The role of the macrophage is an area of emerging interest in tendinopathy and tendon healing. The macrophage has been found to play a key role in regulating the healing process of the healing tendon. The specific function of the macrophage depends on its functional phenotype. While the M1 macrophage phenotype exhibits a phagocytic and proinflammatory function, the M2 macrophage phenotype is associated with the resolution of inflammation and tissue deposition. Several studies have been conducted on animal models looking at enhancing or suppressing macrophage function, targeting specific phenotypes. These studies include the use of exogenous biological and pharmacological substances and more recently the use of transgenic and genetically modified animals. The outcomes of these studies have been promising. In particular, enhancement of M2 macrophage activity in the healing tendon of animal models have shown decreased scar formation, accelerated healing, decreased inflammation and even enhanced biomechanical strength. Currently our understanding of the role of the macrophage in tendinopathy and tendon healing is limited. Furthermore, the roles of therapies targeting macrophages to enhance tendon healing is unclear. Clinical Significance: An increased understanding of the significance of the macrophage and its functional phenotypes in the healing tendon may be the key to enhancing tendon healing. This review will present the current literature on the function of macrophages in tendinopathy and tendon healing and the potential of therapies targeting macrophages to enhance tendon healing.
Managing massive irreparable rotator cuff tears is a challenge. Interposition graft repairs to bridge the torn defect are a promising solution. Many graft materials are available for interposition repairs including the following: allografts, autografts, extracellular matrix, and synthetic grafts. Currently, it is unknown how these materials compare biomechanically or in their clinical outcomes when used for interposition graft repairs of massive irreparable rotator cuff tears. Most allografts and autografts are similar, in maximal load and stiffness, to intact rotator cuff tendons. Synthetic grafts have similar maximal load but lower stiffness, whereas extracellular matrix grafts are lower in maximal load and stiffness compared with intact rotator cuff tendons. Overall interposition graft repairs have shown some promising 2-year outcomes in patient and physician-reported functional outcomes, regardless of graft type. Few reported complications or repair failure associated with interposition graft repairs of massive irreparable rotator cuff tears at 2 years postsurgery have been noted.
The slide-and-grip technique took less time than the weave technique for the interpositional patch repair of massive irreparable rotator cuff tears and when correctly performed had comparable biomechanical strength.
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