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. 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 which provides its shock absorbing capacity.
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).
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 of osteoarthritis. 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.
