A 78-year-old man presents to your office with new onset right knee pain 3 years after total knee replacement. The pain is worse with weightbearing and he now has to use a cane. Ibuprofen initially gave him pain relief, but he now reports constant pain. Figure A and B represent his 1-year and 3-year (current) radiographs, respectively. ESR is 14, CRP 2.3, and an aspirate reveals 900 nucleated cells with a negative gram stain and negative leukocyte esterase. What is the best next step in management?