MENISCUS TRANSPLANTATION

Donor graft showing the top of the Tibia with both the medial and lateral menisci
Initial view of the inside of the knee showing that there is no meniscus between the femur (thigh bone) at the top of the picture and the tibia (shin bone) at the bottom
Arthroscopic photograph of the new meniscus sutured into place and filling the space between femur and tibia
The meniscus is a ‘C’ shaped structure that acts as a cushion to protect the smooth joint surfaces of the knee joint. There are two—one on each side of the knee joint—and if removed at an operation following injury then there is less protection of the bearing surfaces such that the joint will wear out sooner.  The symptoms will include pain and swelling of the knee after activity and limitation in tolerance of impact type sports. Symptoms may gradually get worse over the years as the joint slowly wears.

After a meniscus tear there are 5 options:

  • Leave alone and allow symptoms to settle reducing activity levels – safe if this results in no pain and no swelling in the knee
  • Arthroscopic surgery to remove the torn fragment—a very common and successful procedure
  • Arthroscopic surgery to repair the torn fragment—performed when the torn fragment is large and the tear extends to the edge of the meniscus where there is a good blood supply to help it heal
  • Replacement of part of the meniscus using synthetic implant (Menaflex or Actifit) as a scaffold for the body to regenerate new tissue. Indicated for partial loss
  • Meniscal transplantation to replace the whole meniscus

Meniscal Transplantation involves implanting a donor graft (allograft) supplied from a tissue bank in the UK or from the USA. The remnants of the old meniscus are trimmed back to make a fresh bed for the new meniscus which is then inserted by keyhole surgery (arthroscopy) and stitched to the original bed. It then heals to the bed on the side capsule of the knee joint so that it can provide cushioning for the smooth articulating surfaces.

Grafts are donated rather like heart transplant donors and are very carefully prepared by the regulated tissue banks to ensure that the tissue is as free of disease risk as is possible. This process has been highly regulated and advances in testing for infections such as Hepatitis and HIV has meant that the risk of contracting severe infections through the grafting operation are now very small. Though difficult to fully quantify, the risk is less than that from a blood transfusion—something that is of course frequently carried out. Grafts are decontaminated and then cryopreserved (very cold) until required.

Unfortunately the strict requirements to have such ideal grafts combined with the need to have the meniscus exactly matched for size based on x-ray measurements, has meant that there is often a delay in obtaining an appropriate graft. This can sometimes take many months.

The procedure is indicated when there is no effective rim of meniscus remaining to support the joint surfaces. This occurs when there has been a large tear and when it was not possible for the surgeon to salvage the meniscus by repairing it. Not everyone needs a transplant but if there is progressive pain and symptoms limiting activity then the procedure may be indicated.

There is often a feeling that it is necessary to replace the meniscus if it is removed, based on the argument that it will prevent or delay the onset of later arthritis. This is a difficult issue, but because the rehabilitation period is long and because the operation is not without risks, meniscal transplantation is usually only performed when symptoms of pain on activity begin to cause interference with your quality of life.

The quality of the result of the operation is a key factor in deciding the indications as the replacement tissue is, after all, a donor graft that may not be as strong as the original and it takes time for it to fully integrate into the knee. Having invested a year of time in getting it right after surgery the thought of going back to full contact sports such as football and rugby could be considered ill-advised!

Recent research looking at the outcome by the leading surgeons in the US and in Europe would indicate that at 10 – 13 years approximately 70% of patients still have good function and have not had further surgery. Most have been able to do light sports. The occasional professional athlete may report being able to get back to high level but it should be remembered that professional athletes may have different goals.

Following surgery the rehabilitation process involves using a knee brace for the first 6 weeks while the new meniscus heals in place. The rehabilitation regime is detailed on a separate part of this website.

Quite often the transplantation operation is performed in conjunction with other procedures and depending on this the rehabilitation regime my change. Additional procedures may include:

  • Surgical procedures to repair the joint surface such as microfracture or autologous chondrocyte implantation
  • If the joint is failing because the leg is out of alignment (bow-legged or knock-kneed) then osteotomy or realignment corrective surgery is needed.
  • If the knee is unstable due to a ligament injury then transplantation can be combined with anterior cruciate or posterior cruciate ligament reconstruction.

Overall meniscal transplant is an exciting option for the damaged knee allowing for substantial improvement in the quality of your life. Though a challenging procedure with a long rehabilitation program, the technique alone or when combined with other surgery, provides a realistic biological option for knees, hopefully avoiding, or at least delaying, the need for metal and plastic knee replacement operations.