[Effects on single segmental lumbar stability after graded facetectomy and laminectomy: a finite element study].
OBJECTIVE
To explore the effects on degenerative single segmental lumbar spinal stability after posterior graded laminectomy and facetectomy by a finite element method.


METHODS
A finite element model of L3-S1 segments with a single segmental degeneration at L4-5 level was established. Different models of L4-L5 segmental instability after posterior graded laminectomy and facetectomy were established. And interior 1/3, 1/2, 2/3 of laminar and bilateral facet joints were resected. Physical loads were applied to the models and the changes of range of motion (ROM) at L4-5 level in different models were recorded during flexion, extension, lateral bending and rotation.


RESULTS
As compared to preoperative model, after resecting 1/3 bilateral facet joints at L4-5 level, L4-5 segmental ROM increased 18% during flexion, 27% during extension and 45% during torsion. And the increased degree of ROM became more obvious along with a greater resection range of bilateral facet joints. No significant difference existed in L4-5 segmental ROM during lateral bending in all models.


CONCLUSIONS
Facet joints play vital roles in lumbar segmental stability. And segmental instability may occur when 1/3 bilateral facet joints are resected.
Zhao
Z
Fan
Liu
L
Zheng
Wang
W
Bingqiang
Yang
Y
Yong
Li
L
Dong
Lin
L
Jisheng
Ma
M
Zhao
Wang
W
Qi
Yan
Y
Huagang
Fei
F
Qi
D020342:Finite Element Analysis; D006801:Humans; D007796:Laminectomy; D008159:Lumbar Vertebrae; D008161:Lumbosacral Region; D011187:Posture; D016059:Range of Motion, Articular; D012399:Rotation; D021801:Zygapophyseal Joint