What should you know about swelling in knee bone?

Swelling over the kneecap can involve a bursa, while fullness behind the knee can be a Baker's cyst. After twisting or landing awkwardly, an ACL tear or meniscus tear may cause swelling, locking or instability. Knee osteoarthritis can produce activity-related aching and stiffness. A hot, very tender joint may occur with gout or infection and needs prompt evaluation. The exact location, speed of onset, injury history and ability to bear weight help a clinician narrow the cause.

Reduce impact and avoid kneeling, running or deep bending while the knee is swollen. Elevate the leg and use a wrapped cool pack for short periods if this feels helpful. Keep the knee moving gently within a comfortable range so it does not stiffen. Do not try to drain the swelling yourself. A clinician may recommend examination, imaging or joint aspiration when fluid needs analysis or pressure relief.

Seek urgent care for a hot red knee with fever, severe pain, rapid swelling, inability to bear weight, a visible deformity, or a locked joint. Sudden calf swelling or pain with breathlessness or chest pain is an emergency. Arrange review when swelling persists, repeatedly returns, follows a significant twist, or is accompanied by giving way or night pain.

Ask whether the swelling is inside the joint, in a bursa or behind the knee, and whether you need imaging or fluid testing. Explain the trigger, location, heat, stiffness, locking, clicking, fever and weight-bearing ability.