动物造模,闭合性大鼠胫骨骨折模型 z-bio 2021-12-23 530

　　Background: Based on the model previously designed by Bonnarens et al., a rat fracture model is described. In this model, an intramedullary nail (IM) is retrogradely implanted from the knee joint before the fracture. Then, it fell into the fixed-weight blunt guillotine bone, forming a standardized closed central femoral fracture. Several studies have reported repeated complications in rat femoral fracture models using blunt decapitation, including death, fracture dislocation, excessive grinding, and deep infection. In addition, in the process of fracture healing, different degrees of fracture healing are particularly difficult. The degree of comminuted fracture affects the formation of callus, and the rat fracture model has a certain correlation with the formation of comminuted callus. The result of using a rat tibia fracture model to confirm the fracture is that the degree of compression is small, but the bone mass is significantly moved, and the needle tip angle exceeds 10°. The use of three-point forceps in the rat tibia fracture model showed minimal edema and death, but the tibia bone call was significantly reduced 6 months after the fracture, and the needle angle was 80±2°. Due to the limitations of existing fracture models, a feasible, reproducible and reliable fracture model is needed, especially in laboratory animals. Method: Animals: 10 30-week-old rats and 71 8-week-old rats were used. As described below, use three-point bending forceps for fractures. A total of 25 (n = 25) 8-week-old female Sprague-Dawley rats were used in the in vivo study, with an average weight of 187.04±10.15 grams. A total of 25 (n = 25) 8-week-old female SD rats were used in the in vivo study, with an average weight of 187.04±10.15 grams. There is a one-week adaptation period before the start of the experiment. After the adaptation period, the rats were fasted for 12 hours before the operation.

　　Surgery: All operations were performed with ketamine and xylazine before anesthesia. After intramuscular injection of ketamine (40 mg/kg) and xylazine (5 mg/kg), each group of rats was operated on and X-ray photographs were taken. A 4mm skin incision was used for the surgical incision, and a scalpel blade (#15) was used for the surgical resection of the knee joint. The tibia is exposed to stainless steel, and the tibia and skull are connected to the anterior cruciate ligament and the anterior horn of the meniscus, and a sharp probe is manually introduced to determine the area of the intramedullary needle entrance. Insert a 23G, 11/2" needle into the distal end of the tibia. The penetration depth of the needle is approximately 22 mm. After the intramedullary nail has completely penetrated the tibia, use a bone knife to cut the proximal end again. Cut the incision. 4/ 0 Closing with nylon sutures has been especially improved by modifying the upper jaw compression of Otto et al.’s upper jaw to change the tibia fracture in rats. We constructed a 3-point bending forceps with a diameter of 10 x 0.1 mm and the same size; change three Point bending forceps; change the two supporting claws from 17 mm to 7 mm; use the forceps to locate visually; control and close the forceps until the crack is heard; then immediately release the pressure. Create a large rat tibia or femur fracture according to the above principles In the model, the left tibia fracture and the right tibia in the control group were intact. In the control group, each animal was placed in a separate cage to allow free movement after the operation. Tramadol was used while the operation was performed at 5 mg/day after the operation. kg, as an analgesic for 3 consecutive days, euthanize the animal by intraperitoneal injection of 20 mg/kg pentobarbital and perform radiological observation

　　Commonly seen in fracture ratings: Since the fracture is pre-fixed with an intramedullary nail in the fractured bone, the fracture is considered stable and does not require an external support bandage after the operation. The tibia is an induced fracture and has never been amputation. Extremities collection (control) 5 After 1, 2, 3, 4, and 6 rats died from the surrounding area (n = 5). The tibia was dissected and controlled. A dissecting stereo microscope was used. The lid index was 3.1μm pixels and the bone The call area is measured on the opposite side of the tibia fracture and the bone call width (mm) after tibia fracture healing in rats, as the correct tibia control of the lateral rat, using IMAGE software to measure the ratio of crimp index, cals area, cals index, and needle use The same software measures angle and proximity; end fractures, total length; radial assessment of fractures and normal control bones; fracture radiology: two-angle X-ray examination of the intact tibia opposite the fracture using X-rays immediately after surgery Use this equipment to take pictures of bones and joints, bone call formation, bone fragmentation, pin angle, X-ray bone call index and other indicators once a week after surgery. X-ray bone us index is the maximum width of bone call in the middle of the tibia, including the original bone. The width of the contralateral control bone. This is split. A crushed fracture is when a bone splits or breaks into two or more pieces. First of all, the two images before and after will not be squeezed. Then crush the small pieces. Its size is smaller than the diameter of the nail. \u003c1.1mm; Third, it is severely crushed (a large piece larger than the diameter of the intramedullary nail). Histological examination of fractures: Animals were sacrificed at 1, 2, 3, and 4 weeks after the operation, and anatomical tibia specimens were taken from the fractured limbs every week (n = 5). Under the fracture site (obviously forming callus), the bone was cut into 2 mm and fixed with 10% formaldehyde for 24 hours. Decalcification 10%. Formic acid was applied for 4 days, then processed and stained with H&E standards. Results: A preliminary study on 30-week-old rats (n = 10) showed that tibial fractures were mainly ground, tilted and separated. The median is dominant. In 8-week-old rats (n = 65), the results showed that the main tibia was not compressed on the horizontal and central axis. Another 8-week-old rat (n = 6) was used to compare the types of femoral and tibia fractures. The main types of femur and tibia fractures are lateral and non-comminuted fractures located on the central axis of the bone. In vivo studies found that all induced fractures in the middle of the third tibia. The average driving time is 3.90±0.55 minutes. All animals survived the operation without complications, soft tissue damage at the fracture site or stiffness of the adjacent knee and ankle joints. There was no sign of necrosis or severe edema at the fracture site. Twenty-four hours after the fracture, the rats behaved normally. After a week or two, the mice began to aggravate their affected limbs. After two weeks, all mice began to weigh on all four paws. The formation of callus was observed in the first week and gradually decreased in the sixth week. The angle between the fracture line and the long axis of the tibia is measured by radiography to determine the type of fracture. The main type of fracture is lateral fracture (89.41±2.11). The average length of proximal fractures was 41.02, accounting for ±3.27% of the average length of intact bone. The average angles of the IM needle at the outer and front and rear positions were 167.33±3.67° and 161.47±4.87°, respectively. The formation of callus around the fracture site is clearly visible on the X-ray film. The density of callus increased within 3-4 weeks, making it difficult to observe the fracture line. The fracture line disappeared in the 4th week, and the fracture healed completely. In the first week, the X-ray callus index was almost impossible to measure, and in the second week, it was small and almost invisible. It reached its highest point in the 3rd week and gradually decreased in the 4th and 6th weeks. Mild comminuted fractures were observed in 4 animals, and no comminuted fractures were observed in the remaining animals. Histological examination after the fracture showed hematoma and chondrocyte hyperplasia in the first week after the fracture, and the cartilage cell area and cancellous bone increased in the second week. In the 3rd and 4th weeks, cancellous bone increased with the appearance of hypertrophic chondrocytes and bone marrow. Conclusion: The modified three-point curved forceps used in this study are very useful for reproducible closed fractures that produce few complications in rats.