[Design and biomechanical analysis of nickel-titanium open shape memory alloy artificial vertebral body].
OBJECTIVE
To design an open shape memory alloy artificial vertebral body that can be used to reconstruct the vertebral body in spine diseases, such as thoracic-lumbar spine tumors, burst fracture of the vertebrae, kyphosis and scoliosis, and to evaluate the biomechanical stability of lumbar functional segment unit after insertion with the shape memory alloy artificial vertebral body.


METHODS
The open shape memory alloy artificial vertebral body with nickel-titanium (NiTi) alloy was made. Eight fresh spine specimens (T14-L5) from normal adult porcine were used to detect the range of motion (ROM) in 4 models and were divided into 4 groups: intact vertebrae served as group A; pedicle screw fixation of T15, L1, L3, and L4 was given in group B; after total resection of L2, it was reconstructed by open shape memory alloy artificial vertebral body combined with pedicle screw fixation of T15, L1, L3, and L4 in group C; and after total resection of L2, it was reconstructed by titanium cage vertebral body combined with pedicle screw fixation of T15, L1, L3, and L4 in group D. The three-dimensional ROM of flexion, extension, left/right lateral bending, and left/right rotation in T15-L1, L1-3, and L3,4 segments were detected in turn by the spinal three-dimensional test machine MTS-858 (load 0-8 N x m).


RESULTS
Compared with group A, groups B, C, and D had good stability in flexion, extension, left/right lateral bending, and left/right rotation, showing significant differences (P < 0.05). There was no significant difference in the degree of each motion between group B and group C (P > 0.05). Group C had less degree of motion in T15-L1 and L3,4 segments than group D, showing significant differences (P < 0.05), but there was no significant difference in L1-3 segment (P > 0.05).


CONCLUSIONS
The open shape memory alloy artificial vertebral body has a reasonable structure and good biomechanical stability, it can be used to stabilize the spinal segment with pedicle screw fixation.
Department of Orthopedic Trauma Center, 175th Hospital of PLA, Affiliated Southeast Hospital of Xiamen University, Zhangzhou Fujian 363000, PR China.
Hui
H
Liu
Kejian
K
Lian
Lijun
L
Liao
Wenliang
W
Zhai
Zhenqi
Z
Ding
D000497:Alloys; D000818:Animals; D001696:Biomechanical Phenomena; D001863:Bone Screws; D016268:Internal Fixators; D007595:Joint Prosthesis; D008159:Lumbar Vertebrae; D009532:Nickel; D011474:Prosthesis Design; D013552:Swine; D014025:Titanium
D000497:Alloys; C040654:titanium nickelide; D009532:Nickel; D014025:Titanium