The Knee Bone’s Connected to the Hip Bone . . .

    “How come we are working on my hips so much?”

    “Because your knees were giving you some trouble.  Remember how you were complaining about feeling them during a squat?”

    “That’s right.  I had forgotten about that.  I don’t notice them anymore.”

    “That’s because we strengthened your hips.”

    “Huh.  I didn’t realize the two were connected.”

    The knee is a stable joint stuck between two mobile joints, the hip and the ankle.  The knee bends and extends.  It isn’t supposed to move side-to-side.  Movement at the hip and ankle affect movement at the knee.  When the muscles that stabilize the hip or ankle are weak, this can cause excessive movement at the knee joint, eventually leading to pain or even structural damage.  Injury at the knee is rarely a result of dysfunction at the knee; rather, it is a result of dysfunction at either the hip or ankle.

    The foot is the body’s first point of contact with the ground.  The muscles of the ankle and foot control how the foot comes into contact with the ground.  When the foot everts more than normal, or excessively pronates, this places the tibia into internal rotation.  This internal rotation forces the knee to move inward.  Not only does this cause stress on the knee joint, it also forces some of the muscles which control the foot and ankle to become excessively tight and others to become overly lengthened or weak.  The lateral gastrocnemius, or outer calf muscle, becomes tight and shortened.  The short head of the biceps femoris, which decelerates knee extension and tibial internal rotation, also becomes tight.  Conversely, the muscles opposing the gastrocnemius, the posterior and anterior tibialis, are weak and overstretched.  These are the muscles that control ankle dorsiflexion, slow down ankle plantar flexion, and stabilize the arch of the foot.  The medial hamstring, which decelerates tibial external rotation, is also overstretched and weak.  

    Some of the muscles at the hip control femoral internal rotation.  When the femur rotates inward, the knee will also move inward.  Many muscles in the hip control the motion of the thighbone, or femur.  The gluteus medius (GM) has two functions: it acts to slow hip adduction and external rotation and also decelerates internal rotation of the femur.  The TFL, or tensor fascia latae, isn’t located as deeply as the GM and acts to slow hip extension, adduction, and external rotation.  When the GM is weak, the TFL acts as a prime mover.  This means it no longer just assists the GM; rather, it does the GM’s job while the GM is out to lunch.  The problem with this is when the GM isn’t working to counterbalance it, the TFL will internally rotate the femur, moving the knee inward at initial contact.  The knee functions best when it points straight ahead, bending forwards and backwards, not moving side to side.  Repeatedly asking the knee to move inward at foot strike will eventually lead to knee pain.  

    As you can see, understanding what is going on at the ankle and hip allows a professional to identify potential sources of knee pain.  If you would like to get an idea of whether your knees are functioning properly, stand in front of a mirror, feet hip distance apart, hands on your hips, feet pointing straight ahead.  Perform a squat by sitting back like you are sitting in a chair, keeping your chest lifted.  Watch your knees.  Do they stay pointing straight ahead over your second and third toes or do they wonder in or out?  If you would like to further assess your knee function and you have good balance, stand on one leg, hands on your hips, foot pointing straight ahead.  Perform a partial single leg squat by sitting back as described above.  Again, watch your knee.  What does it do?  After performing three or four reps, switch sides.  Often, one side is fine while the other has some trouble.  The “good” side can sometimes mask problems during the double leg squat, but when asked to stand alone during a single leg squat, the “weak” side can no longer hide.    

Yours in health and wellness,

Jenn