Dem bones, dem bones... Knees and pelvises

Posted by Nell Mead at 14:00 on 20 Jun 2011

Dem bones, dem bones, dem dry bones

Dem bones, dem bones, dem dry bones

Dem bones, dem bones, dem dry bones

Hear the word of the Lord

Toe bone connected to your foot bone

Foot bone connected to your ankle bone

Ankle bone connected to your leg bone

Leg bone connected to your knee bone...

OK... you've probably heard a verson of James Weldon Johnson's spiritual somewhere before, and while it's not technically accurate in its anatomy, the concept (that everything in the body is linked and works together, rather than a body being a collection of separate joints) is one I reference a lot.

Today I'm going to talk about the link between knee pain and your pelvis - or, as JWJ might have put it, your knee bone's connected to your back bone.

The large muscles of the thigh - quadriceps at the front, and hamstrings at the back - are biarthroidal muscles.  This means they cover two joints, the hip and the knee.  The quadriceps work to flex (bend forward) the hip and extend (straighten) the knee.  The agonist (opposing) hamstrings work to extend the hip and flex the knee.  Both groups of muscles attach to the pelvis at the top, and to the shin (tibia and fibula) at the bottom.

When you walk, and more violently when you run, your quadriceps pull to swing your leg forward, as your hamstrings pay out at a controlled rate to prevent you from hyperextending and jarring your knee, facilitated by a slight backward rotation of the sacroiliac joint in your pelvis.  As your foot lands, both the quadriceps and the hamstrings contract to control your landing, and then the hamstrings begin to pull to provide the power to propel you forward over your landing foot.

So far, so good.  Everything is working normally; and normal functioning of joints with no structural deficits will cause no pain.  But what happens when there is a glitch somewhere in the system?

The sacroiliac joint of the pelvis (between the sacrum at the base of the spine and the iliac "wings" of the pelvis) is a pretty common source of problems.  There are many reasons why the sacroiliac joint can stop functioning properly - ranging from an impact injury such as a car crash or a fall, to a general poor posture which involves staying too still and not using the joint enough - but the effect generally is that it stops rotating effectively.  When this happens, it impacts on the hamstring's ability to pay out in the swinging leg, and the joint's ability to absorb shock when the foot lands.

When the hamstring doesn't pay out effectively, your body will respond by altering your gait so that it doesn't have to.  You'll take ever-shorter strides and your running gait will alter from a smooth glide forward to a jerky bob-up-and-down movement, which requires more shock absorption from the sacroiliac joints... and thus the cycle is perpetuated.  And if the sacroiliac joints can't absorb shock properly - well, the shock of impact has to be absorbed somewhere, and the knee (particularly the patellofemoral or kneecap joint) is often the victim.  In my experience, this is a very common cause of knee pain, especially in runners.

What can you do to break the cycle?  You need to reverse it: get your pelvis moving, and your hamstrings flexible.  I'll explain how in my next post, so watch this space!

If you are struggling with knee pain when you run, it may well be linked to a dysfunction at your pelvis.  Please contact me for assessment and treatment.