MEASUREMENT OF INTRA-KNEE JOINT SPACING OF THE FEMUR AND TIBIA USING X-RAY FILM IMAGES

Abstract

This paper describes a method to determine the alignment of the femur-tibia spacing using a standard X-ray study of the human knee, front view of the lag taken in the lying position, where there is no weight load on teh knee. The method involves analysis of an outline image of the bones around and including the knee joint, requiring sufficient kength of both femur and tibia to enalble a meaningful estimate of the bone orientation. This length is normally provided in the X-ray film exposure. The method estimates the bone orientation based on finding a centreline between two straight line approximations to the bone edges, found using a threshold criterion on the Mean Square Error of the bone edge and the estimate. The normal to this line is found to provide a definiiton of the width of the joint, and a plot of the distance between the femur and tibia is produced over the full width of the joint. The method automatically distinguishes the tibia and fibula in the lower leg region.