Shoulder injuries are one of the most common tendon disorders found in the normal healthy population. Damage to the rotator cuff tendons can occur with overuse or by direct trauma. Tendon tears not only affect the biomechanical properties of the tendon, but also lead to debilitation of the muscles attached to the tendons. The supraspinatus muscle, in particular, is most affected by rotator cuff injuries because it is the primary muscle involved with shoulder stabilization and movement. In humans, a combination of lack of muscle activity due to the pain of movement and the potential shortened state of the detached muscle fibers can lead to severe muscle atrophy and the accumulation of fibrotic tissue or fat in the areas normally occupied by healthy muscle. While tendon repair can be performed in an attempt to restore a firm connection between the bone and muscle, a delay between the time of tendon insult and surgical repair can inhibit the healing process, resulting in weak, fatty muscles. This suggests that there are additional factors which can affect the ultimate healing process of muscle and tendon after surgical repair. Interventions that aid the repair processes of muscle and tendon could improve the prognosis of successful healing. In muscle, high levels of insulin-like growth factor I (IGF-I) increase the regenerative capacity of the tissue. If increased expression of IGF-I is introduced prior to tendon repair, it is possible that the resultant enhanced regenerative capacity would lead to accelerated recovery of the muscle, and potentially the tendon. The goals of this grant are, first, to characterize the morphological changes in the supraspinatus muscle after tendon detachment in a well-established rat model for rotator cuff injury. After this has been achieved, muscle recovery upon tendon reattachment will be assessed with and without enhanced regenerative capacity. Ultimately, the goal the of proposed study is to develop appropriate therapeutic strategies for the treatment of rotator cuff injury.
| Barton, Elisabeth R (2006) Viral expression of insulin-like growth factor-I isoforms promotes different responses in skeletal muscle. J Appl Physiol 100:1778-84 |
