A boy baby aged 3 1/2 weeks, a Negro, was admitted to the Pediatric Service of St. John's Hospital April 12, 1939, with painful swelling of the left knee. Three weeks prior to the birth of the child the father acquired gonorrheal urethritis. One week before delivery the mother had migratory joint pains of the wrist, knee and ankle. At the time of delivery she had a profuse vaginal discharge. The infant was born at full term and by spontaneous delivery. He was discharged after the usual postpartum period and no defects were noted.
When the child was 3 weeks old the mother noticed a swelling of his left knee. He kept the knee flexed and any attempt to extend it caused pain. Three days after the onset of the swelling the child was brought to the hospital. There was no history of trauma. His bowels had been regular and there