[The biomechanical change of lumbar unilateral graded facetectomy and strategies of its microsurgical reconstruction: report of 23 cases].
OBJECTIVE
To study the effects of unilateral graded facetectomy on lumbar stability through biomechanical analysis. The primary clinical results of unilateral facetectomy, posterior lumbar interbody fusion and unilateral pedicle screw instrumentation using X-tube system were also evaluated.


METHODS
5 functional spinal units (FSU) from fresh cadavers of 5 adults were made, divided into 5 groups to remain intact, or with the lateral 1/4, 1/2, or 3/4 or the whole of the left L4/5 articular process, and then put in the biomechanical testing apparatus to evaluate the effects of operation on the lumbar motion range of flexion, extension, lateral bending and axial rotation. Twenty-three patients, 16 males and 7 females, aged 47.7 (32 - 74), underwent unilateral facetectomy, posterior lumbar interbody fusion, and unilateral pedicle screw instrumentation using X-tube system. The clinical outcomes of the 23 patients were assessed by use of the visual analog score (VAS), Oswestry disability index (ODI), and Nakai criteria.


RESULTS
The experiment of the 5 FSUs showed that no significantly negative effects on the change in lumbar motion range of flexion, extension after unilateral graded facetectomy (all P > 0.05), and the stability of lateral bending and axial rotation had been greatly affected with the range of graded facetectomy exceeding 1/2 (P < 0.05). According to the Nakai criteria, the clinical effect was excellent in 15 cases (65.2%), good in 6 cases (26.1%), and fair in 2 cases (8.7%). The excellent and good cases accounted for 91.3% with a fusion rate of 95.6%.


CONCLUSIONS
The lumbar stability is significantly affected if the range of graded facetectomy exceeds 1/2. The use of procedures of unilateral facetectomy, diskectomy, spinal nerve root decompression, autologous bone grafting, and unilateral pedicle screw fixation using X-tube is an optional strategy for minimally invasive spine technique.
Zhou
Yue
Y
Department of Orthopedics, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China.
Luo
Gang
G
Chu
Tong-wei
TW
Wang
Jian
J
Li
Chang-qing
CQ
Zheng
Wen-jie
WJ
Zhang
Zheng-feng
ZF
Hao
Yong
Y
D000328:Adult; D000368:Aged; D001696:Biomechanical Phenomena; D002102:Cadaver; D017586:Diskectomy; D005260:Female; D005593:Fracture Fixation, Internal; D006801:Humans; D007405:Intervertebral Disc Displacement / Q000503:physiopathology* / Q000601:surgery*; D008159:Lumbar Vertebrae / Q000503:physiopathology* / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D019060:Minimally Invasive Surgical Procedures / Q000379:methods; D019651:Plastic Surgery Procedures / Q000379:methods; D016896:Treatment Outcome