A new internal fixation system using vertebral pedicle screw for unstable lumbar spine: an in vitro biomechanical stability evaluation.
OBJECTIVE
To evaluate the effect of a new internal fixation system utilizing vertebral pedicle screw in fixing unstable lumbar spine in vitro.


METHODS
Twelve lumbar spine specimens (L(2 to 5)) obtained from fresh human cadavers were randomly divided into 2 equal groups, namely groups A and B. All intact specimens were subjected to nondestructive testing in 6 loading modalities on a universal testing machine, before complete L(2 to 5) instability was produced by means of a wedge fracture induced by resection of the posterior ligamentous structures. Specimens in group A were fixed with the new internal fixation system, and group B with SOCON pedicle screw. The same nondestructive testing was repeated to determine the structural stability of the spine after fixation in both groups.


RESULTS
The injured spines fixed with implants in both groups were significantly more stable than the intact specimens in all modes of tests (P < 0.05), especially in flexion and extension tests, in which a stability increase by 62.8% for flexion and 63.9% for extension was recorded in group A, and 54.9% for flexion and 51.0% for extension in group B. The two fixation systems exhibited similar effect in stabilizing the injured lumbar in all the 6 loading modalities (P < 0.05).


CONCLUSIONS
This internal fixation system with vertebral pedicle screw is capable of providing biomechanical stability for unstable lumbar spine.
Huang
Wen-hua
WH
Key Laboratory of Medical Biomechanics of PLA, First Military Medical University, Guangzhou 510515, China. hwh100@163.net
Li
Shu-gang
SG
Yuan
Lin
L
Zhao
Wei-dong
WD
Zhang
Mei-chao
MC
Li
Jian-yi
JY
Fan
Ji-hong
JH
Zhong
Shi-zhen
SZ
D001696:Biomechanical Phenomena; D001863:Bone Screws; D006801:Humans; D016268:Internal Fixators; D008159:Lumbar Vertebrae