In young patients with limited articular cartilage damage, osteochondral allografts may offer an alternative to total joint replacement. The survival of chondrocytes after transplantation and the correlation with clinical outcomes was studied.
Between March 1987 and September 1990, nine patients received fresh osteochondral allografts. Three patients received tibial plateau transplants, three received patellar transplants, two received proximal interphalangeal joints and the remaining patient received a segmental femoral head allograft. Patient ages ranged from 16-51 years (mean = 30). They have been followed in a prospective manner for up to 10 years with clinical, radiographic and histopathological review during the period.
Early histological analyses demonstrated preservation of hyaline cartilage. Subsequent analyses from the periphery of some grafts demonstrated chondrocyte death and a change from hyaline cartilage to fibrocartilage, but one specimen taken from the centre of a tibial plateau graft, nine years after transplantation, demonstrated viable chondrocytes. The three tibial plateau recipients improved at a clinical level from an average pre-operative score of 73 (HSS 0-200) to a postoperative average of 174 points. Two of those patients receiving patellar allografts improved from 91 points to 181 points on average. The third patella allograft recipient underwent a total knee replacement 18 months post-transplantation. The patella was not resurfaced. The proximal interphalangeal joint transplants failed and the femoral head allograft has been lost to follow-up.
The clinical success of the tibial plateau and patellar allografts, irrespective of the histological results, has resulted in the formation of a code of specific indications for this operation. Future enthusiasm, although buoyed by the possibility of long-term chondrocyte viability and good clinical results, must be tempered by the ever-present risk of disease transmission.