Post-laminectomy kyphosis in patients with cervical ossification of the posterior longitudinal ligament : does it cause neurological deterioration?

Abstract

Objective: Total laminectomy (TL) is an effective surgical technique for the treatment of cervical ossification of the posterior longitudinal ligament (OPLL) along multiple levels. However, kyphosis and probable neurological deterioration have been frequently reported after laminectomy. We analyzed the changes in the cervical curvature after TL and subsequent changes in neurological status.

Methods: We retrospectively reviewed the records of 14 patients who underwent TL for the treatment of cervical OPLL between Jan. 1998 and Dec. 2003. TL was selected according to the previously determined criteria. The curvature of the cervical spine was visualized on a lateral cervical spine X-ray and measured using Ishihara's Curvature Index (CI) before the operation and at the last follow-up examination. Perioperative neurological status was estimated using the modified Japanese Orthopedic Association score and the Improvement Rate (IR) at the same time as the images were evaluated.

Results: The mean age of the patients was 57 years, the male/female ratio was 10:4, and the mean follow-up period was 41 months. The mean number of OPLL was 4.9, and the mean number of operated levels was also 4.9. The CI decreased after TL (p=0.002), which was indicative of a kyphotic change. However, this kyphotic change showed no correlation with the length of the follow-up period, number of operated levels and preoperative CI. Neurological examination at the last follow-up showed an improved neurological status in all patients (p=0.001). There was no neurological deterioration in any case during the follow-up period. Moreover, there was no correlation between IR and the degree of kyphotic change. Postoperative complications, such as C5 radiculopathy and epidural bleeding, resolved spontaneously without neurological sequelae.

Conclusion: Kyphotic change was observed in all but one patient who underwent TL for the treatment of cervical OPLL. However, we did not find any contributing factors to kyphosis or evidence of postoperative neurological deterioration.

Keywords: Cervical; Kyphotic change; Neurological status; Ossification of posterior longitudinal ligament (OPLL); Total laminectomy (TL).

Fig. 1

Curvature Index (CI) on lateral cervical spine X-ray.

Fig. 2

A-1, A-2 : Preoperative cervical spine X-ray and magnetic resonance (MR) image. B-1, B-2 : Postoperative cervical spine X-ray and MR image taken at the last follow-up examination. Pre- and postoperative curvature index values were calculated from lateral simple X-rays. The pre- and postoperative status of the cervical lesion and spinal cord were evaluated on MR images if there were other predisposing factors of neurological complications.

Fig. 3

Box graph and scatter diagram. The error bars and three lines in the vertical box in the box graph represent the cut-off values for the 90^th, 75^th, median, 25^th, and 10^th percentiles. A : Comparison of pre- and postoperative curvature of the cervical spine using the Curvature Index (CI). The decrease in CI is indicative of a significant postoperative kyphotic change (^*p=0.002). B : Comparison of pre- and postoperative neurological status as assessed by modified Japanese Orthopedic Association (mJOA) score shows a significant postoperative neurological improvement (^**p=0.001). C : There was no significant correlation between the degree of kyphotic change and rate of improvement (^***p>0.05, ^*correlation coefficient: -0.024 in Spearman's rho, -0.056 in Kendall's tau-b).