Paper 39: Overreduction of Type V Acromioclavicular Joint Dislocations During Acute Fixation is Associated with Improved Postoperative Rockwood Classification
Authors: Feeley Scott , Pluta Natalia , Colantonio Donald , Panarello Nicholas , Harrington Colin , Dickens Jonathan , Kilcoyne Kelly 
Published: August 2024

Objectives: Loss of reduction is a common postoperative complication following fixation for acromioclavicular joint (ACJ) dislocations with previously identified surgical risk factors in small military cohorts. However, those studies did not include isolated suspensory fixation or examine the effect of intraoperative overreduction. Therefore, the purpose of this study was to evaluate loss of reduction after acute fixation and risk factors associated with loss of reduction for Rockwood Type V ACJ dislocations in a young, active population with different fixation methods. Methods: We performed a retrospective cohort study of patients in the Military Health System who underwent coracoclavicular (CC) ligament repair or reconstruction between October 2013 and March 2020. Patients were included if they sustained a Type V ACJ dislocation and were treated acutely, defined as within 6 weeks. We excluded patients for inadequate pre- or postoperative imaging, less than 1 year follow-up, if a hookplate was used for fixation, pre- or postoperative fracture, or reoperation for infection or hardware removal. We reviewed the electronic health records to collect patient demographics and operative technique. Radiographs were analyzed for two measures of loss of reduction, known risk factors for loss of reduction, and overreduction of the ACJ during surgery. We defined radiographic loss of reduction as an increase in CC distance of 6 mm. Clinical loss of reduction was defined as a Rockwood grade greater than two on final imaging. We defined overreduction as the inferior border of the clavicle being inferior to the inferior aspect of the acromion and measured this difference. The primary outcome was loss of reduction. Secondary outcomes included return to duty and complications. We statistically analyzed risk factors for loss of reduction using Student t-tests, ANOVA, and logistic regression. Univariate analysis was performed with Fisher’s exact tests and logistic regression. Results: 183 patients met inclusion and exclusion criteria with a mean age of 28.6 years (SD 8.1), were 94.5% male, and 92.3% active duty. Repair occurred in 99 (54.1%). Mean time to surgery was 11.8 days (SD 9.0) from injury. Isolated suspensory fixation occurred in 91 (49.7%) patients, 47 (25.7%) were suspensory fixation with graft reconstruction, and 37 (20.2%) were isolated graft reconstruction. There was a statistically significant difference in time to surgery based on fixation type with means of 9.0 days for isolated suspensory fixation, 14.0 days for isolated graft reconstruction, and 18.1 days for suspensory fixation with graft reconstruction. Overall radiographic loss of reduction rate was 37.2%. The procedural CC distance change was the only significant variable identified on univariate analysis for radiographic loss of reduction (p=0.005). Risk factors for radiographic loss of reduction are in Table 1. Fixation type was not a statistically significant risk factor for radiographic loss of reduction on logistic regression. At the time of surgery, 55 (30.0%) were overreduced beyond a Rockwood Type I by a mean 5.2 mm (SD 2.4). With the clinical loss of reduction definition, overreduction had an odds ratio of 0.14 (CI 0.015-0.60, p=0.002) for a Rockwood Type 3 or greater at final imaging. Risk factors for clinical loss of reduction are in Table 2. Reoperation for pain or loss of reduction occurred in 9 patients (4.9%) and medical discharge occurred in 5 cases (2.7%). Conclusions: In a young, active population with Type V ACJ dislocation treated acutely, a high percentage lost reduction yet still returned to duty. AC joint overreduction was not protective for loss of reduction when defined as a radiographic CC distance increase of 6mm. Patients that were overreduced at time of fixation were seven times more likely to maintain reduction clinically, defined as a Rockwood Type II or less postoperatively. Surgeons should consider overreduction at the time of fixation to decrease the rate of clinically important loss of reduction, regardless of time to surgery.