| Objective:Approximately 1% of the world's adult population is affected by joint pain and disability resulting from ankle osteoarthritis(OA). The ankle posttraumatic OA(ankle PTOA) accounts for 78% of ankle OA in etiology. Moreover, malleolar ankle fracture is common and in clinic ankle PTOA induced by fracture with dislocation is more usual. It is necessary for researchers to use a ankle OA model to diagnose and treat human ankle OA. However, this ankle fracture-induced OA model has not been made yet in the world. Therefore, it is crucial to design a rat model to study ankle OA. Methods:Eight-week-old male SD rats were randomized into 2 groups(n=19 per group, 200 gm each): 1) medial melleolus facture with dislocation on the right ankle; 2)medial melleolus fracture on the right ankle. The contralateral ankle joints were used as control groups. Surgical induction: 1) the rat was anesthetized with 10% Chloral Hydrate and maintained at supine position with the right knee joint 90 degree flex and hip joint abduction prepared for aseptic surgery; 2) a 1 cm longitudinal incision from the medial melleolus to top was performed then blunt dissection of the superficial and deep fascia and the tibialis posterior tendon was carried out to expose the medial melleolus; 3) the osteotome combined with the angle fixator(37 degree) was put in the distal tibia and peened into the medial melleolus until the resistance disappeared suddenly; 4) the incision of fracture group was closed by 3-0 suture with single-layer, and the dislocation group was performed a malleolar varus mildly and a reduction immediately before closing the incision; 5) the rat was placed in the x-ray cabinet to make sure the articular surface was involved by trauma. 8 weeks after surgery, we used x-ray, fluorescence molecular tomography(FMT), histology, immunohistochemistry, real-time quantitative PCR and enzyme-linked immunosorbent assay(ELISA) to detect whether the OA symptom could be observed. Statistical differences were assessed with the paired Student's t test. Safranin O assessment between two experimental groups was analyzed with the unpaired Student's t test. Results were expressed as the mean ± standard error of the mean(S.E.M.) of the maximum score and P values smaller than 0.05 were considered statistically significant. Results:1. X-ray shows that the joint space of the experimental groups was narrow compared to the control groups and subchondral sclerosis appeared at 8 weeks after surgery. 2. FMT data indicated that the MMPs ROI were higher in the surgical ankle than the contralateral one at 8 weeks after surgery. 3. Safranin O and the modified Osteoarthritis Research Society International(OARSI) grading system shows that the summed ankle joint scores were 12.45 ± 1.21 in the dislocation model and 1.73 ± 0.33 in its control group(P < 0.05), while 11.45 ± 0.85 in the fracture model and 1.27 ± 0.27 in its control group(P < 0.05). However, there was no significant statistical difference between two model(P > 0.05). 4. Type II collagen staining in both experimental groups was less than control. Moreover, type X collagen and MMP-13 staining were detected stronger in both experimental groups. 5. The PCR results indicated that the both model had lower levels of m RNA for Col2a1 and Acan and enhanced the level of m RNA for MMP-13 compared to control. 6. The MMP-13 concentration of synovial fluid lavages detected by ELISA in both experimental groups was higher than control groups. Conclusion:The results of this study suggest that the two models can induce OA successfully and the difference between them is not significant through the modified OARSI score, it is significant for researchers to diagnose and treat human ankle OA with these models. |
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