| Part I. Analysis of the fault and complications of the anterior cervical fusion cageObjective: To study what causes the fault and complications of the anterior cervical fusion cage. Methods: Ninety-six patients with cervical spondylotic myelopathy, acute protrusion of cervical disc, traumatic cervical instability were treated with the anterior cervical fusion cage. The fault and complications of the anterior cervical fusion cage were observed. Results: The fault related to anterior cervical fusion cage occurred in 3 patients was the misplacement of the cervical cage. The complications related to anterior cervical fusion cage occurred in seven patients that included decrement of cervical physiological lordosis, mobilization, rotation, dislocation, and subsidence into the adjacent vertebrae, nonunion of the fusion cage. Conclusion: The strategy for diminution fault and decrement complications is to have correct patient selection, follow the principles of surgical procedure and improvement the designation of the anterior cervical fusion cage.Part II. The research and development of absorbable anatomical design fusion cage.Objective: Absorbable anatomical design fusion cage was made using absorbable polymer of poly-DL-lactic acid. Methods: ADFC was designed as hollow column, and the section is polygon. Disintegration and compressivestrength were carried out. Results: ADFC using poly-DL-lactic acid with the molecular weight of 20 million can resist the compression of 850 kg, and can resist the compression of 240 kg after vitro degradation for six months. Conclusion: ADFC applying anatomical design, its advantages lies in effectively prevent the subsidence of cage and content the paradoxical requirements of cage designation.Part III. A relative property biomechanical research about the effect of absorbable anatomical design fusion cage on the cervical stability.Objective: To investigate the biomechanical properties of cages with various material and shape, and to compares the initial stability of cages and the effect of material and shape on the cervical stability, subsidences of cages. Methods: Cervical fusion specimens are made using ten fresh cadavers. The biomechanical properties of cages are tested applying stress-analysis method. Results: Of the four cages, the stiffness of titanium cages is the highest and with the lest strain; the strength, stiffness of ADFC is similar to those of AFC and with difference, while comparing with auto iliac crest, it has difference. As far as the stability is concerned, the implant of auto iliac crest is the best; titanium cage is the worst; ADFC and AFC are between them. Under the cyclic loading, titanium cage has the largest subsidence, the subsidence of ADFC and AFC is small, and which of the auto iliac crest is the smallest. Titanium cage has the largest pullout strength, and that of ADFC and AFC is also large. There is significant difference among them. Conclusion: ADFC is an ideal fusion cage with its strength, high stiffness, and the small subsidence.Part IV .The vivo research about the effect of absorbable anatomical design fusion cage on anterior cervical fusion.Objective: To investigates the effect of ADFC on anterior cervical fusion. Methods: Anterior cervical fusion was performed at 10 female goats, and five of them were implanted with ADFC, others were implanted with iliac crest. Interbody fusion was assessed by high-resolution radiography at 6, 10,14, 18, 24 weeks after operation. To investigate the disc space height, graft collapse and fusion. Fusion was reassessed by histological analysis. Results: At 24 weeks, three-grade fusion was found in five goats implanted with ADFC, two-grade fusion was found in two goats implanted with auto iliac crest, and three-grade fusion was found in three goats implanted with auto iliac crest. Histological scores of ADFC are 4, which make it clear that ADFC has achieved bony fusion. Conclusion: ADFC has good biocompatibility without evident toxically by side effects, and it can reduce fusion time... |
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