Symptom · Legs & feet
Knee pain
Also known as: sore knee
Pain in or around the knee, the body's largest joint, where the femur, tibia and patella meet, cushioned by the menisci and held by four main ligaments. Causes divide into injury, wear and inflammation.
Seek urgent care if
- A hot, swollen knee with fever or feeling unwell
- Inability to bear weight, obvious deformity or a knee that locks after injury
- Sudden calf pain and swelling behind the knee (possible clot)
- Numbness or a cold, pale foot after injury
Common causes
OsteoarthritisAche and stiffness that build over months or years, worse after activity and at the end of the day, with creaking and swelling.
Ligament injuriesA twist or blow tears the anterior cruciate (a pop, rapid swelling, giving way) or the medial collateral ligament (pain on the inner side).
Meniscal tearsTwisting injuries or wear produce pain on the joint line, catching and locking.
Patellofemoral pain and runner's kneePain at the front of the knee with stairs, squatting and sitting.
Tendon and bursa problemsPatellar tendinopathy in jumpers, iliotibial band syndrome in runners, bursitis from kneeling.
Less common causes
Gout and pseudogoutA red, hot, exquisitely tender joint appearing overnight.
Septic arthritisHot swollen joint with fever; an emergency that destroys cartilage within days.
Rheumatoid arthritisSymmetrical swelling with prolonged morning stiffness.
Referred pain from the hipEspecially in children and adolescents.
Baker's cystA swelling behind the knee from joint fluid.
Often occurs with
Conditions to read about
How it is investigated
Educational content. This page explains what a symptom can mean so that the anatomy and the medical reasoning make sense. It cannot tell you what is causing yours: only a clinician who can examine you and order tests can do that.