Three days after total hip arthroplasty via a posterolateral approach, a patient cannot maintain pelvis level on single-leg stance of the operated side, with a positive Trendelenburg sign. Which nerve was most likely injured?

• A Obturator nerve
• B Inferior gluteal nerve
• C Superior gluteal nerve ✓
• D Femoral nerve

Explanation

C positive Trendelenburg sign indicates abductor failure of the hip, mediated by gluteus medius and minimus, both supplied by the superior gluteal nerve (L4 to S1). The superior gluteal nerve crosses deep to the abductors and can be injured in the posterolateral approach to the hip. The inferior gluteal nerve supplies gluteus maximus, an extensor, so its loss impairs rising from sitting and climbing stairs rather than producing the sign.

Reference: Gray's Anatomy for Students, 4th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.