BACKGROUND:Lumbar spinal stenosis can result in lumbar nerve root pain and other symptoms or even disability, which seriously impacts people’s quality of life. Interbody fusion is the main clinical treatment. Studies have shown that an interspinous fusion cage is prone to have hairline fractures and loss of implant; therefore, biomechanical properties and biocompatibility of the interbody fusion cage at L4/5need to be studied.
OBJECTIVE:To analyze the stability of the interspinous fusion cage at L4/5, and to explore the biomechanical properties and biocompatibility of adjacent segments.
METHODS: Ten adult fresh frozen spine specimens were selected and divided into normal group and model group, with five specimens in each group. The specimens were numbered and placed in a special fixture. The interspinous fusion cage, made in Zhengzhou Cast Medical Instrument Co., Ltd., China, was implantedin vivo and fixed using a cage fixator made of Ti6AL-4V ELI.
RESULTS AND CONCLUSION:Artificial vertebral bodies had less strain changes than the normal vertebrae in different implantation positions in terms of central compression, anteflexion, rear protraction, lateroflexion (P < 0.05). During vertebral displacement under the maximum load of 500 N, the linear displacement and angular displacement in anteflexion, rear protraction, left lateral flexion, levorotation were decreased significantly in the model group than the normal group (P < 0.05). These findings indicate that the interspinous fusion cage can maximaly preserve the range of motion of the injured vertebral body, maintain the stability of the segment, and reduce the stress of the intervertebral disc.