The Efficacy of the Unicortical Screw in the Anterior Cervical Fusion of the Degenerative Cervical Spine Disease

ABSTRACT

Anterior cervical fusion without internal fixation destabilizes an already unstable spine and can result in tenuous bone graft stability and potential for incorporation. Anterior fusion of cervical spine with screw-plates is gaining in popularity in the management of anterior cervical spine instability. Eighty six cases that underwent anterior fusion with or without internal fixation and autogenous iliac bone graft were compared and analyzed. The pathologies included 40 cases of cervical disc disease, 43 of cervical spondylosis and 3 of ossification of posterior longitudinal ligament. Changes in the alignment of the total cervical spine and of the fused segment were evaluated in both groups. Dislodgement of the grafted bone, which was observed in 2 of 11 cases in the nonplate group, was not seen in the plate group. Hardware failure was developed in 3 of 24 cases in the bicortical group, but not in 51 cases in the unicortical group. Alignment of the cervical spine was corrected and relatively well manintained in the plate group compared with the nonplate group. We concluded that a unicortical screw fixation was superior than a bicortical screw and a fusion without plating system could not keep a cervical lordotic curve in the treatment of the degenerative cervical disease.