Abstract
Introduction: The rotator cuff is subject to constant pressure from the head of the humerus. This tends to ‘wring out’ the blood supply resulting in a functionally avascular critical zone, although microvessels can be identified. This zone is the site of degeneration and tears. Damage repair under these conditions would be difficult. Myofibroblasts are characteristic of the contractile phase of wound healing. We have examined their distribution in both healthy resected and torn, degenerating rotator cuff tissue and correlated their presence with vascularity and hypoxia in the surrounding tissue. Methods: Rotator cuff tissue was obtained from ten patients undergoing surgical repair. The size of tear was 1–4.5cm, Immunohistochemical staining with commercial monoclonal antibodies to HIF-1α (Hypoxia inducible factor), vimentin, smooth muscle actin (SMA), CD31 and VEGF was performed on formalin fixed paraffin embedded tissues. Visualisation used standard DAB chromagen technique. Results: Focal myofibroblast positivity (SMA+/VIM+) was detected, areas of positivity were found at the interface between torn and degenerating tissues adjacent to the tear. Myofibroblasts were absent in degenerating tissue. The areas of myofibroblast positivity were well vascularized, with strong VEGF positivity. Nuclear HIF-1α positivity was identified in the adjacent endothelial cell population and sporadically in fibroblast population, although not in the myofibroblasts. Conclusion: Evidence of an ongoing wound healing response was found in tissue from torn rotator cuffs. However, it was patchy and infrequent.
Theses abstracts were prepared by Professor Dr. Frantz Langlais. Correspondence should be addressed to him at EFORT Central Office, Freihofstrasse 22, CH-8700 Küsnacht, Switzerland.
