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.