Klein's line

Line of Klein
Radiogram of slipped capital femoral epiphysis

Klein's line or the line of Klein is a virtual line that can be drawn on an X-ray of an adolescent's hip parallel to the anatomically upper edge of the femoral neck. It was the first tool to aid in the early diagnosis of a slipped capital femoral epiphysis (SCFE), which if treated late or left untreated leads to crippling arthritis, leg length discrepancy and lost range of motion. It is named after the American orthopedic surgeon Armin Klein at Harvard University, who published its description and usefulness in 1952. Subsequent modification of its use has increased the sensitivity and reliability of the tool.