Comparison of human lumbar disc pressure characteristics during simulated spinal manipulation vs. spinal mobilization

The present study aimed to investigate the differences in human lumbar intradiscal pressure (IDP) characteristics during simulated spinal manipulation and spinal mobilization. A total of 12 adult fresh lumbar spinal specimens (T12-S2) were randomly divided into two groups. The parameters of simulated spinal mobilization were as follows: Preload angle, 15 degrees (speed, 3 degrees/sec); maximum angle, 20 degrees (speed, 1 degrees/sec); and 9 N horizontal force to the L5 spinous process. The parameters of simulated spinal manipulation were as follows: Preload angle, 15 degrees (speed, 3 degrees/sec); impulse angle, 20 degrees (impulse speed, 33 degrees/sec) and 22 N horizontal force to the L5 spinous process. The maximal IDP during both techniques was greater than the initial and end pressures (P<0.01). There was no difference between the initial and end IDP (P>0.05). The maximal IDP on the rotating side was greater than that on the contralateral side during the two techniques (P<0.05). There was no difference in both initial and end IDPs between the two sides (P>0.05). There was no difference in the maximal IDP between the two techniques (P>0.05). The ascending speed of IDP during manipulation was faster than during mobilization (P<0.01), while there was no difference in the descending speed between the two techniques (P>0.05). The maximal IDP on the rotating side was greater than the contralateral side during simulated spinal mobilization and manipulation (P<0.05). The ascending speed of IDP was faster during manipulation than mobilization (P<0.01). Therefore, thrust manipulation may have more instant impact to discs than mobilization.