Interference screw insertion angle has no effect on graft fixation strength for insertional Achilles tendon reconstruction.

PURPOSE: To compare the effect of two interference screw insertion angles on the biomechanical properties of the insertional Achilles tendon (IAT) reconstruction.

METHODS: Nine matched pairs of fresh-frozen human cadaveric Achilles tendon specimens were randomized to two groups with interference screw insertion angles of 60° and 120°. The IAT reconstruction was performed by fixing the graft tendon with the interference screw. Each specimen was loaded to failure. The load at failure, stiffness, and mode of failure were documented. Differences in load at failure and stiffness were analysed.

RESULTS: There was no statistically significant difference between the 60° and 120° groups for failure load (149.137 ± 20.836 versus 155.428 ± 28.343 N, respectively, n.s.) and stiffness (14.523 ± 2.824 N/mm versus 14.727 ± 2.192 N/mm, respectively, n.s.). The most common mode of failure was the graft pulling out of the bone tunnel when the screw broke.

CONCLUSIONS: Graft fixation at two different interference screw insertion angles for IAT reconstruction exhibited equivalent biomechanical performance. When performing this procedure, surgeons may choose the interference screw insertion angle based on personal preference.