Biomechanical comparison of acromioclavicular joint reconstructions using coracoclavicular tendon grafts with and without coracoacromial ligament transfer.

PURPOSE: The purpose of this study was to compare the initial strength of acromioclavicular joint reconstructions using coracoclavicular (CC) tendon grafts with and without coracoacromial (CA) ligament transfers.

METHODS: Two different acromioclavicular joint reconstructions were performed in 7 matched pairs of cadaveric shoulders. Paired shoulders were repaired with either a hamstring allograft CC reconstruction (group 1) or a hamstring allograft CC reconstruction plus a CA ligament transfer (group 2). Intact specimens and then reconstructions were cycled from 0 to 100 N at 1 Hz for 100 cycles in a superior direction, and displacements were recorded. Finally, the stiffness of the reconstructions and the ultimate load to failure were recorded.

RESULTS: Superior displacement of the reconstructions after cyclic loading was 4.43 ± 1.82 mm in group 1 and 3.75 ± 1.56 mm in group 2 (P = .38). Ultimate load after load to failure was 970.3 ± 361.03 N in group 1 and 952.7 ± 296.89 N in group 2 (P = .94). Finally, stiffness of the reconstructions was 50.6 ± 6.14 N/mm in group 1 and 65.6 ± 18.45 N/mm in group 2 (P = .12).

CONCLUSIONS: The addition of a transfer of the CA ligament to an acromioclavicular joint reconstruction with a CC hamstring graft does not appear to significantly improve its overall initial biomechanical strength.

CLINICAL RELEVANCE: These data suggest that a CA ligament transfer may add very little to a CC tendon graft reconstruction augmented with high-strength suture with regard to initial, time zero displacement and strength.