Today I’m going to talk about the link between knee pain and your pelvis — or, as the old song goes, 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!
NB — Please note that although I am an experienced physiotherapist, unless I have examined you, I am unable to give individual advice about your specific case. Every case is different, and this blog reflects cases I have seen in the past and is not a substitute for individual medical advice. You must not rely on the information on my website as an alternative to medical advice from your doctor or other professional healthcare provider. If you have any specific questions about any medical matter, you should consult your doctor or other professional healthcare provider. You should never delay seeking medical advice, disregard medical advice or discontinue medical treatment because of information on my blog. However, if you would like individual advice, please do call 0207 175 0150 to arrange an assessment.