A radiolucent lesion in the medial femoral condyle was observed in 40 knees in 39 patients over age 60. Mast patients had had spontaneous onset of severe knee pain. Twelve knees were radiographically normal within 2 months following onset of pain. Seven knees proceeded to osteoarthritis whereas others became rather asymptomatic. Strontium-85 scintimetry of symptomatic knees showed N THE COURSE of prospective studies I of osteoarthritis of the knee we became aware of a peculiar radiolucent lesion of subchondral bone in the medial femoral condyle. Radiographically, this lesion differed from osteochondritis dissecans in appearance and location. It afEicted aged rather than adolescent individuals and was associated with spontaneous pain in the knee. This particular lesion has received only minimal attention; previous descrip-

Simultaneous defecography and peritoneography can be performed without technical difficulties or complications. Peritoneal outlines and pouches can, therefore, be studied directly during the act of defecation. An unexplained widening of the rectovaginal space at defecography can be clarified as a peritoneocele, with or without an enterocele. Peritoneocele can be of three different types: rectal, septal, or vaginal.

Anorectal disorders that disturb normal defecation are described, especially intussusception of the rectum (internal procidentia). A review of 190 patients, half of whom were treated operatively and the other half conservatively, is presented. Diagnostic procedures, symptoms, and indications for operations are evaluated. We believe that intussusception of the rectum is a relatively common cause of difficult emptying of the rectum and, when the correct diagnosis is established, operation presents a fair chance for improvement.