Is horizontal stabilization necessary in chronic acromioclavicular reconstructions?

Background: The role of horizontal acromioclavicular (AC) stabilization in chronic AC dislocation reconstructions remains uncertain. While commonly used techniques focus on coracoclavicular (CC) ligament reconstruction, the potential benefit of adding horizontal AC stabilization has not been clearly established. The aim of this study was to evaluate whether horizontal AC stabilization in chronic AC dislocations treated with CC ligament reconstruction improves clinical outcomes, reduces failure, complications, or revisions, and enhances radiographic reduction. Methods: A retrospective multicenter study included 209 patients (mean age 44.5 ± 14.1 years, 90.9% male) who underwent CC ligament reconstruction (Weaver-Dunn, anatomic biologic reconstruction, or synthetic ligament) between 2006 and 2024. Patients were stratified according to the addition of horizontal AC stabilization. Primary outcome was the Constant score at final follow-up. Secondary outcomes included Subjective Shoulder Value, visual analog scale pain, radiographic AC distance, failures, complications, and revisions. Multivariate linear regression and 1:1 propensity score matching were performed. Conclusion: Horizontal AC stabilization in chronic AC dislocations treated with CC ligament reconstruction does not significantly improve clinical outcomes or reduce failures, but it appears to lower complication rates and provide superior radiographic reduction. These results suggest a potential stabilizing benefit of horizontal AC fixation, although further prospective studies are needed to validate its clinical relevance.