Objective To investigate the research advances of the peripheral nerve allograft.Methods The recent articles on peripheral nerve allograft were reviewed extensively. The treatments of allograft and host were analyzed. Results The immunogenicity of allograft was relieved by the physical,chemical or biological treatments; the immunosuppressive therapy makes the rejection relieved and the regeneration of axon accelerated. Conclusion The effect of peripheral nerve allograft is inferior to autograft. If the immunologic tolerance are inducedsuccessfully, the problem shall be solved.
Objective To review the latest researches of synthetic biodegradable polymers for bone repair and reconstruction, to predict the progress of bone substitute materials and bone tissue engineering scaffolds in future. Methods The l iterature concerning synthetic biodegradable polymers as bone substitute materials or bone tissue engineering scaffolds was collected and discussed. Results Al i phatic polyester, polyanhydride, polyurethane and poly (amino acids) were the most extensively studied synthetic biodegradable polymers as bone substitutes and the scaffolds. Each polymer was of good biological safety and biocompatibil ity, and the degradation products were nontoxic to human body. The mechanical properties and degradation rate of the polymers could be adjusted by the type or number of the monomers anddifferent synthetic methods. Therefore, the polymers with suitable mechanical strength and degradation rate could be produced according to the different requirements for bone grafting. Prel iminary studies in vivo showed their favorable capacity for bone repair. Conclusion The synthetic biodegradable polymers, especially the copolymers, composite materials and those carrying bone growth factors are expected to be the most promising and ideal biomaterials for bone repair and reconstruction.
Objective The biomechanical characteristics of three internal fixation modes for femoral subtrochanteric spiral fracture in osteoporotic patients were compared and analyzed by finite element technology, so as to provide the basis for the optimization of fixation methods for femoral subtrochanteric spiral fracture. MethodsTen female patients with osteoporosis and femoral subtrochanteric spiral fractures caused by trauma, aged 65-75 years old, with a height of 160-170 cm and a body weight mass of 60-70 kg, were selected as the study subjects. The femur was scanned by spiral CT and a three-dimensional model of the femur was established by digital technology. The computer aided design models of proximal intramedullary nail (PFN), proximal femoral locking plate (PFLP), and the combination of the two (PFLP+PFN) were constructed under the condition of subtrochanteric fracture. Then the same load of 500 N was applied to the femoral head, and the stress distribution of the internal fixators, the stress distribution of the femur, and the displacement of femur after fracture fixation were compared and analyzed under the three finite element internal fixation modes, so as to evaluate the fixation effect. ResultsIn the PFLP fixation mode, the stress of the plate was mainly concentrated in the main screw channel, the stresses of the different part of the plate were not equal, and gradually decreased from the head to the tail. In the PFN fixation mode, the stress was concentrated in the upper part of the lateral middle segment. In the PFLP+PFN fixation mode, the maximum stress appeared between the first and the second screws in the lower segment, and the maximum stress appeared in the lateral part of the middle segment of the PFN. The maximum stress of PFLP+PFN fixation mode was significantly higher than that of PFLP fixation mode, but significantly lower than that of PFN fixation mode (P<0.05). In PFLP and PFN fixation modes, the maximum stress of femur appeared in the medial and lateral cortical bone of the middle femur and the lower side of the lowest screw. In PFLP+PFN fixation mode, the stress of femur concentrated in the medial and lateral of the middle femur. There was no significant difference in the maximum stress of femur among the three finite element fixation modes (P>0.05). The maximum displacement occurred at the femoral head after three finite element fixation modes were used to fix subtrochanteric femoral fractures. The maximum displacement of femur in PFLP fixation mode was the largest, followed by PFN, and PFLP+PFN was the minimum, with significant differences (P<0.05). ConclusionUnder static loading conditions, the PFLP+PFN fixation mode produces the smallest maximum displacement when compared with the single PFN and PFLP fixation modes, but its maximum plate stress is greater than the single PFN and PFLP fixation mode, suggesting that the combination mode has higher stability, but the plate load is greater, and the possibility of fixation failure is higher.
Objective To sum up the recent progress of common biodegradable internal fixation materials and to forecast the possible directions for further research. Methods The latest original articles about biomechanical properties, degradation characteristics, advantages and disadvantages of biodegradable internal fixation materials were extensively reviewed.Several common biodegradable materials were selected and expounded in different categories. Results The disadvantages of stress shielding and the second time removal, could be avoided by using biodegradable internal fixation materials instead of metal materials. Biodegradable internal fixation materials could fix fracture stably and they were ideal orthopedic internal fixation materials. Natural biodegradable polymers had excellent biocompatibil ity but poor mechanical strength. Synthetic biodegradable materials could be artificially regulated their degradation rate and had better mechanical strength, however, they had shortcomings in biocompatibil ity. Composite materials could learn from others’ b points to offset their weakness, therefore, they had pronounced advantages over the former two materials. Conclusion There still exist many problems in present biodegradable internal fixation materials although they are of great potential in its appl ication. Combining various biomaterials and using the specific processing technology to develop a biodegradable material which has better biomechanical properties, chemical properties and physical structure is the direction for future research.
Objective To study an effect of the peripheral nerve allograft with subcutaneous preservation at different times on the sciatic nerve regenerationin rats. Methods Fifty-five Wistar rats were used in this experiment, which were randomly divided into the following 5 groups: the experimental groups (Groups A, B, C, 10 rats), the control group (Group D, 10 rats), and the donorgroup (Group E, 15 rats). In the experimental groups, a 15-mm segment of the sciatic nerve harvested from the donors was separately inserted into the subcutaneous compartment on the left thigh after the 1week (Group A), 2-week (Group B), and 3week (Group C) preservation; the segment of the sciatic nerve in the subcutaneous compartment was removed and transplanted into a 10-mm defect of theright sciatic nerve, which was made immediately. In Group D, a 10-mm sciatic nerve defect was made and immediately repaired in situ on the right thigh. The function of the sciatic nerve was evaluated by the sciatic functional index (SFI) at 2, 4, 6, 8, 10 and 12 weeks after operation. The histological and electrophysiological examinations were performed at 12 weeks after operation. Results After operation, SFI decreased gradually at 12 weeks afteroperation, SFI inGroups A and D was at the minimal level and had a significant difference compared with that in Groups B and C (Plt;0.05).There was no significant difference between Group A and Group D. A large number of the myelinated nerve fibers and a small number of the unmyelinated nerve fibers were regenerated in Groups A and D. The number and the structure of the regenerated nerve were similar to the normal ones. The number and the size of the regenerated axon had a significant difference compared with those in Groups B and C (Plt;0.05). There was no significant difference between Group A and Group D. The conduction velocity and the latent period of the motor nerve had significant differences between Groups A and D and Groups B and C (Plt;0.05), and there was no significant difference betweenGroupA and Group D. Conclusion The nerve allograft with a 1-weeksubcutaneous preservation can promote nerve regeneration better.
Objective To summarize the physicochemical properties, manufacturing technique, and biological characteristics of porous tantalum and its application progress and related problems in spinal surgery. Methods The domestic and foreign related literature about porous tantalum was summarized and analyzed. Results Porous tantalum is characterized by high porosity, high coefficient of friction, low elastic modulus, good biocompatibility, and superior osseointegration capability. Its manufacture methods include chemical vapor deposition and infiltration technique, foam impregnation and powder metallurgy technique, and heat treatment method. Good clinical efficacy has achieved in the application of porous tantalum interbody fusion Cage in cervical and lumbar fusion surgery, but there is controversy in spinal fusion rate, especially in cervical fusion rate. Surface modification can increase the osseointegration capability of porous tantalum and intervertebral bony fusion. Conclusion Good clinical efficacy has achieved in the application of porous tantalum interbody fusion Cage in lumbar fusion surgery, while there is a dispute in cervical fusion surgery. In order to further observation, studies with more patients and longer follow-up would be needed.
Objective To investigate the research advance in repair of the peripheral nerve defect with an acellular nerve allograft. Methods The recent related literature was extensively and comprehensively reviewed. The methods and the effects of the allografts with acellular nerves were analyzed. Results The immunogenicity of the allograft was more significantly relieved by the chemical treatment than by the physicaltreatment. The effect of the chemical treatment on the axon regeneration was better than that of the physical treatment. Conclusion Because of the limitation of the host Schwann cell translation in the longsegment acellular nerve allografts, the effect of Schwann cells is not satisfactory and regeneration of the nerve is limited. So, the recellularized treatment with some related measures can enhance the host Schwann cell translation so that this problem can be solved.
Objective To explore a new method of treating early avascular necrosis of femoral head (AVNFH). Methods Sixty-nine New Zealand adult rabbitswith a mean weight of 2.8 kg after AVNFH presenting were randomly divided into three groups. In group A, deproteinized bone(DPB) combined with the recombinant plasmid pcDNA3.1/vascular endothelial growth factor 165(VEGF165) was implanted in the drilled channel of the necrotic femoral head. In group B, only DPB was implanted. In group C, channel was drilled without DPB or plasmid implanted. Femoral head specimens were obtained 3 days, 1, 2, 4, 8 and 16 weeks after operation. The expression of VEGF165 was examined by RT-PCR, Western blot and immunohistochemical techniques. X-ray testedbone formation generally. Angiogenesis and repair of the femoral head were observed by histological and histomorphometric analysis. Results In group A, the expressions of VEGF165 mRNA and protein were detected 3 days postoperatively, reached apex 1 week and lasted more than 3 weeks after implantation. The ratios of IOD of collagen type Ⅰ were 0.29±0.11, 0.55±0.13 and 0.67±0.10 IOD/μm2 respectively at 2, 4 and 8 weeks postoperatively and the ratios of IOD of new capillary vessels were 0.33±0.10and 0.57±0.16 IOD/μm2 respectively at 2, 4 weeks postoperatively in group A, showing statistically significant difference (Plt;0.01) when compared with groups B and D. X-ray test indicated much bone callus formed early. Conclusion Transfection of the VEGF165 gene can enhance local angiogenesis at early stage andDPBVEGF165 compound can improve bone formation. Deproteinized bone combined with VEGF165 gene provides a potential method for therapy of osteonecrosis.
Objective To study the development, investigation, and application of the artificial vertebral body so as to provide an essential reference for the future research and clinical application. Methods The recent articles on materials, types, and clinical applications of the artificial vertebral body were reviewed.Results The materials used for the artificial vertebral body were porcelain, alloy, variant bone, and composite. But each of them had its own advantages and disadvantages. The types of the artificial vertebral body were grouped as expandable and non-expandable ones; however, the expandable type was much better. The artificial vertebral body had been applied to the treatments of spinal tumor, tuberculosis, fracture, and infection, with better effects. Conclusion The artificial vertebral body can beextensively applied. However, the materials and types need to be improved.