Pre-operative soft tissue injuries as independent predictors of elbow stiffness after radial head fracture fixation: a pilot study.

Background: Post-operative elbow stiffness is a common and debilitating complication following open reduction and internal fixation for displaced radial head fractures. The relative contributions of post-operative immobilization and intrinsic soft tissue damage remain debated. The purpose of this pilot study was to generate preliminary data on this relationship to inform the design of future, definitive research. Methods: This study retrospectively reviewed 45 patients who underwent open reduction and internal fixation for displaced radial head fractures. Pre-operative magnetic resonance imaging was used to identify injuries to the anterior capsule (AC), posterior band of the medial collateral ligament (pMCL), and lateral collateral ligament complex. Primary outcomes were final range of motion. For descriptive purposes, patients were categorized by immobilization duration (<3 weeks vs. ≥3 weeks). To assess independent predictors of final motion, multivariate linear regression analysis was performed, treating immobilization duration as a continuous variable (in days). Results: No statistically significant differences in final range of motion were found between the short and long immobilization groups. Specific soft tissue injuries were strongly associated with motion loss. AC tears were linked to greater extension loss (mean deficit 15.0° vs. 2.0°, Conclusion: This pilot study provides strong preliminary evidence that specific soft tissue injuries, particularly of the AC and pMCL, are independent predictors of post-operative stiffness, whereas immobilization duration is not. The study was underpowered to definitively rule out a small effect of immobilization. These findings justify the need for a large, multicenter trial to confirm these associations and establish evidence-based post-operative guidelines.