The meniscus is essential for joint homeostasis. When the meniscus is injured or deficient, increased contact forces over decreased contact area lead to wearing of the articular cartilage. When considering cartilage restoration, it is critical to evaluate and restore meniscus function.
Meniscus tissue is characterized by low cell density and a dense extracellular matrix (ECM), which mainly consists of water, type I collagen, glycosaminoglycans (GAGs) and elastin. With their semilunar wedge-shaped structure, the menisci play an important role in shock absorption, load transmission and stability of the knee. Damage to the meniscus is a very common injury, which leads to loss of its role in chondroprotection in the knee. Especially in young patients with high activity levels, loss of meniscus function can lead to an increased risk of developing early osteoarthritis (OA). (Partial) meniscectomy used to be the first choice in treatment of meniscus tears; however, due to the high risk of developing post-meniscectomy osteoarthritis secondary to increased contact pressure on cartilage, meniscus repair is becoming more popular. Meniscus repair is not suitable for all types of tears; therefore, meniscus restoration using allograft transplantation or biodegradable meniscus scaffolds are of interest.
Meniscus repair provides improved long-term outcomes, better clinical outcome scores, and less severe degenerative changes seen radiographically compared with partial meniscectomy. Advancements in surgical techniques have expanded the capability for meniscal repair, while the implementation of biologic augmentation appears to improve healing rates. However, clinical data remain sparse, and prospective randomized trials are needed. It is critical that surgeons treating meniscal tears be familiar with the evolving repair techniques to optimize the health and longevity of the knee joint.
Similarly, advances in meniscus allograft transplantation and partial meniscus replacement have improved recently. Future advances will include approaches to meniscus regeneration through available scaffolds, MSCs, and recycled meniscus cells. It would be cost effective, a lower patient burden, and logistically attractive to use these cells in a one-stage procedure for meniscus regeneration. Recently, a clinical study showed the safety and feasibility of a combination of recycled autologous chondrons with allogeneic Mesenchymal stromal cells (MSCs) in cartilage repair.(de Windt and Saris et al., 2017) This and other studies suggest that allogeneic MSCs provide stimulatory and immunomodulatory factors for tissue repair, and could positively stimulate a smaller number of meniscus cells. Further investigation is needed.
In summary, the meniscus is essential to normal knee joint homeostasis. Preservation of the meniscus--by avoiding total meniscectomy, and repair of the meniscus when possible--is vital to normal articular cartilage function. When the mensicsu is absent, meniscus allograft transplantation is a good option. Further efforts need to be made for partial meniscus restoration and regeneration solutions.
Woodmass JM, LaPrade RF, Sgaglione NA, Nakamura N, Krych AJ. Meniscal Repair: Reconsidering Indications, Techniques, and Biologic Augmentation. J Bone Joint Surg Am. 2017 Jul 19;99(14):1222-1231
Moatshe G, Cinque ME, Godin JA, Vap AR, Chahla J, LaPrade RF. Comparable Outcomes After Bucket-Handle Meniscal Repair and Vertical Meniscal Repair Can Be Achieved at a Minimum 2 Years' Follow-up. Am J Sports Med. 2017 Nov;45(13):3104-3110.
Cinque ME, Geeslin AG, Chahla J, Dornan GJ, LaPrade RF. Two-Tunnel Transtibial Repair of Radial Meniscus Tears Produces Comparable Results to Inside-Out Repair of Vertical Meniscus Tears. Am J Sports Med. 2017 Aug;45(10):2253-2259.