My knee is very swollen

Marked knee swelling can reflect fluid in the joint, inflammation, or an injury and deserves careful assessment. The amount of swelling, how quickly it appeared, and whether the knee is hot or difficult to move help guide the next step.

A very swollen knee deserves medical assessment, especially when swelling is sudden, movement is limited, or the joint is hot and painful. A meniscus tear or ACL tear may follow a twist and can be accompanied by swelling or reduced motion. Knee osteoarthritis may cause activity-related stiffness and swelling. A Baker's cyst can create fullness behind the knee. Knee bursitis affects a fluid-filled cushion near the joint, while gout can cause sudden inflammatory pain and swelling. These symptoms overlap, so the pattern and examination matter.

Rest from movements that increase pain, particularly deep bending, kneeling, and repeated stairs. Elevate the leg when resting and use a wrapped cold pack for short periods. Keep gentle movement within a comfortable range so the knee does not become stiff, but do not force the bend. Record when the swelling started, any recent activity or injury, and whether redness or warmth is present. A clinician may consider joint aspiration when fluid needs assessment or pressure relief.

Seek urgent assessment if the knee is hot, red, severely painful, or accompanied by fever. Prompt care is also needed if you cannot bear weight, the joint is locked, swelling appeared rapidly after an injury, or the knee looks misshapen. New calf swelling, chest pain, or breathlessness needs emergency help.

What is the likely source of the swelling? Do I need imaging or fluid testing? Which activities should I pause, and which movements are safe? Could medication or aspiration be appropriate? What symptoms mean I should return urgently?