AJSM - 2026-06-02 - Journal Article
Incomplete Restoration of Coracoclavicular Ligament Thickness After Surgical Treatment of Rockwood Type 5 Acromioclavicular Dislocations: A Contralateral-Controlled MRI Study With Functional Outcomes.
Koluman AC, Tingir M, Ziroglu N, Ercin E, Moroder P
Topics
Key Takeaway
After surgical repair of Rockwood Type 5 AC dislocations, trapezoid ligament thickness remains reduced compared to the contralateral side regardless of fixation technique, yet functional outcome scores are favorable and ligament thickness does not correlate with patient-reported outcomes.
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Summary
This contralateral-controlled MRI study evaluated CC ligament morphology and functional outcomes in 46 patients (28 hook plate, 18 EndoButton) after surgical fixation of Rockwood Type 5 AC dislocations. Operated shoulders demonstrated persistently reduced trapezoid and total CC ligament thickness versus the contralateral control side, while conoid thickness was comparable; neither technique restored complete ligament morphology. Despite this, functional scores (VAS, Constant, UCLA, QuickDASH) were favorable across both groups with no clinically meaningful between-group differences, and ligament thickness parameters showed no correlation with patient-reported outcomes.
Key Limitation
The sample size of 46 patients with unequal group allocation (28 vs. 18) is underpowered to detect meaningful between-technique differences in ligament thickness or functional outcomes.
Original 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.