Clinical and Radiographic Outcomes of Head-Preserving Plate Fixation for Four-Part Posterior Fracture-Dislocations of the Proximal Humerus

Four-part posterior fracture-dislocations of the proximal humerus are rare and severe injuries associated with a substantial risk of humeral head osteonecrosis and functional impairment, while evidence regarding outcomes after head-preserving fixation remains limited. This study aimed to evaluate the clinical, functional, and radiographic outcomes of head-preserving plate fixation in this injury pattern. This retrospective case series included five patients with seven four-part posterior fracture-dislocations treated with open reduction and plate osteosynthesis. Functional outcomes were assessed using the UCLA, Constant–Murley, SPADI, and ASES scores, while radiographic outcomes included avascular necrosis (AVN) according to the Cruess classification and glenohumeral osteoarthritis according to the Samilson–Prieto classification. The mean follow-up was 53.7 ± 42.2 months. Mean UCLA, Constant–Murley, SPADI, and ASES scores were 18.9 ± 8.3, 45.1 ± 7.7, 41.6 ± 17.8, and 63.4 ± 20.7, respectively. Radiographic AVN (Cruess stage ≥ II) was present in six of seven shoulders (85.7%), including two stage III and four stage IV shoulders. All shoulders demonstrated Samilson–Prieto grade I or II changes. Three shoulders underwent reoperation, including one conversion to reverse shoulder arthroplasty. Head-preserving fixation was associated with heterogeneous functional outcomes and frequent structural deterioration, although advanced radiographic deterioration did not invariably result in conversion to arthroplasty.