Dislocated knee swelling: what to know

Swelling after a forceful injury can come from bleeding or irritation within the joint. A dislocation may also stretch or tear supporting tissues and can be associated with an ACL tear. Other causes of a swollen knee include a meniscus tear, bursitis, gout, osteoarthritis, or a Baker's cyst. The pattern, onset, warmth, examination, and imaging help separate these possibilities.

Knee swelling is a symptom, not a diagnosis. It does not by itself show that the knee is dislocated.

Stop weight-bearing if the knee is unstable or very painful. Support it in the position found, use a wrapped cold pack for short periods, and keep the leg elevated. Do not force the knee straight or try to relocate it. A clinician may consider joint aspiration when excess fluid needs assessment or relief, but this is not a self-care procedure.

Seek emergency care for a visible deformity, an open injury, inability to move the foot, new numbness, severe pain, or a foot that is pale, blue, or cold. Rapid swelling after trauma also needs urgent assessment because circulation and major internal injuries must be checked.

Ask what is causing the fluid, whether ligaments or cartilage are injured, and whether imaging is needed. Clarify safe weight-bearing, whether aspiration is appropriate, and which symptoms should prompt immediate return.