Quantitative 3-dimensional computerized tomography modeling of isolated greater tuberosity fractures with and without shoulder dislocation

Background: The aim of this study was to assess differences in fracture morphology and displacement between isolated greater tuberosity (GT) fractures (i.e. fractures of the greater tuberosity without other fractures of the proximal humerus) with and without shoulder dislocation utilizing quantitative 3-dimensional CT imaging. Methods: Thirty-four CT-scans of isolated greater tuberosity fractures were measured with 3-dimensional modeling. Twenty patients (59%) had concomitant dislocation of the shoulder that was reduced prior to CT-scanning. We measured: degree and direction of GT displacement, size of the main fracture fragment, the number of fracture fragments, and overlap of the GT fracture fragment over the intact proximal humerus. Results: We found: (1) more overlap -over the intact humerus- in patients without concomitant shoulder dislocation as compared to those with shoulder dislocation (P=0.03), (2) there was a trend towards greater magnitude of displacement between those without (mean 19mm) and those with (mean 11mm) a concomitant shoulder dislocation (P=0.07), and (3) fractures were comparable in direction of displacement (P=0.50) and size of the fracture fragment (P=0.53). Conclusion: We found substantial variation in degree and direction of displacement of GT fracture fragments. Variation in degree of overlap and displacement is partially explained by concomitant shoulder dislocation.