(Objective) Anterior spinal fusion was performed on patients who developed myelopathy as a result of mild cervical instability, and the results of treatment and degree of instability were investigated. (Subjects and Methods) Subjects were seven patients (four male, three female; ages 42 to 78 years; mean age 61.7) who developed myelopathy due to cervical instability after November 2001. JOA scores were compared before and after surgery, and cervical instability was assessed using plain X-ray (dynamic imaging). (Results) The degree of slippage of the cervical spine as assessed on plain X-rays ranged from 2 to 5 mm (mean: 3.3mm). The direction of slippage was forward in three patients and backward in four patients. Slippage was confirmed in one intervertebral space in six patients (C4/5 in three patients, C3/4 in two patients, and C5/6 in one patient) and in two intervertebral spaces in one patient (C3/4 and C4/5). In all patients, MRI confirmed a change in the spinal luminance in these areas. Preoperatively, the JOA score (maximum score of 17 points) ranged from 7 to 15 points (mean: 11.3 points), and postoperatively, it ranged from 11 to 17 points (mean: 14.2 points), thus confirming improvement. Although the patients were followed up for only a short period of time, the clinical courses for these patients were favorable.
