English: This photograph depicts a lateral view of a patient's right knee, who had been diagnosed with Clutton’s joints, due to what was determined to be congenital syphilis, caused by the bacterium Treponema pallidum. See PHIL 4102, for a view of the patient's knees, from an anterior perspective. Clutton's joints, also referred to as symmetrical hydrarthrosis of the knee joints, is a painless condition that often occurs during the late stages of congenital syphilis. It involves synovitis, or swelling of the joint, accompanied by collections of fluid within the joint capsule.