Construction Of A Rat Model Of Subtotal Lumbar Vertebral Body Fusion

Part 1:Comparison of two kinds of lumbar vertebral body subtotal spine fusion rat model construction of surgical approachObjectiveIn this experimental study,by measuring the bone structure data of the lumbar spine in rats,designing a titanium alloy mesh fusion cage of appropriate specifications for subtotal lumbar vertebral body fusion,comparing the two methods of transabdominal anterior approach and transperitoneal approach Surgery time and complications to choose a safer and more reliable operation.MethodsTen healthy SPF male Sprague-Dawley rats(8 weeks of age,weight 340±10g)were selected and sacrificed by sodium pentobarbital anesthesia.The height,anteroposterior diameter,and left and right diameters of the 5 lumbar vertebrae were measured.According to the measured parameters,a 3D printed rat lumbar titanium alloy mesh fusion cage was designed.Select 40 healthy male SPF-grade Sprague-Dawley rats(8 weeks of age,weight 340±10g),and randomly divide them into two groups,each with 20 rats,using 3D printed rat lumbar titanium alloy mesh fusion cages.Anterior approach and transperitoneal approach were performed for subtotal lumbar vertebral body fusion surgery.Compare the difference of operation time,surgical complications and 4-week survival rate of different surgical methods.ResultsIn this experiment,a self-designed 3D printed rat lumbar titanium alloy mesh fusion cage was used to successfully complete the subtotal fusion of the rat lumbar 5 vertebral bodies through two different approaches.The average operation time of the transabdominal anterior approach was 31.49±1.83 minutes,and the average operation time of the transabdominal extraperitoneal approach was 41.86±2.12 minutes.It can be found that the operation time of the transabdominal anterior approach was significantly less than that of the transabdominal extraperitoneal approach(P<0.05).The surgical complications of the transabdominal anterior approach are significantly less than those of the extraperitoneal surgery.The 4-week survival rate of the anterior abdominal approach was significantly higher than that of the extraperitoneal approach.ConclusionIn the two surgical methods for constructing a rat model of subtotal lumbar vertebral body resection spinal fusion:the anterior abdominal approach is more advantageous than the extraperitoneal approach.Part 2:Evaluation of a rat model of subtotal lumbar vertebral body fusion via anterior abdominal approachObjectiveA spinal fusion model was constructed by subtotal fusion of 5 lumbar vertebral bodies in rats through a transabdominal anterior approach,and the effectiveness of the model was verified by comparing the ingrowth effect of new bone tissue in the titanium mesh at different time points.MethodsTen Sprague-Dawley rats(8 weeks old,340±10g weight)were selected and randomly divided into two groups:4-week group and 8-week group(n=5).Both groups of rats underwent subtotal fusion of 5 lumbar vertebral bodies through the anterior abdominal approach.They were sacrificed 4 and 8 weeks after the operation and the corresponding spinal segments were taken out.After surgery,X-ray was used to evaluate the position of internal fixation,Micro-CT was used to compare the fusion rate,bone volume fraction,trabecular bone thickness and number of trabecular bone in each group.Hard tissue sections+methylene blue acid fuchsin staining were used for histological evaluation.The indicators were analyzed statistically,and P<0.05 indicated that the difference was statistically significant.ResultsAll rats successfully completed the modeling operation and survived.The fusion rate in the 4-week group was 40%,which was significantly lower than that in the 8-week group(100%),P<0.05;Micro-CT indicated that a large number of titanium meshes were visible in the 8-week group New bone tissue grows in,and a small amount of fibrous tissue filling can be seen in the middle of the titanium mesh.The distribution of new bone in the titanium mesh in the 4-week group is less,and most of the area is fibrocartilage tissue.Through three-dimensional modeling analysis,the bone volume fraction in the titanium mesh in the 8-week group The number of bone trabeculae was significantly higher than that of the 4-week group(the bone volume fraction of the 4-week group was 29.02±3.25%,the number of trabecular bone was 1.97±0.40(1/mm),and the bone volume fraction of the 8-week group was 42.20±10.50%.The number of trabeculae was 4.66±1.23,P<0.05),the thickness of trabecular bone in the titanium mesh in the 4-week group was significantly greater than that in the 8-week group(the thickness of the trabecular bone in the 4-week group was 0.14±0.02mm,and the thickness of the trabecular bone in the 8-week group was 0.09±0.03mm,P<0.05).The histological test results indicated that a large amount of new bone tissue was seen at both ends of the titanium mesh in the 8-week group,new bone tissue and fibrous tissue were seen in the middle of the titanium mesh,with cartilage tissue locally,and a small amount of bone tissue grew into the titanium mesh in the 4-week group.It is mainly filled with fibrous tissue;through image software analysis,the bone intrusion distance and the percentage of new bone area in the titanium mesh in the 8-week group were significantly higher than those in the 4-week group(the percentage of new bone area at 4 weeks was 12.36± 16.93%,and at 8 weeks it was 35.72± 12.80%,the bone ingrowth distance was 2.02±1.16mm at 4 weeks,and the bone ingrowth distance was 4.97±2.58mm at 8 weeks,P<0.05).ConclusionThe rat model of subtotal lumbar vertebral body fusion via anterior abdominal approach can effectively simulate the process of subtotal vertebral body fusion.