Presence and Measurement of Axial Rotation of Lumbar Vertebra in Patients Undergoing Spinal Surgery (Laminectomy) and Its Comparison before and after Operation

Based on a new finding an axially rotated lumbar vertebra may be occasionally spotted on lumbar MR images obtained in non-weight-bearing position. This study was performed to evaluate the possibility of a relationship between this new finding and segmental instability after laminectomy.
Methods & Materials: A total of 96 lumbar MR images of patients with previous laminectomy with and without discectomy were reviewed. An axially rotated lumbar vertebra was reported when the posterior borders of two successive vertebral bodies were not aligned at the extreme parasagittal sections. The frequency of this imaging finding was compared before and after laminectomy.

An axially rotated lumbar vertebra was present in 3 patients (6.3%) before operation and in 6 patients (12.5%) after it. Only 3 new cases (6.3%) with axial vertebral rotation were identified after laminectomy. While the etiology of recurrent back pain was unknown in 3 cases, other underlying causes were disc reherniation in 22 patients, spondylolisthesis/ retrospondylolisthesis in 9 patients, presence of scar tissue in 8 patients, ligamentum flavum hypertrophy in 2 patients, infected operation site and diastematomyelia each one in 1 patient.

Laminectomy-induced segmental instability is not a probable cause of evident axial rotation of lumbar vertebra on MR images of patients with post- laminectomy syndrome.