In vitro study on biomechanical comparison between cervical arthroplasty and fusion / 医用生物力学

ABSTRACT

Objective To analyze biomechanical properties of cervical spine after anterior cervical discectomy and fusion (ACDF) and total disc replacement (TDR) surgery. Methods Twelve cadaveric cervical spines (C2-T1) were adopted, and the motion and load distributions of the cervical segments under intact state and after ACDF and TDR surgery were tested using a three-dimensional (3D) optoelectronics measurement system. All the tests were carried out with displacement control in directions of flexion (Flex), extension (Ext), left bending (LB), right bending (RB), left rotation (LR) and right rotation (RR). Motion characteristics of the normal cervical spine and the implant were also discussed. Results In TDR-treated specimens, range of motion (ROM) was well preserved and could restore to the normal ROM distributions, especially in Flex/Ext and LR/RR direction. While in ACDF-treated specimens, ROM presented a large decrease as much as to 73.41% under the same condition compared with TDR, and ROM distributions were also changed obviously in other motions for the segments. Significant changes of ROM in LB/RB direction occurred in both TDR and ACDF group, which were up to 45.92% and 108.06%, respectively. The experimental data indicated that the normal motion of cervical spines was a 3D coupled motion, especially in LB/RB direction, where a 35% rotation around X-axis existed. The cervical spine could recover close to normal coupled motion after TDR surgery. Conclusions TDR surgery can restore the physiological motion of cervical spines more close to the normal state, especially in Flex/Ext and LR/RR direction. The study provides a theoretical basis and quantitative reference for TDR and ACDF surgery in clinic.