Unilateral Dynamic Stabilization for One-side Facet Joint Resection: Report of Four Cases

Introduction:There are three articulations in a vertebral segment: One intervertebral disc and two facet joints. The facet joint carries an estimated 16-25% of the compressive load in the lumbar spine. The facet joints also obtain stiffness and resistance against to shear and translational forces. The unilateral total lumbar facetectomy lead to increase in the range of motion at functional segmental unit(FSU). When lumbar spinal pathologies affected one-side such as foraminal or extraforaminal disc herniations and spinal cord tumors (especially dumbbell-shaped tumors), they may be treated via a unilateral spinal approach. In these cases, one side-of the total facetectomy can cause to instability on FSU and the patients will be worsen at the follow-up. We reported four cases suffered from dumbbell schwannoma were treated by unilateral dynamic stabilization after removing the tumors..

Material and Method :All of the patients have dumbbell tumor that schwannoma was diagnosed by histopathologists. The first case was 46 years-old-male with left L3 nerve root tumor(NRT). The second case was 42 yearsold- female with left L5 NRT. The third case was 32 years-old-female with left L1 NRT and the last case was 33 years-old-female with right L3 tumor. Same surgical procedure, unilateral approach, was performed for removing tumor where settled segment. The procedure included unilateral facet joint and lamina resection for visualization of tumor, after removing of them, unilateral pedicle screws were placed under fluoroscopy then dynamic stabilization was completed with applying the dynamic rod.

Results :The patients were followed-up meanly 14,1 months and they have no neurological deficits. The dynamic X-rays showed that there was no instability or pathological motion at the operated segment.

Conclusions :Unilateral dynamic stabilization without fusion at where performed facetectomy may provide adequately stabilization and allow limited motion on FSU. The system may preserve FSU and will be taken of the place the facet joint by developing technologies.