Healing processes of the glenoid labral lesion in a rabbit model of shoulder dislocation

Traumatic dislocation most commonly occurs at the shoulder joint. After an initial dislocation of the shoulder, the labrum is usually detached from the glenoid (Bankart lesion). If this lesion fails to heal, surgical repair is necessary. The purpose of this study was to determine the histological and biomechanical healing process of a simulated Bankart lesion created in rabbits. A labral injury was surgically created in 40 Japanese White rabbits. The labrum was sharply dissected from the glenoid rim simulating a Bankart lesion, and was repositioned without sutures. The joint capsule, the supraspinatus and infraspinatus tendons, and the deltoid were anatomically repaired with sutures. Eight rabbits each were sacrificed at 1, 2, 3, 4, and 5 weeks after the surgery for histological and biomechanical examinations (4 animals each). The histology and biomechanical properties of the normal capsulolabral structure was examined in 8 control rabbits. Inflammatory cell infiltration into the gap between the glenoid and the labrum was noted from 1 week. The gap was covered with fibrous connective tissue accompanied by the collagen fibers by 3 weeks. The healing process was completed histologically by 3 weeks. Biomechanically, the tensile load, which decreased significantly at 1 week, gradually increased and returned to the level of intact shoulder at 4 weeks. At least four weeks are necessary for the healing of the labral injury in rabbits. Considering the difference between humans and rabbits, it seems reasonable to let the patients go back to sports 2 to 3 months after dislocation or surgical repair.