Spinal Mechanics

PPT Manipulation and Synergetic Spinal Mechanics

7

The articulation assumes that the facets  dislocate at the superior and inferior borders even after a minimum of rotation as shown in figure B on the previous page. This seems to be an odd theory because it presumes that the normal physiological movement is based on the semi-dislocation of the joint.

 

If we pretend that the bony protuberance running down the the middle of the anterior border of the iliac articulator surface is  like a circular tram line, which our eyes tell us is untrue, and  if we  forget that the anterior protuberance is there to stop the sacrum slipping during weight bearing, what could be achieved by such a vertical rotation movement?

 

Well if we indulge ourselves in this theory and imagine both innominates moving anteriorly  against both sides of sacral facets at the same time both legs would be weight bearing and parallel.   How the person moves forward after this  would be very interesting to witness. Presumably with the jump of a kangaroo.

 

If we were to entertain the idea that the nutation theory allows for each ilium to move independently on either side of the sacrum,  the shape of the iliac facets would  guide one leg outwards and forward.    Whilst the other leg would be guided inwards and backward, which is an odd gait by anybodies standards.

 

If one side of the ilium rotates in one direction and the ilium on the other side rotates in the opposite direction, the sacrum would have to remain level at all times. Trapped in the middle, the sacrum would be unable to side-bend and therefore would deprive the lumbar vertebrae of real world rotation during walking or standing.    

 

If the person attempted to side-bend their pelvis to overcome this little problem, the leg on the opposite side to that being leaned into would be forced laterally and upwards. So every time the person wanted to rotate they would have to cock a leg.

 

 

Other Theories

 

If you look at picture ‘C’ below the three poles have been drawn in together with  their planes of axes. Notice how they would cause the sacral facet to overlap the anterior perimeter of the iliac facet.  

 

Any theory that relies on semi-dislocation to explain a  normal physiological articulation cannot be taken seriously as either valid or scientific, so I am not going to waste time on this one.