Objective      To comparatively analyze biomechanical characteristics of cervical hybrid surgery (artificial cervical disc replacement combined with segmental fusion) in continuous two-level with finite element method.        Methods      C2~T1 finite element model was established to simulate arthroplasty by Prestige-LP prosthesis

and arthrodesis by anterior plate/screw/allograft in C3~C5

C4~C6 and C5~C7 segments. The difference and change trend of range of motion (ROM) and stress of facet joint (Von Mises stress

Mises stress) of corresponding hybrid surgery were compared.        Results      (1) With C3~C5 hybrid surgery

the ROM of C3~C4 segments was increased by 119%

186%

208%

and 173% in flexion

extension

axial rotation

and lateral bending

respectively

while that of C4~C5 segments was increased by 142%

262%

251%

and 164%

respectively. The facet Mises stress of C3~C4 segments was increased by 256%

187%

and 185% in extension

axial rotation

and lateral bending

respectively

while that of C4~C5 segments was increased by 50%

54%

and 124%

respectively. (2) With C4~C6 hybrid surgery

the ROM of C4~C5 segments was increased by 107%

200%

238%

and 145% in flexion

extension

axial rotation

and lateral bending

respectively

while that of C5~C6 segments was increased by 65%

130%

147%

and 111%

respectively. The facet Mises stress of C4~C5 segments was increased by 20%

53%

and 111% in extension

axial rotation

and lateral bending

respectively

while that of C5~C6 segments was reduced by 8% in extension

and increased by 297% and 60% in rotation and later bending

respectively. (3) With C5~C7 hybrid surgery

the ROM of C5~C6 segments was increased by 77%

167%

179%

and 122% in flexion

extension

axial rotation

and lateral bending

respectively

and that of C6~C7 segments was increased by 84%

268%

324%

and 230%

respectively. The facet Mises stress of C5~C6 segments was increased by 267% and 63% in axial rotation and lateral bending

respectively; while that of C6~C7 segments was increased by 202%

155%

204%

and 145% in flexion

extension

axial rotation

and lateral bending

respectively.       Conclusion      The ROM and Mises stress of the replacement segments in the hybrid surgery are increased. The segments with larger ROM are selected for arthroplasty while the segments with smaller ROM are selected for arthrodesis

and the hybrid surgery has less effect on the cervical biomechanics.