The rotator cuff: from bench to bedside. Developments in tissue engineering, surgical techniques and pathogenetic factors

This thesis originates from the difficulties in the management of patients with rotator cuff tears. Since tendon healing rate is relatively slow compared with other connective tissues, we reviewed the available literature on tissue engineered biological augmentation for tendon healing, including growth factors and cytokines, gene therapy and tissue engineering with mesenchymal stem cells. We also reviewed the current state of knowledge in the field of biomaterials for augmentation of tendon injuries We evaluated the histopathological features of the macroscopic intact portion of the rotator cuff tendon in patients with a rotator cuff tear. A full thickness supraspinatus tendon biopsy was harvested en bloc within the arthroscopically intact middle portion of the tendon. The mean pathologic sum-score of ruptured tendons was significantly greater than the mean pathologic score of control tendons. In another study, we compared the histopathological features of the gleno-humeral and subacromial portions of the rotator cuff. We found thinning and disorientation of collagen fibers and chondroid metaplasia to be more pronounced on the articular side of the specimens from patients with rotator cuff tear. We performed a frequency-matched case-control study of the plasma glucose level obtained from non-diabetic patients undergoing arthroscopic rotator cuff repair, and compared with a matched control group of patients of a similar age. Patients with rotator cuff tears showed statistically significantly higher fasting plasma glucose levels within the normoglycemic range. We evaluated the role of serum triglyceride concentration and total serum cholesterol concentration in developing a rotator cuff tear. There was no difference either in serum triglyceride concentration or total serum cholesterol concentration in the control and study group. We compared single and double row suture anchor techniques in a randomised controlled trial. At the 2 year follow-up, no statistically significant differences were seen with respect to the UCLA score and ROM values. We evaluated the efficacy and safety of platelet-rich fibrin matrix (PRFM) for augmentation of RC repair in a randomised controlled trial. There was no statistically significant difference in total Constant Score and MRI when comparing the results of arthroscopic repair of the 2 groups. Since several shoulder scores are available to evaluate patients with shoulder pain, we evaluated the methodological quality of studies on the measurement properties of rotator cuff questionnaires. A systematic COSMIN review of published studies on the measurement properties of rotator cuff questionnaires was performed. The methodological quality of the included studies was adequate on some properties (construct validity, reliability, responsiveness, internal consistency, and translation) but need to be improved on other aspects. The most important methodological aspects that need to be developed are as follows: measurement error, content validity, structural validity, cross-cultural validity, criterion validity, interpretability. Since the absence of validated animal models for the study of shoulder pathology challenges the research on this field, we evaluated the role of different animal models in rotator cuff research. There is a lack of validation for these animal models, which provides challenge to the further research in this field