Comparative Study of 2 Different Arthroscopic Coracoid Tunnel–free Coracoclavicular Sling Fixation Techniques for the Treatment of Acute High-Grade Acromioclavicular Dislocation

Background: Acromioclavicular (AC) dislocations are common shoulder injuries. Coracoid tunnel–free coracoclavicular (CC) sling fixation techniques using either allograft or Tightrope represent viable treatment options. Purpose: To (1) compare the clinical outcomes of 2 different coracoid tunnel–free CC sling fixation techniques (allograft vs Tightrope) in treating patients with acute Rockwood type 3 and 5 AC dislocations for a minimum of 24-month follow-up and to (2) identify risk factors for loss of reduction (LOR). Study Design: Cohort study; Level of evidence, 3. Methods: We compared patients treated for AC dislocations using CC sling fixation with either allograft or Tightrope. Functional outcomes (visual analog scale, American Shoulder and Elbow Surgeons score, Constant score, and return to sport) were recorded at 12- and 24-month follow-ups. CC distance (CCD) and complications were evaluated at 3, 6, and 12 months postoperatively. Univariate and multivariate analyses were performed to identify risk factors for LOR. Results: Of the 50 patients included, 23 were in the allograft group and 27 in the Tightrope group. Both groups demonstrated significant improvements in functional outcome postoperatively, without significant intergroup differences. Although CCD significantly decreased in both groups, CCD in the Tightrope group was significantly smaller at each follow-up. Compared with CCD immediately after surgery, CCD remained stable in the Tightrope group at 3-month follow-up ( P = .13), whereas it significantly increased in the allograft group ( P = .004.). The allograft group exhibited a significantly higher rate of LOR than the Tightrope group (43% vs 15%; P = .03), heterotopic ossification (48% vs 11%; P = .005), and greater tunnel widening ( P < .001). The trapezoid tunnel ratio was identified as an independent risk factor for LOR in the allograft group (odds ratio, 0.033; P = .017). Conclusion: Despite similar functional outcome, CC sling fixation with Tightrope demonstrated superior maintenance of CCD in the early postoperative stage, a significantly lower rate of LOR and heterotopic ossification and less tunnel widening compared with allograft. Malposition of the trapezoid tunnel was an independent risk factor for LOR in the allograft group.