ABSTRACT
Objective:To develop a specialized clival-cervical plate fixation (CCPF) for anterior surgery to treat craniovertebral instability, and to compare it with a posterior occipitocervical fixation (POCF) in biomechanical validation.Methods:Based on the measurement of 40 adult dry bones and 30 volunteers CT images, the clival-cervical plate was designed and manufactured. 8 cadaveric specimens (occiput-C 3) were tested in five conditions including the intact status, the intact+CCPF status, the injury status, the injury+CCPF status, and the injury+POCF status. Specimens were applied a pure moment of 1.5 N·m in flexion, extension, lateral bending, and axial rotation. Calculating and comparing the range of motion (ROM) and neutral zone (NZ) for the occiput to C 2. The effects of different fixation methods on the distribution of ROMs at the occipitocervical region were compared. Results:The injury+CCPF status constrained ROMs to 1.7° in flexion ( q=4.68, P=0.055) , 1.2° in extension ( q=0.39, P=0.9922) , 2.8° in lateral bending ( q=1.25, P=0.814) , and 4.3° in axial rotation ( q=5.08, P=0.035) , resulted in larger ROM in axial rotation but similar ROMs in other directions ( P>0.05) when compared with the injury+POCF status. There were no significant differences between the above two fixation methods in flexion-extension ( q=1.94, P=0.554) , lateral bending ( q=1.79, P=0.611) and axial rotation ( q=2.14, P=0.478) for the NZs. For the flexion, extension,lateral bendingand axial rotation direction, the proportion of the C 1, 2 ROM to the overall ROM was 28%, 25%, 34% and 56% respectively in the injury+CCPF status, and it was 59%, 53%, 42% and 71% respectively in the injury+POCF status. Conclusion:CCPF is a biomechanically effective alternative or supplemental method of POCF for the craniocervical instability.