| Objective:To study the effects of CPC in the treatment of rabbit radius distal osteoporotic fracture, providing a theoretical basis for clinical application of calcium phosphate cement to fill osteoporotic fracture of the distal radius.Methods:Establishment of animal models of osteoporosis in rabbits,6 months of 33 female new zealand white rabbits were randomly divided into experimental group of 29 rabbits and control group of 4 rabbits. Experimental group underwent bilateral ovariectomy and injected dexamethasone 0.5mg/kg 1 week after surgery, twice a week for 8 weeks.Control group had no surgery and hormone injections.8 weeks postoperation, dual energy X-ray absorptiometry scan were performed to verify the experimental model of osteoporosis success.Then the osteoporotic animals were produced to bilateral distal radius fracture model,From the 54 forelimbs in the 24 rabbits of experimental group,16 selected randomly fixed with Kirschner wire (Kirschner wire group),19 selected randomly fixed with simple CPC(CPC group) and with CPC and-Kirschner wire(CPC-Kirschner wire group).the general condition of rabbits was observed after operation; 10 cases of complete radial specimens were selected randomly from each group 24 hours after fixation for biomechanical testing of anti-axial compression; 4,8,12 weeks after fixation, Kirschner wire group,4 weeks after fixation showed that:fracture callus formation; 8 weeks after fixation showed that:more callus formation than before, edge of fracture defect was blurry; 12 weeks after fixation showed that:fracture defect nearly disappearance,bone moulding was poor; CPC group,4 weeks after fixation showed that: CPC clear visualization, Clear boundaries between fracture, volume was not obviously change.8 weeks after fixation showed that:CPC imaging developed fuzzy than before, dissolution of peripheral absorption phenomena appeared,12 weeks after fixation showed that:CPC visualization clear fuzzy, the dissolution and absorption phenomenon in edge significantly more obvious than before, bone moulding was good. CPC-Kirschner wire group has similar changes in CPC group.Each group were examed by X-ray to observe bone callus growth in bone defect area, material degradation and bone connections, comprehensively scoring according to Lane-Sandhu criterion; The animals were killed 12 weeks after fixation for gross observation, HE staining and scanning electron microscopy, and morphometric evaluation performed to observe bonding conditions between the CPC and the host bone, the ultrastructure and the formation of new bone.All data were analyzed using SPSS 15.0 statistical softwareResult:8 weeks after ovariectomy, bone mineral density test results show:a successful animal model of osteoporosis founded, of which 3 animals died. Iimmune rejection such as depilate, diarrhea, significant weight loss did not appear after surgery; Anti-axial compression test 24 hours after fixtion showed:ultimate compressive strength in Kirschner wire group, CPC group and CPC-Kirschner wire group was(13.93±0.73) Mpa,(21.87±1.04) Mpa, (22.46±0.64) Mpa respectively, the difference between CPC group and CPC-Kirschner group was not significant (P> 0.05), and both were significantly higher than the Kirschner wire group, statistical differences were a remarkable significant (P<0.01). Statistics analysis of Lane-Sandhu score results of X-ray at 4,8,12 weeks postoperations demonstrated:Kirschner wire group compaired with CPC group and CPC-Kirschner wire group was statistically significant difference (P <0.05), the difference between CPC group and CPC-Kirschner group was not statistically significant(P>0.05). Gross observation 12 weeks postoperations showed:defect area irregular and surface rough in Kirschner wire group; bone shape smooth and shaping good in the other two groups of CPC implanted.12 weeks after fixation, CPC group and CPC-Kirschner wire group, HE staining showed:reaction are similar. It can be seen that ripe bone tissue grow CPC interior.seen ripe lamellar bone,bone tissue ingrowth to the interior and divided the material, the inner sees the ripe bone cell, outer-ring sees the Osteoblast, has not seen the obvious inflammation cell. Tissue morphometric results by statistical analysis showed:new bone formation and residual CPC was no significant difference between other two groups of CPC implanted(P<0.05).Electron microscopy observation 12 weeks after fixation demonstrated:CPC integrating with the host bone closely, continuous transition interface between materials and bone tissueingrown, having no seam, the bone tissue inrushing to the CPC.Conclusion:CPC can provide immediate local stability,having good fixed effects, either alone, can also be applied association with Kirschner;also acting as scaffolds contributed to bone ingrowth, promoting fracture healing,having a good therapeutic effect of osteoporotic fractures of the distal radius. This study provided a convincing theoretical basis for clinical application of calcium phosphate cement to fill osteoporotic fracture of the distal radius.
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