Association of Coronoid Height Loss with Functional Outcomes in Terrible Triad Injuries Treated Using a Selective Fixation Algorithm

Background: The purpose of this study was to assess whether coronoid fragment size, expressed as coronoid height loss, is associated with functional outcomes in terrible triad injuries treated using a selective coronoid fixation algorithm based on intraoperative elbow stability. Methods: This retrospective cohort study included adult patients with terrible triad injuries treated between 2016 and 2022. All patients underwent preoperative computed tomography evaluation with standardized measurement of coronoid height loss and fracture classification using Mason and Regan–Morrey/O’Driscoll systems. Radial head fixation or arthroplasty and lateral ulnar collateral ligament repair were routinely performed. Coronoid fixation was applied selectively, guided by intraoperative fluoroscopic stability assessment. Patients requiring secondary procedures for stiffness or radial head avascular necrosis were excluded from the final functional analysis, a potential source of attrition bias since these represent treatment failures rather than random missing observations. Functional outcomes at a minimum 24-month follow-up included elbow range of motion, Mayo Elbow Performance Score, and Quick Disabilities of the Arm, Shoulder and Hand score. Results: Functional outcomes were analyzed in 26 patients with coronoid fixation and 23 patients without fixation. Although coronoid height loss was higher in the fixation group, no significant differences were observed in range of motion or clinical outcome scores. Univariable and adjusted regression analyses did not demonstrate a significant association between coronoid height loss and range of motion or functional outcome scores. Findings were unchanged when coronoid fracture classification, determined independently of the continuous height-loss measurement, was used as the exposure variable. Conclusions: In this retrospective cohort, coronoid height loss was not significantly associated with functional outcomes in terrible triad injuries treated using a selective fixation algorithm. These findings suggest that intraoperative stability assessment may help guide coronoid fixation decisions; however, they should not be interpreted as proving that fragment size has no clinical relevance.