Figure 1

Full-length radiographs of both lower extremities showing neutral (left), varus (middle), and valgus (right) limb alignment. A line is drawn on each image from the center of the femoral head (representing the center of the hip joint) to the center of the ankle joint (talus). Left. When the line transects the knee joint, as in the neutral alignment, the weight-bearing stresses are well distributed in the lower extremity. Middle. When the line is medial to the center of the knee joint (varus alignment), there is an abnormal distribution of weight-bearing stresses on the medial (inner) aspect of the knee joint. Right. Conversely, when the line is located lateral to the center of the knee joint (valgus alignment), the weight-bearing stresses are greater on the lateral aspect of the knee joint.