Radiographic and Histopathologic Evidences of Movement versus Immobilization Effects on Enthesis Formation in Rabbits

Enthesis joins tendon, ligament, or joint capsule to the bone, which are two very different tissues. As a result, it is more prone to stress and increased risk of rupture. The purposes of this study were to evaluate the role of limb movement or immobilization in enthesis healing after surgical repair and found out if radiography could be a reliable method for determining its prognosis. Fourteen New Zealand white rabbits were randomly divided into two groups. After detaching the Achilles tendon from the bone surface, the tendon was re-attached to the bone with a modified Kessler suture pattern. The limb of group 1 rabbits was externally fixed with the fiberglass cast. In group 2, however, no cast was used. Radiographs were taken after surgery and in weeks 2, 4, 6, and 8 post-operation. Samples were taken from the area after 8 weeks and stained by the hematoxylin-eosin method. The results were reported descriptively. Bone growth, increased chondrocytes in the cartilaginous region, and increased fibroblasts and fibrocytes were seen in group 1. While erosion, collagen fibers regularity, and tissue maturity were more predominant in group 2. Although early limb movement during the enthesis healing period helps to increase the regularity of collagen fibers in the tendinous zone of the enthesis, it does not increase the amount of callus in the bone and increases the risk of bone erosions and even fractures. While stabilizing the limb in the first two months of enthesis healing protects the bone against the forces and helps bone formation, which has a positive role in healing the enthesis.