Abstract:

Objective　To explore the roles of stress on the postoperative recovery after acute rotator cuff injury.　Methods　26 adult male New Zealand white rabbits were used in this study. Taking as the control, 2 rabbits were randomly selected to conduct MRI scan preoperatively. The acute rotator cuff tear was performed in other 24 animals, followed by the randomly group division: stress loading group with the passive activities on bilateral shoulder joints 2 weeks postoperatively, and non-stress loading group without any postoperative movement behavior. MRI survey was performed on 3 rabbits randomly selected in each group at the week of 2, 4, 6 and 8 after operation, respectively.　Results　2 weeks postoperatively, T2WI showed high signal on the insertion of the tendon of supraspinatus muscle, at 4 weeks, the areas of the low signals of the tissues connected tendon and bone were slightly larger than that in non-stress group, at 6 weeks, the signals were larger than that in non-stress group, however, which was not significant between two groups. At 8 weeks, the high signals of the crack still preserved, although the intensity decreased compared to that of other time points. The lower signal area of the healed tendinous structure was slightly larger in stress loading group, but the signals of synovial fluid were not significant compared to that of the unloading groups.　Conclusions　MRI is valuable for monitoring the repairing process of postreconstructive acute rotator cuff tear, while, stress stimulation plays an active role for the repairing of reconstructed rotator cuff tear.

Key words: Stress, Postreconstruction, The repair of tendon-bone, MRI