The subgroups represent a variation within the group and the one illustrated is indicated with red in the text.
A1 Extra-articular fracture, avulsion
.1 of the fibular head
.2 of the tibial tuberosity
.3 of the cruciate insertion
A2 Extra-articular fracture, metphyseal simple
.1 oblique in the frontal plane
.2 oblique in the sagittal plane
.3 transverse
A3 Extra-articular fracture, metaphyseal
multifragmentary
.1 intact wedge
.2 fragmented wedge
.3 complex
B1 Partial articular fracture, pure split
.1 of the lateral surface
.2 of the medial surface
.3 oblique, involving the tibial spines and one of the surfaces
B2 Partial articular fracture, pure depression
.1 lateral total
.2 lateral limited
.3 medial
B3 Partial articular fracture, split-depression
.1 lateral
.2 medial
.3 oblique, involving the tibial spines and one of the surfaces
C1 Complete articular fracture, articular simple,
metaphyseal simple
.1 slight displacement
.2 one condyle displaced
.3 both condyles displaced
C2 Complete articular fracture, articular simple,
metaphyseal multifragmentary
.1 intact wedge
.2 fragmented wedge
.3 complex
C3 Complete articular fracture, multifragmentary
.1 lateral
.2 medial
.3 lateral and medial