Meniscus Tears

Overview

The meniscus is a thick, durable fibrocartilage that sits between the femur and tibia. There are two menisci in every knee: the medial meniscus on the inside and the lateral meniscus on the outside. I think of the meniscus as both a shock absorber and a cushion that helps the rounded femur fit more smoothly against the relatively flat tibia while also serving as a secondary stabilizer. As we age, the meniscus becomes more brittle and susceptible to tearing.

Types of Meniscus Tears

Traumatic tears usually occur in younger patients after a twisting injury and are often associated with ACL or other ligament injuries. Degenerative tears develop gradually with aging and arthritis and most commonly involve the medial meniscus.

Blood Supply

The outer edge of the meniscus (the red zone) has a blood supply and therefore healing potential. The inner portion (the white zone) has essentially no direct blood supply and generally cannot heal after tearing.

Symptoms and Diagnosis

Typical symptoms include joint-line pain, swelling, catching, locking, clicking, and pain with twisting or squatting. MRI is usually necessary to define the size, location, and pattern of the tear.

Treatment

Initial treatment may include activity modification, anti-inflammatory medication, physical therapy, and cortisone injection when appropriate. Most symptomatic degenerative tears are treated with arthroscopic partial meniscectomy and typically recover within 4–6 weeks with few restrictions. Selected tears in the red zone may allow repair, preserving the meniscus rather than removing it. Because the repair must heal, rehabilitation is considerably more restrictive and may take 3–4 months before returning to full activities.

Prognosis

Once the meniscus is torn, it is no longer functioning normally, and patients typically feel better once the unstable portion has been removed. The more healthy meniscus that can be preserved, the better the long-term outcome. Larger resections reduce the knee's shock-absorbing ability and increase the risk of arthritis over time.