title: Mobility of the cervical spine after anterior interbody fusion for spondylotic myelopathy-a radiographic study.
abstract: To study the influence of anterior body fusion on the adjacent vertebral discs, the radiographs of 101 patients with cervical spondylotic myelopathy (CSM) were analysed, and cervical mobility and intersegmental mobility were determined. Single level fusions were carried out in 29 patients, double level fusions in 45 patients and triple level fusions in 27 patients. Cervical mobility after surgery was inversely proportional to the number of fused discs. Angles were reduced by fusion in proportion to the number of fused discs. The compensatory increase in motion at the disc adjacent to the fusion was slight, and the number of fused discs had little influence on the compensatory increase in motion. Regarding cervical motion, extension and flexion were limited to the same extent in single level fusions, flexion was more limited in double level fusions and limitation of extension was much larger in triple level fusions. Seven patients underwent a second operation after a double level fusion, and one patient underwent a second operation after a single level fusion. In all five patients whose radiographs before the second operation were available, flexion was adequately limited, but extension was not limited at all. These results suggest that the failure to limit extension is responsible for the recurrence of CSM.
authors.affiliation: Department of Orthopaedic Surgery, Okayama University Medical School, Japan.
authors.forename: N
authors.initials: N
authors.lastname: Yoshii
authors.forename: S
authors.initials: S
authors.lastname: Nakahara