Abstract Bilateral total knee arthroplasty for a painful stiff knee was performed in a 50-year-old woman with rheumatoid arthritis who had spontaneous fusion of the right hip. Despite several manipulations, the range of motion of the right knee worsened. After total hip arthroplasty and ipsilateral knee revision, the right knee had a stable range motion of -15° to 75°. This case suggests that even if the ankylosed hip is in a good position, ipsilateral knee arthroplasty with a fused hip may result in a poorer range of motion than that after total hip arthroplasty.