Autologous cartilage cell transplantation (ACT) is a procedure for cultivating new cartilage from the body's own cartilage cells. These new cartilage cells can then repair cartilage damage in the body. Short and medium-term results of autologous cartilage transplantation are promising, but long-term results are still pending. In the knee joint in particular, concomitant injuries from cartilage damage must also be treated in order to achieve a good result.
What is cartilage and how does cartilage damage occur?
Cartilage can have an elastic or fibrous structure and is mainly found in the area of the joints, in the skeletal system and on body appendages such as the nose and auricles. The thin layer of cartilage on the joint surfaces ensures that joint movement is possible without the ends of the bones rubbing against each other. If the joint cartilage is destroyed, the bony joint surfaces rub directly against each other. This causes the characteristic pain of osteoarthritis, for example.
Cartilage essentially consists of a connective tissue cartilage matrix and the cartilage cells (chondrocytes) embedded in it. Cartilage does not have blood vessels running through it, which is why the cartilage cells are mainly supplied by diffusion processes. Oxygen and nutrients are transported through the cartilage matrix to the chondrocytes. Waste products andCO2 are transported away in the opposite direction. The cartilage is supplied by synovia, a fluid that also acts as a kind of "synovial fluid".
Joint bones are covered with cartilage at the contact points © crevis | AdobeStock
Due to its very slow supply, the cartilage is less easily reached by antibiotics, for example. This makes it more difficult to treat bacterial inflammation. In addition, the ability of cartilage tissue to regenerate is limited by the slower diffusion.
This leads in particular to
- inflammatory processes,
- accidents,
- circulatory disorders and the
- mechanical wear and tear of the joint cartilage
which can be further exacerbated by incorrect loading and overloading. Such degradation processes are found, for example, in arthritis (inflammatory joint cartilage degradation) or osteoarthritis (mechanical joint cartilage degradation).
As already mentioned, cartilage damage to the large joints is mainly caused either by wear and tear (osteoarthritis) or by an accident. It is important to know that articular cartilage damage caused by osteoarthritis is not eligible for autologous cartilage cell transplantation.
Depending on the extent of the cartilage damage, very different forms of therapy are available. Cartilage transplantation is primarily used for localized cartilage damage, for example in the area of the
- knee,
- ankle joint or
- hip joint.
Localized cartilage damage is mainly manifested by pain on exertion and a tendency to swell due to inflammation. Over time, the overloading of the joint can also lead to pain at rest. The diagnosis is usually made using X-rays or magnetic resonance imaging (MRI). In individual cases, however, the doctor can only determine whether the extent of the cartilage damage can be treated with a cartilage transplant during an arthroscopy (joint endoscopy). In the case of localized damage to the cartilage, a cartilage transplant may be an option.
In autologous cartilage cell transplantation (ACT), cartilage is removed from an unaffected area of the body during an initial arthroscopy. Using a special procedure, the fibers are then removed to expose the cartilage cells (chondrocytes).
The released cartilage cells can then be multiplied in a test tube - some centers for cartilage transplants use around 20 million cartilage cells as a suitable basis for the further cultivation of transplants. The body's own cartilage is cultivated in a laboratory on different carrier materials (matrices) to form a larger cartilage transplant. This process usually takes several weeks.
The transplant or matrix is transplanted to the defective area, for example in the knee, in a second procedure - arthroscopically or by means of open joint surgery. In the case of deep, usually accident-related defects that extend to or even into the bone, the bone may have to be remodeled using cancellous bone grafting.
Illustration of a cartilage transplant © giana | AdobeStock
Over the course of the next few months, the cartilage cells in the transplant produce new cartilage that corresponds to the natural cartilage. Joint parts that are well suited for cartilage transplantation are
- The femoral condyles of the knee joint,
- the back surface of the kneecap and
- the talus joint surface of the upper ankle joint.
In the case of knee joint injuries, meniscus damage or cruciate ligament injuries must also be treated surgically in order to prevent further joint damage after the operation. However, this requires individual therapy planning.
The main problems with cartilage transplantation are the incomplete growth of the transplanted cartilage and a graft that is not resilient. In particular, older people, people with previous illnesses, smokers and people who have had previous surgery on the same joint have a higher risk of graft failure. In addition, there is always a risk of infection with bacterial inflammatory pathogens during repeated arthroscopy, which can significantly slow down healing.
The healing prospects for isolated, smaller defects are better than for larger defects. Cartilage damage caused by accidents has a better prognosis than cartilage damage caused by osteoarthritis. The composition of the body's own transplanted joint cartilage is superior to other procedures involving artificial joint replacement. Better long-term results than with conventional therapies can be expected for cartilage cell transplantation.
The freshly transplanted cartilage is not yet able to bear weight. It therefore requires a special aftercare regimen depending on the affected joint. This includes several weeks of rest and restrictions on the range of movement.
After a cartilage transplant, follow-up treatment is very important © Andrey Popov | AdobeStock
The aim of autologous cartilage transplantation is to restore the ability to play sports in younger athletes with accident-related cartilage damage. The prerequisites for this are a stably healed transplant, good regained coordination and good reconstruction of the muscles. Overall, the studies show that two to three years of postoperative sports training can significantly improve the chances of recovery and long-term results.
Compared to major surgery with an artificial joint replacement, autologous cartilage transplantation has decisive advantages, such as
- Less pain as a result of a smaller surgical access,
- restoration of the joint's load-bearing capacity through natural cartilage
- improved mobility by restoring the natural structures in the joint cartilage,
- reconstruction of the body's own cartilage layer and
- the avoidance of artificial joint replacement (endoprosthetics).
However, the cartilage cell transplantation procedure cannot be used for all patients without restrictions. The best results can be expected under these conditions
- Age > 30-35 years,
- active sportsman,
- no previous operations on the joint,
- male gender,
- pain symptoms for no longer than 12 months,
- only a small defect size and
- non-smoker status.
The exact cost of a cartilage cell transplant can vary from person to person and also depends on the respective surgical and hospital costs. However, it can be assumed that the cultivation of the cartilage cells and their multiplication in the laboratory alone costs far more than 4,500-6,500 euros.
If the indication is correct, the relevant health insurance company will generally cover the costs of an autologous cartilage cell transplant. Despite the expected high costs of the procedure, its cost-effectiveness has recently been proven in studies from the USA and Germany. In addition, the procedure has also been assessed as beneficial by the Joint Federal Committee (G-BA) in Germany.
Bone cell transplantation is a well-researched procedure in orthopaedics and trauma surgery. However, in order to be allowed to perform autologous cartilage transplants as an orthopaedic or trauma surgeon, extensive certification and further training measures are required.
Furthermore, the operation requires a great deal of bureaucracy, which is why only a few doctors and centers have specialized in cartilage cell transplantation. At Leading Medicine Guide, we list some specialists and orthopaedic centers that offer autologous cartilage transplantation and have expert knowledge and very good surgical experience in this field.
