Grafts in tendon repair

Inferior healing after tendon rupture often necessitates the use of grafts to reinforce tendon repair and promote the regeneration of functional tissue. Autograft or allograft implantations are considered the gold standard in tendon reconstruction, though these types of treatment may not always be feasible due to limited availability and patient-specific considerations. In such cases, commercial tendon grafts, encompassing bridging and augmenting grafts are preferred but may not always lead to optimal healing. Consequently, research into the development of more effective constructs for tendon repair is constantly evolving. Here, we review progress in the field by considering the structure and biology of tendons as well as the natural tendon healing processes that inform the evolution of tissue engineered tendon grafts. The limitations of commercial tendon constructs are outlined to establish the opportunities presented by a range of structures, materials, and bioactive adjuncts currently being engineered into tendon grafts to improve tendon recovery and regeneration. We present in vivo animal models that have been established to evaluate graft efficacy, and that are critical for the translation to clinical use.