Clavicular tunnel position is associated with reduction loss after arthroscopic coracoclavicular ligament reconstruction: a computed tomography-based analysis.

Background: Post-operative reduction loss remains a major concern after arthroscopic coracoclavicular ligament (CCL) reconstruction. Although bone tunnel position has been suggested as a contributing factor, most previous studies have relied on plain radiographs, which are limited in evaluating three-dimensional positioning. The purpose of this study was to evaluate clavicular and coracoid bone tunnel positions using computed tomography and to investigate their association with post-operative reduction loss. Methods: This retrospective, single-center study included 22 patients who underwent arthroscopic CCL reconstruction for acute acromioclavicular joint dislocation or distal clavicle fracture with CCL rupture. Post-operative computed tomography with multiplanar reconstruction was used to assess the anteroposterior (AP) and mediolateral (ML) positions of the clavicular and coracoid tunnels. Reduction loss was defined as the percentage increase in coracoclavicular distance at final follow-up relative to the immediate post-operative value. Correlation analyses were performed between tunnel positions and reduction loss. Redisplacement was defined as ≥25% compared with the contralateral side, and clinical outcomes (American Shoulder and Elbow Surgeons, Constant score, and Subjective Shoulder Value) were compared between groups. Results: The ML position of the clavicular tunnel showed a moderate correlation with reduction loss, whereas the AP position of the clavicular tunnel and both ML and AP positions of the coracoid tunnel showed weak or no significant correlation. The overcorrection rate demonstrated a strong correlation with reduction loss, whereas the pre-operative displacement rate showed no significant association. Redisplacement occurred in 7 of 22 patients (31.8%) but was not associated with clinical outcomes. Conclusion: The ML position of clavicular tunnel plays an important role in post-operative stability following arthroscopic CCL reconstruction. In contrast, AP tunnel position and coracoid tunnel position appear to have less influence on reduction loss. Although redisplacement was not associated with clinical outcomes, its relatively high incidence (31.8%) remains a concern. Accordingly, preventing redisplacement remains important, and particular attention should be paid to the ML position of the clavicular tunnel during arthroscopic CCL reconstruction.