A 20-year-old male presented with pain and limited motion in the right knee for 15 years. The patient presented to our clinic with HA, restricted flexion and extension of the right knee and a sagittal deformity of the right femur 8 months prior to the surgery. He was diagnosed with severe haemophilia A (coagulation factor VIII was 1.52%) and haemophilic arthritis of right knee. At the age of 13, the patient was fixed with plaster for a fracture of the femoral shaft, which resulted in a malunion. Because he was positive for inhibitors, the patient was re-examined regularly by the Haematology Clinic after discharge. The patient did not take any interventions during the first 4 months while being positive for inhibitors. During this period, the patient suffered from knee joint bleeding and recovered after ice compression and lying in bed. In the 5th month after the discovery of the inhibitors, the patient received irregular injections of factor VIII intravenously (1,000 IU, BIW or TIW, Kovaltry, Bayer), which did not follow the haematologist's recommendation. After 66 days of injections, he was still positive for inhibitors. Since then, the patient started to receive regular injections of factor VIII (1,500 IU, BID) intravenously. Forty-nine days after the first injection, he became negative for inhibitors (). The patient came to the hospital again 3 days prior to the surgery. Preoperative examinations showed the patient had pain in his right knee. His right foot could not touch the ground. The range of joint motion (ROM) was 20°–90°, the visual analogue scale (VAS) was 7 and the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) was 106 (, ). Other systemic examinations were normal. X-ray and CT showed that the patient's right knee joint space was narrow, with a right femoral flexion deformity (30°, sagittal, anterior) ().