TYPE A

TYPE B

TYPE C

Avulsion, Stable Ring
from www.trauma.org

Rotationally Unstable
from www.trauma.org

Rotationally and Vertically Unstable
from www.trauma.org

AP COMPRESSION

LATERAL COMPRESSION

VERTICAL SHEAR INJURY

• APC 1 - Rupture of anterior SI ligs, attenuation of sacrospinous and sacrotuberous ligs.
• APC 2 - Rupture of sacrospinous and sacrotuberous ligs.
• APC 3 - Rupture of posterior SI ligs

• LC 1 - Buckle sacral alar fx (horizontal/coronal anterior fx; bilateral = Straddle Fx).
• LC 2 - Posterior Iliac "crescent" fx (anterior to SI joints - leaving a posterior iliac fragment attached to the sacrum)
• LC 3 - Contralateral anterior SI joint, sacro spinal/tuberous lig rupture

• Rupture of anterior SI, posterior SI,sacrospinous, sacrotuberous ligs
• Injured hemipelvis cephalad, posterior & externally rotated.