Acromioclavicular joint reconstruction: a comparative biomechanical study of three techniques

Background: Acute acromioclavicular joint dislocations indicated for surgery can be treated with several stabilization techniques. This in vitro study evaluated the acromioclavicular joint stability after 3 types of validated repair techniques compared with the native situation. Materials and methods: Nine pairs (right-left) of intact cadaveric shoulder specimens were assigned to 3 study groups with randomly distributed samples according to the coracoclavicular distance. The groups were instrumented with acromioclavicular and coracoclavicular cerclages (CE), a Twin Tail TightRope (TR), or a locking compression superior and anterior clavicle plate (CP). Native and instrumented specimens were tested quasi-static nondestructively (superior: 70 N; anteroposterior: +/- 35 N, 10 mm/min) and cyclically until failure (superior, valley load: 20 N; initial peak load: 70 N; increment: 0.02 N/cycle). Results: The TR study group showed the highest (in N/mm) superoinferior (73.77 +/- 14.04) and anteroposterior (29.58 +/- 1.52) stiffness, followed by CE (superoinferior: 59.73 +/- 10.33; anteroposterior: 24.31 +/- 4.14) and CP (superoinferior: 24.08 +/- 5.29). Instrumentation generally led to increased superoinferior and anteroposterior stiffness in each study group but to a significant superoinferior stiffness reduction for CP (P=.029). Significantly lower coracoclavicular displacement at valley load after 1 and 500 cycles was observed for TR (P=.018) and CE (P=.041) compared with CP. Cycles to failure were significantly higher in CE (7298 +/- 1244 cycles, P=.011) and TR (4434 +/- 727 cycles, P=.031) compared with CP (1683 +/- 509 cycles). Conclusions: The CE and TR techniques led to similar biomechanical performances. The CE repair might mimic the native acromioclavicular joint stiffness better than the other 2 setups, leading to more physiological stabilization. Level of evidence: Basic science study, Biomechanical study. (C) 2013 Journal of Shoulder and Elbow Surgery Board of Trustees.