In vitro biomechanical study of anterior cervical micromemory compression alloy plate

English Keywords:Biomechanics  Cadaveric specimens  Fusion  Cervical spine

English Abstract:

  【Abstract】 Objectives: To evaluate the immediate stability of a new miniature memory compression alloy plate (GYZ memory alloy plate) for anterior cervical discectomy and fusion through biomechanical test in fresh cadaver specimens. Methods: Thin layer CT scan and bone density examination were on the cervical spine of 6 fresh cadaveric specimens(male, average age: 55.2±7.1 years old, average height: 175.4±3.8cm, average weight: 72.3±6.0kg) to exclude fractures, deformities and osteoporosis. All specimens were removed from peripheral blood vessels, muscles and other soft tissues, while ligaments and joint capsules were retained. Then, the specimens were divided into intact group, injury group, new alloy plate group and traditional titanium plate group. In the intact group no treatment was given. In the injury group, only the C3/4 intervertebral disc was damaged. In the new prosthesis group, C3/4 intervertebral fusion and fixation with GYZ memory alloy plate was given. In the traditional titanium plate group, C3/4 intervertebral fusion and fixation with traditional titanium platewas given. Each group was loaded under 1.5N·m in the direction of flexion, extension, left and right lateral bending and left and right torsion. The results of the third experiment were recorded and the range of motion (ROM) of C3/4 intervertebral disc in flexion, extension, left and right lateral bending and left and right torsion direction of the four groups were collected and analyzed. Results: Postoperative imaging showed that the position of the prostheses was normal. In the intact group, the ROMs of C3/4 disc in flexion, extension, left lateral bending, right lateral bending, left rotation and right rotation were 4.8°±0.5°, 2.5°±0.1°, 2.4°±0.3°, 2.6°±0.3°, 2.0°±0.2° and 3.9°±0.1°, respectively. The ROMs of C3/4 disc in the injury group were respectively 6.0°±0.7°, 3.4°±0.3°, 3.4°±0.5°, 3.8°±0.6°, 2.4°±0.9° and 5.7°±1.3°. Compared with the intact group, the C3/4 ROMs in the injury group in flexion, extension, lateral bending and rotation direction increased significantly(P<0.05). The C3/4 ROMs in the new alloy plate group in the above six directions were 0.6°±0.1°, 0.4°±0.1°, 0.5°±0.1°, 0.7°±0.1°, 0.6°±0.1° and 1.0°±0.1°, respectively, while those in the traditional titanium plate group were 0.6°±0.1°, 0.5°±0.1°, 0.5°±0.1°, 0.7°±0.1°, 0.5°±0.1° and 1.0°±0.1°. The ROMs of the new alloy plate group and the traditional titanium plate group decreased significantly in the above directions(P<0.05). There was no significant difference in ROMs between the new alloy plate group and the traditional titanium plate group in the above directions(P>0.05). Conclusions: The miniature memory alloy plate can obtain the fixation strength and the immediate stability of the operation site similar to the traditional titanium plate.