Fig. 1

Experimental methodology & manipulation devices. Xray of miniature pressure sensor inserted in the L4-L5 intervertebral disc (A) with an enlargement showing the sensor (*) projecting from the tip of a 18 gauge needle (B). Photos of commercially available Activator V® and Pulstar® devices that deliver spinal manipulative impulses of 2-3 ms duration. C. Photos of anesthetized feline on a hinged motorized flexion device in the horizontal and 20° flexion position