Robotic-arm assisted total knee replacement in an ankylosed knee

A patient with rheumatoid arthritis in her 30s who had a left knee that had been ankylosed for 10 years was treated with robotic-arm assisted total knee replacement (RA-TKR) and surgical release of the ankyloses. For RA-TKR, accurate bony registration is essential. It was difficult to record the bone intraoperatively in an ankylosed knee with changed morphology. With careful preparation and implementation, RA-TKR can be an effective option in complicated situations like ankyloses.