Predictive factors for functional outcome and failure in angular stable osteosynthesis of the proximal humerus

Angular stable osteosynthesis has become the gold standard in the operative treatment of proximal humeral fractures. The aim of this article is to determine the indications for osteosynthesis versus primary arthroplasty based on clinical and radiological parameters.

A total of 368 surgically treated proximal humeral fractures were reviewed. Preoperative X-rays were used to evaluate the displacement and vascularity of the humeral head (according to the Hertel criteria) and the AO (Arbeitsgemeinschaft für Osteosynthesefragen) fracture type. Postoperative X-rays were analysed to assess the quality of the reduction, the reconstruction of the medial hinge and the displacement of the tuberosities. Follow-up X-rays were used to evaluate healing progress, the occurrence of avascular necrosis, loss of reduction and implant related failures. The American Shoulder and Elbow Surgeons score (ASES score) was used to evaluate the functional outcome. Correlations between a set of variables, type of treatment and eventual outcome were verified in both univariate and multivariate settings, with the significance rate set at p<0.05.

In total, 307 shoulders were evaluated. Mean follow-up was 4.3 years and showed a 15.3% failure rate, a 23.8% re-operation rate and a mean ASES score of 75.3. Better results were noted in patients who were younger at the time of surgery. More displaced fractures, AO type C fractures, varus fracture configuration and reduced head vascularity all led to a worse outcome. Anatomical reduction correlated with better results. Articular fractures had better results when treated with a plate.

Surgical treatment of proximal humeral fractures remains difficult, with a failure rate of 15.3% and a re-operation rate of 23.8% at 4.3 years. A significantly displaced varus articular fracture in the older patient results in the worst outcome.