1. ) Should I sleep with leg elevation after knee surgery?
Yes, elevating your leg after knee surgery will reduce the chances of excessive swelling, as well as help, improve knee extension range of motion.
The most common recommendation is to sleep flat on your back with your knee straight and the ankle raised above the level of your heart.
If you are not able to sleep on your back because of back pain, spinal stenosis, sciatica, or sleep apnea, then click on this link to read Sleeping After Knee Replacement – 3 Best Positions.
2. ) How do I elevate my leg after knee surgery?
A wedge pillow is a great option for elevating your leg after a total knee replacement or ACL reconstruction. A wedge pillow may be purchased in different sizes and heights.
These pillows come with different coverings. Some are cotton and removable for easy cleaning while others are vinyl and easily wiped down.
If you don’t have a wedge pillow you may stack multiple pillows in a manner that would allow you to raise your ankle above the level of your heart.
In the video below I share some examples of a three-stack pillow system.
3. ) Where do you put a pillow after total knee replacement knee surgery?
There are two main ways to position a pillow after total knee replacement surgery.
To maximize knee extension range of motion the pillow or stack of pillows would be placed under the patient’s ankle. The back of the knee would not contact the pillow or bed surface.
A far more comfortable way to place a pillow under your leg while sleeping is to turn the pillow parallel with your leg and have the full surface of the pillow support the full backside of your leg.
4. ) Why can’t I put a pillow under my knee after total knee replacement surgery?
The concern is not placing a pillow under your knee, the concern is HOW you place a pillow under your knee. Your surgeon wants your knee to achieve full extension. If you place a pillow under your knee perpendicular to the leg, the knee will remain slightly flexed for a prolonged period of time and this may result in limited knee extension.
If you place the pillow parallel with the leg the knee will remain in extension and your knee range of motion may improve.
5.) Is it OK to elevate your legs while sleeping?
If you have peripheral artery disease it may hurt to elevate your leg at night. 
It is important that if you experience an increase in leg pain with elevation you discuss this with your surgeon and possibly your cardiologist.
6.) What happens if you don’t elevate my leg after knee surgery?
If you are experiencing excessive swelling in the leg after total knee replacement surgery, and you choose not to elevate your leg at night you may be susceptible to complications associated with lymphedema, pain, and infection. 
Excessive and persistent edema may also limit your range of motion, your ability to ambulate and move, as well as your ability to return to normal walking.
7.) Is it OK to sleep in a recliner after knee replacement?
If you are unable to sleep in a bed due to back pain or other complicating factors, sleeping in a recliner may be your second best option.
It is important to keep in mind that even while sleeping in a recliner you should consider elevating your leg above the level of your heart with a wedge pillow or normal pillows.
Thin wedge pillows like the one shown below work great in a recliner. They allow you to elevate the surgical leg without interfering with the non-surgical leg.
8.) Should I keep my knee straight while elevating after total knee replacement surgery?
If you are having trouble gaining full knee extension range of motion then yes, you should keep your knee straight while elevating your leg.
If your knee extension is normal at zero degrees of extension then it is not as important to keep the knee straight. The most important factor in recovery is great quality sleep.
9.) How high should I elevate my leg at night after total knee replacement surgery?
One of my favorite research articles suggests that while 90 degrees of hip flexion is best to reduce swelling, most patients find that position painful and respond better to 45 degrees of hip flexion. 
In the video below I share a strategy for getting the leg elevated while laying on the couch.
10.) What is the BEST wedge pillow to use after total knee replacement knee surgery?
Best Adjustable Wedge Pillow:
Best Vinyl Cover Wedge Pillow:
Best Cotton Cover Wedge Pillow:
Question from YouTube:
“So, how many days after surgery do I have elevate that high? How much time can I be in a sitting position. This is a very painful and tiring position to be in for a very long time.
The answer depends on your current level of edema, swelling, and range of motion.
If you are minmal swelling and full extension you do not have to continue elevation.
But if swelling remains a problem you will continue to elevate until that swelling normalizes.
This could be weeks or even months.
If it doesn’t improve with elevation I recommend consulting a lymphedema therapist who may try using compression.
Question from YouTube:
“How long and frequently should I elevate?”
“How long do we have to be in this position?”
If you are elevating your leg during the day, it may be recommended to maintain this position for 30 or more minutes.
If you are elevating at night, it is usually recommended that you fall asleep in this position.
Depending on the severity of the swelling some patients may choose to elevate 4 times a day.