[The effect of continuous passive motion after repair of Achilles tendon ruptures: an experimental study in rabbits].

OBJECTIVES: The effect of continuous early passive motion on morphologic and histologic healing following repair of Achilles tendon rupture was evaluated in comparison with cast immobilization.

METHODS: Achilles tendons of 20 adult rabbits were repaired with the use of modified Kessler technique after surgical transection. Throughout the postoperative six weeks, the rabbits were randomly assigned to cast immobilization (n=10) and to continuous early passive motion four hours a day (n=10). All the rabbits were sacrificed at the end of six weeks and their tendon tissues were removed for macroscopic and histologic examinations.

RESULTS: On macroscopic evaluation, findings on adhesions at the operation site, periarticular atrophy, and the ROM of the ankle joint were found significantly more favorable with continuous early passive motion than those of the control group (p<0.001, p<0.05, and p<0.001, respectively). On histologic evaluation, regular collagen bundle alignment was 70% and 20% in the study and control groups, respectively (p<0.05), whereas findings on hyalinization and inflammatory infiltration were not significantly different.

CONCLUSION: The utilization of continuous controlled passive motion following repair of Achilles tendon rupture was shown to have beneficial effects on tendon healing and ankle range of movement, without leading to eventual ruptures.