Simple injuries to the internal and external lateral ligaments of the knee are fairly frequent in this day of automobile accidents, but complicating injuries to adjacent knee structures are of such frequent occurrence that to confine one's theme entirely to simple injuries involving the lateral ligaments is rather difficult. The injuries to the internal lateral ligament are far more numerous than those to the external ligament, the proportion being about ten to one in my experience. Mechanically and physically, the knee joint is a weak, unstable structure made up of the end articulations of the femur and tibia, with the patella, which is really a sesamoid bone, gliding over the articular surface of the femur as it is flexed or extended. The integrity of the knee joint lies in the splendid arrangement and great strength of the ligaments which surround it and fortify it against derangements. The joint capsule, attached