After a knee replacement, sleep on your back with the operated leg STRAIGHT. If you want the leg raised, put the pillows under your calf and ankle, never under the knee.
Once lying on your side feels comfortable, sleep on your good side with a pillow between your knees. If your surgeon gives you different instructions, use theirs.
Expect broken sleep for the first six weeks or so. Sleep usually gets noticeably better by about three months, and many people sleep better at a year than they did before surgery.
Why nights are so hard
- Swelling builds through the day. By bedtime the knee is at its fullest and tightest, and it throbs when you finally lie still
- Pain relief wears off overnight. A dose taken at dinner may run out at 2 or 3 a.m.
- You can’t move the way you normally do. Most people shift position many times a night without noticing. After a knee replacement, every turn wakes you up
- Daytime napping. Long naps in the first weeks make the night even longer
Some pain at night is common for several weeks after surgery. It does not mean something is wrong with the new joint.
The best positions
- On your back, leg straight: the safest position for the first few weeks. Let the back of the knee sink toward the mattress
- Pillows under the calf and ankle, not the knee: this raises the leg to help swelling drain and lets gravity gently straighten the knee at the same time
- On your good side: most people can do this once the wound and the knee are comfortable enough. Put one or two pillows between your knees and ankles so the operated leg rests level instead of dropping forward
- On your operated side: usually too tender for the first few weeks. Try it once that side of the knee is no longer tender to lie on, with a pillow between your knees
- On your stomach: possible later, once you’re comfortable. A pillow under the shin stops the kneecap pressing into the mattress
Why no pillow under the knee
A pillow under the knee feels wonderful. The knee is slightly bent, the tissues at the back relax, and the ache eases. That is exactly the problem.
Eight hours a night with the knee bent lets the back of the knee tighten. Within weeks you can lose the last few degrees of straightening, and that lost straightness is much harder to win back than bend. A knee that won’t go fully straight makes you limp and makes walking more tiring. The NHS knee replacement recovery advice says the same: no pillow under your knee.
A pillow under the knee buys you one comfortable night and costs you weeks of work.
See stiff knee after knee replacement for how much straightening and bend to expect.
Your bedtime routine
- Time your pain relief: take it as prescribed so it is working when you go to bed, not after you’ve woken in pain. Ask your team how to spread doses through the night
- Ice for 15 to 20 minutes before bed: with a thin cloth between the ice and your skin, and keep the dressing dry
- Raise the leg for half an hour before bed: lying down, ankle above the level of your heart, to take the edge off the swelling. See swelling after knee replacement
- Do your last exercises earlier in the evening, not right before sleep, so the knee has time to settle. See exercises after knee replacement
- Keep naps short and get up at your usual time
- Set up the night: walker or crutches beside the bed, a night light on the way to the bathroom, water and phone within reach
- Sleeping tablets: don’t add anything on your own on top of your pain medication. Ask your doctor or pharmacist
Getting in and out of bed
- Getting in: sit on the edge of the bed, then lift the legs in together while you lean back. Use your good leg or a looped belt or towel under the operated foot to help lift it
- Getting out: slide to the edge, lower the legs down, sit for a moment before you stand so you don’t feel dizzy, then stand with your walker in front of you
- Bed height: high enough that your hips are level with or a little above your knees when you sit on the edge
When sleep gets better
- Weeks 0 to 6: the hardest stretch. Sleep often gets a little WORSE before it improves, as you do more in the day and the knee swells more at night
- Weeks 6 to 12: pain and swelling ease, and most people start sleeping longer stretches
- Months 3 to 6: sleep keeps improving and many people are back to their pre-surgery sleep
- Around a year: many people sleep better than before surgery, because the arthritis pain that used to wake them is gone
For the full picture, see knee replacement recovery time week by week.
Call your surgeon today if
- You have pain, swelling, warmth or tenderness in your CALF, or new swelling in your ankle and foot. These can be signs of a blood clot. See blood clot after surgery
- You have a fever, shivers or feel generally unwell
- The wound is getting redder, more swollen or more tender, or is leaking
- Night pain is getting steadily worse instead of better, or your pain medication isn’t touching it
Go to the emergency department if
- You are suddenly short of breath or have chest pain, especially when you breathe in
- You cough up blood
Mention it at your next review if
- You still can’t sleep more than a couple of hours at a stretch after about three months
- The knee won’t lie flat on the bed even when you relax it
- Low mood or worry is keeping you awake
Pillows under the ankle, never the knee: one comfortable night isn’t worth a knee that won’t straighten.