Knee pain: when to see a doctor

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.

See a doctor if knee pain does not improve within a few weeks ^[1]. See a doctor if you are worried. Do not self-diagnose ^[1]. Knee pain can often be treated at home ^[1]. For mild knee pain without an injury or the warning signs, the NHS says you should start to feel better in a few days ^[1].

Knee pain can often be treated at home ^[1]. For mild knee pain without an injury or the warning signs, the NHS says you should start to feel better in a few days ^[1]. See a doctor if knee pain does not improve within a few weeks ^[1]. Some signs should not wait; they are listed below.

When should I see a doctor for knee pain?

• See a doctor if knee pain does not improve within a few weeks ^[1].
• See a doctor if you are worried. Do not self-diagnose ^[1].
• A doctor can suggest treatment based on what is causing the knee pain ^[1].

What’s covered on this webpage

• When should I see a doctor for knee pain?
• When is urgent help needed?
• What can cause knee pain?
• What should I do next?

When is urgent help needed?

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

What can cause knee pain?

After an injury

• Sprains and strains: pain after overstretching, overusing or twisting, often during exercise ^[1]. A sprain is a torn or twisted ligament (tissue that connects the joints) ^[2]. A strain is an overstretched or torn muscle (also known as a pulled muscle) ^[2].
• Tendonitis: pain between your kneecap and shin, often caused by repetitive running or jumping ^[1]. Tendons connect your muscles to bones in your joints, for example, in your knees, elbows and shoulders ^[3]. Tendonitis is when a tendon swells (becomes inflamed) after an injury ^[3].
• A torn ligament, tendon or meniscus, or cartilage damage: the knee may feel unstable, or give way when you try to stand ^[1]. The meniscus is the shock-absorbing cartilage in the knee ^[4].
• A dislocated kneecap: the kneecap changes shape after a collision or sudden change in direction ^[1].
• A broken bone in the leg: you may have broken your leg if you have injured it and it is painful, swollen and bruised, and difficult to move ^[5]. It can sometimes be hard to tell if a bone is broken, and you will probably need an X-ray ^[5].

If you think you have an anterior cruciate ligament (ACL) injury, see a doctor ^[4]. Do not play sports or do other activities until you have seen your doctor and have been treated ^[4].

With no obvious injury

• Osteoarthritis: the protective cartilage on the ends of the bones breaks down ^[6].
• Gout: sudden, severe joint pain, usually in the big toe but sometimes in the knees ^[7].
• A Baker’s cyst: a fluid-filled lump at the back of the knee ^[8]. The main symptom is a soft lump at the back of the knee ^[8]. A Baker’s cyst does not always need treatment, and you should get any lumps checked by a doctor ^[8].

More on the ligaments of the knee

• Medial collateral ligament (MCL) runs along the inside of the knee. It prevents the knee from bending inward ^[4].
• Lateral collateral ligament (LCL) runs along the outside of the knee. It prevents the knee from bending outward ^[4].
• Anterior cruciate ligament (ACL) is in the middle of the knee. It prevents the shin bone from sliding out in front of the thigh bone ^[4].
• Posterior cruciate ligament (PCL) works just opposite to the ACL. It prevents the shin bone from sliding backward under the femur ^[4].
• Basketball, football, soccer and skiing are common sports linked to ACL tears ^[4].

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 ACL reconstruction surgery.
• Read about what can be behind knee pain.
• Read about knee symptoms that should not be ignored.
• Arrange a knee assessment when you are ready.

References

1. NHS. Knee pain. https://www.nhs.uk/symptoms/knee-pain/
2. NHS. Sprains and strains. https://www.nhs.uk/conditions/sprains-and-strains/
3. NHS. Tendonitis. https://www.nhs.uk/conditions/tendonitis/
4. MedlinePlus. Anterior cruciate ligament (ACL) injury. https://medlineplus.gov/ency/article/001074.htm
5. NHS. Broken leg. https://www.nhs.uk/conditions/broken-leg/
6. NHS. Osteoarthritis. https://www.nhs.uk/conditions/osteoarthritis/
7. NHS. Gout. https://www.nhs.uk/conditions/gout/
8. NHS. Baker’s cyst. https://www.nhs.uk/conditions/bakers-cyst/