| Objective: To compare the biomechanical differences between thenew kidney-shaped nano-hydroxyapatite/polyamide66(n-HA/PA66) cageand the bullet-shaped n-HA/PA66cage by simulating transforaminallumbar interbody fusion(TLIF) operation on porcine lumbar specimens. soas to provide theoretical basis for producing intervertebral fusion cage withbetter mechanical properties.Methods:10adult male pigs’L2-L5spinal specimens were harvestedand divided into four groups: control group, nucleus pulposus（NP）resection group, bullet-shaped cage group, kidney-shaped cage group. Eachgroup had5motor units, and20at whole. X-ray examination to excludespinal disorders and measure the height of intervertebral height. NPresection group were excised NP underwent posterior fenestrationlaminectomy operation. Bullet-shaped cage group and kidney-shaped cagegroup were simulated to take TLIF through left intervertebral foramen andsupplemented by posterior pedicle screw fixation. Intervertebral height,position of the pedicle screw and cage were observed through X-ray. Biomechanical test data were suggested to calculate range of motion(ROM)of each groups.Results:(1)Intervertebral height: the NP resection group has nosignificant change compared with preoperative and controlgroup(6.0±0.54mm vs6.02±0.53mm and6.08±0.30mm, P>0.05), thebullet-shaped group and the kidney-shaped cage group were increasedslightly after TLIF surgery compared with the preoperative and the controlgroup, but no statistically significant(6.36±0.29vs6.06±0.30mm and6.10±0.23vs5.92±0.38mm,P>0.05).(2)The location of the cage: thekidney-shaped cages were closer to the middle and back of the vertebralbody, but the bullet-shaped cages were closer to left.(3)ROM: the NPresection group were increased in all directions compared with the controlgroup, statistically significant (P<0.05);the bullet-shaped cage group andthe kidney-shaped cage group were reduced compared with the controlgroup and NP resection group in all direction, statistically significant(P<0.05); The right bending and compression ROM of the bullet-shapedgroup were increased than the kidney-shaped cage group, statisticallysignificant (2.02±0.11vs1.23±0.06mm,1.52±0.33vs0.65±0.19mm,P <0.05),but there were no statistically significant in the other directions(P>0.05).Conclusions: Kidney-shaped cage could recover intervertebral heightand maintain the stability of spine the same as the bullet-shaped cage. Butkidney-shaped cage could contact more areas to vertebral endplate and disperse stress. Because of the curved design, Kidney-shaped cage could bebetter placed in the middle and back of the vertebral body in TLIF surgery.So it was more stable on the axial compression and the bending loadopposite implant, but no significant difference in other direction. |
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