LATERAL MENISCUS TEAR
The meniscus is a pliable substance made up of soft tissue that sits between the two bones in the knee, the femur (thigh bone) and tibia (shin bone). There are two, c-shaped menisci in the knee, one on the inside of the knee (medial meniscus) and one on the outside of the knee (lateral meniscus). Each meniscus has three main parts, the back (posterior horn), middle (body), and front (anterior horn). Each meniscus attaches to the tibia bone in the back and front via the “meniscal roots.” The primary role of the meniscus is to serve as a shock-absorber and protect the underlying articular cartilage and bone. The meniscus has additional roles, including joint stability and joint lubrication. The meniscus is typically torn during a twisting episode and may occur in the setting of an ACL or other ligament tear.
The location of the tear within the meniscus is an important variable that Dr. Keller considers in each patient. The periphery of the meniscus is called the “red-red” zone because there is a robust bloody supply, and peripheral meniscus tears are more likely to heal than meniscus tears located closer to the center of the knee. The central portion of the meniscus has a poor bloody supply and is called the “white-white” zone.
There are several other variables that Dr. Keller considers in each patient with a meniscus tear:
Tear Pattern: there are many different tear patterns, including longitudinal, radial, vertical, and parrot beak tears.
Complete vs. Incomplete Tears: an incomplete meniscal tear refers to a tear that involves only one side of the meniscus. A complete tear implies that the tear extends all the way through the entire thickness of the meniscus. A complete tear usually causes more significant symptoms than an incomplete tear.
Meniscal Root Tears: a tear that involves the meniscal root completely destabilizes the meniscus. When the meniscus root tears, one side of the meniscus completely separates from the bone attachment. As a result, the tension in the meniscus is lost and the entire meniscus no longer functions. Dr. Keller recommends surgical repair for most root tears.
Acute vs. Degenerative Meniscus Tears: an acute meniscus tear occurs as a result of a twisting injury to the knee. During the injury, the meniscus is strained so much that it tears. In patients with arthritis (articular cartilage breakdown) in the knee, the meniscus may tear without a significant twisting injury. This type of tear is called a degenerative tear. The meniscus tears because it is no longer healthy.
- Pain and swelling on the outside of the knee
- Catching in the knee
- A sense of instability in knee with side to side motion
Diagnosis And Treatment
Dr. Keller considers each patient’s symptoms, as well as a detailed physical examination, x-rays, and usually and MRI of the knee to make the diagnosis. Some patients with meniscus tears can be treated with a combination of activity modification and a focused physical therapy program. Physical therapy focuses on maintaining knee range of motion and strengthening certain muscle-tendon unit that provide stability to the knee, such as the quadriceps and hamstrings. Other patients with persistent symptoms or certain tear patterns (such as a meniscal root tear) require surgery.