The relationship between humeral head angulation and bone void within the humeral head in proximal humerus fractures

The variability of humeral head angulation in proximal humerus fractures (PHFs) is a noteworthy observation. The purpose of this study was to investigate the potential association between humeral head angulation and bone void within the humeral head in PHFs. We used the reconstruction function in Mimics software to generate three-dimensional models of fractures. Bony landmarks were employed to accurately define the calcar and humeral head zone. Boolean subtraction was performed to calculate the volume of head bone void. The cohort consisted of 60 (74.1 %) varus, 21 (25.9 %) valgus, and 23 (22.1 %) neutral angulated PHFs. The mean percentage of humeral head bone void was 38.5 ± 17.8 in varus, 36.3 ± 15.7 in valgus, and 30.1 ± 10.6 in neutral angulated PHFs. A significant difference was observed between the varus and neutral groups (P = 0.035). In addition, an analysis of humeral head bone void was conducted among patients aged over 65 years old, revealing a mean percentage of 42.7 ± 16.4 in varus (27 cases), 34.8 ± 14.5 in valgus (13 cases), and 28.1 ± 11.8 in neutral (8 cases) angulated PHFs. The difference between the varus and neutral groups was also significant (P = 0.023). All types of angulation patterns exhibited humeral head bone void to some extent, with the varus-displaced PHFs demonstrating more obvious defects in comparison to the neutral angulated type. •All kinds of angulation patterns showed bone void within the humeral head to varying degrees.•Bone void was more pronounced in varus-displaced as compared to the neutral angulated type PHFs.•Incorporation of bone grafting techniques within the humeral head region may be necessary for patients with osteoporotic bone structure.