LAUSR

BACKGROUND Treatment for proximal humerus fractures remains controversial. Studies of open reduction and internal fixation (ORIF) rarely account for reduction quality, while surgeon experience and sagittal plane reduction remain unstudied. In a retrospective case series analysis of AO/OTA C-type proximal humerus fractures treated with ORIF using a locking plate, we hypothesized that reduction quality would be associated with outcome, and reductions would improve with experience. METHODS We retrospectively identified 41 3- and 4-part proximal humerus fractures treated with ORIF by a single orthopaedic traumatologist. Two blinded traumatologists assessed injury and post-operative radiographs for medial calcar disruption and five measures of deformity. Major complications and functional outcome were assessed. RESULTS Outcome by ASES score was similar to previous reports (mean 73.6, std dev 22.5). Eleven of 35 patients (31.4%) with greater than six months follow-up experienced a complication. Post-reduction sagittal HSa<25° (RR = =9.44, p = =0.024) and medial calcar disruption (RR = =3.82, p = =0.009) were associated with complications. Post-reduction coronal and sagittal HSa improved with experience (p < 0.001 and p = =0.032, respectively) as did the likelihood of overall anatomic reduction (p = =0.006). ROC analysis found a threshold for superior reduction quality after 23 cases (AUC = =0.873, p < 0.001). CONCLUSION Sagittal reduction quality and medial calcar disruption were associated with complications. Additionally, reduction quality improved with experience. Future studies of proximal humerus ORIF should include multiplanar assessments of reduction while accounting for surgeon experience.