Knee Posture

When you think about it, we take our knees for granted, except when they are bothersome.  Just as good postural habits can help our spine and neck, good positioning of the knees may forestall problems in the knee joint.

How the knees are supposed to work
Moving 
Our knee is a simple hinge.  It can bend and straighten and brace.  There can be no sideways movement or twisting without issues arising.  We can strengthen bending and flexing and we can strengthen bracing. We can ensure joint health by doing stretches, in this one plane of movement.

We must guard against twisting the knee, especially while loaded up with body weight.  Think of those careful Tai Chi steps.  When we place our foot down angling the toe outwards, it allows us to easily step to the diagonal.  Similarly side stepping, when we place our foot toe-down first of all, we can load up with body weight without compromising the knee.

Sitting Knee Posture

Consider what it is like sitting at the desk, completely absorbed in work.  We already know how to keep our spine happy - stack sit, "behind" behind you. What about our feet and knees?  If your legs are tucked under the seat and your ankles are crossed, it would be bad news for the knees and the circulation of the legs altogether. It will also cause our spinal positioning to suffer.
Ideal seated-knee posture means both feet are on the floor and the knees are at 90 degrees

Standing Knee Posture 

Unlock your knees, simple.... 

Try this experiment. Stand up with your legs straight, now tighten the leg muscles so that your knees hyper extend, you can also call it locking the knees. They seem to poke out the back a little. This has effects upon the the posture - your spine will extend and your head comes forward.  Two things you don't want.  Certainly, it is easier to lock out the knees - you hang from your skeleton instead of relying on muscles.  This is only a short term advantage, though.  

Our head forward posture costs us a lot of energy and possibly neck and shoulder pain.  Maybe even a sway in our back starts to ache. So let's unlocked those knees stay a little more agile; allow for better circulation,and  make it easier to stand strong and straight.