Torsion-Induced Pressure Distribution Changes in Human Intervertebral Discs

Abstract

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.

Influence of Cervical Spine Position, Turning Time, and Cervical Segment on Cadaver Intradiscal Pressure During Cervical Spinal Manipulative Therapy

“…The linear variable differential transformer on the torsion cell measuring torque has a measurement error of approximately 1%. 32 Prolonged unloading of the postmortem in vitro intervertebral disk changes the water content and, thus, the response to force application. In addition, axial compression substantially affects IDP.…”

“…Radiographs were taken to exclude violation of the disc space by the mounting screws. 32 All specimens were kept hydrated with normal saline during preparation and testing.…”

Effects of Axial Torsion on Disc Height Distribution: An In Vivo Study

“…31, 32 A similar study using human cadaveric lumbar spines, however, showed neither a decrease in disc pressure nor an increase in disc height during axial rotation. 31 These in vitro studies allowed measurements of disc pressure and disc height using cadaveric specimens. However, lumbar segmental movements may be different in vivo .…”

“…30, 31 An in vitro study using porcine lumbar spines demonstrated that small vertebral rotations cause depressurization of the nucleus pulposus via an increase in intervertebral disc height during torsion. 31, 32 A similar study using human cadaveric lumbar spines, however, showed neither a decrease in disc pressure nor an increase in disc height during axial rotation. 31 These in vitro studies allowed measurements of disc pressure and disc height using cadaveric specimens.…”

Reduction in Disk and Fiber Stresses by Axial Distraction is Higher in Cervical Disk With Fibers Oriented Toward the Vertical Rather Than Horizontal Plane: A Finite Element Model Analysis

“…On the other hand, no changes in disk pressure and disk space were observed with axial rotation, which was thought to be an unlikely mechanism for clinical pain relief obtained during spinal manipulation. 46 Ferrara et al 47 unloaded cadaveric spines with an externally applied vest fitted to the torso. They reported a 25% reduction in L4-L5 disk pressure.…”