SUBCHONDRAL BONE AND CARTILAGE REPAIR WITH BIOACTIVE GLASSES, HYDROXYAPATITE, AND HYDROXYAPATITE-GLASS COMPOSITE

The repair of an osteochondral defect in rabbit femur was studied with three kinds of bioactive glasses (BG), hydroxyapatite (HA), and hydro xyapatite-glass (HAG) composite. Seventy-two osteochondral defects wer e created in 18 rabbits. Sixty-four cylinders were implanted and eight defects were left empty as controls. Histomorphometry, scanning elect ron microscopy (SEM) and energy dispersive X-ray analysis (EDXA) were used for evaluation. Small osteochondral defects in rabbit femur found to heal themselves by regeneration. The three BGs, HA, and HAG led to direct lamellar bone repair of subchondral bone and restoration of ar ticular surfaces mostly with hyalinelike cartilage in 12 weeks. Howeve r, the composition of the materials affects their behavior. Chondrogen esis took place earlier with the BGs than with HA. HAG degraded too mu ch, glass 14 was too reactive and brittle, and the high alumina conten t in glass 11 disturbed its bone-bonding ability. Glass 7 and HA were the most balanced in the repair process. A special preparation method was used to retain soft tissues fairly unchanged and enable them to th e observed together with hard tissues in SEM analysis. (C) 1996 John W iley & Sons, Inc.