M12.4: Intermittent hydrarthrosis

Intermittent hydrarthrosis, also known as periodic synoviosis, is a rare medical condition that primarily affects the knees. In this condition, the lining of the joints, known as the synovial membrane, produces excess fluid causing the joint to swell and potentially become painful. The swelling, also known as edema, is recurrent, meaning it comes and goes intermittently, hence the term "intermittent hydrarthrosis." Symptoms include recurrent joint swelling, stiffness, and sometimes pain, which may last for several days to a week and then resolve on their own. Despite this, the overall function of the joint remains relatively unimpaired, but the condition can cause discomfort and reduced mobility during flare-ups. The exact cause of this condition is unknown, but it has been linked to certain forms of arthritis. An individual suffering with this condition often experiences periods of normalcy in between the episodes of swelling.