Part 3

Marinko Rade, Michael Shacklock, Mervi Könönen, Jarkko Marttila, Ritva Vanninen, Markku Kankaanpää, Olavi Airaksinen
2015 Spine  
Study Design. Controlled radiological study. Objective. Verify (1) whether conus medullaris displacement varies with the range of hip fl exion and (2) whether the acquired data support the "principle of linear dependence." Summary of Background Data. We have previously quantifi ed normal displacement of the conus with unilateral and bilateral straight leg raise (SLR) and have described the "principle of linear dependence." However, we have since effected methodological advances that have
more » ... d data that surpass previous studies. Methods. Ten asymptomatic volunteers were scanned with a 1.5-T magnetic resonance scanner using T2-weighted spc 3-dimensional scanning sequences and a device that permits greater ranges of SLR. Displacement of the conus medullaris during the unilateral and bilateral SLRs was quantifi ed reliably with a randomized procedure. Results. Pearson correlations were higher than 0.99 for both intraand interobserver reliability and the observed power was 1 for each tested maneuver. The conus displaced caudally in the spinal canal by 3.54 ± 0.87 mm ( μ ± SD) with unilateral ( P ≤ 0.001) and 7.42 ± 2.09 mm with bilateral SLR ( P ≤ 0.001). Conclusion. To the authors' knowledge, these are the fi rst data on noninvasive, in vivo , normative measurement of spinal cord displacement with the SLR test at 60 ° of hip fl exion. Conus medullaris displacement increased with hip fl exion angle, while maintaining the relationship between magnitude of conus displacement and number of nerve roots involved into the movement, supporting the "principle of linear dependence." The use of T2-weighted spc 3-dimensional sequence allows for better reliability testing, which is important for future clinical utility. DISCUSSION We investigated in vivo spinal cord displacement in the thoracolumbar vertebral canal during the clinically applied unilateral SLR on each side and bilateral SLR in asymptomatic
doi:10.1097/brs.0000000000000914 pmid:25839389 fatcat:gt4tjiz5r5c3tc234nrfpeccce