Hepp’s classification: (Type I) Both condyles are approximately the same height and width and almost equally rounded.

The sulcus lies approximately in the middle of the trochlea. (Type II) The lateral condyle is slightly wider and clearly higher than the medial one. The sulcus depth is shifted somewhat medially. (Type III) Hypoplasia of the medial condyle and hyperplasia of the lateral condyle. The sulcus is flattened and clearly shifted medially. Compared to the lateral condyle, the medial one becomes shorter and flatter. (Type IV) Flattening of both condyles. The lateral condyle is usually slightly longer and higher than the medial one. The sulcus is flat. (Type V) The sulcus is not present. The trochlea is flat and in extreme cases even convex [21].