Cartilage damage (chondropathy) – when joints hurt

In this technique, cartilage components that have become detached or are in the process of detaching are surgically removed. The goal is to smooth off the cartilage surface so that inflammation processes in the joint can be reduced. This method can be used to alleviate the symptoms associated with certain cartilage lesions. However, the cartilage is not regenerated.

With bone marrow stimulation, the subchondral bone underneath the cartilage damage is opened with an awl, chisel or drill. As a result of these micro-injuries, blood from the bone marrow enters the cartilage defect. The pluripotent stem cells contained in this blood can form so-called repair cartilage (fibrous cartilage) in the damaged area. To support the process, an absorbable scaffold structure can be implanted in the cartilage defect, which serves as a matrix for the cells. In terms of biomechanical properties, repair cartilage is quite different to hyaline cartilage – it is softer and significantly less shock-resistant.

Autologous OCT (autologous osteochondral transplantation) is a cartilage/bone transplant. Here, cylindrical plugs are removed from the bone cartilage from unloaded points on the same joint and grafted at the point of the cartilage defect. If multiple such cylindrical plugs are used then this is referred to as mosaicplasty. This method is limited, as only a few of these cylindrical plugs can be taken from healthy tissue. In addition, a defect is produced at the removal site, which can cause pain in some cases, even if it is outside of the loaded area. The gaps remaining between the plugs are filled with lower-quality scar tissue. Cartilage/bone plugs from the same joint are also referred to as osteochondral autografts. In contrast to this there are also osteochondral allografts, which are transplanted from multiple organ donors or deceased donors.

Two surgical procedures are required for cartilage cell transplantation. As the first step, cartilage biopsies are taken via arthroscopy from an unloaded area of the healthy joint cartilage. In the laboratory, cartilage cells are extracted from this tissue and multiplied. Afterwards the cultivated cartilage cells are inserted into the damaged cartilage in a second procedure. This technique is referred to as autologous chondrocyte transplantation (ACT). With matrix-assisted autologous chondrocyte transplantation (MACT), the isolated cartilage cells are implanted together with a three-dimensional scaffold matrix to promote cartilage regeneration.

As well as cartilage cell transplantation, there is also the gentler option of using a high-quality acellular biological matrix as an implant in the cartilage defect. The goal here is that endogenous cartilage cells and stem cells from the surroundings settle on the implant and are encouraged to form hyaline-like cartilage. At the same time, the exposed subchondral bone is protected with a protective matrix layer. In contrast to cartilage cell transplantation, this technique requires only one surgical procedure and involves no damage to cartilage through extraction of biopsies and no bone injuries due to microfracturing.

If the cartilage damage has progressed to a point where none of the techniques described above can be used, the last available therapeutic option for consideration is the implantation of an artificial prosthesis made of metal and plastic. However, the durability of artificial joints is limited. In addition, sufficient bone mass must be available to anchor the prosthetic. It must also be considered that prostheses cannot simply be replaced, as bone loss occurs after the first implantation. For this reason, this method should only be employed on older patients.