Post-operative aneurysm of the descending genicular artery presenting as a pulsating haemarthrosis of the knee.

A man aged twenty-two years was admitted to the Minia Public Hospital with chronic arthritis of the left knee. Synovectomy was carried out through a parapatellar incision. At operation the synovial membrane was hypertrophied and inflamed, with creeping pannus at the periphery of the articular cartilage. The membrane was removed and the patella, which showed multiple erosions, was excised. After operation the limb was put in plaster, which had to be split on the next day because ofsevere pain. On the third day after operation the dressings were heavily soaked with blood and the joint was markedly distended. Aspiration on three occasions yielded fresh blood. As aspiration was followed by almost immediate recurrence of the haemarthrosis, a vascular complication was suspected and the patient was transferred to Kasr-El-Aini hospital. On admission two months after synovectomy there was severe and persistent pain. Examination revealed a warm, tense, pulsating swelling of the joint. Compression of the