I work for an orthopaedic group. I had a PCPs office call me yesterday about a patient that they did an H&P on the day before one of my docs did a total knee. We billed 27447 with no modifier. The PCPs office billed 27447 with mod 56. They are telling me we should have billed with a mod 54. Even though they did an H&P, we also managed the patient per-operatively. What is the correct coding for this situation? Should the PCPs office bill and E/M?