The posterior horn of the medial meniscus is that portion of the medial meniscus in the back part of the knee. It varies from the main weightbearing portion of the meniscus up to where it attaches on the tibia at its lateral aspect, called the root attachment.
Description of Posterior Horn Medial Meniscus Tear
The posterior horn of the medial meniscus is the most important weightbearing portion of the meniscus. While the medial meniscus absorbs 50% of the weight transmitted across the medial compartment, the posterior horn of the medial meniscus is the most important portion of the meniscus that provides the shock absorbing capacity.
Symptoms of a posterior horn medial meniscus tear:
• Swelling and stiffness, increases gradually from hours to days after injury
• Catching or locking
• An inability to straighten the knee
• Pain in the back of the knee with deep squatting
Because the posterior horn of the medial meniscus absorbs most of the weight of the medial compartment, it is also by far the most frequent area that a meniscus tear occurs in. This is especially true in patients who have an ACL tear, where this portion of the meniscus then acts as the main structure to prevent the knee from slipping forward (anteriorly).
Longitudinal Tear of the Posterior Horn Medial Meniscus. (Click to Enlarge)
Treatment for Posterior Horn of the Medial Meniscus Tear
It is well recognized that only about 10% meniscal tears are repairable. Thus, all efforts should be made to try to repair a medial meniscus tear of the posterior horn to prevent the further development ofosteoarthritis. If a posterior horn meniscus tear cannot be repaired, it is recommended that patients be followed up closely for any signs of pain or swelling with activities. These are the signs of arthritis and one should be evaluated carefully after a partial meniscectomy to assess for the progression of arthritis whereby further treatment, such as activity modification, physical therapy, injections or a meniscal transplantation, may be performed prior to advanced wear of the cartilage on the medial aspect of the knee.
The treatment for patients who undergo a partial medial meniscectomy is to initiate physical therapy on the first day after surgery. A treatment regimen working on reactivation of the quadriceps muscles, regaining of full knee and patellar mobility, and a quick resolution of knee swelling is emphasized. In general, we recommend that patients who have a minimal amount of meniscus trimmed out hold back on any impact activities until a minimum of 6 weeks after surgery. In patients who have a significant amount of meniscus resected, it is often recommended to avoid significant impact activities due to the higher risk of the development of osteoarthritis in these patients with this activity.
For patients who have an isolated medial meniscal repair (as in not with a concurrent ACL reconstruction), patients are kept non-weightbearing for 6 weeks. Motion is limited to 90 degrees of knee flexion for the first two weeks after surgery, after which full knee motion is allowed. The use of a stationary bike may be initiated at 6 weeks after surgery and patients are allowed to perform leg presses at ¼ body weight to a maximum of 70 degrees of knee flexion. Impact activities, deep squats, squatting and lifting, and sitting cross legged are limited for the first 4 months postoperatively to maximize healing of the meniscal repair.
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