The Functional Knee: A Victim of Circumstances

The Functional Knee: A Victim of Circumstances


To kick off our injury blog series, I thought I’d talk about one of the most common diagnoses presented at Longevity Physical Therapy: knee injuries.  Knee injuries, numerous as they are, come in all types, shapes, and sizes.  We will first briefly review basic knee anatomy and the functional knee, then discuss particular knee injuries, their causes, and their treatment, according to our world of Applied Functional Science (

The knee joint consists of the thigh bone (femur) to the north and the shin bone (tibia and fibula) to the south.  We often call the knee a “dumb joint” given the joint’s complete dependence on its two neighboring bones.  A happy knee joint is one where the thigh and shin are on the same three-dimensional page, movement wise.  When the knee flexes, it’s happy when the thigh bone and shin bone are moving the proper amount at the proper speed.  Likewise, when the thigh bone moves sideways, the knee is happy when the shin bone moves sideways a commensurate amount.  Finally, when the thigh bone rotates, the knee is a happy camper when the shin bone rotates approximately the same amount and at the same speed.  It’s when the thigh bone and the shin bone are not on the same 3-D page that the knee is not going to be very happy.  During these times, the knee is not able to absorb normal physical stresses caused by such things as gravity, ground reaction forces, mass, and momentum.

The Functional Knee: Bones of the Leg


Why and when don’t the thigh bone and shin bone get along?  Well, here’s where the plot really thickens.  To get a clear picture of why the thigh bone isn’t working properly at the knee, we have to look to the hip.  Since the hip essentially controls the thigh bone, we have to assess the hip in 3-D.  Is the hip joint too mobile?  Not mobile enough? Too tight?  Too weak?  To get a clear picture of why the shin bone isn’t working properly, we have to look at the foot/ankle joints.  Since the shin bone is largely controlled by the foot/ankle joints, we have to assess the foot/ankle in 3-D.  Is the foot/ankle too stiff?  Too floppy?  Too high-arched?  Too flat?  Is the calf too tight?  Too weak?

It soon becomes apparent that, at the end of the day, to properly assess the knee, we at least have to properly assess the hip and the foot/ankle in three planes of motion.  To truly be thorough, we also have to assess the rest of the body, but we don’t have the time or space to review that process here.  So, in many cases, a sore knee is more a victim of circumstances than the offending joint.

In subsequent posts, we’ll go over specific knee injuries, briefly review our 3-D assessment of the possible causes, and then briefly set out some useful treatment strategies.

Michael Van Gilder, co-owner of Longevity Physical Therapy, is a Doctor of Physical Therapy and is a Fellow of Applied Functional Science with the Gray Institute for Functional Transformation.  Find out more about Michael in his bio by clicking here.

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