The Increase in Spinal Canal Area After Inverse Laminoplasty

Kemal Yucesoy, MD
Neil K. Crawford, PhD (Phoenix,AZ)

Study Design:

In vitro measurement of the area of the spinal canal in the rostral and caudal portions of lumbar vertebrae before and after application of a new technique called "inverse laminoplasty."

Objectives:

To quantify the normal area of the spinal canal in the rostral and caudal portions of lumbar vertebrae and the amount of enlargement gained after inverse laminoplasty. Summary and Background Data. The rostral part of the spinal canal is reported to be narrower than the caudal part, but the difference has never been quantified. Inverse laminoplasty has been performed in 15 patients but has not been evaluated in vitro.

Methods:

The transverse and anteroposterior diameter of the spinal canal was measured in 34 vertebrae from seven cadavers using digital calipers. In each vertebra, the laminae and spinous process were removed en bloc using a high–speed drill. The removed piece was inverted and reattached with titanium mini–plates. The area of the spinal canal was again measured and compared with the prelaminoplasty measurements using paired Student's t–tests.

Results:

The anteroposterior diameter and area of the spinal canal were significantly smaller in the rostral than in the caudal part of the vertebrae (p < 10–3). Both rostral and caudal anteroposterior diameters and the area of the spinal canal increased significantly after the laminae were inverted (p < 10–3).

Conclusion:

Because inverse laminoplasty is simple and significantly increases the area of the spinal canal, it is a useful surgical technique for the treatment of lumbar spinal stenosis.