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.