Interposition Graft Repair of Irreparable Rotator Cuff Tears: A Review of Biomechanics and Clinical Outcomes.

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 role of the macrophage in tendinopathy and tendon healing.

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.

A Comparison of Two Arthroscopic Techniques for Interpositional Polytetrafluoroethylene Patch Repair for Massive Irreparable Rotator Cuff Tears: Speed and Biomechanics.

BACKGROUND: Interpositional synthetic patch repairs are a novel method of treating massive irreparable rotator cuff tears. However, surgeons experience difficulty in the arthroscopic insertion of these patches. QUESTIONS/PURPOSES: We compared two methods of arthroscopic interpositional synthetic patch repair: the newly devised slide-and-grip technique, using pre-loaded sliding knots and no arthroscopic knots, and the weave technique, using less arthroscopic knot tying than the earlier mattress technique. Study questions were as follows: (1) Would the slide-and-grip technique take less time than the weave technique? (2) Would the biomechanical strength of the two methods be comparable? METHODS: Fourteen paired ovine infraspinatus tendon ex vivo models of the degenerative human rotator cuff underwent timed repair with a synthetic polytetrafluoroethylene (PTFE) patch, using either the weave technique (n = 7) or the slide-and-grip technique (n = 7). Each was pulled to failure using a tensile testing machine, the Instron 8874. RESULTS: The time to complete the slide-and-grip repairs was shorter (12 ± 0.9 min) than that of the weave repairs (23 ± 1 min). Ultimate load to failure was comparable for the slide-and-grip and weave techniques (211 ± 27 N vs. 295 ± 35 N, respectively), and the slide-and-grip was less stiff (14 ± 1 N/mm vs. 19 ± 1 N/mm). CONCLUSIONS: 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.