What are the Menisci?
The menisci are crucial shock absorbers within the knee, with one located on the medial side and the other on the lateral side. Together, they contribute to knee stability and maintain joint health. The medial meniscus, positioned on the inside of the knee, absorbs approximately 50% of the knee joint's impact, playing a pivotal role in preventing osteoarthritis, particularly in individuals with bowlegged alignment (varus alignment).
Furthermore, the medial meniscus is vital for patients who lack an anterior cruciate ligament (ACL) or have undergone ACL reconstruction. The posterior horn of the medial meniscus acts as a backup, preventing anterior sliding of the knee, which could jeopardize an ACL reconstruction if the meniscus were absent.
On the other hand, the lateral meniscus absorbs even more shock than the medial meniscus, accounting for about 70% of the impact on the lateral knee compartment. This is why young, active patients can develop arthritis shortly after a partial lateral meniscectomy. In addition to its shock-absorbing role, the lateral meniscus contributes significantly to protecting an ACL reconstruction and providing stability when the ACL is torn. In the absence of both an ACL and lateral meniscus, there is a notable degree of rotational instability, as evident in the pivot-shift test.
What is a meniscus transplant?
Meniscus transplantation becomes necessary when an individual experiences persistent pain, swelling, or instability following the removal of their own meniscus. In such cases, a donor meniscus from a deceased individual, known as a cadaver graft, can be utilized. This graft must be a precise match in terms of size and the side of the knee it's intended for. The objective is to reintroduce this donor meniscus into the knee, addressing the deficiency created by the previous meniscus removal. This procedure is what we refer to as meniscus transplantation.
Can a meniscus transplant be performed for osteoarthritis?
In the context of a meniscus transplant, its effectiveness is often influenced by the degree of osteoarthritis present in the knee. When there is extensive osteoarthritis, a meniscus transplant may not yield significant benefits. On the other hand, if there are mild levels of arthritis, typically categorized as grades 1 to 2 chondromalacia, a meniscus transplant can be a viable option for relief. However, when arthritis has progressed to more advanced stages, reaching grade 3 or 4 chondromalacia, the suitability for a transplant graft becomes limited unless the cartilage damage is primarily located on the femur with relatively intact tibia cartilage. In such cases, a simultaneous replacement of both the femur cartilage and the meniscus may be considered.
What are the indications for a meniscus transplant?
A part from the prior removal of a meniscus, certain indications are considered when determining the suitability for meniscus transplantation. These include having a neutral or correctable knee alignment, maintaining a stable or correctable status of knee ligaments, and having no more than grade 1 to 2 chondromalacia in the affected compartment of the knee. Additionally, individuals being considered for meniscus transplantation should exhibit symptoms resulting from the absence of a meniscus, typically characterized by pain and swelling during physical activities.
What are the long-term results of meniscus transplants?
Current data suggests that the majority of meniscus transplants have a lifespan of approximately 12 to 15 years, with the potential for some to endure even longer. As a result, it is generally believed that these transplants can effectively decelerate the advancement of arthritis for a period of a decade or more. However, in cases where the transplant wears out or develops a tear while the cartilage remains relatively healthy, patients may require a second meniscus transplant to address the situation.