Allografts in articular cartilage repair.

Hyaline articular cartilage is an avascular and insensate tissue with a distinct structural organization, which provides a low-friction and wear-resistant interface for weight-bearing surface articulation in diarthrodial joints. Ideally, articular cartilage is maintained in homeostasis over the lifetime of an individual, with its biomechanical properties inherently suited to transmit a variety of physiologic loads through a functional range of motion. However, in the skeletally mature individual, articular cartilage does not heal effectively when injured. Although several restorative options for biomimetic replacement in acquired articular cartilage defects do exist, fresh osteochondral allografting currently remains the only technique that restores anatomically appropriate, mature hyaline cartilage in large articular defects. The fundamental paradigm of fresh osteochondral allografting is the transplantation of mature orthotopic hyaline cartilage, with viable chondrocytes that survive hypothermic storage and subsequent transplantation while maintaining their metabolic activity and sustaining the surrounding collagen matrix. Fresh osteochondral allografts have application in the treatment of a wide spectrum of articular pathology, particularly conditions that include both an osseous and a chondral component. The surgical procedure for femoral condyle lesions is straightforward but demands precision to achieve reproducible results and to minimize early graft failures related to surgical technique. As with other cartilage-restorative procedures, the indications for use of fresh osteochondral allografts are still being expanded. Many clinical and basic scientific studies support the theoretical foundation and efficacy of small fragment allografting, although more scientific validation of empirical clinical practice is still needed.