Table 1.

The alphanumeric classification (ANC) of osteoporotic pelvic ring injuries (OPRI)

Types		Groupsa		Subgroupsa
A	Isolated anterior OPRI	1	Unilateral posterior OPRI	1	Incomplete sacral fracture
P	Isolated posterior OPRI	2	Bilateral posterior OPRI	2	Complete sacral fracture
AP	Combined anterior and posterior OPRI	3	Bilateral posterior OPRI crossing the sagittal midline (i.e. U-, H- or Y-sacral fracture variants)	3	Extrasacral posterior OPRIb

^aOnly type P and AP injuries are further divided into groups and subgroups

^bExtrasacral posterior OPRI include SI-joint disruptions, crescent fracture dislocations and iliac fractures resulting in transiliac instability