Review of Meniscal Allograft Transplantation Focusing on Long-term Results and Evaluation Methods

With recognition of the biomechanical role of the meniscus, such as load distribution and joint stability in the knee joint, there has been a shift in the treatment of meniscal tears from open total meniscectomy to preservation of the meniscal functions as much as possible with symptomatic relief. Recently, technical development of meniscal surgery, with advanced arthroscopic equipment and instruments, enables biological reconstruction of load bearing functions in the meniscus deficient knee through allograft tissue transplantation as well as repair of torn menisci. Meniscal allograft transplantation (MAT) has been considered as one of the few viable treatment options for the young meniscectomized knees based on various animal experiments and clinical studies. Still, there is insufficient evidence for the long-term chondroprotective effect of human MAT. Some long-term follow-up studies showed that the technique resulted in graft degeneration, deformation, and tear, and structural changes in the remodeling process in early MAT cases, disrupting functional restoration of the original meniscus. Nevertheless, advanced outcomes are documented in some recent studies. The purpose of this article is to review the mid- and long-term follow-up results of MAT and to improve understanding of MAT with evaluation methods of meniscal transplants using magnetic resonance imaging or second-look arthroscopy.