OBJECTIVETo observe the basic characteristics of rats with subluxation, which was hypomobility of motion.

METHODSOne hundred and eight male SD rats (weighted, 350 to 450 g) were randomly divided into experimental group (simple fixation and rotatory fixation) and sham operation group. Each group was subdivided into four groups, including 2, 4, 8 and 12 weeks sub-groups. Simple fixation and rotatory fixation group were modeled by implanting external linked fixation system; Sham operation group was dealed with operation intervention. At the end of connection, X-ray films was used to observe posterier body angle (PBA); Spinal stiffness system for stiffness in simple fixation group and rotatory fixation group.

RESULTSRadiographic results showed that variation of PBA n experimental groups tended to decrease; and there was no significant difference between simple fixation group and rotatory fixation group at the end of linking time (P > 0.05). But there was significant difference between the experimental group and sham operation group (P < 0.05). The degree of stiffness showed that the stiffness in experimental group increased with the linking time, but no meaning between groups (P > 0.05).

CONCLUSIONRats with subluxation induced by external linked fixation system can effectively change biomechanical characteristics of spine, reduced the motion with linking time.