Knee pain

Knee pain is a symptom, not a diagnosis. It can come from the joint itself or from nearby muscles, tendons, ligaments, fluid-filled sacs, or nerves. Pain from the hip or lower back can sometimes be felt at the knee.

The cause may be clear, such as a fall or sudden twist. At other times, pain develops gradually after repeated activity or without an obvious injury.

Your age, usual activities, recent injuries, and other symptoms can all help narrow down the possible cause. Most knee pain is not an emergency, but a hot, very swollen knee or a badly injured knee needs prompt assessment.

Knee pain may be dull, aching, sharp, burning, or throbbing. It can affect the front, back, inside, or outside of the knee. Some people feel pain deep within the joint.

Other symptoms may include:

• Swelling, warmth, or redness
• Stiffness after rest or in the morning
• Pain when walking, climbing stairs, kneeling, or squatting
• Clicking, grinding, catching, or locking
• A feeling that the knee may give way
• Bruising after an injury
• Difficulty fully bending or straightening the knee

Painless clicking is common and does not always mean something is wrong. Clicking with pain, swelling, locking, or instability is more useful to mention at an appointment.

Minor sprains and strains can follow a twist, awkward step, increase in exercise, or unfamiliar activity. These injuries affect muscles, tendons, or ligaments around the knee.

Overuse can irritate a tendon or the tissues around the kneecap. Pain at the front of the knee is often linked to running, jumping, stairs, prolonged sitting, or a rapid change in training.

Osteoarthritis is the gradual change of joint cartilage and bone. It can cause activity-related pain, brief stiffness after rest, swelling, or a grinding feeling. Symptoms may come and go rather than worsen steadily.

Other possible causes include:

• A meniscus injury involving the shock-absorbing cartilage inside the knee
• Bursitis, which is inflammation of a small fluid-filled cushioning sac
• A Baker’s cyst, a fluid-filled swelling behind the knee
• Gout or calcium crystal arthritis
• Inflammatory arthritis, which may affect several joints
• Pain referred from the hip, thigh, or lower back

Less commonly, sudden severe pain may come from a fracture, kneecap dislocation, major ligament injury, or joint infection. These causes usually produce other warning signs, such as a clear injury, deformity, rapid swelling, fever, or an inability to use the leg.

Seek same-day medical care if your knee becomes hot, red, very swollen, and painful, especially if you have a fever or feel generally unwell. A joint infection needs prompt treatment. Sudden severe swelling without a clear cause also needs urgent assessment.

Get urgent help after an injury if you cannot put weight on the leg, cannot move the knee, heard a crack, or the knee changed shape. Rapid swelling soon after a twist or impact can suggest a significant internal injury.

Call emergency services if the leg or foot becomes cold, pale, blue, or numb after an injury. Chest pain or sudden breathlessness with new leg swelling is also an emergency.

Book a routine appointment if pain lasts for several weeks, keeps returning, disturbs sleep, or limits work, exercise, or everyday activities. Arrange follow-up sooner if the knee repeatedly locks or gives way, or if swelling does not settle.

A healthcare professional will ask where the pain is, how it began, and what makes it better or worse. Mention any injury, swelling, locking, instability, fever, other painful joints, or recent illness.

They may examine how you stand and walk, check movement and strength, and feel for tenderness, warmth, swelling, or fluid. The hip and lower back may also be checked.

Tests are not always needed. An X-ray can show fractures and changes in bone or joint space. Ultrasound may help assess fluid, tendons, or a cyst. MRI gives more detail about ligaments, cartilage, and other soft tissues but is usually reserved for situations where the result could change treatment.

If the knee is hot and swollen, fluid may be removed with a needle. Testing this fluid can help identify infection or crystals such as gout.

Treatment depends on the cause, severity, and effect on your daily life. For mild pain after activity, temporarily reduce movements that clearly worsen it. Avoid complete rest for long periods, as this can increase stiffness and weakness.

A wrapped cold pack used for brief periods may ease pain and swelling after a recent strain. Elevating the leg can also help with swelling. When movement becomes more comfortable, return to activity gradually.

Strengthening the thigh and hip muscles can support the knee. A physiotherapist can suggest exercises suited to the suspected cause and your current ability. Lower-impact activities, such as cycling or swimming, may be easier than running during recovery.

Pain medicines or anti-inflammatory gels may help some people. Ask a pharmacist or clinician what is safe if you have other health conditions, take other medicines, or are pregnant.

Some conditions need specific treatment. This may include a brace, injection, antibiotics and joint drainage for infection, or surgery for selected fractures and severe internal injuries. Surgery is not needed for most knee pain.

A mild strain or activity-related flare may improve over days to a few weeks. Recovery from a major injury usually takes longer and may require rehabilitation.

Long-term conditions such as osteoarthritis often have better and worse periods. Regular movement, suitable strengthening, and adjusting activities can help maintain function even if symptoms do not disappear completely.

If the pain is not improving as expected, arrange follow-up. A reassessment can check whether the original plan needs to change.

Should I keep exercising?

Gentle movement is usually helpful if it does not sharply increase pain or swelling. Reduce the intensity, distance, or impact and build back gradually. Stop and seek advice if the knee repeatedly gives way, locks, or becomes much more swollen.

Does clicking mean I have arthritis?

Not necessarily. Knees can click or crack without pain because tissues move or gas bubbles form within joint fluid. Painful clicking with swelling, locking, or reduced movement deserves assessment.

Can the location of pain reveal the cause?

Location provides clues but rarely gives a diagnosis by itself. For example, pain at the front may involve the kneecap or a tendon, while pain behind the knee may come from a cyst, muscle, or the joint.

Will I need a scan?

Many causes can be assessed from your symptoms and an examination. A scan is more useful when there has been significant trauma, the diagnosis remains unclear, or the result would affect treatment.