LAUSR

Abstract To observe thoracolumbar segmental mobility using kinetic magnetic resonance imaging (kMRI) in patients with minimal thoracolumbar spondylosis and establish normal values for translational and angular segmental motion as well as the relative contribution of each segment to total thoracolumbar segmental motion in order to obtain a more complete understanding of this segmental motion in healthy and pathological conditions. Mid-sagittal images obtained by weight-bearing, multi-position kMRI in patients with symptomatic low back pain or radiculopathy were reviewed. The translational motion and angular variation of each segment from T10–L2 were calculated using MRAnalyzer Automated software. Only patients with a Pfirrmann grade of I or II, indicating minimal disc disease, for all thoracolumbar discs from T10–T11 to L1–L2 were included for further analysis. The mean translational motion measurements for each level of the lumbar spine were 1.15 mm at T10–T11, 1.20 mm at T11–T12, 1.23 mm at T12–L1, and 1.34 mm at L1–L2 (P < .05 for L1–L2 vs T10–T11). The mean angular motion measurements at each level were 3.26° at T10–T11, 3.92° at T11–T12, 4.95° at T12–L1, and 6.85° at L1–L2. The L1–L2 segment had significantly more angular motion than all other levels (P < .05). The mean percentage contribution of each level to the total angular mobility of the thoracolumbar spine was highest at L1–L2 (36.1%) and least at T10–T11 (17.1%; P < .01). Segmental motion was greatest in the proximal lumbar levels, and angular motion showed a gradually increasing trend from T10 to L2.