Incomplete Restoration of Coracoclavicular Ligament Thickness After Surgical Treatment of Rockwood Type 5 Acromioclavicular Dislocations: A Contralateral-Controlled MRI Study With Functional Outcomes

Abstract

Background: Surgical fixation of Rockwood type 5 acromioclavicular (AC) dislocations can restore coracoclavicular (CC) distance radiographically, but whether the CC ligaments regain their native morphology is unknown.Purpose: To evaluate postoperative CC ligament thickness on magnetic resonance imaging (MRI) compared with the contralateral side and to assess its relationship with functional outcomes.Study Design: Cohort study; Level of evidence, 2.Methods: A total of 46 patients (28 hook plate, 18 EndoButton) with >= 24 months of follow-up received bilateral radiographs and sagittal oblique MRI sequences. CC distance and conoid and trapezoid ligament thickness were measured, with contralateral shoulders serving as individualized controls. Functional outcomes included the visual analog scale, Constant, University of California Los Angeles, and Quick Disabilities of the Arm, Shoulder and Hand scores.Results: Surgical shoulders showed increased CC distance and reduced trapezoid and total CC thickness, whereas conoid thickness was comparable to that of the contralateral side. Neither fixation method achieved complete restoration of CC ligament thickness. Functional scores were favorable across all patients, with no clinically relevant differences between fixation techniques. The overall rate of complications was similar between groups; however, complication patterns differed, with AC arthritis/osteolysis more common after hook plate fixation and implant-related complications more frequent after EndoButton fixation. Ligament thickness parameters did not correlate with patient-reported outcomes.Conclusion: To the authors' knowledge, this is the first contralateral-controlled MRI study to quantify CC ligament thickness after surgical treatment of Rockwood type 5 AC dislocations. Despite incomplete restoration of ligament morphology, functional recovery was favorable, suggesting that clinical recovery may not be strictly dependent on complete anatomic restoration.