Hook plate with or without coracoclavicular ligament augmentation in the treatment of acute acromioclavicular separation

BACKGROUND: Acromioclavicular (AC) separation can be treated with the use of a hook plate. Some studies have reported that coracoclavicular (CC) ligament augmentation is necessary to reduce the complications of hook plate fixation, whereas others recommend hook plate fixation alone without augmentation. The aim of this study was to compare the results and complications between these two groups. METHODS: This was an observational case-control study. Patients with acute (less than 2 weeks) Rockwood type V AC separation were treated with a hook plate at our hospital. A total of 105 cases received hook plate fixation with CC ligament augmentation (group I), and 112 cases received hook plate fixation without augmentation (group II). Constant-Murley scores were used to evaluate the function before and after implant removal, and radiographs were taken to evaluate the complications. The results and complications were compared between groups. RESULTS: Before removal, the Constant-Murley score was significantly higher in group I (mean, 50.1) than in group II (mean, 42.6) (p = 0.004); however, there was no significant difference between groups at 3 and 6 months after removal. The incidence of significant acromion osteolysis was higher in group II (65/112) than in group I (25/105). Before removal, the patients with significant acromion osteolysis had worse Constant-Murley scores than those of the patients without osteolysis in both groups. The incidence of peri-implant fracture of the hook plate was higher in group II (8/112) than in group I (1/105). CONCLUSION: The patients without CC ligament augmentation had worse functional results before hook plate removal, a higher incidence of radiographic acromion osteolysis, and a higher incidence of peri-implant fractures than those patients with CC ligament augmentation. Therefore, CC ligament augmentation is highly recommended to improve short-term outcomes and decrease complications for Rockwood type V AC separation treated by hook plate.