Aim: Experimentally forming a frayed Achilles tendon rupture model in rabbit and repairing the ruptured site with different methods; after the tendon healing, with the help of biomechanical and histopathological analyses, to find out which repair method is the most ideal.

Material and Method: This study was carried out using 34 mature, female New Zealand type of rabbits with weights ranging 2200 to 2900 grams (2429,4 on average). The animals were divided into two groups named P and V, each with 17 rabbits. In each group, Achilles tendon on the right side was employed for the experiment (Pd and Vd) and the other side as a control (Pk and Vk). In the experiment groups, a frayed Achilles tendon rupture was performed. The control groups, however, received no procedures. After the primary repair, the Achilles tendons in the group Pd were augmented with the plantaris tendon. The Achilles tendons in the group Vd were primarily repaired after releasing gastrocnemius aponeurosis using “inverted-V” incision. In both groups, an above-knee cast was applied on the surgically procedured sides. After six weeks of observation, the repaired sites on tendons in the animals alive were analyzed biomechanically and histopathologically. 12 and 3 animals from each group were used respectively for the biomechanical and the histopathological analyses.

Results: The elongation at tendon to rupture was 3,02±0,47 mm for Pd and 2,86±0,35 mm for Vd. The difference between two groups, however, was not statistically significant (p> 0,05). The maximum load at rupture for Pd was 105,88±38,14 N, and it was 71,95±17,44 N for Vd, thus the difference was statistically significant (p< 0,05). The energy needed to initiate a damage to the tendon was 0,1979±0,0902 J for Pd, and 0,1309±0,0368 J for Vd, the difference was also statistically significant (p< 0,05). The elongation, maximum load and energy values were lower in Pd group than in Pk, and in Vd group than in Vk, and the differences between each groups were statistically significant (p< 0,05). In histopathological sense, the tendon healing process in group Pd was faster than in group Vd.

Conclusion: Although the repairs made with the augmentation of plantaris tendon yielded better results; the tendon, no matter which method is used, could not has its former strength. Results are bound to be better with stronger repair, and if the repair as much as supported by adjacent tendinous structures.

Key Words: Achilles tendon, rupture, primary repair, m. plantaris, rabbit