Written by Dr Sean Leo, a consultant orthopaedic surgeon whose clinical focus is the knee, sports injuries and the lower limb.

Last updated: 9 October 2026.

For joint swelling after an injury, apply ice packs to reduce pain and swelling ^[1]. Wrap the ice in a cloth. Do not place ice directly on the skin ^[1]. Contact a doctor if you have unexplained joint swelling, or joint swelling after an injury ^[1].

Joint swelling is the buildup of fluid in the soft tissue surrounding the joint or the joint itself ^[1]. After an injury, swelling of the joint may mean you have a broken bone or a tear in the muscle tendon or ligament ^[1]. This page covers what can cause it, when to see a doctor, and what may help.

What is knee swelling?

Joint swelling is the buildup of fluid in the soft tissue surrounding the joint or the joint itself ^[1]. It can cause pain or stiffness ^[1]. The swelling may cause the joint to appear larger or abnormally shaped ^[1].

What’s covered on this webpage

What is knee swelling?
What can cause knee swelling?
When should a swollen knee be checked?
When is urgent help needed?
What may help knee swelling after an injury?
What should I do next?

A man steps back into position with his knees bent during doubles badminton in a community hall.

What can cause knee swelling?

After an injury, swelling of the joint may mean you have a broken bone or a tear in the muscle tendon or ligament ^[1]. Swelling can also come from joint conditions:

Gout: a painful type of arthritis caused by buildup of uric acid crystals in a joint ^[1].
Osteoarthritis: a condition that causes joints to become painful and stiff ^[2].
Pseudogout: arthritis caused by buildup of calcium-type crystals in joints ^[1].
Rheumatoid arthritis: inflammation of joints, nearby tissues, and sometimes other organs ^[1].

In plain terms: a ligament is tissue that connects the joints ^[3]. Tendons connect your muscles to bones in your joints, for example, in your knees, elbows and shoulders ^[4].

When should a swollen knee be checked?

Contact a doctor if you have unexplained joint swelling, or joint swelling after an injury ^[1]. See a doctor if knee pain does not improve within a few weeks ^[6].

What a doctor may arrange

Tests that may be used include blood tests, joint x-rays and examination of joint fluid ^[1]. Physical therapy for muscle and joint rehabilitation may be recommended ^[1].

When is urgent help needed?

The list below covers the signs that should not wait for a routine appointment.

Signs that need urgent help

Some symptoms should not wait for a routine appointment. Each item below says where to go.

After an injury

The leg looks twisted or bent, a bone is showing, there is a deep cut, or the foot or leg turns cold, pale, numb, blue or white. Go to an emergency department or call 995.
You cannot lift your leg up with the knee kept straight, and you may feel a gap just above or just below the kneecap. Arrange an urgent same-day assessment.

At any time

The knee is stuck and will not straighten, or it is very painful and you cannot move it or put weight on it. Arrange an urgent same-day assessment.
The knee is suddenly very painful, hot, red and swollen, especially with a fever or feeling generally unwell. Go to an emergency department or call 995.
One calf or thigh is newly painful and swollen. Arrange an urgent same-day assessment. If you also feel short of breath or have chest pain, go to an emergency department or call 995.

After knee surgery

The operated knee becomes more painful, swollen or red, a wound is leaking, or you develop a fever. Go to an emergency department or call 995, or contact your surgical team straight away.

If you are admitted by the doctor at the urgent care centre of one of these private hospitals, the Parkway Pantai hospitals (Mount Elizabeth Orchard, Mount Elizabeth Novena, Gleneagles and Parkway East), Farrer Park Hospital and Thomson Medical Centre, you may ask for Dr Sean Leo to be your attending orthopaedic surgeon. If you are instead discharged and referred for orthopaedic follow-up, you may contact the clinic to arrange an appointment. Both are subject to the hospital’s admission processes and to Dr Leo’s availability.

A woman rests along a sofa with her lower legs elevated on cushions beside a bright window.

What may help knee swelling after an injury?

These steps come from public-health guidance for swelling after an injury. They are not a substitute for an assessment.

For joint swelling after an injury, apply ice packs to reduce pain and swelling ^[1]. Wrap the ice in a cloth. Do not place ice directly on the skin ^[1]. The NHS advises an ice pack or bag of frozen peas wrapped in a tea towel on the knee for up to 20 minutes every 2 to 3 hours ^[6].
If you have reduced feeling in your skin or problems with your circulation, do not use ice unless a doctor or physiotherapist has said it is safe. If you have diabetes, take extra care and check your skin often ^[7].
After an injury, raise the swollen joint so that it is higher than your heart, if possible ^[1].
After an injury, put as little weight as possible on your knee, for example by avoiding standing for a long time ^[6].

What should I do next?

If knee pain is not settling, or you are unsure what is causing it, an assessment is a sensible next step. The assessment brings together the patient’s story, an examination and any tests that help, so that the patient and the surgeon can decide together. It looks at the structure involved, the patient as a whole person and the goal they want to return to. An appointment supports an informed decision. It is not a commitment to surgery.

Read about the Knee Hub.
Read about fractures versus sprains.
Read about the common causes of knee pain.
Read about when a swollen knee should be checked.
Arrange a knee assessment when you are ready.

Arrange a knee assessment

Explore knee treatment options

This page provides general information and cannot diagnose an individual condition. OrthoKinetics does not provide emergency or urgent care through this webpage or its WhatsApp contact.

References

MedlinePlus. Joint swelling. https://www.medlineplus.gov/ency/article/003262.htm
NHS. Osteoarthritis. https://www.nhs.uk/conditions/osteoarthritis/
NHS. Sprains and strains. https://www.nhs.uk/conditions/sprains-and-strains/
NHS. Tendonitis. https://www.nhs.uk/conditions/tendonitis/
NHS. Osteoarthritis – Treatment and support. https://www.nhs.uk/conditions/osteoarthritis/treatment/
NHS. Knee pain. https://www.nhs.uk/symptoms/knee-pain/
South West Yorkshire Partnership NHS Foundation Trust. Ice and heat therapy (patient leaflet). https://www.southwestyorkshire.nhs.uk/wp-content/uploads/2018/05/Ice-and-heat-therapy.pdf

How to reduce knee swelling after an injury