Treatment of chronic Achilles tendon ruptures can be technically demanding due to tendon retraction, atrophy and short distal stumps. Although rare, re-rupture following surgical treatment is a major late complication.

Biomechanical studies on the strength of reconstructed Achilles tendon using autologous tendon grafts have not been well documented.

This study examined the time zero in vitro mechanical properties of a reconstructed Achilles tendon (TA) using the peroneus brevis (PB) or the flexor hallucis longus (FHL) tendons in a human cadaver model (n=17).

The TA was reconstructed using the same technique for all specimens. Biomechanical testing was performed using an MTS 858 Bionix testing machine and structural properties (failure load, stiffness and mode of failure) were determined.

Average failure load was significantly higher in the PB-group (p=0.0116) (PB: 343.82 N (+/− 124.90 N, FHL: 241.54 N (+/− 82.17 N)). There was no significant difference in stiffness (p=0.212), (PB: 16.53 N/mm (+/− 6.25 N/mm), FHL: 14.00 N/mm (+/− 3.84 N/mm)) or energy (p=0.075).

Mode of failure was the same for all specimens, with the tendon graft cutting through either the distal or proximal TA-stump. Reinforcement of these stumps could lead to increased failure loads. Based on the biomechanical data, the present study supports the use of either FHL or PB to reconstruction chronic TA tendon ruptures. The greater failures loads for PB may not be clinically relevant considering the peak loads. The addition of the suturing pattern, whilst is does reconstruct the tendon, does not provide a similar ability to resist the load.