Spinal joint blocking.

The paper describes the history, symptoms and clinical findings of a typical spinal segmental strain with joint blocking. Also provided are an overview and discussion of joint blocking theories. A mechanism is hypothesized whereby joint blocking may be viewed as an actively maintained, reversible, biomechanical phenomenon. The theory proposes that unisegmental multifid and rotator spasm physiologically locks the motion segment. The axes of motion shift towards one facet joint and mobility becomes blocked by the inability of the segment to articulate about its new axis. Manipulative cavitation initiates restoration of the axes of motion, collapse of muscle spasm and recovery of mobility with an immediate reduction of symptoms.