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cartilage transplant

Healthy (hyaline) articular cartilage is essential for proper knee function, allowing virtually frictionless movement. Articular cartilage is capable of absorbing tensions and forces equivalent to up to 8 times body weight.

 

Articular cartilage defects have very little self-repair potential because the cartilage contains very few “living” cells and blood flow is relatively poor. Even a small defect in the articular cartilage of the knee can generate considerable pain, blockage, edema and other symptoms that limit activity and often precipitate degenerative osteoarthritis (DO).

 

Traditional surgical techniques that aim to fill the articular cartilage defect (such as microfractures or debridement) only form scar tissue (fibrocartilage) whose structure is different from that of the original hyaline articular cartilage.

Fibrocartilage is much less resistant to large mechanical stresses in the knee than the original hyaline (articular) cartilage and is usually destroyed within 3 years, causing greater damage to the joint, precipitating the onset of degenerative osteoarthritis of the knee, and the need for an earlier knee arthroplasty. Cartilage transplantation or autologous chondrocyte implantation (ICA) has been developed to fill such traumatic defects with durable and stable hyaline-like cartilage instead of scar tissue (fibrocartilage). In this way, the possibility of much superior clinical results with reduced pain and greater longevity of the knee is offered.

 

Brittberg in 1994 initially described the ICA technique, in which through arthroscopy (minimally invasive surgery) a small biopsy of live cartilage is obtained from the edge of the knee. The few thousand chondrocytes (live cartilage cells) contained in the biopsy are cultured and multiplied (usually between 4 and 8 million live cells are obtained) to be used as a replacement in the knee in a second mini-incision operation, under a synthetic patch (absorbable collagen) that is sutured and glued to the cartilage defect, creating a waterproof seal over the transplanted living cartilage cells that, over 6 – 12 months, produce new cartilage in the knee. Currently there are commercial systems with which transplants can be performed with larger grafts.

Current therapeutic options to treat this problem include:

 

Debridement. It consists of the extraction of unstable chondral fragments, osteophytes, excess synovial membrane, degenerated menisci and torn ligaments. Although debridement has been found to provide relief of pain and improvement of symptoms, symptoms can be expected to return over time.[1] . Current research has shown that the best candidates for debridement and lavage are those who suffer from mechanical symptoms (a catching or locking sensation when trying to bend or straighten the knee), which may be caused by a meniscus tear or loose body.[2] .

 

Perforations (Microfractures): Through arthroscopy, perforations are made in the chondral defect in order to release biological modulators into the microenvironment that stimulate the generation of fibrocartilage.

 

Abrasion: The goal is to debride the boundaries of the articular cartilage defect to support a uniformly contoured edge of fresh collagen, capable of adhering to a fibrin clot. The subchondral bone then breaks and allows blood to perfuse for the formation of a fibrin clot.

 

Autologous osteochondral transplant (Mosaicoplasty - OATS): It is a procedure  in which the arthroscope is used. Cylinders of 5 to 12mm in diameter and 15 to 20mm in length are used, which are taken from areas that do not receive load from the joints to treat small and medium-sized defects.

 

Osteochondral transplant with bank graft (Alogenic): Cadaveric graft is used. This technique exposes the cartilage defect through a small arthrotomy that places a “plug” of osteochondral allograft around the contour of the defect. It is indicated in medium and large cartilage defects.

 

Autologous chondrocyte implantation:It is distinguished by using bioengineering techniques to create hyaline cartilage tissue, such as autologous chondrocyte implantation (ICA) or mesenchymal stem cell implantation (MSC). To date, there are few clinical reports in humans on these implants, but no significant results have been found when comparing them with ICA.

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