If suspected of having knock-knees, the candidate is made to sit on the examination couch with both legs dangling from its edge. The candidate then straightens both legs in the front to a horizontal position and brings them together - if the knees touch each other before the medial (inner) malleoli (the bony prominences at the lower end of the leg, above the ankle) do, knock-knees is present and the distance (gap) between the inner malleoli, with the knees just touching each other, is measured. The acceptable gap is 5 cm or less.