To observe histological change of autogenous bone or allogeneic bone grafts after subchondral bone defects in New Zealand white rabbits at different time points.

Thirty New Zealand white healthy rabbits were randomy divided into autogenous bone group and allogeneic bone group. To establish subchondral bone defects animal models, clinical giant cell tumor of bone with tumor curettage was simulated. Different materials were filled in the bone defects focus (autogenous bone group was filled with bone cement and autogenous bone, allogeneic bone group was filled with bone cement and allogeneic bone). The bone grafts were got at 4, 6, 8 weeks postoperatively. General observation and histological study were performed respectively. The amount of osteoblast and osteoclast in bone grafts between the two groups was compared, two-way analysis of variance was used to compare the amount of osteoblast and osteoclast between the two groups, least significant difference method was used to compare the amount of osteoblast and osteoclast between any two timepoints in the same group, difference was statistically significant when P<0.05.

At 4 weeks postoperatively in autogenous bone group, bone trabeculas were absorbed and some newly born capillaries and neutrophils were found around bone grafts, a few osteoblasts and osteoclasts were found in bone matrix between bone grafts and host bones; no bone trabeculas were absorbed and just some granulation tissue was found in allogenic bone group. At 6 weeks postoperatively in autogenous bone group, the majority of bone trabeculas were absorbed and more newly born capillaries and neutrophils were found around bone matrix, multinucleated osteoclasts and irregular arrangement woven bones were around bone grafts; while in allogenic bone group, sporadic bone trabeculas were found and sequestrum was surrounded by fibrillar connective tissues, some newly born capillaries were found around bone matrix, osteoblasts and osteoclasts were rare. At 8 weeks postoperatively in autogenous bone group, all the bone trabeculas in bone grafts were absorbed, many new bones, newly born capillaries and lamellar bones could be found, osteoblasts were closely spaced around bone matrix and the woven bones were smaller, also had more regular arrangement; while in allogenic bone group, a few newly born capillaries and bone trabeculas, osteoblasts, osteoclasts and lamellar bones were found, calcium deposition was evident in some regions.

The rate of sacralization and bone formation were higher when subchondral bone defects were filled with bone cement and autogenous bone, and there are more osteoblasts and osteoclasts.