DESIGN: A pressure sensor was inserted into the L3-4 disk 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 monoaxial accelerometers to record acceleration in the caudocranial axis and a biaxial accelerometer to record acceleration in the "horizontal" anatomic plane.
SETTING: Laboratory study.
RESULTS: During the thrust, relative intervertebral movements were demonstrated; movements differed with the type of manipulation (in flexion or extension). 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 pressure. This effect, which differs slightly with the different types of manipulation studied, is the consequence of movements of the adjacent vertebrae.
Click on the above link for the PubMed record for this article; full text by subscription.