During posterior hip replacement, the piriformis muscle is an important landmark. Which nerve runs immediately inferior to the piriformis and exits the greater sciatic foramen below it, making it most vulnerable in posterior hip approaches?

• A Posterior femoral cutaneous nerve
• B Inferior gluteal nerve
• C Pudendal nerve
• D Sciatic nerve ✓

Explanation

The sciatic nerve exits the greater sciatic foramen inferior to the piriformis (in 85% of individuals). In posterior hip arthroplasty, retraction and exposure risks stretch or contusion injury to the sciatic nerve. The piriformis is used as the key landmark — structures exiting above the piriformis include the superior gluteal nerve and vessels; those exiting below include the sciatic nerve, inferior gluteal nerve, pudendal nerve, and posterior femoral cutaneous nerve. Sciatic nerve injury is the most functionally devastating complication.

Reference: BD Chaurasia's Human Anatomy, 8th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.