Nothing screams "I'm an enlightened yogi" like padmasana.  It seems to be the quintessential pose where the seated yogi is levitating over his Persian rug in some form of unseen bliss.  I've seen hundreds straining their knees in padmasana and have yet to see a floater.  Maybe they were at the back of the room and I missed them.  You never know.  I hate to judge. 

Padmasana, also referred to as lotus, is that awkward looking pose (see above) where both feet are drawn into the belly and are resting on top of each thigh.  It's a coveted posture, similar to a full forward bend requiring hamstrings like taffy and a U-turn backbend needing the double jointed spines of 10-year old Chinese acrobats.  No, really, I'm exaggerating.  It may not be coveted, but in the Ashtanga practice, it's the basis for many poses. 

It seems easy enough.  Sit in a simple cross-legged position and lift one foot on top of the opposite thigh.  If it doesn't go, just tug some more, move some flesh, tug again and ignore any pain in the knee.  That method works for so many other poses, doesn't it?  Well yes, maybe.  But, the knee is a hinge joint and it has an unenviable location between the highly mobile hip joint and foot.  Padmasana, practiced incorrectly, either instantly or over time, can be damaging to the knees. Leslie Kaminoff has a few things to say about yoga in the article below.

If you are pulling your foot in the direction of your opposite thigh and sickling your foot at the same time, you may be frustrated and wonder, dang it, why won't it go?  Short answer:  It's the hip.  It's all about the hip.  If you have normal to limited range of motion in the hip, padmasana may not be for you without gaining more openness in the hips.  If you're fairly open in the hips, padmasana may seem like no big deal, lucky you. 

There are, however, safe-ish ways to practice padmasana.  Here are a few suggestions:

1.  Putting one leg in first is fairly safe.  It's the second leg that's tricky and potentially injurious.  If you're struggling with putting the first leg in position, try sitting on a block. 

2.  Once the first leg is in (let's say right foot on top of left thigh), straighten the left leg along the mat and place a bolster lengthwise underneath the entire knee and foot.  Then slide the bolster with the shin toward your right knee.  Now, is the right knee lower than the left knee?  If not, continue working on your hip opening exercises.  If yes, slide your left foot off the bolster and onto your right thigh, without lifting the foot to get it there.

3.  Once in padmasana, adjust the feet so that the knees are as close together as possible.

4.  To come out, resist the temptation to pick up the top shin and move it off the lower.  Nuh-uh.  This can torque the knee in the direction that we trying to avoid.  Instead, slide each knee sideways so you end up in a cross-legged sitting position.