Anatomical acromioclavicular ligament reconstruction: A biomechanical comparison of reconstructive techniques of the acromioclavicular joint

Background: Current surgical treatments for acromioclavicular separations do not re-create the anatomy of the acromioclavicular joint. Hypothesis: Anatomical acromioclavicular reconstruction re-creates the strength of the native acromioclavicular joint and is stronger than a modified Weaver-Dunn repair. Study Design: Controlled laboratory study. Methods: The native acromioclavicular joint in 6 fresh-frozen cadaveric upper extremities was stressed to failure under uniaxial tension in the coronal plane. A modified Weaver-Dunn procedure, anatomical acromioclavicular reconstruction using a palmaris longus graft, and anatomical acromioclavicular reconstruction using a flexor carpi radialis graft were then performed sequentially. Each repair was stressed to failure. Load-displacement curves and mechanism of failure were recorded for each. Results: Loads at failure for the native acromioclavicular joint complex, modified Weaver-Dunn procedure, anatomical acromioclavicular reconstruction using a palmaris longus tendon graft, and anatomical acromioclavicular reconstruction using a flexor carpi radialis tendon graft were 815 N, 483 N, 326 N, and 774 N, respectively. The strength of the native acromioclavicular joint complex was significantly different from the modified Weaver-Dunn repair (P < .001) and the anatomical acromioclavicular reconstruction using a palmaris longus tendon graft (P < .001) but not from the anatomical acromioclavicular reconstruction using a flexor carpi radialis tendon graft (P = .607). Conclusion: The strength of the described anatomical acromioclavicular reconstruction is limited by the tendon graft used. Anatomical acromioclavicular reconstruction with a flexor carpi radialis tendon graft re-creates the tensile strength of the native acromioclavicular joint complex and is superior to a modified Weaver-Dunn repair.