“…The time of onset of recurrent hemarthrosis has been reported to be an average of two years after surgery; however, cases have been reported up to 18 years after surgery [1,2,4,5]. While the etiology is poorly understood, the most accepted explanation for spontaneous hemarthrosis is entrapment of synovial tissue or fat pad between the prosthetic surfaces, or repetitive trauma to hypertrophic vascular synovium [1,2,4]. No obvious etiology may be identifiable in a large percentage of cases.…”