The effects of post-surgical loading on the biomechanical and histological properties of the rabbit patellar tendon after removal of the central 10 percent and 40 percent

Complications of using the central one-third of the patellar tendon as autogenous tissue for anterior cruciate ligament reconstruction may result from excessive hypertrophic scarring of the host patellar tendon. It is possible that this damage is a result of increased stresses generated in the host patellar tendon after removal of a portion for ligament reconstruction. In the present research, this hypothesis is tested by increasing the stresses in the rabbit patellar tendon by removing the central 10% and 40% of the tendon prior to subjecting the animal to post surgical exercise on a treadmill. In addition, one group of rabbits with the central 40% removed had a stress shielding device implanted to protect the host tendon from stresses during exercise. The biomechanical and histological properties of the tendons with the central 10% removed closely resembled those of the contralateral control tendons. The tendons with the central 40% removed showed significant hypertrophy and decreased material properties. Stress shielding of the tendon prevented scar formation but encouraged disuse atrophy of the tendon.