Long-term clinical and radiographic outcomes after locking plate fixation of proximal humerus fractures: a 6-year follow-up study

Locking plate fixation is widely used for the treatment of displaced proximal humerus fractures; however, robust long-term data regarding its function and late complications remain limited. We report 6-year clinical and radiographic outcomes of locking plate fixation, including data regarding the relationship between avascular necrosis (AVN), post-traumatic osteoarthritis (PTA), and shoulder function.

Between 2017 and 2019, 31 consecutive patients (21 women, 10 men; mean age, 63 years) with displaced proximal humerus fractures underwent fixation with a locking plate. Follow-up data were obtained at 3, 12, and 72 months. The fractures were classified using the Neer classification system (9 patients with 2-part fractures, 16 with 3-part fractures, and 6 with 4-part fractures). Functional outcomes were assessed using the Constant score. Radiographs were evaluated for AVN (y/n) and PTA (y/n). Reoperations and complications were also recorded.

At 72 months, the mean Constant score was 66.2, with no improvement beyond 12 months. AVN occurred in 19% of patients and PTA in 34% of patients. Despite marked radiographic changes, the patients with AVN showed better shoulder function than those with PTA (P < .05). Reoperations were required in 32% of patients at a mean of 11 months and were most commonly implant removal with or without arthrolysis.

Long-term function after locking plate fixation is moderate and plateaus after one year. Although radiographically severe, AVN does not necessarily impair shoulder function. In contrast, PTA is associated with progressive functional decline. These findings emphasize the importance of differentiating between necrotic and degenerative radiographic sequelae and of carefully tailoring the indication for locking plate fixation, particularly in complex fracture patterns.