A new technique to repair damaged knee cartilage Tissue recovery
By Michael B. Boyd, D.O.
Articular carilagenous injury of the knee is a common problem that affects people of all ages. Such injuries can lead to the early development of arthritis and its consequences, and that fact has prompted researchers to find better treatment options for these injuries, especially for younger patients where traditional treatments – such as unicompartmental and total knee replacements – are relatively contraindicated.
Various treatments such as abrasion chondroplasty and microfracture (marrow-stimulating techniques) and autologous chondrocyte transplantation of the osteochondral defects (transplant using cultured cartilage harvested from the patient) have shown minimal to moderate success. Abrasion chondroplasty and microfracture are considered the initial treatments for relatively small, contained articular cartilage lesions because they are simple to perform and economical. In some cases, they are effective. Unfortunately, these techniques result in fibrocartilagenous repair with wear characteristics and biomechanical properties that are inferior to that of native hyaline cartilage.
Transplanting and Autografting
Autologous chondrocyte transplantation involves the implantation of cultured cartilage cells grown from tissue taken from the patient. The technique must be performed in two surgeries. The first stage involves harvesting of the chondrocytes for culturing. The second stage involves the implantation of the cultured cells. There is a high learning curve for this procedure on the part of the surgeon, and hyaline cartilage quality is inconsistent.
Osteochondral autografting involves transplanting one’s own osteochondral tissue from a lesser weight-bearing area of the joint to a more weight-bearing, diseased region. Unfortunately, there is limited availability of tissue and damaged or diseased tissue at the doner site is an issue.
Using Allografts
An alternative and innovative technique involves the use of fresh osteochondral allografts (cadaver tissue). This procedure involves the transplantation of small-fragment osteochondral grafts to reconstruct articular defects. These grafts have been used for defects of various sizes ranging from 1 cm2 to 30 cm2 and have been used for the knee, ankle, and hip. It is indicated for full thickness chondral defects seen in osteochondritis dessicans (fracture or chipping or lesions of bone surface), avascular necrosis (death of bone tissue due to temporary or permanent loss of the blood supply), trauma, and osteoarthrosis (age-related arthritis due to wear and tear). The allografts are collected by tissue banks and are kept in a special culture medium for about two weeks while microbiological testing is conducted to rule out bacterial or viral contamination. Once the tissue is cleared from a microbiological perspective, it should be transplanted within a week in order to maintain a sufficient chondrocyte survival rate.
The technigue involves preoperative matching of the donor and recipient based on size. There is no tissue or blood type matching. A small incision (mini-arthrotomy) is made (figure 1). The defect is prepared with minimal removal of bone below the cartilage (figure 4a). The fresh graft is fashioned to fit the prepared defect (figure 2). The graft is lavaged (medically washed) to remove marrow elements to help reduce the possibility of tissue rejection due to immune response (figure 3). The graft is press fit with adjunctive internal fixation, as indicated (figure 4a/b). Postoperative immunosuppression is unnecessary.
    
Various institutions that perform this technique have reported success rates as high as 75 percent after 10 years. More recent data out of San Diego has shown as high as 91 percent success in the treatment of femoral condyle lesions. For more extensive disease, a 75 percent success rate was obtained in these patients.
A solution to consider: Articular cartilage injury (damage to articular or hyaline cartilage in the knee) is a difficult problem to manage, especially in younger and more active patients. Fresh osteochondral allografting is a simple, effective treatment option that is not widely offered to patients by orthopaedic surgeons. Relative contraindications to fresh osteochondral allografting include joint instability and uncorrected limb malalignment. Allografting should not be considered an alternative to unicompartmental or total knee arthroplasty in a patient with age, symptoms, and activity level appropriate for prosthetic replacement. Finally, fresh osteochondral allografting should not be performed in the individual with advanced multicompartmental knee arthritis. Should you have any questions regarding fresh osteochondral allografting or know of someone who may benefit from the procedure, please contact Michael Boyd, DO, at Tri-State Orthopaedics, Inc., in Evansville, Indiana, for more information. |
