Fig. 1

Drawing showing, from top to bottom, the anterior, posterior, and axial views of the patella. The proximal part is termed the basis, and the distal part, the apex. The distal pole is entirely devoid of articular cartilage. A longitudinal ridge divides the cartilaginous surface into medial and lateral facets. The odd facet (arrows) is located at the peripheral aspect of the medial facet, and is devoid of cartilage