Comparison between anterior and posterior decompression with instrumentation for cervical spondylotic myelopathy: sagittal alignment and clinical outcome

Abstract

A variety of anterior, posterior, and combined approaches exist to decompress the spinal cord, restore sagittal alignment, and avoid kyphosis, but the optimal surgical strategy remains controversial. The authors compared the anterior and posterior approach used to treat multilevel cervical spondylotic myelopathy (CSM), focusing on sagittal alignment and clinical outcome. The authors studied 48 patients with CSM who underwent multilevel decompressive surgery using an anterior or posterior approach with instrumentation (24 patients in each group), depending on preoperative sagittal alignment and direction of spinal cord compression. In the anterior group, a 1-2-level corpectomy was followed by placement of an expandable titanium cage. In the posterior group, a multilevel laminectomy and posterior instrumentation using lateral mass screws was performed. Postoperative radiography and clinical examinations were performed after 1 week, 12 months, and at last follow-up (range 15-112 months, mean 33 months). The radiological outcome was evaluated using measurement of the cervical and segmental lordosis. Both the posterior multilevel laminectomy (with instrumentation) and the anterior cervical corpectomy (with instrumentation) improved clinical outcome. The anterior group had a significantly lower preoperative cervical and segmental lordosis than the posterior group. The cervical and segmental lordosis improved in the anterior group by 8.8 and 6.2 degrees, respectively, and declined in the posterior group by 6.5 and 3.8 degrees, respectively. The loss of correction was higher in the anterior than in the posterior group (-2.0 vs -0.7 degrees, respectively) at last follow-up. These results demonstrate that both anterior and posterior decompression (with instrumentation) are effective procedures to improve the neurological outcome of patients with CSM. However, sagittal alignment may be better restored using the anterior approach, but harbors a higher rate of loss of correction. In cases involving a preexisting cervical kyphosis, an anterior or combined approach might be necessary to restore the lordotic cervical alignment.