Review Question - QID 211251

A 62-year-old man undergoes total hip arthroplasty 6 months ago. He is now presenting with groin pain, which is exacerbated when he is going up the stairs, but not down the stairs. He has pain and significant weakness with resisted hip flexion. He is afebrile and laboratory markers are unrevealing for infection. His recent radiographs are depicted in Figures A and B. Which of the structures depicted in the representative image in Figure C (labeled 1-5) is responsible for his pain?