Each knee has two semilunar (C-shaped) menisci situated on the inside and outside of the knee joint, referred to as the medial and lateral menisci, respectively. The meniscus attaches to the bone with insertional fibers and several attachments to the ligaments that make up the knee. The meniscus provides mechanical support cushion to the knee by distributing forces across the joint, assisting with load bearing and providing lubrication for smooth movement in the joint. The meniscus also serves as an additional stabilizer to the knee, and studies have shown that a torn ACL with a damaged meniscus has a much higher risk of instability when compared to an ACL tear alone.
A meniscus injury can be caused by a partial or full tear of the cartilage that results from trauma or twisting of the knee. Tears can occur in several directions and can be described as longitudinal, radial, parrot-beak, horizontal, and bucket-handle. Meniscus injuries can also be degenerative and are commonly associated with osteoarthritis. Tears in the meniscus cause pain, occasional swelling, mechanical symptoms (sensation of catching, clicking, or locking in the knee), and occasionally limitations in motion.
Diagnosis of a meniscus tear requires a thorough examination and detailed assessment of radiographs (X-rays) and MRI scans. Treatment is dependent on the patient, his or her activity level, and importantly the presence or absence of arthritis. Nonoperative treatment options will focus on alleviating symptoms but will not facilitate healing of the tear. Nonoperative treatment options include physical therapy, activity modification, oral anti-inflammatory medications (NSAIDs), ice and occasionally steroid injections.
If nonoperative treatments fail to alleviate pain and symptoms, then surgical treatment may be indicated. Surgical treatment of meniscus tears is performed arthroscopically and includes a meniscectomy (torn tissue is trimmed away) and/or a meniscus repair (sutures are inserted to stabilize the tear). The location of the tear and the amount of blood supply to the tissue will determine if the meniscus can be repaired or must be trimmed out. In certain circumstances, a meniscus tear can be large enough and irreparable, leaving the knee without enough meniscus to protect the cartilage of the knee joint (meniscal insufficiency). In the properly selected patient, a meniscus transplant can be performed, providing the patient with a new, cadaver meniscus.