The effect of pentoxifylline on Achilles tendon healing in tenotomized rabbits

This study aims to evaluate the potential effects of pentoxifylline (PTX) on tendon healing and to compare the histopathological and biomechanical findings of the healed tendon among the groups.

The study was conducted on 36 male New Zealand albino rabbits (age, 3 months; weighing, 2.5±0.5 kg). Rabbits were randomized into two groups of 18 rabbits each. Partial Achilles tenotomy was performed 1.5 cm proximally from the calcaneal insertion of the tendon in both lower extremities of each rabbit and all groups were repaired primarily. After the operation, saline was injected intramuscularly to the control group and PTX was injected into the PTX group daily. Nine rabbits from each group were euthanized at weeks four and six postoperatively for histopathological (n=4) and biomechanical (n=5) testing. The histopathological findings were evaluated using the staging method of Curtis and Delee. Biomechanical effects were assessed by tensile testing.

In the biomechanical evaluation results, the maximum displacement and maximum breaking force in the PTX group at fourth week were significantly higher than the control group. In the sixth week, the maximum breaking force in the control group was significantly higher than the PTX group. In the histopathological examination, collagen fiber alignment was more regular and vascularization was more frequent in the PTX group at both fourth and sixth weeks and the difference was significant.

Pentoxifylline increased healing and strength in rabbit Achilles tendon by stimulating collagen synthesis, increasing vascularity and reducing inflammation, particularly in the early period both histopathologically and biomechanically. According to our study, PTX may be favorable for the treatment of human Achilles tendon injuries and tendinopathies.