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.