Highlighting of intervertebral movements and variations of intradiskal pressure during lumbar spine manipulation: A feasibility study

Objectives: To demonstrate relative movement of the vertebrae and variation s in intradiskal pressure during 2 different lumbar spinal manipulations, i n flexion or extension, in 2 unembalmed cadavers. Design: A pressure sensor was inserted into the L3-4 dish in cadaver 1 and into the L1-2 to L4-5 disks in cadaver 2. Two adjacent vertebrae (L3 and L4 in cadaver 1, and L4 and L5 in cadaver 2) were each equipped with 2 monoax ial accelerometers to record acceleration in the caudocranial axis and a bi axial accelerometer to record acceleration in the "horizontal" anatomic pla ne. Setting: Laboratory study. Results: During the thrust, relative intervertebral movements were demonstr ated; movements differed with the type of manipulation (in flexion or exten sion). Intradiskal pressure initially increased, then decreased. Conclusions: Lumbar spinal manipulations have a biomechanical effect on the intervertebral disks, producing a brief but marked change in intradiskal p ressure. This effect, which differs slightly with the different types of ma nipulation studied, is the consequence of movements of the adjacent vertebr ae.