Torsion-Induced Pressure Distribution Changes in Human Intervertebral Discs: An In Vitro Study.

Yantzer, Brenda K. MS+; Freeman, Thomas B. MD; Lee, William E. III PhD; Nichols, Tann MD; Inamasu, Joji MD, PhD; Guiot, Bernard MD, FRCSC; Johnson, Wesley M. PhD

The purpose of this study was to evaluate the effects of small torsion torques on intradiscal pressure and disc height in human lumbar specimens.  Six human lumbar cadaveric functional spine units (FSU) were loaded in the neutral position with 600 N axial compression. Intranuclear pressure measurements were then obtained at 0, 0.5, 1.0, and 2.0 Nm of torsion. Posterior elements were removed and measurements were repeated for the disc body unit (DBU).  There was no statistically significant difference in nuclear pressure or intervertebral disc height with different torsion torques among or between the FSUs and DBUs. However, a disc height increase ranging from 0.13 mm to 0.16 mm occurred with the insertion of a 1.85-mm diameter pressure probe cannula.  The authors conclude that small torsion torques showed no significant difference in intradiscal pressures or disc heights. This is an unlikely mechanism for the perceived benefits of spinal manipulation.

Spine.    32(8):881-884, April 15, 2007.

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