Experimental Research Of Lumbar Facet Joint Biodegradable Fusion Cage On Design Features And Biomechanics

Objective: To design and fabricate the PLGA biodegradable fusion cage of Lumbar facet joint, and to analyze the material characteristics. To investigate the biomechanical variation of the PLGA lumbar facet joint biodegradable fusion cage invitro, for further improvement and providing a theoretical basis for clinical application.Methods: After general anesthesia, Lumbar facet joint were incised in 36 Boer goats, and then two fusion cage was implanted into each Boer goats to detect compressive strength and viscosity in the process of biodegradation. Thirty-six functional spinal units were divided into control group,lumbar zygapophysial joint fusion cage fixation group,lumbar zygapophysial joint damaged group, disc semiresection group, disc semiresection instrumented with facet screw fixation group and disc semiresection instrumented with zygapophysial joint fusion cage fixation group to test the angle range of motion(ROM)of functional spinal unit(FSU) under 6 degrees of freedom.Results: Compressive strength and viscosity decreased at 0,1,2,3 and 6 months after implantation, but compressive strength and viscosity were good at 3 months(12.6 MPa and 0.31 dl/g).Completely destroyed at 6 months. There was significant difference in the angle ROM in other five degrees of freedom difference except extension orientation between lumbar zygapophysial joint fusion cage fixation group and control group(P<0.01).After the nucleus hemisection,the ROM of 6 degrees of freedom in fusion cage fixation group Was obviously less than that in the nucleus hemisection group(P<0.01),while compared with the facet screw fixation group,there was no significant difference(P>0.05)except in flexion and extension orientation.Conclusions: PLGA biodegradable fusion cage have a high stability. The integrity and supportive effect of the fusion cage can meet the requirement of bony fusion.