• Masashi Miyazaki, Yuichiro Morishita, Chikahiro Takita, Toyomi Yoshiiwa, Jeffrey C Wang, and Hiroshi Tsumura.
• Department of Orthopaedic Surgery, Oita University, Oita, Japan. masashim@med.oita-u.ac.jp
• J Spinal Disord Tech. 2010 Jun 1;23(4):242-8.

Study DesignRetrospective cross-sectional study.ObjectiveThis study aimed to elucidate the relationship among facet orientation, kinematics of a spinal unit, and change in lumbar spine canal diameter by using kinetic magnetic resonance imaging.Summary Of Background DataSome studies have suggested an association between increased sagittally oriented facet angles and degenerative lumbar spondylolisthesis. However, no study has specifically addressed the association of facet orientation with the kinematics of a spinal unit and change in canal diameter.MethodsKinetic magnetic resonance imagings were performed with patients in flexion, neutral, and extension positions. Study subjects were classified into 6 groups-AA, BB, CC, AB (BA), BC (CB), and AC (CA)-on the basis of bilateral facet angles (A, narrow; B, normal; and C, wide) and disc and facet joint degeneration. A magnetic resonance imaging analyzer was used for anatomic measurements and for calculating changes in canal diameters and disc bulging as well as the lumbar spine kinematics.ResultsOsseous canal diameters were significantly smaller in the group AA than in the group BB, whereas they were significantly larger in the group CC than in the group BB. Canal diameter at the disc level was significantly smaller in the group AA than in the group BB in all 3 positions, whereas it was significantly larger in the group CC than in the group BB. Translational motion was significantly more in the group AA than in the group BB, whereas it was significantly lesser in the group CC than in the group BB.ConclusionsWe demonstrated the relationship among facet orientation, osseous canal diameter, kinematics of a spinal unit, and change in lumbar spine canal diameter. Patients with sagittally oriented facets had narrow osseous canals with mobility, whereas those with coronally oriented facets had stable and wider osseous canals. This finding is helpful in understanding the mechanism underlying lumbar spinal canal stenosis and degenerative spondylolisthesis.

24 keywords...

hide…