Abstract:

BACKGROUND: Supraspinatus tendon injury is common in rotator cuff injury, the repair difficulty of which is reconstructing the bone-tendon interface. Currently, there are no effective therapeutics and suitable experimental animal models. 
OBJECTIVE: To establish rabbit rotator cuff injury prosthetic experimental animal model and to observe the effect of continuous passive motion (CPM) on early healing of rabbit rotator cuff bone-tendon interface by MRI, which can provide guidance for preparing an optimal rehabilitation strategy after rotator cuff injury.
METHODS: Sixteen male New Zealand rabbits, aged 8 months, were received a rotator cuff acute injury and reconstructing insertion of supraspinatus tendon on greater tuberosity of humerus. The rabbits were randomly divided into cage activity group (n=4) and CPM group (n=12). At 2 days after operation, rabbits were treated by rabbit shoulder joint continuous passive motion apparatus of 75°-75° flexion-extension with various CPM speeds[2 (°)/s, 4 (°)/s, and 10 (°)/s)]. General state and MRI changes of rabbit rotator cuff bone-tendon interface was observed prior to and at weeks 1, 2, and 4 after operation. 
RESULTS AND CONCLUSION: Gross observation showed that the incisions healed very well at 2 weeks after operation. There was no infection, haematoma or disruption after removing the suture. Compared to the cage activity group, the tendon-bone interface of CPM group healed better at weeks 1, 2 and 4, especially at the speed of 4°/s with 75°-75° flexion-extension. Results demonstrated that this animal model can be satisfied to experimental study. From the following day after operation, various CPM speeds can accelerate the healing of tendon-bone interface, and the optimal speed of CPM was 4 (°)/s.