Greater tuberosity fractures are not a continuation of Hill-Sachs lesions, but do they have a similar etiology?

Background: It is unclear whether greater tuberosity fractures (GTF) in the setting of a shoulder dislocation are due to an avulsion of the rotator cuff or a result of an extensive Hill-Sachs lesion (HSL). To explore whether these lesions have similar etiology, the primary aim of this study is to compare the postinjury morphology of the proximal humerus after GTF and HSL. Methods: Computed tomography scans of 19 patients with HSL and 18 patients with GTF after first-time shoulder dislocations were analyzed. We assessed the location by measuring height in relation to the highest point of the humerus and angles for the origin (most medial point of lesion), center, and endpoint (most lateral point of lesion) between GTF and HSL and the bicipital groove. For both GTF and HSL, we assessed whether infraspinatus and supraspinatus insertions were involved and whether they were off-track or on-track. Results: Measured from the bicipital groove, HSLs and GTFs have different origins (153˚ vs. 110˚; P <.0001, respectively), centers (125˚ vs. 60˚; P <.0001, respectively), and endpoints (92˚ vs. 37˚; P <.0001, respectively). HSLs had a higher position (0.76 cm vs. 1.71 cm; P <.0001), involved the supraspinatus footprint less often (16% vs. 72%; P =.0008), and were less likely to be off-track (31% vs. 94%; P =.0002). Half of the GTF were on the lateral side of the glenoid track and thus extra-capsular, versus 0% of HSL. Conclusion: HSLs and GTFs have different anatomical characteristics and thus GTFs are likely to be distinct from extensive HSLs.