The effect of papaverine on tendon healing and adhesion in rats following Achilles tendon repair.

Objectives: The study aimed to examine the histopathological and biomechanical effects of papaverine administered intraperitoneally and locally on Achilles tendon healing in a rat model.

Materials and methods: Forty-eight adult male Sprague-Dawley rats (range, 300 to 400 g) were used in this study conducted between October and November 2022. The rats were divided into three groups, with each group further subdivided into two for sacrifice on either the 15^th (early period) or 30^th (late period) day after surgery. The first (control) group received no treatment following Achilles tendon repair, while papaverine was intraperitoneally administered every other day for 10 days in the second group and locally in the third group after surgery. On the 15^th and 30^th days, the rats were sacrificed, and their Achilles tendons were subjected to biomechanical testing and histopathological evaluation.

Results: Histopathologically, there were no significant differences among the groups on the 15^th day. However, on the 30^th day, the locally applied papaverine group exhibited superior histopathological outcomes compared to the control group (p<0.05). Concerning the highest tensile strength values before rupture, the biomechanical assessment showed that the group receiving local papaverine treatment in the early period and both the group with systemic papaverine treatment and the one with local papaverine treatment in the late period displayed a statistically significant advantage compared to the control group (p<0.05).

Conclusion: Locally administered papaverine has positive biomechanical effects in the early period and exhibits a positive correlation both histopathologically and biomechanically in the late period. Novel therapeutic options may be provided for patients through these findings.