Repair of osteochondral defects in joints--how to achieve success.

Osteochondral defects in the knee are difficult to repair because intrinsic healing of cartilage is poor and gradual progression to "early-onset" osteoarthritis leads to severe pain and disability. Of all methods tested to achieve regeneration of hyaline cartilage and long-lasting repair, autologous chondrocyte transplantation (ACI-C and MACI) has been the most successful with 80% of good results and graft survival in this unit in a very large series over 10 years. The repair mechanism is unclear but our work shows that the criteria for success are: young patient age, no previous operative procedures on the defect, no obesity, no smoking, defect on femoral condyles or trochlea and no pre-existing degenerative joint changes. Future research is aimed at non-transplantation, single-stage procedures aided by use of new scaffolds and growth factors and the extension of such techniques into arthritic joints.