3Nicholson JT,Sherk HH. Anomalies of the occipito cervical articulation[J]. J Bone Joint Surg (Am), 1968,50(2) :295-304.
4Grob D,Schutz U .Piotz G. Occipitocervical fusion in patients with rheumatoid arthritis [J]. Clin Orthop, 1999,(366):46-53.
5Abumi K ,Takada T ,Shono Y ,et al. Posterior occipitocervical reconstruction using cervical pedicle screws and plate-rod systems[J]. Spine, 1999, 24 (14) :1425-1434.
6Jones EL ,Heller JG ,Silcox DH ,et al. Cervical pedicle screws versus lateral mass screws :anatomic feasibility and biomechanical comparison[J].Spine, 1997,22 (9):977-982.