Acetabular Screw Placement

 

Acetabular Quadrants: first line drawn from ASIS to center of acetabulum, second line drawn perpendicular to first line

  • Posterior-superior quadrant:  ideal for supplemental screws. Elevating the hip center in revisions can place sciatic nerve at risk 
  • Posterior-inferior quadrant:  screws exceeding 20mm  risk the sciatic nerve, inferior gluteal nerve and vessels, internal pudendal nerve and vessels
  • Anterior-inferior quadrant: Avoid; risks obturator nerve, artery, and vein
  • Anterior-superior quadrant: Avoid;  risks external iliac vessels.

Exceptions
in the "high hip" the structures in the anterosuperior and anteroinferior quadrants are often found in the posterosuperior quadrant

Safe areas for screws are superior and posterior. The external illiac artery is at risk with anteromedial placement, and the sciatic nerve may be compromised by posterior inferior screw placement.

 

Wasielewski RC, Galat DD, Sheridan KC, et al: Acetabular anatomy and transacetabular screw fixation at the high hip center. Clin Orthop Relat Res 2005;438:171-176. PubMed

Lavernia CJ, Cook CC, Hernandez RA, et al: Neurovascular injury in acetabular reconstruction cage surgery: An anatomical study. J Arthroplasty 2007;22:124-132. PubMed