5 Practical Tips for Better Sleeping With Knee Replacement

1 – Why does the knee prosthesis hurt at night?

Nighttime pain after total or partial knee replacement is a well-known, described, and studied phenomenon.

1 in 2 patients struggles to sleep after total knee replacement (Alipourian 2021).

There are several scientific studies that assess their duration, intensity, and how to relieve them: these are the basis for this article, in addition to my physiotherapy experience.

Sleep difficulties are one of the most common complaints among patients undergoing knee replacement. This can lead to longer hospital stays. And the higher the pain, the more significant the complaint generally (Alipourian 2021).

Pain after knee replacement is mostly inflammatory: it is a defense mechanism of your body that produces substances necessary for tissue healing (damaged by the placement of the prosthesis).

These substances are brought to the treatment area (scar and knee tissues) by body fluids. And these fluids accumulate more, causing swelling and often pain.

This inflammation often increases at night, especially in the later part of the night. Why?

• Because we engage in less physical activity and movement at night: fluids accumulate more.
• Because we secrete hormones differently at night, regardless of our actions. Hormones that promote inflammation are more secreted at night.

Added to this is anxiety, which for most people is more significant at night. This can increase pain and difficulty finding a comfortable sleeping position.

As for the difficulties in sleeping after knee replacement, they can be related to post-operative pain. But also (Bartosiak 2022):

• to certain medications taken that have an impact on sleep;
• to pre-existing sleep disorders before the operation (such as sleep apnea syndrome, common in people undergoing knee replacement) which are exacerbated by the operation, pain, and medications.

2 – There are no forbidden positions to take at night with a knee replacement!

My knee surgery patients often ask me, “Can I sleep on my side, won’t it damage the prosthesis?” Or even on their stomach.

Rest assured: no position is likely to damage the replacement. The prosthesis is well stabilized, and it is not a simple position that can make it move.

So, any position you find comfortable can be adopted.

3 – Different positions you can try for sleeping with your replacement

You may find it very comfortable to sleep with pillows under your knee, which bend it slightly, like this:

🚨 This position is often comfortable, but if maintained for too long, it may stiffen your knee: it may remain slightly flexed, whereas it should be fully extended to avoid discomfort during walking and other activities.

Here’s what I recommend to my patients who only find comfort in this position (pillows under the knee) at night:

• Avoid it as much as possible during the day.
• At night, regularly try other positions and adopt this position only if other positions do not work.
• Gradually reduce the height of the pillow: the lower the pillow, the less flexed your knee is, the better.

Here is another comfortable sleeping position after knee replacement, shown in the photo: lying on your side with a pillow between your legs, with the knee slightly bent. The operated knee is on top.

Here too, the knee is slightly bent. But it’s better than lying on your back because:

• The knee can more easily extend; while sleeping, unconsciously, you can potentially extend it, straighten it.
• There is no gravity that increases the stress on the knee.

As shown in the photo, you can use any pillow you have at home. Nursing pillows made of microbeads can also be very comfortable (see on Amazon), as well as small foam pillows that fit between the legs (see on Amazon).

You can also ensure that your feet are higher than your heart while sleeping: on a decline. For example, by:

• Elevating the foot of your bed.
• Wedging pillows under your feet and up to the knee.
• Using an adjustable bed that allows you to elevate your legs.

Elevating the feet can help better drain fluids and reduce accumulation in the knee, which can cause swelling and pain.

4 – Other ways to relieve nighttime pain after knee replacement surgery

Finding a more comfortable sleeping position is one way to relieve pain and sleep better with a knee prosthesis.

But anything that aims to relieve knee pain can potentially improve your sleep as well!

Here are things that can relieve nighttime pain:

Apply cold to the knee.

You can buy cold packs to place in the freezer. Or simply use a bag of frozen peas, which will conform well to the shape of your knee.

Always put something between the ice pack and your skin to avoid burning yourself. You can apply it as often as you want, even continuously, if your skin responds well.

Massage your thigh or the sore parts of the leg.

Massage can provide relief in the moment. And some people are not responsive to it at all. There is no “right” massage technique; what matters is being able to alleviate some discomfort through touch. Like with cold therapy, the effect fades quickly afterward.

Review the medications you are taking.

In the days and weeks following the operation, it is often necessary to readjust the quantity and type of pain medications taken.

Usually, you leave the hospital or clinic with a prescription for pain medications for at least 2 weeks or even a month. But if you don’t feel relieved enough, you can review with your general practitioner who can adjust your medication intake.

Wear compression stockings.

Compression stockings are usually removed at night. But if you tolerate them well and feel better with them on, you can also keep them on.

See my more comprehensive article on knee pain after knee replacement surgery.

5 – Whatever you do, you will sleep better at night over the weeks

Here is more information on the duration of sleep difficulties after knee replacement surgery:

• In the first four nights after the operation, sleep cycles are disrupted: the phase of paradoxical sleep decreases, but returns to normal after 4 days (Krenk 2012);
• One month after the operation, sleep quality is poorer in people who have had surgery compared to those who have not (Herrero 2014);
• Three months after the operation, most people describe an improvement in their sleep (Mehmet 2014);
• Sleep is better AFTER knee replacement surgery than BEFORE knee replacement surgery 4 to 6 weeks after the operation, but also 3 to 6 months after the operation (Alipourian 2021).

Conclusion: Whatever you do, it is highly likely that your sleep will be better approximately 1 month to 1 and a half months after the operation. Better than before the operation!