Iliosacral Screws: Radiographs & Anatomy

• Iliosacral Screw “Safe Zone”

From Posterior Pelvic-Ring Disruptions: Iliosacral Screws, M.L Chip Routt, Jr. M.D. and Peter T. Simonian, M.D. in Master Techniques in Orthopaedic Surgery: Fractures. Lippincott Williams & Wilkins, 1998.

Sacral Ala (L5)

S1 Foramen

Upper Sacral Nerve Root Tunnel (S1)

Spinal Canal (cauda)

Imaging

All patients have different anatomy

Varying amounts of lordosis

Varying sacral slope

Views determined by anatomy

Not textbook (40-40)

Inlet Radiograph

Superimposed S1 And S2 Bodies (Inlet)

Spinal Canal

Wollinsky & Lee, JOT 2007

Outlet Radiograph

Sacral Foramina En Face; S2 ~ superior rami

From Posterior Pelvic-Ring Disruptions: Iliosacral Screws, M.L Chip Routt, Jr. M.D. and Peter T. Simonian, M.D. in Master Techniques in Orthopaedic Surgery: Fractures. Lippincott Williams & Wilkins, 1998.

Sacral Ala = 3D structure; Inlet/Outlet insufficient to r/o breach

Perfect Lateral of SacrumNeed REDUCED pelvis!

Superimposition Of AICD or Greater Notches Parallax makes both difficult

Farrell JOT 2009

Farrell JOT 2009

Traction & Fluoroscopy Set Up

o Anterior/Caudad Traction Vector Appropriate For Most Fracture Displacements

From Posterior Pelvic-Ring Disruptions: Iliosacral Screws, M.L Chip Routt, Jr. M.D. and Peter T. Simonian, M.D. in Master Techniques in Orthopaedic Surgery: Fractures. Lippincott Williams & Wilkins, 1998.

Iliosacral Screw Inlet (Anterior / Posterior)Make Translations / Rotation In Relation To Beam (Perpendicular)

Iliosacral Screw Outlet (Cephalad / Caudad)Make Translations / Rotation In Relation To Beam (Perpendicular)

***Inlet-Outlet Orthogonal ??***

80-100o

Not always

Iliosacral Screw Placement: Case 130 year old Hispanic male

Fall from scaffolding

Injury films obtained in binder

Hemodynamically unstable

Bladder injury

Iliosacral Screw Placement: Case 1

Immediate concerns?Unstable pelvic ring with hemodynamic instability

Binder vs ex-fix

Angiography?

Iliosacral Screw Placement: Case 1

Converted from binder to external fixatorAnterior ring injury more apparent out of binder

Bladder neck injury treated with foley catheter

Pelvic angiography

Iliosacral Screw Placement: Case 1

Definitive treatment?

Iliosacral Screw Placement: Case 1

Planned open reduction of anterior sacrum and SI joint

IS screw fixation of central fracture

Continued external fixation of anterior ring injury

Issues?

Iliosacral Screw Placement: Case 1

Anterior sacral fragment and SI joint reduced

Central sacral fracture badly malreduced

IS screw a little anterior

Iliosacral Screw Placement: Case 1

Solution?Anterior sacral ORIF revised

ORIF of symphysis performed Bladder injury repaired

Improved central sacral reduction

IS screw removed

Postop CT to assess reduction

Iliosacral Screw Placement: Case 1

Iliosacral Screw Placement: Case 1