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 front 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. (c) 2009 Journal of Shoulder and Elbow Surgery Board of Trustees.