The subgroups represent a variation within the group and the one illustrated is indicated with red in the text.
A1
Extra-articular fracture, simple
.1 apophyseal
.2 metaphyseal oblique or spiral
.3 metaphyseal transverse
A2 Extra-articular fracture, metaphyseal wedge
.1 intact
.2 fragmented, lateral
.3 fragmented, medial
A3 Extra-articular fracture, metaphyseal complex
.1 with an intermediate split segment
.2 irregular, limited to the metaphysis
.3 irregular, extending into the diaphysis
B1 Partial articular fracture, lateral condyle, sagittal
.1 simple, through the notch
.2 simple, through the load-bearing surface
.3 multifragmentary
B2 Partial articular fracture, medial condyle, sagittal
.1 simple, through the notch
.2 simple, through the load-bearing surface
.3 multifragmentary
B3 Partial articular fracture, frontal
.1 anterior and laterl flake fracture
.2 unicondylar posterior (Hoffa)
.3 bicondylar posterior
C1 Complete articular fracture, articular simple,
metaphyseal simple
.1 T-or Y-shaped, with slight displacement
.2 T- or Y-shaped, with marked displacement
.3 T-shaped epiphyseal
C2 Complete articular fracture, articular simple,
metaphyseal multifragmentary
.1 with an intact wedge
.2 with a fragmented wedge
.3 complex
C3 Complete articular fracture, multifragmentary
.1 metaphyseal simple
.2 metaphyseal multifragmentary
.3 metaphysio-diaphyseal multifragmentary