Biomechanical properties of repairs for dislocated AC joints using suture button systems with integrated tendon augmentation

Purpose To evaluate the biomechanical performance of different techniques for CC reconstruction using suture button systems with integrated tendon augmentation. Hypothesis was that (1) reconstructions using a cortical button combined with a biological augmentation (semitendinosus allograft) will demonstrate improved stability than a modified Weaver–Dunn procedure and (2) constructs using two tunnels at the clavicle for fixation will show superior horizontal stability than single-tunnel constructs. Methods The acromioclavicular joints of 47 cadaveric shoulders were tested for anterior, posterior, and superior translations (70 N load) and maximal load to failure (superior). Shoulders were assigned to 4 groups: (1) native ( n = 18) and after sectioning the AC and CC ligaments; (2) CC reconstruction with 1 clavicular and 1 coracoid tunnel (GR-ST) augmented with semitendinosus graft ( n = 15); (3) CC reconstruction augmented with semitendinosus tendon (GR-DT) with 2 clavicular and 1 coracoid tunnel ( n = 8); and (4) modified Weaver–Dunn reconstruction ( n = 6). Results The Weaver–Dunn demonstrated statistically more translation than the native joint for posterior direction ( P = 0.038). The GR-ST had significantly less translation than the Weaver–Dunn for anterior and posterior translations ( P = 0.003, P = 0.004) and compared to the native for superior translation ( P = 0.028). The GR-DT differed significantly in anterior and posterior translations compared to the Weaver–Dunn ( P = 0.002, P = 0.001). The modified Weaver–Dunn failed at significantly less load to failure compared to all other groups ( P = 0.002, P = 0.002, P = 0.005). There was no significant difference between the native and the other reconstructions. Conclusion The evaluated techniques for isolated CC ligament reconstruction (GR-ST) in AC joint dislocation showed biomechanical stability superior to the modified Weaver–Dunn procedure and obtained similar measures compared to the native control. A modified technique (GR-DT), which used two fixation points at the clavicle, did not result in decreased horizontal or vertical translation and therefore no superiority of the GR-DT technique could be shown compared to the GR-ST. Level of evidence Controlled laboratory study.