Stability of acromioclavicular joint reconstruction - Biomechanical testing of various surgical techniques in a cadaveric model

Background: Despite reports of excellent results with the Weaver-Dunn coracoacromial ligament transfer, many authors recommend augmenting the transfer with supplemental fixation. The authors of this study sought to determine whether there is a biomechanical basis for this assertion and which augmentative method, if any, most closely restored acromioclavicular motion to normal. Hypothesis: Augmentative coracoclavicular fixation provides better restoration of normal acromioclavicular joint laxity and an increased failure load when compared with the Weaver-Dunn reconstruction alone. Study Design: Controlled laboratory cadaveric study. Methods: Native acromioclavicular joint motion was measured using an infrared optical measurement system. Acromioclavicular and coracoclavicular ligaments were then cut, and 1 of 6 reconstructions was performed: Weaver-Dunn, suture cerclage, and 4 different suture anchors. Acromioclavicular joint motion was reassessed, a cyclic loading test was performed, and the failure load was recorded. Results: After Weaver-Dunn reconstruction, mean anteroposterior laxity increased from 8.8 +/- 2.9 mm in the native state to 41.9 +/- 7.6 mm (P less than or equal to .01), and mean superior laxity increased from 3.1 +/- 1.5 mm to 13.6 +/- 4.4 mm (P less than or equal to .01). Weaver-Dunn reconstructions failed at a lower load (177 +/- 9 N) than all other reconstructions (range, 278-369 N) (P less than or equal to .05). Reconstruction using augmentative fixation allowed less acromioclavicular motion than Weaver-Dunn reconstruction (P less than or equal to .05) but more motion than the native ligaments (P less than or equal to .05). Specifically, mean superior laxity after reconstruction ranged between 6.5 and 9.0 mm compared with the native ligaments (3.1 +/- 1.5 mm) and the Weaver-Dunn reconstructions (13.6 +/- 4.4 mm). Mean anteroposterior laxity after the reconstructions tested ranged between 21.8 and 33.2 mm, compared with the native ligaments (8.8 +/- 2.9 mm) and the Weaver-Dunn reconstructions (41.9 +/- 7.6 mm). Conclusion: Although none of the augmentative methods tested restored acromioclavicular stability to normal, all proved superior to the Weaver-Dunn reconstruction alone. Clinical Relevance: This study suggests that when performing acromioclavicular reconstruction, supplemental fixation should be used because it provides more stability and pull-out strength than the Weaver-Dunn reconstruction alone.