Reconstruction of large rotator-cuff tears with acellular dermal matrix grafts in rats.

HYPOTHESIS With the acellular dermal matrix (ADM), it may be possible to bridge large rotator cuff tears and induce tendon regeneration. MATERIALS AND METHODS A 3 x 5 mm defect of the rotator cuff was created on both shoulders of adult male Sprague-Dawley rats. The graft group (n = 15) underwent reconstruction of the rotator cuff defect with an ADM patch graft; in the defect group (n = 15) no repair was performed. We sacrificed 5 rats from each group at 2, 6, and 12 weeks after surgery and harvested both shoulders; 3 specimens were subjected to histological analysis and the other 7 specimens were used for biomechanical testing. The controls were 5 unoperated rats; they were sacrificed to obtain 3 histologic and 7 biomechanical control shoulder specimens. RESULTS At each time points, the graft group had significantly higher modified tendon maturing scores than the defect group (p < 0.002); specimens from the graft group demonstrated a greater mean ultimate force to failure than those from the defect group (p < 0.05). Within 12 weeks, the ADM graft was histologically incorporated into a structure resembling control specimen; the mean ultimate force to failure in control was significantly greater than in specimens from both groups (p < 0.01). DISCUSSION Although the defect was restored in the defect group, histologically and biomechanically specimens from the defect group were inferior to the graft group. CONCLUSION ADM grafts were useful as a scaffold in the reconstruction of large rotator cuff defects in rats. LEVEL OF EVIDENCE Basic science study.