How long does swelling last after knee replacement surgery

How long knee swelling usually lasts

Most patients develop swelling in the operated leg after a joint replacement, according to the Hospital for Special Surgery (HSS) in New York, which describes swelling in the leg, knee, ankle or foot as normal after the operation and notes that the amount varies from one patient to the next. The American Academy of Orthopaedic Surgeons (AAOS), in its OrthoInfo guide to activities after knee replacement, says you may have moderate to severe swelling in the first few days or weeks after surgery and mild to moderate swelling for about 3 to 6 months.

The first weeks are the heaviest. HSS orthopedic surgeon Cynthia Kahlenberg, MD, says it is very common to have a lot of swelling in the first couple of weeks, and that her team wants to see a little improvement each week. Her yardstick is the direction over several weeks, not how the knee looks on one particular evening.

Bruising runs on a shorter clock. HSS says the black-and-blue bruising that often comes with the swelling usually fades gradually over several weeks. The NHS frames the whole recovery more broadly: it may take several months or longer to fully recover from a knee replacement, depending on age and general health. A knee that is still a little puffy at the three-month mark is inside the time frame these guides describe.

Why swelling comes and goes during the day

Swelling is not a fixed amount. It changes with position and with what you have been doing. HSS's rehabilitation guide for knee replacement says that for the first month, sitting for long periods with the foot down tends to make the swelling worse, and it advises against sitting for more than 30 to 45 minutes at a time.

Standing does something similar. The NHS tells knee replacement patients not to stand for long periods because it could cause swelling in the ankles. HSS also lists the ankle and foot, not only the knee, among the places swelling appears, so a puffy ankle after an operation on the knee is something both guides mention.

Busy days show up too. AAOS's advice for the weeks at home is not to do too much, too soon, and to expect some good days and some bad days alongside gradual improvement. Travel is a special case: AAOS says pressure changes and long periods without moving during a flight may cause swelling in the operated leg while it is healing, and asks patients to check with their doctor before flying.

What helps bring the swelling down

Ice, raising the leg and compression come up again and again in hospital guidance. AAOS says to raise the leg and apply ice to reduce swelling, and that compression stockings may also help. HSS is more specific about ice: 20 minutes on the surgical area a few times a day, especially before and after exercises.

Height matters when you raise the leg. HSS says the ankle should be above the level of the heart, for example lying flat with the operated leg on one or two pillows, and suggests alternating periods of walking with periods of lying down with the leg up, including an hour lying down in the late morning or afternoon. The NHS simply says to keep the leg raised as much as possible. It also says not to sleep with a pillow under the knee, so ask your physical therapist exactly how they want the leg supported.

Compression stockings do two jobs. The NHS says you will usually be given them before leaving hospital to help prevent blood clots, that they should be worn at all times and taken off only for washing, and that most people need them for at least 6 weeks. If your hospital gave you different instructions, those come first.

Moving the ankle helps as well. AAOS encourages foot and ankle movement right after surgery to increase blood flow in the leg muscles, which helps prevent leg swelling and blood clots, and HSS includes ankle exercises in its list of ways to reduce swelling. AAOS also says to keep doing the exercises your physical therapist prescribed for at least 2 months after surgery.

When swelling is a warning sign

This guide summarizes public patient information from AAOS, the NHS and HSS. It is not medical advice and cannot tell you if your own swelling is expected. If anything about your knee or leg worries you, call your surgeon or physical therapist.

Swelling matters because it is also a sign of two complications. AAOS says to tell your doctor about new or severe swelling because it may be a warning sign of a blood clot. Its listed signs of a clot in the leg are increasing pain in the calf, tenderness or redness above or below the knee, and new or increasing swelling in the calf, ankle and foot.

Infection is the other. AAOS lists persistent fever higher than 100°F taken by mouth, chills, increasing redness, tenderness or swelling of the knee wound, drainage from the wound, and knee pain that increases both with activity and at rest. The NHS says to ask for an urgent GP appointment or contact NHS 111 if, after a recent knee replacement, you have throbbing or cramping pain in the leg, a high temperature or feel hot, cold or shivery, oozing or pus from the wound, or redness, tenderness, swelling or pain in the knee that is not getting better or is getting worse.

Some combinations are emergencies. AAOS and the NHS both say that sudden shortness of breath or chest pain can mean a clot has traveled to the lungs, called a pulmonary embolism. The NHS advice is to call 999 or go to A&E if you have pain and swelling in the leg together with difficulty breathing or chest pain. Outside the UK, call your local emergency number.

Common mistakes with knee swelling

Sitting through the evening with the foot down. A film or a long family meal can easily mean two hours in a chair. HSS's limit of 30 to 45 minutes at a time for the first month is easy to forget, so a timer that reminds you to get up, walk a little and then lie down with the leg raised is a simple way to keep to it.

Stopping the compression stockings because the knee looks better. The NHS guidance is at least 6 weeks for most people, and the stockings are there to help prevent clots, not only to manage swelling.

Expecting the swelling to be gone by the six-week check. The NHS says the follow-up appointment is about 6 weeks after the operation, but AAOS describes mild to moderate swelling for about 3 to 6 months. Swelling that is still there at that visit is within the range AAOS describes. Swelling that is new, severe or getting worse is what AAOS and the NHS say to report.

Judging one bad day instead of the week. Dr. Kahlenberg's measure at HSS is a little improvement each week, and a short daily record makes that easier to see: how swollen the knee looked, what you did, how long you sat. JointRoad, for example, lets you log swelling and bruising each day as None, A little or A lot with an optional note, and keeps a separate list of questions that goes onto the last page of a summary PDF for your next appointment.

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