Review Question - QID 220107

A 45-year-old male presents to the orthopedic clinic for a second opinion. He underwent right elbow extensor carpi radialis brevis debridement and release 6 months prior. The patient has had significant difficulty getting back to sports, including tennis. He works an office job and reports rising from his chair with elbow extension is painful. On exam, he is tender over his surgical incision and has a positive lateral pivot-shift test. Which structure in Figure A was most likely injured during the index procedure?