Anatomy Msk · Year 1 · from Anatomy Msk
Case 3: Trendelenburg Gait from Superior Gluteal Nerve Injury
Clinical Image
Source: Wikimedia Commons - Trendelenburg Sign - CC BY-SA 4.0
Case Presentation
A 55-year-old woman presents to orthopedic clinic 3 months after undergoing right total hip arthroplasty for osteoarthritis via a direct lateral approach. While her pain has improved significantly, she has noticed a limp and weakness when climbing stairs. She reports that her pelvis "drops" to the left when she stands on her right leg. Physical examination reveals antalgic gait with the pelvis dropping toward the unsupported (left) side during the stance phase of the right leg - a positive Trendelenburg sign. She compensates by leaning her trunk over the affected hip (abductor lurch). Manual muscle testing demonstrates 3/5 strength of right hip abduction (gluteus medius and minimus) compared to 5/5 on the left. Hip flexion, extension, and rotation strength are normal. There is no pain with range of motion, and the surgical incision is well-healed. Radiographs show a well-positioned prosthesis. EMG confirms denervation of the gluteus medius consistent with superior gluteal nerve injury. She is referred for physical therapy with abductor strengthening exercises. At 9-month follow-up, she has improved to 4/5 hip abduction strength with improving gait.
Key Learning Points
- The superior gluteal nerve (L4-S1) innervates gluteus medius, gluteus minimus, and tensor fasciae latae
- The nerve exits the pelvis above the piriformis muscle and courses between gluteus medius and minimus
- Superior gluteal nerve injury causes weakness of hip abduction and positive Trendelenburg sign
- During single-leg stance, hip abductors stabilize the pelvis; weakness causes the contralateral pelvis to drop
- Lateral surgical approaches to the hip place the superior gluteal nerve at risk