Structural properties of the intact and the reconstructed coracoclavicularligament complex

Numerous procedures have been described for the operative management of acr omioclavicular joint injuries, but surprisingly little information is avail able on the ultimate mechanical behavior of the native coracoclavicular lig ament complex or on the various methods of reconstruction. We tested 19 fre sh-frozen cadaveric bone-ligament-bone preparations of the coracoclavicular ligament in uniaxial tension at 25 mm/min until failure. Seven specimens w ere left intact, six had the trapezoid ligament sectioned, and six had the conoid ligament sectioned, Reconstruction of the coracoclavicular ligament was achieved using coracoacromial ligament transfers, woven polyester sling s, suture anchors, and Bosworth screws; all reconstructions were also teste d to failure. The intact coracoclavicular ligament failed by avulsion or mi dsubstance tear at 500 (+/-134) N, with a stiffness of 103 (+/-30) N/mm and elongation to failure of 7.7 (+/-1.9) mm. There was no significant differe nce between the contributions of the conoid or trapezoid ligaments in this loading configuration. Coracoclavicular slings and suture anchors provided strength similar to that of the coracoclavicular ligament, but with signifi cantly greater deformations (14 to 26 mm). Screw fixation resulted in compa rable stiffness and superior strength to the coracoclavicular ligament, but only if bicortical purchase was obtained. Coracoacromial ligament transfer s were the weakest and least stiff, and augmentation with another form of c oracoclavicular fixation is recommended. These results provide a useful bas eline for comparison of the initial performance of reconstructive technique s with the performance of the native coracoclavicular ligament.