What is a meniscal allograft transplantation (MAT)?
MAT is a surgical procedure to replace the damaged meniscus of the knee with healthy cartilage. It is a technically challenging procedure that is available to patients who have failed a prior meniscal repair and subsequently underwent a total meniscectomy. These patients are typically followed closely for the rapid development of osteoarthritis and are offered meniscal replacement to preserve their joint health. The goal of MAT is to restore proper function and structure to a knee that has lost its native meniscus. This is accomplished using an allograft so that a healthy meniscus from a donor is transplanted to replace the damaged meniscus in your joint.
Who is a candidate for a meniscal transplant?
It is typically indicated for younger patients who have underwent a total meniscectomy and have continued to have symptoms that are affecting their quality of life or ability to perform activities of daily living. These patients must fail to have an adequate improvement with non-operative management before a meniscus transplant can be recommended. Patients with extensive cartilage damage are also poor candidates for the procedure as there will be difficulty in placing the transplanted meniscus due to the reduced joint space associated with an arthritic joint.
The eligibility criteria for meniscal transplantation include:
- Young to middle-aged patients (below 50 years of age)
- Patients with stable, well-aligned knees
- Patients with intact or minimally damaged articular cartilage in the joint
- Patients who have already undergone a prior meniscectomy (removal of meniscus)
- Patients who complain of persistent activity-related pain
- Meniscal transplantation is not recommended for patients with severe arthritic changes within the joint
What does the process of MAT involve?
The process of using an allograft involves first measuring the size of your current meniscus and matching it to a donor with a healthy meniscus. This is done by obtaining pre-operative imaging. The process of size matching to a donor can take some time and you may be placed on a waiting list. Once a match becomes available, the donor undergoes extensive testing to make sure the donor is safe and free of all illnesses and diseases.
During the procedure, an incision is made and the meniscus allograft is inserted where the previous meniscus was removed. The meniscus is secured into place using a variety of techniques. Depending on the severity and nature of the damage, additional procedures such as ligament or cartilage repair may also be performed along with the MAT. Once the graft has been placed in your joint, it takes months to grow into your body and extensive physical therapy to recover.
Is the process of MAT safe and successful?
There are scientific studies showing patient with successful recovery lasting over 20 years and the chance of disease transmission or infection is less than 1 percent. It is important to make sure your surgeon is familiar with the graft company that provides the donor meniscus and also has experience in meniscal transplant surgery. Additionally, there are extremely strict criteria for tissue donation including a thorough review of the donor’s medical records and social history to maximize the tissue quality and minimize the risk to recipients.
What are the chances that my body will reject the donated tissue? Do I need to take medication to prevent rejection?
Unlike live organ transplants, tissue rejection is not a concern with meniscal transplantation; therefore, you will not need to take anti-rejection medication.
How long will I have to wait for a donor meniscus to be found?
Waiting time depends on the availability of a graft. This time can be between three to twelve months. Once a graft has been identified surgery can be scheduled. Unlike other types of cartilage transplantation that need to be transplanted right away, meniscus can have some flexibility to schedule surgery at a time that works best for you. The graft is frozen in a tissue bank and is available for transplantation for a few years.
Is any other surgery performed at the same time as a MAT procedure?
It is very common for other surgical techniques to be performed at the time of MAT. It is very important to correct any problem with the knee not being straight (bow legged or knock kneed), especially if this is putting more load on the damaged side. The leg needs to be straightened by carefully reshaping the bone around the knee. Another example is if the knee is unstable due to damage to the anterior cruciate ligament (ACL) then this can be rebuilt at the same operation.
What is the postoperative rehabilitation like with MAT?
Among the rehabilitation regimens after a meniscal surgery, rehabilitation for a meniscal transplant is the strictest. The transplanted meniscus needs to be allowed a generous amount of time to integrate with the surrounding tissue. Failure to adhere to the strict rehabilitation regimen could lead to the ultimate failure of the surgical intervention. You may be able to resume work after a few weeks or a few months, depending on the nature of your work. Rehab protocols will vary from surgeon to surgeon. Click here to see examples of MERCuRE member Rehab Protocols.
Can I return to sport after my surgery?
The main goal of meniscal transplantation surgery is to preserve the joint surfaces. Returning to high sporting activity is not the ideal end stage outcome. Non-impact sports such as swimming and cycling are preferable, although you may feel that higher activity levels are possible. At this stage you must consider the higher risks of re-injury to the transplanted meniscus and joint surfaces upon return to sport. It is important to discuss expectations of returning to sport with your doctor.