| Objective: This research is to explore the possibility of bone formation around and within the hollow porous titanium prostheses ( HPTP ) which are used as bone-regenerating frameworks in rabbits, and to discuss the feasibility of HPTP and deimmunized bovine cancellous bone matrix ( CBM ) complexes used as bone-integration stimulative devices, in which CBM is hypothesized to be able to promote osteoblastic activity. We hope the results will provide an experimental basis for the study of hollow porous artificial joint prostheses and other bone-regeneration implants, and will be beneficial for the design and improvement of biological artificial joint.Methods: We designed HPTP with many holes (2mm in diameter) and "solid imperforate" titanium prostheses (SITP) used in control group. Sections going to be implanted in bone in all the prostheses were coated with hydroxyapatite (HA). There were 3 groups in this research: SITP group (group A), HPTP group (group B), HPTP and CBM group (group C), and all the implants were placed in the femoral condyles of 16 New Zealand white rabbits (4-6 months old) transversely. The animals were kept until 3,8, 12 weeks later respectively, then we took out corresponding specimens in scheduled time, and studied the bone formation evolvement around and within the prostheses and CBM through X-ray, common light microscopy, fluorescence microscopy, scanning electron microscopy (SEM) and some other methods such as computer software for norphometry. Besides, 6 specimens at the 12th week point in each group were used for biomechanical tests. The effects of bone integration in each group could be examined and analyzed through a pull-out test.SPSS 13.0 software was used for statistical analysis, and measurement data were expressed in the form of mean value±standard deviation((x|-_±s).Results: There was similar bone formation effect on the HA coating surface of the prostheses in all the 3 groups at different time points respectively, while bone tissue could finally grow into the 2mm holes in porous prostheses of group B and group C to get an interlocking fixation effect; However, bone formation within HPTP in group B was very difficult, and there was very few thin bone-like tissue which is quite thin among a mass of blood clots and fibrous tissue and along the internal walls of HPTP. On the contrary, bone formation in group C was ideal: Many bone-like tissues in CBM could be seen at the 3rd week point, and part of the CBM had been absorbed in 8 weeks, and there would be better bone integration at the 12th week point (However, bone still didn't fill up the cavity of HPTP). In biomechanical tests, pull-out forces needed in group B and group C were significantly stronger than group A, but there was no statistical difference between group B and group C.Conclusion: 1. Histomorphological results and biomechanical tests both prove that the porous structure of HPTP can improve integration of prostheses and bone tissue significantly than SITP by achieving interlocking fixation effect.2. Osteoblastic stimulative materials such as CBM in the big internal space in HPTP can improve bone formation earlier and better, making HPTP, CBM and newborn bone be an organic whole.3. Integration of HA coating and bone around prostheses can produce very strong anti-shear strength, and the bottleneck of anti-shear strength of the "solid imperforate" prostheses should mainly be the strength between HA coating and prostheses.4. The idea for HPTP is feasible, and our study provides a successful model and plenty of data for reference for the further tissue engineering (TE) study. The aperture size of 2mm may be an appropriate size in the model.Our experiment in vivo shows that hollow porous prostheses loading osteoblastic stimulative materials are advantageous when compared with traditional solid imperforate prostheses. However, there should be more studies on how to promote better bone integration on this issue in the future.
|
PDF Full Text Request