AXIAL ROTATION IN THE LUMBAR SPINE AND ITS EFFECTS ON ASSOCIATED
NERVE TISSUE
Graham R. Mayberry
School of Kinesiology and Health Science, Faculty of Health, York University
Supervisor: Dr. Janessa D.M. Drake
Introduction:
The lumbar spine has been characterized under a variety of different conditions, providing
researchers with a strong understanding of its functional anatomy. Of the fundamental
movements, axial rotation has been strongly associated with 60% of workplace back injuries
(Kumar et al., 2001). The source of the pain could be from injury to bone, muscular tissue,
connective tissue, or nervous tissue. The proposed study will remain focused on the nervous
tissue as it has remained relatively unstudied in axially rotated positions. The relationship
between the intervertebral foramen (IVF) and the spinal nerve root (NR) that exits through it has
not been quantified, though it may play a significant role in how or whether individuals
experience LBP (Lee et al, 2009). A invitro study by Nowick et al. (1996) investigated nerve
root compression by the ligamentum flavum or intervetebral disc using magnetic resonance
imaging (MRI), while more recently Seno et al. (2014) quantified the heights and widths of the
lumbar forman using computerized tomography invivo. These works did not quantify the IVFNR relationship in various postures invivo using MRI, leaving a gap in the literature that needs
to be filled. The aim of this study to characterize and quantify the change in nerve root diameter
and intervertebral foramen between a normal supine position and an axially rotated position.
Methods:
Ten healthy males will be recruited for this study with no history of LBP over the previous 12
months and successfully pass the MRI screening process. During the imaging session,
participants will be asked to lie in a supine position with their shoulders strapped down while 3D
MRI scans were acquired (Siemens MAGNETOM 3T Trio MRI scanner). The participants will
then be moved to their maximal axially-rotated position (with their knees pointing to the left).
Wedges will be placed behind the hips and between the knees, with straps being fastened around
the shoulders, knees and hips to ensure they arre comfortable and will not move during imaging.
The lumbar spine will be imaged in sections of two sequential vertebrae to provide a complete
functional spinal unit. The imaging protocol used will be T2SPC, with a slice thickness of
0.781mm. The images will be analyzed using OsiriX (© Pixmeo Sarl, V 5.0.1) to measure crosssectional area (CSA) of the NR and IVF from a series of subsampled slices that represent the
best view of both features. The NR:IVF ratio will then be calculated and compared for both the
left and right sides, and at various spinal levels of the lumbar and lower thoracic regions.
Expected Significance:
A study by Boos et al. (1995) found that nerve root impingement was found in more than 50% of
patients with low back pain and contact between bone and nerve root was at 83%. Thus, a
greater understanding of how the nerve root changes with respect to orientation can be quite
significant in future research and job safety. Additionally, disc degeneration, a known cause of
LBP, ameliorates the intervertebral foramen space which would put the nerve root at greater risk
of impingement. Surgical procedures such as stents and discectomies require a better
understanding of the impact that these procedures will have on the future activities of that
patient.