目的：设计膝关节打击器，并评估其制作兔膝关节软骨下骨微损伤模型的稳定性。方法遵循重物坠落致伤原理设计膝关节打击器。将12只新西兰大白兔随机分成两组，A组6只兔6个膝关节为实验组，对侧膝关节为对照组，将质量1.74 kg重物从30 cm高自由坠落，撞击髌股关节。B组6只兔6个膝关节为对象，对侧膝关节为对照组，将质量1.14 kg重物从28 cm高自由坠落，撞击兔股骨外侧髁。分别于撞击前后行X线检查，撞击后行MRI检查，取股骨髁部行HE染色。结果 X线平片检测，股骨均未出现骨折。A组MRI检查发现6个膝关节股骨干骺端T1加权像、T2加权像和脂肪抑制像低信号；HE染色显示软骨和软骨下骨皮质完整，骨小梁局部排列紊乱或连续性中断，髓腔内可见多处不规则排列大片红细胞。B组1只兔膝关节MRI图像质量较差，余5个膝关节可见股骨外侧髁处T1加权像低信号，T2加权像和脂肪抑制像高信号；HE染色显示软骨和软骨下骨皮质完整，骨小梁局部排列紊乱。对照组MRI检查未见异常信号，HE染色未见异常。结论设计的膝关节打击器操作方便可控，能可靠地复制兔膝关节软骨下骨微损伤模型。%Objective To develop a knee joint impact device to produce animal model of subchondral bone micro-fracture in rabbits. Methods A knee joint impact device was designed. 12 New Zealand rabbits were divided into group A (n=6) and Group B (n=6). In the group A, 6 patellar-femoral joints of the 6 rabbits were impacted (1.74 kg from height of 30 cm). In the group B, 6 femoral condyles of the 6 rabbits were impacted (1.14 kg from height of 28 cm). All the rabbits were evaluated with X-ray and MRI post injury. The femora of all the rabbits were observed with HE staining. Results No fracture line was found in all the animals with X-rays. The MRI of the 6 knee joints in the group A showed low signal intensities on T1 weighted, T2 weighted and fat suppression images. Histopathology demonstrated integrated cartilage and sunchondral bone plate, micro-fractures of cancellous and bleeding in marrow. The MRI of the 5 knee joints in the group B showed low signal intensities on T1 weighted images and high signal intensities on T2 weighted and fat suppression images. Histopathology demonstrated integrated cartilage and sunchondral bone plate, micro-fractures of cancellous and bleeding in marrow. No disorder was found with MRI and histology in the contral sides. Conclusion The impact device of the knee joint can produce controllable and reproducible sub-chondral bone micro-fracture in rabbits.
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