Development Of Biodegradable Anatomic NHA/PLGA Intervertebral Fusion Cage

Part one: The study on the design of biodegradable anatomic nHAPLGA intervertebral fusion cageOBJECTIVE: In this study,a statistical method combined with computer technology was designed to conform to the anatomical morphology of different segments of the neck and lumbar spine,and the intervertebral fusion device was matched with the size and morphology of each intervertebral space.METHODS:1.50 healthy adult volunteers and 50 elderly patients with cervical and lumbar degenerative diseases were selected for cervical and lumbar CT scans to obtain anatomical data on the edges of the vertebrae at the upper and lower vertebral margins of the neck,lumbar vertebrae and vertebrae,and to reconstruct and analyze their data,collect healthy adults and have degenerative necks,Anatomical data of elderly patients with lumbar spine.According to their anatomical morphology,the median anatomical morphological data of cervical and lumbar intervertebral space were calculated,and the reconstruction was carried out according to the data of cervical and lumbar intervertebral space in normal Chinese.2.The anatomical intervertebral fusion device was designed to match the anatomical morphology,size and pore structure of vertebral space according to the data of different segments of cervical and lumbar vertebrae.3.According to the elastic modulus and mechanical strength of normal human vertebrae,the composition and ratio parameters of nHA/PLGA of degradable materials are calculated by statistical method when the fusion device has certain porosity and aperture size,It is mainly designed to find the proportion and construction method of nHA and PLGA with the same elastic modulus of vertebral bone and the same biomechanical strength as normal body.4.According to the nHA and PLGA ratios obtained in the third step and the database data obtained in the second step,3D printing technology is used to print out the required different segments of the neck and lumbar vertebrae biodegradable anatomical nHA/PLGA intervertebral fusion device.RESULTS: According to the relevant research data in the early stage of this study,3D printing technology was used to print out the need for different segments of the neck and lumbar vertebrae degradable anatomical type nHA/PLGA intervertebral fusion device.CONCLUSION: In this study,a statistical method combined with computer technology was used to design an intervertebral fusion device which conforms to the anatomical morphology of different segments of the neck and lumbar spine and matches the size and morphology of each intervertebral space,which lays a foundation for the further study of biological performance detection.Part two:Biological performance test of degradable anatomical type n HA/PLGA intervertebral fusion deviceOBJECTIVE: The mechanical indexes and internal and external biological indexes of the synthesized biodegradable anatomical type n HA/PLGA intervertebral fusion device were tested and verified.METHODS:1.The first part of the synthesized anatomical n HA/PLGA intervertebral fusion device was implanted into the vertebral space in the corpse specimen to detect the stability of the biodegradable anatomical type n HA/PLGA intervertebral fusion device and the biomechanical characteristics of various mechanical loads.2.Using the biodegradable anatomical type n HA/PLGA intervertebral fusion device synthesized in the first part,the soaking experiment was carried out at different time in the physiological body fluids in vitro to verify the change characteristics of morphology,mechanical strength and elastic modulus under the immersion of long-term physiological humoral conditions.3.In the first part of the synthesis of the degradable anatomical n HA/PLGA intervertebral Fusion device by MTT method inoculation of 3T3 cells,by observing the growth and reproduction of cells on the fusion device,the cell compatibility of the fusion,cytotoxicity and other in vitro cytology experiments were detected.4.Biocompatibility test,Allergy Test,hemolysis experiment and other tests were carried out on the first part of the biodegradable anatomical type n HA/PLGA intervertebral fusion device.5.Using the biodegradable anatomical type n HA/PLGA intervertebral fusion device synthesized in the first part,it was implanted into the muscle bag of animal femoral part to observe the degradation,measure the mechanical strength and shape volume at different time points,and record the changes of degradation and mechanical strength in vivo.RESULTS: 1.The degree of matching between the biodegradable anatomical type n HA/PLGA intervertebral fusion device and the vertebral gap in the corpse specimen and the stability of the fusion device after implantation of the cadaver specimen and the biomechanical characteristics of various mechanical loads are good;2.The biodegradable anatomical type n HA/PLGA intervertebral fusion was used to soak experiments at different times in vitro physiological body fluids,which proved that the properties of morphology,mechanical strength and elastic modulus under long-term physiological humoral immersion were stable;3.The immersion experiment of degradable anatomical n HA/PLGA intervertebral fusion device at different times in vitro physiological body fluids proved that its properties were stable in the aspects of morphology,mechanical strength and elastic modulus under long-term physiological humoral immersion;4.The 3T3 cells were inoculated with MTT method on the biodegradable anatomical n HA/PLGA intervertebral fusion device,and the cell compatibility and cytotoxicity experiments showed that the cells had good growth and reproduction on the degradable anatomical n HA/PLGA intervertebral fusion device;5.The results of degradation and mechanical strength change in biodegradable anatomical type n HA/PLGA intervertebral fusion device were good,and the degradation of degradable anatomical n HA/PLGA intervertebral fusion device into the muscle bag of animal femoral was recorded and the changes of mechanical strength and shape volume in different time periods were measured.CONCLUSION: Through the further testing and study of the physicochemical and biomechanical properties of the degradable anatomical type n HA/PLGA intervertebral fusion device,it is found that the mechanical indexes of the fusion device and the biological indexes in vivo and in vitro are good,which meet the requirements of the indexes required in this study.Part three:The study on animal experiment of degradable anatomical type Nha/plga intervertebral fusion deviceOBJECTIVE: 3D printing degradable anatomical n HA/PLGA intervertebral Fusion was used to observe the fusion of cervical vertebrae and lumbar vertebrae in goats,and the intervertebral fusion and degradation and absorption of the fusion device in goats were observed.METHODS:1.The anatomical data of vertebral space were obtained by three-dimensional CT scan for the intervertebral space of goat operation(C3/4,L4/5)required for animal experiments,and the degradable anatomical n HA/PLGA intervertebral fusion device was printed by 3D printing method to match the anatomical morphology of intervertebral space in experimental animal goats.2.Choose 16 local goats and randomly group them.After the animal model was completed,the animals were randomly divided into 2 groups,8 in each group,of which 8 were only the control group and 8 were the experimental group.Routine intervertebral bone grafting with experimental animals in control group(taking goat autologous iliac bone).The 4 groups of time were January,February,March and June after surgery.3.Using electronic balance,ion sputtering instrument,scanning electron microscope,optical microscope,paraffin slicer,Polyformaldehyde,glutaraldehyde,microscopic optical photographic system and other experimental equipment to the specimen material and corresponding treatment,and through general observation,light microscope observation,scanning electron microscope and other relevant experimental data.RESULTS: The site of goat operation(C3/4,L4/5)intervertebral space grafting,the fiber cartilage connection began in January after operation,and there was a significant bone fusion at the site of vertebral interstitial bone grafting at the postoperative site in February,where the appearance of cartilage bone and fibrous osteogenesis was an indispensable process to achieve bone fusion.In the first February,there was no significant difference in the appearance of intervertebral space grafting in the two groups of surgical sites,indicating that in the early stage of bone fusion,the effects of n HA/PLGA and initial degradation products of degradable materials on fibrous osteogenesis and cartilage callus,which promoted bone fusion,were not obvious.After February,the degradation rate of degradable materials n HA/PLGA increased,and the metabolites produced led to the change of the environment in the operative section,which led to the decrease of the rate of bone fusion,and the n HA/PLGA of degradable materials could be replaced by the autologous bone of goats after they were completely degraded.CONCLUSION:Degradable anatomical n HA/PLGA intervertebral fusion device,in the early stage of bone fusion,the material itself and the initial degradation products have little effect on promoting the bone fusion of the surgical site(C3/4,L4/5),and there is no significant difference between the two groups of cartilage bone and fibrous osteogenesis.In the medium term,with degradable materials n HA/ The gradual degradation of PLGA and the increase of degradation products,the surgical site due to the degree of ossification of cartilage and fibrous tissue was slightly inhibited,resulting in the surgical site of vertebral space bone fusion process slowed down,in the later stage,the degradable material n HA/PLGA in the experimental group observed that its degradation rate is significantly different from the control group,Most of the biodegradable anatomical n HA/PLGA intervertebral fusion device implanted in the experimental group has been degraded,and it has been accompanied by the appearance of bone structure in the process of degradation and absorption.