What should you know about one knee swelling?

Swelling soon after a twist or sporting injury can occur with an ACL Tear or Meniscus Tear. Pain and swelling at the front of the knee may fit Knee Bursitis, while swelling behind the knee can occur with a Baker's Cyst. A hot, intensely painful joint may present with Gout or infection and needs prompt evaluation. Gradual swelling with activity-related aching can accompany Knee Osteoarthritis. The amount of swelling alone cannot identify the cause.

Reduce impact and kneeling for now, elevate the leg, and use a wrapped cool pack for short periods if that feels helpful. Gentle movement can limit stiffness, but stop if pain sharply increases or the knee gives way. Avoid trying to drain the knee yourself. A clinician may examine stability and movement; Joint Aspiration is sometimes used to analyse or remove fluid when clinically appropriate.

Get urgent care if the knee is hot and red with fever, pain is severe, you cannot bear weight, the knee is locked or visibly deformed, or swelling followed a significant injury. Sudden calf swelling or breathlessness also needs emergency assessment. Arrange a routine appointment when swelling persists, repeatedly returns, or limits stairs, walking, or sleep. For an overview, see Knee Swelling.

Is the fluid inside the joint or around it? Which examination or scan would clarify the cause? Should I use a brace, exercises, or temporary activity changes? Would fluid testing be useful?