Effect of Glenohumeral Joint Bone Morphology on Anterior Shoulder Instability: A Case-Control Study.

PURPOSE: Glenohumeral joint compatibility and bone morphology are among the most critical factors in shoulder stabilization. Our study investigated the effect of the bone morphological structure of the shoulder joint on anterior shoulder dislocation.

METHODS: In our study, people with a history of shoulder dislocation were selected as the patient group. In the control group, patients with shoulder MRIs for any reason and no history of shoulder dislocation were included. Those who have a fracture around the shoulder, a congenital deformity in the shoulder region, arthrosis of the shoulder, those whose MRI images cannot be measured, those with Hill-Sachs lesion, connective tissue diseases (such as Ehler Danlos), who are unsure of their diagnosis, or who have incomplete and incorrect suspicious information in their patient file have been excluded. In our retrospective case-control study, glenoid width, glenoid height, glenoid's height-to-width ratio, glenoid's depth, glenoid's version, glenoid's inclination, humerus radius of curvature, glenoid radius of curvature, and bony shoulder stability ratio were measured on MRI images of the patients. The sample size for each group was determined using a power analysis method. The intra-class coefficient (ICC) assessed interobserver and intraobserver reliability.

RESULTS: A total of 80 patients, 40 each in the control and patient groups, were included in the study. Glenoid width was measured as 24.27 ± 1.58 in the patient group, 25.61 ± 1.72 in the control group; glenoid height was as measured 36.49 ± 2.26 in the patient group, 36.74 ± 1.99 in the control group; height-to-width ratio was measured as 1.5 ± 0.08 in the patient group, 1.43 ± 0.05 in the control group; glenoid version was as measured -0.53 ± 1.17 in the patient group, -1.44 ± 1.1 in the control group; glenoid inclination was measured as 1.44 ± 3.93 patient group, 2.64 ± 3.81 in the control group; glenoid depth was measured as 1.69 ± 0.41 in the patient group, 2.12 ± 0.53 in the control group; humerus radius of curvature was measured as 29.70 ± 6.76 in the patient group, 24.98 ± 3.22 in the control group; glenoid axial radius of curvature was measured as 61.8 ± 13.52 in the patient group, 52.53 ± 15.69 in the control group; glenoid coronal radius of curvature was measured as 43.01 ± 7.47 in the patient group, 37.74 ± 6.89 in the control group; the bony shoulder stability ratio was measured as 0.35 ± 0.06 in the patient group and 0.44 ± 0.06 in the control group. In the statistical evaluation, the glenoid width ( p < 0.001), the glenoid height/width ratio ( p < 0.001), the glenoid version ( p < 0.001), the depth of the glenoid cavity ( p < 0.001), and the radius of curvature measurements of the humeral head ( p < 0.001) and the glenoid (axial, p < 0.007; coronal, p < 0.001) were found to be significantly different. Glenoid height and inclination were similar in both groups.

CONCLUSIONS: The detection of bone morphological features that constitute risk factors for shoulder dislocations plays an important role in preventing shoulder dislocations. In this way, it provides essential data on personalized rehabilitation programs and treatment selection for recurrent dislocations.