All transverse fractures of the sacrum and coccyx are classified as AO/OTA 61A3 fractures.
For a more detailed classification, please refer to the spine section of the AO Surgery Reference.
Sacrococcygeal dislocation

Sacrococcygeal dislocation
This is a dislocation through the sacro-coccygeal joint.
Undisplaced sacral fracture

Undisplaced sacral fracture
This is a transverse undisplaced sacral body fracture below S2.
Displaced sacral fracture

Displaced sacral fracture
This is a transverse displaced sacral body fracture below S2.