Table 2.

Pelvic Screw Perforation Score (PSPS)

Grade 0:	The screw is entirely inside the cancellous bone without contact with the internal surface of the cortical lamina.
Grade 1:	The screw penetrates the internal cortical lamina but not its external surface.
Grade 2:	The screw partially penetrates the external cortical lamina, with less than 3 mm; furthermore, the tip of the screw ends within the cancellous bone.
Grade 3:	The screw penetrates the external cortical lamina in a range between 3 and 6 mm, with the tip of the screw ending within the soft tissues.
Grade 4:	The screw penetrates the external cortical lamina with more than 6 mm.