Radiological study on rat lumbar vertebral semidislocation model

OBJECTIVE: To investigate the impact of fixation in part lumbar segment on rat model with radiography. METHODS: One hundred and twenty SPF male SD rats (350～450g) were randomly divided into simple fixation group (SF group), rotary fixation group (RF group) and sham-operation group (Sham group). The external link fixation system was implanted into the L4-L6 of SF group and RF group rats. In RF group, L5 spinous process of rats was rotated to the right side, making the L4, L6 and L5 spinous process not in a straight line. In SF group, the external link fixation system was implanted simply and not rotated. The anterior and posterior diameter in the intervertebral space and the distance between spinous processes were examined 1, 4, 8 and 12 weeks after fixation. RESULTS: The anterior diameter in the intervertebral space between L3-L4, L4-L5, L5-L6, and L6-S1 of SF groups 4 weeks after fixation were 28.11 ± 3.94, 25.73 ± 4.70, 29.51 ± 6.34 and 34.97 ± 4.65 pixels; the posterior diameter were 7.39 ± 1.63, 6.65 ± 1.76, 7.02±1.52 and 9.62 ± 2.50 pixels; the distance between spinous process were 39.33 ± 11.74, 14.11 ± 5.75, 21.32 ± 6.84 and 77.43 ± 13.69 pixels, the values were less than those in Sham groups (P<0.05). The anterior and posterior diameter in the intervertebral space and the distance between spinous process of SF groups 8 and 12 weeks after fixation continuously decreased compared with Sham group rats (P<0.05). The results of RF groups were consistent with the measurement of SF groups, the anterior and posterior diameter in the intervertebral space and the distance between spinous process of RF group rats were less than those in Sham groups 4, 8 and 12 weeks after fixation (P<0.05). Osteophyte formation was observed in SF and RF groups 8 weeks after fixation. CONCLUSION: The fixation in part lumbar segment can result in the decrease of intervertebral space and the formation of osteophytes.