Meniscal injuries

The menisci are fibrocartilaginous structures with gross and microscopic structural properties that provide load distribution, lubrication, and stability to the knee joint. Diagnosis of a symptomatic meniscal tear requires a thorough patient history, a physical examination with meniscus-specific tests, and often, imaging studies. The anatomy, function, and vascular supply of the menisci have implications for the treatment of a meniscal tear. The long-term outcome after a total or subtotal meniscectomy is likely to include osteoarthritis. Biomechanical studies found an increase in contact pressure after subtotal meniscectomy or a high-grade radial tear causing loss of the ability to absorb hoop stresses. Strain on the anterior cruciate ligament (ACL) in medial meniscus-deficient knees and strain on the medial meniscus in ACL-deficient knees proves the important stabilizing function of the meniscus. These results have led to an increase in the number of meniscal repairs performed to preserve load absorption and stabilization. Clinical and radiographic healing rates of 60% to 85% have been reported after repair. Meniscal repair with concomitant ACL surgery leads to a higher rate of healing than isolated meniscal repair, probably because of the release of bone marrow-derived stem cells during tunnel reaming. Irreparable tears and postmeniscectomy pain syndrome are common in young patients and are difficult to treat. Collagen scaffold implants and synthetic polyurethane scaffolds have had promising results in animal and human studies for filling large defects after partial meniscectomy. Relatively young patients who need to undergo total or subtotal meniscectomy as a primary procedure may be candidates for meniscal allograft transplantation. Biomechanical studies found that strain on the ACL is reduced and knee kinematics and contact pressures are improved to near-baseline levels after transplantation.