Spinal Mechanics

PPT Manipulation and Synergetic Spinal Mechanics

Purpose: To find the source of spinal and sacroiliac movement.

 

Test A for rotation

 

Ask a colleague to sit sideways on a plinth with their back straight and their feet firmly on the floor. Their weight must be equally balanced on both buttocks. Stand or squat behind the colleague and place your hands around their pelvis in such a way as to completely immobilize it. By doing this,  lumbar rotation is isolated. If muscles are the singular cause of lumbar rotation the L3 joint will rotate.

 

Ask your colleague to rotate their lumbar slowly in either direction and be very careful not to force the movement. This will lever the pelvis, so take care to keep it in all planes.

 

The result of this test is that the spine locks after only a few degrees of rotation.

 

Test B for side-bending

 

So we know the L3 joint cannot be rotated very far when the pelvis is immobilized. So let us  test side-bending.   If the test above is repeated but instead of rotation, side-bending is  attempted, we find side-bending is also restricted to only a few degrees.

Test C  for combined side-bending and rotation

 

Next we need to check what happens in the lumbar when side-bending and rotation are combined with the pelvis immobilized. Again, be sure not to allow even small amounts of pelvic movement to influence your results.  Ask the colleague to side-bend their lumbar as best they can  and then attempt rotation to the opposite side. If  Fryette's laws are correct this combination movement  should account for real world lumbar flexion rotation. However,  the amount of rotation possible is still minimal and the lumbar vertebrae quickly lock.   

 

Test D for combined rotation and side-bending

 

The experiment can be repeated starting with lumbar rotation followed by side-bending  to the same side, which   according to Fryette is how the lumbar vertebrae rotate in neutral and extension. Also try leaning forwards but you will discover that this does not improve rotation.  The outcome of this test fares no better.

 

So what can be learned from these primitive experiments?

 

These simple tests indicate  that isolated combinations of side-bending and rotation and vice versa in the lumbar spine most certainly do not account for the amount of lumbar rotation a normal person takes for granted in the real world.

 

Judging by the leverage placed on the pelvis during the tests, the pelvis could have a role to play  in lumbar rotation. If so, we need to establish that role.

 

To find this out we need to experiment further.

 

 

Experimentation

 

TESTS