[Static and dynamic modifications of the cervical spine after laminoplasty for cervical spondylotic myelopathy].

PURPOSE OF THE STUDY

Cervical laminoplasty has been widely used in Japan as the treatment of progressive cervical myelopathy. However, in 1993, Guigui reported that extensive cervical laminectomy was enough for the treatment of cervical myelopathy secondary to stenotic conditions. The purpose of this report was to compare the results of extensive laminectomy as reported by Guigui in 1998 with those of laminoplasty in our series using exactly the same criteria for anatomic analysis.

MATERIAL AND METHODS

Thirty patients aged over 40 years who underwent a spinous process splitting laminoplasty using a threadwire saw from C3 to C7 without fusion for cervical spondylotic myelopathy were reviewed retrospectively with an average follow-up of 3.7 years. Functional results were evaluated according to the Japanese Orthopedic Association scoring system for cervical myelopathy. Lateral views in the neutral position, in flexion, and in extension of the preoperative cervical roentgenograms were analyzed in comparison with the last follow-up films in order to identify the change in the curvature of the cervical alignment, in the range of neck motion, in the intervertebral angular mobility, and in the anteroposterior displacement of the vertebral bodies, and finally to identify the incidence of spinal instability. These data were compared with those of extensive laminectomy published by Guigui.

RESULTS

Seven patients (23%) developed postoperative changes in cervical spine curvature. Only one patient had a new destabilized level postoperatively. No patient required new surgery. Compared with the results obtained after extensive cervical laminectomy, incidence of new destabilized level or aggravated level was statistically lower after laminoplasty than after laminectomy.

CONCLUSION

Spinous process splitting laminoplasty causes an ossification between the remaining spinous process and an unexpected fusion of the lateral mass. These results may prevent postoperative segmental destabilization.