Does plate-screw density affect the functional outcomes in the treatment of proximal humerus fractures?

BACKGROUND: The aim of the study is to evaluate the relationship between plate-screw density (PSD), functional results, and complication rates in the treatment of proximal humerus fractures (PHFs) with proximal humerus locking anatomical plate (PHLAP). METHODS: Consecutive 43 patients (22 females and 21 males) who underwent PHLAP for the treatment of PHF between 2010 and 2016 were evaluated. AO classifications were used for the classification of fractures. Based on the biomechanical stability theory of Erhardt et al., the patients were divided into two groups as <60% and >60% according to the number of screws fixed to the humeral head for the determination of PSD. The patients were divided into two groups as PSD <60% (n=21) and PSD>60% (n=22) according to the number of screws fixed to the humeral head for the determination of PSD. Functional results were evaluated using the Constant-Murley shoulder score (CMS). Radiological evaluation was performed with collodiaphyseal angle (CDA), varus-valgus angulation, avascular necrosis (AVN), and arthrosis. The groups were compared in terms of demographic characteristics, functional results, radiological scores, and complications. RESULTS: The mean age was 54.47±17.43 years and the mean follow-up time was 19.51±5.27 months. Although the CMS scores of patients with a PSD of over 60% were higher than those below 60%, the CMS score did not differ statistically. In groups, the mean CDA of the operated shoulder was significantly lower than that of the non-injured side (p=0.002). Eight patients had varus angulation, whereas two patients had humerus head AVN. No significant relationship was observed between PDS and functional scores, radiological results, and complications. CONCLUSION: Functional results of PSD >60% are higher than PSD <60% group but there is no statistical difference between groups according to functional, radiological results, and complications.