Bones Move and Joints Feel – A Big Difference

Last week I talked about the difference between position and motion.  It made me think a lot about FASTER’s insight into movement, which reads:

  • Bones Move
  • Joints Feel
  • Muscles React

It seems like such a simple thing, but we know that often simple is better!!  However, ever since John spoke those words to me I knew it was big and I knew that it was something that in part would shape our thinking, but also would help explain our thought process.

There is a massive difference between what a bone does and what a joint feels.  Obviously, the two are linked, however, do not make the mistake of thinking they are the same thing!!  It’s been a while since I looked at that at this kind of research, but I seem to remember that in most cases the focus is on the joint motions.  I think this may be a mistake…something has to happen for a joint to feel a motion…a bone has to move.

We know a joint is named by the result of what the distal bone does on the proximal bone.  Though this is pretty straight forward in theory, it is not so easy when considering 3 dimensions with both proximal and distal bones moving at the same time!  That’s why the first step of determining the bone motions helps so much.  The bone motions are often simpler to determine and once you have built the bone motions into your movement analysis the whole movement analysis picture begins to take shape.  Building analysis this way also leads you down a path that helps you find and correct errors.  This is because the bones move, joints feel, muscles react strategy builds a picture of the body moving as a whole and not simply one joint or dis-jointed segments.  This means that the analysis flows from one joint to another (like function) and a mistake at one joint will be highlighted by the fact that it will not fit into the whole functional picture.

I don’t recall ever being taught a language for bone motions, at FASTER we developed our own way of describing bone motions.  We went through a couple of different terms, through trial and error we settled on anterior/posterior tilt, left/right tilt and left/right rotation.  The reason I think this works so well is that it does not interfere (in language terms) with the joint terminology.  You never use these terms for joint motions so it limits confusion.

The biggest reason it helps to think of bones moving first is that body segments (bones) can be moving in the opposite direction to what the joint is feeling.  This can be very confusing if you are leaping ahead to joint motions first.  For example, in standing, if you simply rotate the pelvis to the left…the pelvis, legs and trunk will all be rotating left.  However, the resultant transverse plane joint motions tell a far more complicated story:

  • The lumbar spine will feel right rotation
  • The left hip will feel internal rotation
  • The right hip will feel external rotation
  • The left knee will feel internal rotation
  • The right knee will feel external rotation

This is a simple example using only one plane a very simple movement, however, you can see how the left rotation of the pelvis is only the start of the story. If you build your movement analysis from this point you will get deep into both the segment, joint and sequence of movement. I think it is the development and understanding of sequencing that is really the key to understanding function.

It takes a fair bit to get underway of using this thought process as you get swamped by a massive wave of information…all the joints, in all three planes, in complex movements. However, if you stick with it you will build a picture of function that allows you to assess and treat in the most functional way 🙂




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  1. My Week in the Clinic | Physioblogger - July 29, 2012

    […] really enjoyed the post on the ‘Difference Between Bones Moving and Joints Feeling‘, it is a really interesting tweak to the traditional thought process.  Then tied in really […]

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