Review Question - QID 220011

A 65-year-old golfer presents 3 years after undergoing the procedure shown in Figure A. She had no problems after the surgery and experienced complete resolution of her pre-operative pain until taking a huge divot on one of her golf swings while vacationing in Maui last week. Since then, she has experienced pain, swelling, and the inability to completely elevate her arm. On examination, she is unable to keep her hand elevated off of her lower back when passively placed there by the examiner, and an axillary radiograph no longer shows a well-centered humeral head. Which of the following is the most likely cause of her current symptoms?