Presentation of Case First admission. A fifty-nine-year-old married Italian laborer was admitted to the hospital because of back pain.Five months before admission the patient was first seen in the Out Patient Department because of pain in the left sacroiliac region, which had begun two and a half months previously while he was shoveling in a gravel pit. He admitted that similar brief attacks had occurred for about six months, but these had always cleared spontaneously. For the past two and a half months, however, the pain persisted despite strapping, heat, massage and rest. He also complained at bedtime of . . .