Follow-Up of Osteochondral Plug Transfers in a Goat Model

Abstract

Osteochondral transfer procedures are increasingly used to resurface full-thickness articular cartilage defects. There has not been long-term assessment/description of autogenous donor and recipient sites. The healing process occurs at the donor/host cartilage and bone interfaces. Histologic, biochemical, and biomechanical changes were assessed 6 months after an osteochondral transfer in a goat model. Eight adult goats were studied. In the 6 osteochondral transfer goats, 2 autogenous plugs were transferred from the femoral trochlea to defects in the weightbearing portion of the medial femoral condyle. The goats were allowed free range for 6 months. Randomly assigned plugs were assessed. Knees of the sacrificed animals had preservation of the joint space with mild chondromalacic changes in both transfer and contralateral control groups. Histologically, no evidence of cartilage (host/donor) healing was seen. Subchondral bone of the plug was contiguous with the surrounding recipient bone. Cellular viability in the autogenous osteochondral plug was seen, and 35SO4 uptake of the articular cartilage was not statistically different from the contralateral control condyle. The indentation stiffness of the transfer plug (mosaicplasty) and the contralateral donor site were similar—much stiffer than normal cartilage including surrounding condylar cartilage. Large structural stiffness of transferred cores and donor sites appeared to be related to their thinner cartilage layer. At 6-month follow-up, a cleft between host and transferred articular regions remained, with no integration between the two. Autogenous transplantation of osteochondral plugs is possible with integration of subchondral bone and preservation of chondral viability.