinear temporal pattern, with most events occurring early after reduction: 87% within the first 14 days, with apparent peaks at days 3-4 and 7-14. In multivariable analysis, initial lateral displacement percentage >85% (hazard ratio [HR] 3.52, 95% confidence interval (CI): 1.82-6.83) and severe soft-tissue swelling (HR 3.08, 95% CI: 1.61-5.89) were independently associated with redisplacement, whereas Gartland classification was not. Conclusions: Redisplacement risk after nonoperative management of pediatric SCHFs appears concentrated in early post-reduction periods. Displacement magnitude and severity of soft-tissue swelling may provide more clinically relevant prognostic information than fracture classification alone. The observed temporal pattern may be influenced by discrete follow-up intervals and requires prospective validation.