Allogenous bone with collagen for repair of deep osteochondral defects

A scaffold for treatment of deep osteochondral defects should be stable, integrate well, and provide a surface for chondrocytes. To meet these demands, a biphasic scaffold of allogenous sterilized bone with a collagen surface was developed. Integration was tested in the sheep model.

Cartilage chips were taken from the nonweight-bearing area of the left knee of 12 sheep and cultured. After 4 wk a second procedure followed and defects of 9.4-mm diameter at the weight-bearing area of the medial femoral condyle of the right knee were created. The sterilized scaffold was inserted and the cultured autologous chondrocytes were dripped onto the surface. After 6 wk, 3 mo, and 6 mo the animals were sacrificed; the explanted femoral condyles were evaluated macroscopically and using histologic, immunohistochemical, and electronmicroscopic methods.

After 6 wk the level of the surface was well preserved, after 3 mo parts of the scaffold were sintered but after 6 mo the surface was continuous. Full integration of the allogenous bone could be observed after 6 mo. The surface of the scaffold after 6 wk consisted of bone, but after 3 mo some chondrocytes and after 6 mo a continuous chondral layer could be detected.

The biphasic scaffold of allogenous bone and collagen proved to be stable and sufficiently integrated in the short- and midterm interval. Whether the chondrocytes on the surface had been derived from implanted chondrocytes or the scaffold with its surface was sufficiently chondroconductive must be answered in further investigations.