Risk factors of loss of reduction after acromioclavicular joint dislocation treated with a hook plate

BACKGROUND: Acromioclavicular joint fixation using a hook plate is effective for the treatment of acute acromioclavicular joint dislocation. However, several studies have reported some complications including loss of reduction after surgery for acromioclavicular joint dislocation. This study aimed to identify the risk factors associated with the loss of reduction after acromioclavicular joint dislocation surgery using a hook plate. METHODS: This was a retrospective study that assessed 118 patients with acromioclavicular joint dislocation, who were diagnosed between March 2013 and January 2019 and underwent surgical treatment using the hook plate (reduction loss group: n = 38; maintenance group: n = 80). The mean follow-up period was 29.9 months (range, 24–40 months). We assessed the range of motion, the American Shoulder and Elbow Surgeons score (ASES), visual analog scale score for pain, and a subjective shoulder value. Radiological assessment of coracoid clavicular distance was performed. The risk factors of reduction loss were analyzed using multivariable logistic regression analysis. RESULTS: Age (p = 0.049), sex (female, p = 0.03, odds ratio OR = 4.81), Rockwood type V (p = 0.049, OR = 2.20), and time from injury to surgery > 7 days (p = 0.018, OR = 2.59) were statistically significant factors in the reduction loss group. There were no significant differences in the clinical outcomes for range of motion, ASES, subjective shoulder value, and visual analog scale scores between the two groups. In the radiological results, preoperative coracoid clavicular distance (p = 0.039) and ratio (p = 0.001), and over-reduction (p = 0.023, OR = 0.40) were significantly different between the two groups. The multivariate logistic regression analysis identified the female sex (p = 0.037, OR = 5.88), a time from injury to surgery > 7 days (p = 0.019, OR = 3.36), and the preoperative coracoid clavicular displacement ratio of the injured shoulder (p < 0.001, OR = 1.03) as risk factors associated with reduction loss following surgery using a hook plate for acromioclavicular dislocation. CONCLUSION: A delayed timing of surgery > 7 days, preoperative coracoid clavicular displacement ratio of the injured shoulder, and female sex were identified as risk factors for loss of reduction after surgery using a hook plate for acromioclavicular joint dislocation. Level of evidence: Level IV; retrospective comparison; treatment study