Contour Extraction of Femur and Tibia Condyles on Plain Anteroposterior (AP) Radiograph

Abstract

Condyle of femur (F) and tibia (T) are key bony landmarks around the knee joint. The condyles contour extraction is the first key step towards: quantification of femorotibial (FT) joint space width (JSW), to assess FT joint space narrowing (JSN), to determine knee joint alignment angles and in defining the lateral and medial condyle radii. This paper aims to contour extraction of femur and tibia condyles on plain anteroposterior (AP) knee radiograph. A number of standard OA and non-OA AP radiographs in DICOM format are acquired. The images are resized and filtered to detect femoral and tibia condyles edge pixels respectively. Thresholding is then applied which introduce outliers. After removing outliers spline interpolation and smoothing is applied to trace and extract the femur and tibia contours. The results demonstrates promising extracted contours on non-OA and moderate OA radiographs but needs improvement in radiographs showing severe OA. The femur and tibia contours obtained are well localized, smooth and have no broken lines.