[Biomechanical evaluation of the U shape lumbar biological dynamic fixation system].
OBJECTIVE
To evaluate biomechanical characteristics of a new U-shaped lumbar bioelastic internal fixation deuice (UBD).


METHODS
Six fresh calf lumbar (L2-L5) samples were divided into 4 groups, namely the normal group, traumatic instability group, instability group with rigid internal fixation and instability group with UBD fixation. The vertebral 3-dimensional range of motion (ROM) and rigidity of the 4 group were tested.


RESULTS
Elastic fixation and rigid fixation both significantly increased vertebral segment stability for flexion, extension, lateral curvature and rotations. Compared with rigid fixation, elastic fixation obviously increased the ROM by 2.22 degrees in flexion and extension, but significantly decreased the rigidity in forward bending and backward bending and compression (P<0.01).


CONCLUSIONS
The UBD may enhance the load sharing and decrease stress-shielding and stress concentration without sacrificing lumbar stability.
Xue
Jian
J
Department of Orthopedics, Zhujiang Hospital, and Department of Anatomy and Biomechanics, Southern Medical University, Guangzhou 510282, China. gdwjxj@163.com
Jin
An-min
AM
Yu
Bo
B
Zhao
Wei-dong
WD
Feng
Wei
W
D000818:Animals; D001696:Biomechanical Phenomena; D002417:Cattle; D016268:Internal Fixators; D007593:Joint Instability / Q000601:surgery*; D008159:Lumbar Vertebrae / Q000601:surgery*; D013123:Spinal Fusion / Q000295:instrumentation* / Q000379:methods; D013314:Stress, Mechanical