Coralline hydroxyapatite is a suitable bone graft substitute in an intra-articular goat defect model

Intra-articular defects can be filled with an autologous bone graft taken from the iliac crest. This can be indicated after trauma or following correcting osteotomy. Patients may encounter donor site morbidity after this procedure. In this in vivo study, we studied if coralline hydroxyapatite (CHA) is a suitable material to replace autologous bone graft to fill a defect in the femoral trochlea of goats. CHA did not evoke any negative reaction in the synovium, and the articular cartilage was comparable to controls. In the bone graft group, we found scattered areas of (enchondral formed) bone. Most bone graft had been resorbed or remodeled, and the scarce remnants were incorporated into new bone. Resorption of CHA was limited or absent and most CHA was surrounded by new bone. In areas with fragmented CHA, close to the joint surface, numerous giant cells were found. The study shows that in this animal model, CHA inserted in a defect that directly communicates with the joint space incorporates into bone. This study did not show any negative effects of CHA in a joint environment.