Three-dimensional morphological analysis of acromioclavicular joint in patients with and without subacromial erosion after hook plate fixation

OBJECTIVE: To investigate the role of acromioclavicular joint morphology in the presence of subacromial erosion after hook plate fixation. METHODS: We retrospectively analyzed the clinical data of 36 patients (17 men, 19 women; mean age, 48.7 years; range, 21–76 years) treated with hook plate fixation for distal clavicular fractures (n = 20) or acromioclavicular joint dislocation (n = 16) from August 2011 to March 2013. The patients were divided into two groups: the subacromial erosion group (18 patients) and the normal group (18 patients). Differences in multiple anatomical parameters between the two groups were measured and compared. RESULTS: The distal clavicle–acromion angle was significantly larger in the subacromial erosion group (mean, 51.37° ± 5.59°) than in the normal group (mean, 44.20° ± 3.83°), as was the distal clavicle–coronal angle (mean, 25.44° ± 2.51° vs. 21.67° ± 4.06°, respectively). The thickness of the acromion was significantly different between men and women (9.72 ± 1.13 vs. 8.16 ± 1.89 mm, respectively). CONCLUSION: The results of this study indicate that the distal clavicle–acromion angle and distal clavicle–coronal angle are closely correlated with the occurrence of subacromial erosion after hook plate fixation.