Biomechanical Evaluation of a Novel Reverse Coracoacromial Ligament Reconstruction for Acromioclavicular Joint Separation

Abstract

Background: Enhancing anterior-posterior (AP) stability in acromioclavicular (AC) reconstruction may be advantageous.Purpose: To compare the initial stability of AC reconstructions with and without augmentation by either (1) a novel “reverse” coracoacromial (CA) ligament transfer or (2) an intramedullary AC tendon graft.Hypothesis: Reverse CA transfer will improve AP stability compared with isolated coracoclavicular (CC) reconstruction.Study Design: Controlled laboratory study.Methods: Six matched pairs of cadaveric shoulders underwent distal clavicle resection and CC reconstruction. Displacement (mm) was measured during cyclic loading along AP (±25 N) and superior-inferior (SI; 10-N compression, 70-N tension) axes. Pairs were randomized to receive each augmentation and the same loading protocol applied.Results: Reverse CA transfer (3.71 ± 1.3 mm, standard error of the mean [SEM]; P = .03) and intramedullary graft (3.41 ± 1.1 mm; P = .03) decreased AP translation compared with CC reconstruction alone. The SI displacement did not differ. Equivalence tests suggest no difference between augmentations in AP or SI restraint.Conclusion: Addition of either reverse CA transfer or intramedullary graft demonstrates improved AP restraint and provides similar SI stability compared with isolated CC reconstruction.Clinical Relevance: Reverse CA ligament transfer may be a reasonable alternative to a free tendon graft to augment AP restraint in AC reconstruction.