The current state of scaffolds for musculoskeletal regenerative applications.

Musculoskeletal disease and injury are highly prevalent conditions that lead to many surgical procedures. Autologous tissue transfer, allograft transplantation and nontissue prosthetics are currently used for the surgical treatment of critical-sized defects. However, the field of tissue engineering is actively investigating tissue-replacement solutions, many of which involve 3D scaffolds. Scaffolds must provide a balance of shape, biomechanical function and biocompatibility in order to achieve tissue replacement success. Different tissues can have different requirements for success, which has led to the development of various materials with unique characteristics. Articular cartilage scaffolds have the most robust clinical experience, with many scaffolds, mostly constructed of natural materials, showing promise, but levels of success vary. Tendon scaffolds also have proven clinical applications, with human-dermis-derived scaffolds showing the most potential. Synthetic and naturally derived meniscus scaffolds have been investigated in few clinical studies, but the results are encouraging. Bone scaffolds are limited to amorphous pastes and putties, owing to difficulties achieving adequate vascularization and biomechanical optimization. The complex physiological function and vascular demands of skeletal muscle have limited the widespread clinical use of scaffolds for engineering this tissue. Continued progress in preclinical study, not only of scaffolds, but also of other facets of tissue engineering, should enable the successful translation of musculoskeletal tissue engineering solutions to the clinic.