Advances in biology and mechanics of rotator cuff repair

High initial fixation strength, mechanical stability and biological healing of\r\nthe tendon-to-bone interface are the main goals after rotator cuff repair\r\nsurgery. Advances in the understanding of rotator cuff biology and biomechanics\r\nas well as improvements in surgical techniques have led to the development of new\r\nstrategies that may allow a tendon-to-bone interface healing process, rather than\r\nthe formation of a fibrovascular scar tissue. Although single-row repair remains \r\nthe most cost-effective technique to address a rotator cuff tear, some biological\r\nintervention has been recently introduced to improve tissue healing and clinical \r\noutcome of rotator cuff repair. Animal models are critical to ensure safety and\r\nefficacy of new treatment strategies; however, although rat shoulders as well as \r\nsheep and goats are considered the most appropriate models for studying rotator\r\ncuff pathology, no one of them can fully reproduce the human condition. Emerging \r\ntherapies involve growth factors, stem cells and tissue engineering. Experimental\r\napplication of growth factors and platelet-rich plasma demonstrated promising\r\nresults, but has not yet been transferred into standardized clinical practice.\r\nAlthough preclinical animal studies showed promising results on the efficacy of\r\nenhanced biological approaches, application of these techniques in human rotator \r\ncuff repairs is still very limited. Randomized controlled clinical trials and\r\npost-marketing surveillance are needed to clearly prove the clinical efficacy and\r\ndefine proper indications for the use of combined biological approaches. The\r\nfollowing review article outlines the state of the art of rotator cuff repair and\r\nthe use of growth factors, scaffolds and stem cells therapy, providing future\r\ndirections to improve tendon healing after rotator cuff repair.LEVEL OF EVIDENCE:\r\nExpert opinion, Level V.