The Patellofemoral Joint

Could this be why your knee hurts?

The patellofemoral joint is formed from the femur (or thigh bone) and the patellar (or kneecap).  Its really just a fancy pulley system which makes a hinge joint.  It’s a really important joint for going up stairs, standing up from a chair and various other activities including walking and running.

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What the patellofemoral joint does is that when the quads muscles, which are the largest group of muscles in the body, attach to the top of the kneecap and as they pull they transmit the force through the kneecap onto the shin bone or tibia and that enables the leg to become straight.  So this is really important for lifting body weight out of a chair, pushing you up against gravity.

What can happen is that whenever this contraction happens because the quads muscles attach to the outside of the pelvis they are angled out to the side this can cause the kneecap to slide out to the side, creating pressure behind the kneecap and therefore pain.  This can happen in a number of people, typically it happens in females as they grow.  In teenage females as their pelvis gets wider the quads muscle angle increases causing more pressure and therefore more pain.

What normally happens is that there is a muscle on the inside of the knee which pulls in moves the kneecap across which evens out the pressure, a muscle called VMO.  What can happen is either the knee swells or that muscle can be pain inhibited.  When these things happen that muscle gets less active.  With this reduction in activity the pressure increases.  So as a patient gets out of a chair or if someone sits for a while the kneecap drifts out to the side and twists causing pain commonly on the inside of the front of the knee or compresses the structures causing pain on the outside of the knee.

What can be done?

With this problem there are a number of things we can do to strengthen the muscle on the inside, to alleviate the pressure behind the kneecap and therefore reduce symptoms.  That said we need to find out what caused the problem; is it just a growth problem or is there an underlying problem which causes the knee to become painful or to swell and does that need to be addressed first.

If you have been suffering from this problem click on the link to book online by clicking here or give us a ring on 094481277 to see what we can do to help.