A 67-year-old male presents with left shoulder pain. He underwent surgery on his left shoulder 10 years prior. Initially, he was pain-free following surgery, however, his pain has returned and has been increasing in intensity. On physical examination, his incision is healed with no erythema. He actively exhibits 120° of forward flexion, 25° of external rotation, and internal rotation to L3. He exhibits 5/5 strength with forward flexion, internal rotation, and external rotation. He has a negative belly-press test, negative hornblower's sign, and a negative Spurling's test. Distally, he is neurovascularly intact. Joint aspiration is performed in the office and reveals a white blood cell count (WBC) of 1900 x10^9/L, with 20% polymorphonuclear leukocytes (PMNs). Cultures were held for 3 weeks and exhibited no growth to date. Radiographs are obtained and shown in Figures A & B. Which of the following is the next best step in the treatment of this patient?