Osteochondral allografting has a long and successful history and is becoming increasingly popular in the field of cartilage restoration.
Who is a candidate for this procedure?
The typical individual considered a candidate for fresh osteochondral allografting is a younger, more active individual with a symptomatic, disabling cartilage injury or disease present in the knee, ankle or other joints such as the shoulder. Candidates are generally under 50 years of age and have a diagnosis such as traumatic chondral or osteochondral injury, osteochondritis dissecans, avascular necrosis, post traumatic arthrosis, focal secondary arthrosis, or patella femoral problems. Often, individuals have failed other forms of treatment, or felt to have disease states which are not amenable to any other type of procedure. Osteochondral allografts are particularly suited for osteochondral lesions such as Osteochondritis Dissecans, focal osteonecrosis or periarticular trauma where bone deformity or deficiency occurs in association with chondral disease.
Common Reasons for Osteochondral Allografting
- Chondral and osteochondral lesions greater than 2 sq cm.
- Revision or salvage of other cartilage surgery
- Osteochondritis dissecans type III or IV
- Post traumatic reconstruction after fracture
Candidates for the procedure are first evaluated with a careful history and clinical examination as well as documentation of the size and type of lesion within the knee. This either includes an arthroscopic photo or video, or a MRI, along with plain radiographs. At this point, if the individual is felt to be a candidate, a radiograph is obtained and the size of the knee joint is determined. The individual is then placed on a waiting list. Donor tissue is obtained from an accredited tissue bank that specializes in the complex process of recovering and preparing fresh, living osteochondral tissue. The tissue is transplanted fresh (usually within 28 days of recovery), not frozen or processed like other tissue allografts. This allows for the cartilage cells to survive and maintain the transplanted cartilage tissue. No tissue type matching is performed because the allograft is felt to be only minimally immunogenic. Donor recipient matching is done primary by size to ensure optimum fit of the allograft. When a donor becomes available and is matched to the appropriate recipient, this individual is contacted and scheduled for the surgical procedure, preferably within 48-72 hours. The procedure is 1-3 hours in length and essentially consists of replacing the damaged joint surface with a carefully fitted graft from the donor joint. Typical hospitalization is zero to three days and there is a period of protected weight bearing and physical therapy for up to three months. Patients are encouraged to complete a therapy program, including range of motion and muscle rehabilitation, which begins immediately after surgery. Initial follow-ups are scheduled at 4-6 weeks, 3 months, 6 months and yearly. Radiographs are obtained to check graft healing. If the graft appears to be functioning and incorporating, then a progressive weight-bearing program is initiated. At six months, if the individual has healed appropriately, then he/she is allowed to begin more strenuous activity and return to sports or other athletic endeavors. Most patients feel they have not completed their full recovery until up to a year after surgery. Transplant recipients are followed on a routine basis every year indefinitely. This is important because the long-term outcome of allografting procedures is not completely known.
Surgical Technique Summary
- Available instrument can create grafts between 10 and 35 mm diameter
- Osteochondral allografting is performed through a mini or standard arthrotomy.
- The defect is exposed and sized and a guide pin placed through the center of the lesion, perpendicular to the joint surface
- The lesion is reamed to a modest depth removing diseased cartilageand a small (3-6 mm) amount of bone.
- Depth measurements are taken from the prepared recipient site
- The allograft plug is removed from the donor tissue utilizing a coring reamer.
- Recipient depth measurements are marked on the plug and excess bone removed, creating an osteochondral graft matching the size and depth of the prepared recipient site
- The graft is lavaged to remove blood and debris and bony edges trimmed to facilitate insertion
- The graft is gently inserted with a tamp or with joint compression during range of motion
- Loose grafts are fixed with absorbable pins or screws
Cost of Procedure and Insurance Issues
Insurance issues are a concern quite frequently because the procedure is uncommon and unfamiliar to many insurers. Therefore, many insurers feel that this is an experimental procedure and initially will not approve it. However, after documentation of efficacy (based on scientific studies) and an explanation of the unique nature of the procedure and lack of alternatives for individuals who are typically quite disabled and have a very poor prognosis for their knee. The allografting procedure is often done in specialized centers or by experienced surgeons, where the complex requirements of procurement of allograft material, preparation and technical aspects of performing the surgery have been established. The total cost of this procedure is very comparable with knee replacement or other cartilage repair techniques, including the surgical cost, the hospitalization, and the cost of the donor tissue.
Figure 1. This is the medial femoral condyle of a knee joint with cartilage damage caused by osteochondritis dissecans.
Figure 2. This is the allograft tissue prior to preparation of the graft
Figure 3. The damaged area has been prepared to accept the allograft transplant
Figure 4. The allograft tissue has been inserted into the knee joint and the damage is repaired.