Inclusion Criteria:  1.Simple knee medial compartment osteoarthritis High tibial osteotomy. 2. With varus deformity, medial proximal tibia angle <85° 3. Unilateral High tibial osteotomy 4. Informed consent: Participants must be able to understand and voluntarily sign a written informed consent and follow the research protocol and interview process  Exclusion Criteria:  1.Patients who underwent other knee surgery within 6 months 2.Preoperative combined anemia (Hb<100g/l) 3.Patients with severe cardiovascular, hepatic, renal and hematopoietic diseases