Improved Achilles tendon healing by early mechanical loading in a rabbit model

Objective: To investigate the structure and the attachment strength of a healing tendon-bone interface and the role of mechanical loading in tendon healing. Methods: Sixty rabbits underwent unilateral detachment and repair of the Achilles tendon. Thirty animals were immobilized (Group A), and the others wereallowed loadingimmediately postoperatively (Group B). Animals were sacrificed at 4 weeks and evaluated for histological and biomechanical testing. Statistical analysis was performed with an independent t test with significance set at P = 0.05. Results: The ultimate stress was greater in group B (4.598 +/- 1.321 N/mm(2)) compared with the control group (3.388 +/- 0.994 N/mm(2)) (P < 0.05). Similarly, a more organized tendon-to-bone interface with a larger area of chondrocytes was found in group B (P < 0.05). Conclusion: Mechanical loading improves the structure and the attachment strength of the healing tendon-to-bone interface.