Clinicoradiologic study of cervical laminoplasty with posterolateral fusion or bone graft

Study Design. A retrospective study of cervical expansive laminoplasty for cervical myelopathy from a clinico-radiologic perspective. Objective. To clarify the correlation among sagittal curvature of the cervical spine, cervical range of motion, sagittal plane translation, spinal cord atrophy, and myelopathic symptoms in patients who have undergone laminoplasty. Summary of Background Data. Laminoplasties were developed to diminish thr undesirable effects of laminectomy, which include postoperative kyphothic changes and instability. However, the superiority of laminoplasty over laminectomy remains controversial. Methods. Fifty-one patients with cervical spondylotic myelopathy or ossification of the cervical posterior, longitudinal ligament who underwent laminoplasty were radiologically assessed before and after surgery. The index of the sagittal curvature, intervertebral range of motion, site of maximal compression were measured to evaluate interrelations among those parameters and myelopathic symptoms. Results. There were no patients with kyphotic curvature before surgery. The postoperative curvature tended to be less lordotic. This tendency did not adversely affect postoperative symptoms. The intervertebral range of motion was significantly decreased except at C1-C2. The final C4-C5 range of motion and the postoperative myelopathic symptoms were negatively correlated. A significant correlation was observed between the postoperative spinal cord atrophy and the final myelopathic symptoms. Conclusions. The decrease in the lordotic curvature index and the decrease in the intervertebral range of motion after laminoplasty did not cause neurologic deterioration. In the C4-C5 intervertebral segment with a high incidence of listhesis, the restriction of the C4-C5 range of motion improved the clinical myelopathic symptoms. The radiologic prognostic factors were the postoperative restriction of intervertebral range of motion in preoperatively unstable segments and the anatomic reversibility of spinal cord insult.