Varus malposition relates to functional outcomes following open reduction and internal fixation for proximal humeral fractures: A retrospective comparative cohort study with minimum 2 years follow-up

Abstract

Background: The aim of this study was to evaluate functional outcomes in patients with varus malposition following open reduction and internal fixation of displaced proximal humeral fractures.

Methods: Data of 685 patients with a mean age of 67±15.8 years (67% female), that were treated by open reduction and internal fixation for a displaced proximal humeral fracture at a level 1 trauma center, were analyzed. On standardized x-ray imaging, the degree of varus displacement was measured over a minimum of two years follow-up and patients were divided into three groups. Group A: anatomic or <10° of varus or valgus malposition, group B: 10-20° of varus malposition and group C: >20° varus malposition, while anatomic head-shaft-angle was defined 135° The groups were compared with regards to functional outcomes by means of the Constant Score (CS).

Results: In 565 patients with anatomic to minor <10° varus or valgus malposition (Group A), the mean CS was 72.5 ± 18.8 points. The %CS to the uninjured side was 87.2 ± 24.1 and the age and gender normalized nCS was 84.7 ± 21.7. In comparison, in group B (10-20° varus) the mean CS was 64.7 ± 16.9, the mean %CS was 84.5 ± 18.3 and the mean nCS was 76.2 ± 20.6. In group C (>20° varus) the mean CS was 54.1 ± 19.5, the mean was %CS: 72.3 ± 26.4 and the mean nCS was 64.8 ± 23.8 (p = 0.02, p = 0.03, p = 0.01). Overall, the CS, %CS and nCS correlated significantly with the degree of varus position (Pearson correlation, r = 0.23, r = 0.21, r = 0.25).

Conclusion: Varus malposition is related to inferior functional outcomes compared to anatomic healing in patients treated by open reduction and internal fixation for proximal humeral fractures. The data supports suggestions to prevent varus malposition in open reduction and internal fixation. In severe >20° of varus malposition, revision surgery should be considered.

Keywords: Complications; Locked plating; Open reduction internal fixation proximal humerus; Proximal humeral fracture; Proximal humerus fracture; Varus dislocation; Varus displacement; Varus malposition.