Effect of initial immobilization type on the management of humeral shaft fractures

Objectives The optimal initial immobilization method for humeral shaft fractures remains undefined. This study evaluates whether initial emergency department (ED) immobilization type affects fracture alignment or the likelihood of requiring unplanned surgical intervention. Methods Adult patients (≥18 years) with humeral shaft fractures (OTA/AO 12) treated between May 2018 and July 2023 at a single level I academic trauma center were included. Exclusion criteria were pediatric patients, open fractures (except ballistic injuries), and inadequate pre- or post-immobilization radiographs. Patients were grouped based on initial ED immobilization: posterior long-arm splint (PLA), cuff and collar sling, or coaptation splint/functional brace. The primary outcome was change in coronal and sagittal alignment following initial immobilization. Secondary outcomes included the proportion of patients achieving acceptable alignment (<30° coronal, <20° sagittal angulation) and the rate of unplanned surgical intervention despite an initial non-operative treatment plan. Multivariable regression analyses controlled for confounding variables. Results Sixty-five patients met inclusion criteria (PLA: 22, cuff and collar: 24, functional brace/coaptation splint: 19). Groups were similar in demographics, injury mechanism, and initial alignment. Mean improvement in coronal and sagittal alignment was 8.3° and 7.3°, respectively, with no significant differences between immobilization types (p = 0.732, p = 0.623). Post-immobilization, 86.2 % of patients achieved acceptable alignment (p = 0.148). Among patients initially managed non-operatively, 10.9 % required unplanned surgery, with no significant differences between groups (p = 0.703). Conclusions Initial ED immobilization type does not significantly impact fracture alignment or unplanned surgical intervention. These findings support the feasibility of multiple immobilization methods, allowing patient comfort, resource availability, and cost considerations to guide decision-making.