Figure 1.

(A) Midpoint method: The joint space widths (JSWs) for the medial and lateral compartments were measured between the tibial and femoral surfaces at the midpoints of the lines depicting each compartment and parallel to the long axis of the tibia. (B) Surface-fit method: The x-axis of the coordinate system was defined by a line (shown in blue) tangent to the edge of the femoral condyles in both compartments. The y-axis was defined by a line in the medial compartment perpendicular to the x-axis and tangent to the peripheral edge of the femur (shown in blue). A line defining x = 1.0 was tangent to the peripheral edge of the femur in the lateral compartment (shown in blue). The JSW in the medial compartment was measured. The surface fits for the femur and tibia are shown in green and purple. The JSW in the medial and lateral compartments was measured between these 2 surfaces along the x-axis at x = 0.25 and x = 0.725, respectively (red arrows).