THE INFLUENCE OF OSTEOPOROSIS ON WEAR PARTICLES INDUCED OSTEOLYSIS IN ANIMAL MODEL

Summary Osteoporosis reduces particle-induced osteolysis in rat model. Introduction Wear particle induced osteolysis is considered to be a vital factor that reduces the life span of joint prosthesis. Osteoporosis is not rare in patients with indication for arthroplasty. However, the influence of osteoporosis on wear particles induced osteolysis is not clear. This study is aimed to explore on this issue by using animal model. Methods 42 female Sprague-Dawley (SD) rats aged 6 months were randomly divided into 3 groups: A, B and C group. Group A and B contained 18 rats each, and group C contained 6 rats. The rats in group A underwent bilateral ovariectomy. Group B was normal control, and group C was sham control. After 3 months, 6 rats in group A, 6 rats in group B and all the rats of group C were sacrificed. Bone mineral density (BMD), μCT and bone histomorphometry were conducted. The rest of rats in group A were randomly divided into 2 groups: group A1 and group A2, and so were the rats in group B. 5mg titanium particles were implanted onto the calvaria of groups A1 and B1, and isometric PBS solution were injected to group A2 and B2. Calvaria were harvested after 14 days. Calvaria were analyzed by μCT and histomorphometry to measure the osteolysis area of calvarial sagittal suture. Results Compared with B and C group, BMD and bone histomorphometry index of group A was significantly reduced ( P <0.05), and tibial trabeculae of group A was slimmer. Area of calvarial sagittal suture osteolysis were 0.262±0.009mm2, 0.130±0.013mm2, 0.307±0.013mm2 and 0.178±0.011mm2 in A1, A2, B1and B2 groups, respectively. There was significant difference among the groups. Conclusions Osteoporosis may reduce particle-induced osteolysis in rat model.