The Impact of the Position of the Humeral Head Relative to the Glenoid on Iatrogenic Fractures During Shoulder Dislocation Reduction

Background and Objectives: The aim of this study was to investigate the relationship between the position of the humeral head relative to the glenoid and the occurrence of iatrogenic surgical neck fractures of the humerus during anterior glenohumeral dislocation reductions. Materials and Methods: Patients with first-time anterior shoulder dislocations without generalized joint hyperlaxity were included. The humeral head displacement ratio was calculated as the distance between the medial border of the humeral head and the anterior glenoid rim divided by the diameter of the humeral head. Demographic data, concomitant tuberculum majus fractures, and the deltoid tuberosity index were recorded. Patients were divided into three groups: Group 1 (iatrogenic fracture development during closed reduction (CR)), Group 2 (failed CR), and Group 3 (successful reduction without iatrogenic fracture). Complicated dislocations were included in Groups 1 and 2, while uncomplicated dislocations were those in Group 3. Results: The study included 89 patients with a mean age of 46.44 ± 19.02 years (64 males, 25 females). Concomitant tuberculum majus fractures occurred in 37 (41.6%) cases. Iatrogenic surgical neck fractures occurred in 10 patients (Group 1), and CR was unsuccessful in 8 patients (Group 2), totaling 18 cases of complicated dislocations. Reduction without iatrogenic fracture was achieved in 71 cases (Group 3). The mean humeral head displacement ratio was higher in the complex dislocation group (92.91 ± 15.34 vs. 75.01 ± 13.80; p < 0.001). Complicated dislocations were more frequent in patients with tuberculum majus fractures (p = 0.031). Subgroup analysis showed higher humeral head displacement ratios in Groups 1 and 2 compared to Group 3 (p = 0.010 and p = 0.06, respectively). Tuberculum majus fractures were more frequent in Group 1 compared to Group 3 (p = 0.013), with no significant difference between Groups 2 and 3. Conclusions: In patients experiencing first-time traumatic anterior shoulder dislocations, a greater medial displacement of the humeral head relative to the glenoid rim significantly increases the risk of iatrogenic humeral fractures and the likelihood of unsuccessful closed reduction attempts.