WBR0449

Author	[[PageAuthor::Rim Halaby, M.D. [1] (Reviewed by Will Gibson)]]
Exam Type	ExamType::USMLE Step 1
Main Category	MainCategory::Anatomy
Sub Category	SubCategory::Musculoskeletal/Rheumatology
Prompt	[[Prompt::A 45 year old male who sustained a motor vehicle collision presents to the physician’s office with posterior hip dislocation. The patient undergoes a surgical reduction of the hip and is discharged from the hospital. Several days later, he presents to his physician’s office complaining he cannot abduct his thigh. On physical examination, the patient’s right hip drops when he stands on the left leg. Which of the following nerves is most likely injured in this patient following his trauma?]]
Answer A	AnswerA::Left superior gluteal nerve
Answer A Explanation	AnswerAExp::Left superior gluteal nerve injury occurs with posterior hip dislocation and the patient’s right hip drops when he stands on the left leg.
Answer B	AnswerB::Right superior gluteal nerve
Answer B Explanation	AnswerBExp::Right superior gluteal nerve injury occurs with posterior hip dislocation and the patient’s left hip drops when he stands on the right leg.
Answer C	AnswerC::Left inferior gluteal nerve
Answer C Explanation	[[AnswerCExp::Left inferior gluteal nerve innervates the gluteus maximus. The patient will most likely be unable to stand from a seated position. Posterior hip dislocation can also cause inferior gluteal nerve injury but Trendelenburg sign would not be present.]]
Answer D	AnswerD::Right inferior gluteal nerve
Answer D Explanation	[[AnswerDExp::Right inferior gluteal nerve innervates the gluteus maximus. The patient will most likely be unable to stand from a seated position. Posterior hip dislocation can also cause inferior gluteal nerve injury but Trendelenburg sign would not be present.]]
Answer E	AnswerE::Femoral nerve
Answer E Explanation	AnswerEExp::Femoral nerve is commonly injured in pelvic fractures. In this case, the patient will be unable to flex the thigh or extend the leg. Trendelenburg sign would not be present.
Right Answer	RightAnswer::A
Explanation	[[Explanation::The patient most likely presents with superior gluteal nerve injury because he cannot abduct his thigh following posterior hip dislocation. The superior gluteal nerve innervates the gluteus medius and gluteus minimus muscles. Trendelenburg sign is the contralateral hip drop when standing on the leg ipsilateral to the injured nerve. In this patient, his right hip drops when he stands on the left leg; hence his left superior gluteal nerve is likely injured. Educational Objective: The superior gluteal nerve innervates the gluteus medius and gluteus minimus muscles. It is commonly injured in posterior hip dislocation. Trendelenburg sign is contralateral hip drop when standing on the leg ipsilateral to the injured nerve. References: First Aid 2015 page 421]]
Approved	Approved::Yes
Keyword	WBRKeyword::Posterior hip dislocation, WBRKeyword::Abduct, WBRKeyword::Thigh, WBRKeyword::Trendelenburg sign, WBRKeyword::Trauma, WBRKeyword::Leg, WBRKeyword::Lower limb, WBRKeyword::Gluteal nerve, WBRKeyword::Musculoskeletal anatomy
Linked Question	Linked::
Order in Linked Questions	LinkedOrder::