title: Effect of different postoperative limb positions on blood loss and range of motion in total knee arthroplasty: An updated meta-analysis of randomized controlled trials.
abstract: BACKGROUND
  Postoperative limb positioning has been reported to be an efficient and simple way to reduce blood loss and improve range of motion following total knee arthroplasty (TKA). This meta-analysis was designed to compare the effectiveness of two different limb positions in primary TKA.
  
  
  METHODS
  A meta-analysis of the PubMed, CENTRAL, Web of Science, EMBASE and Google Search Engine electronic databases was performed. In this meta-analysis, two postoperative limb positions were considered: mild-flexion (flexion less than 60°) and high-flexion (flexion at 60° or more). The subgroups were analysed using RevMan 5.3.
  
  
  RESULTS
  Nine RCTs were included with a total sample size of 913 patients. The mild- and high-flexion positions significantly reduced postoperative total blood loss (P = 0.04 and P = 0.01; respectively). Subgroup analysis indicated that knee flexion significantly reduced hidden blood loss when the knee was fixed in mild-flexion (P = 0.0004) and significantly reduced transfusion requirements (P = 0.03) and improved range of motion (ROM) (P < 0.00001) when the knee was fixed in high-flexion. However, the rates of wound-related infection, deep venous thrombosis (DVT) and pulmonary embolism (PE) did not significantly differ between the two flexion groups.
  
  
  CONCLUSIONS
  This meta-analysis suggests that mild- and high-flexion positions have similar efficacy in reducing total blood loss. In addition, subgroup analysis indicates that the mild-flexion position is superior in decreasing hidden blood loss compared with high-flexion; the high-flexion position is superior to mild-flexion in reducing transfusion requirements and improving postoperative ROM. Thus, the use of the high-flexion position is a viable option to reduce blood loss in patients following primary TKA without increasing the risk of wound-related infection, DVT or PE.
authors.affiliation: Department of Orthopaedic Surgery, West China Hospital, West China Medical School, Sichuan University, Chengdu, Sichuan Province, 610041, China. Electronic address: wuyuangang23@163.com.
authors.forename: Yuangang
authors.initials: Y
authors.lastname: Wu
authors.affiliation: Department of Orthopaedic Surgery, People's Hospital of Tibet Autonomous Region, Lasa, 850000, China. Electronic address: ytm313@sohu.com.
authors.forename: Timin
authors.initials: T
authors.lastname: Yang
authors.affiliation: Department of Orthopaedic Surgery, West China Hospital, West China Medical School, Sichuan University, Chengdu, Sichuan Province, 610041, China. Electronic address: zengyigd@126.com.
authors.forename: Yi
authors.initials: Y
authors.lastname: Zeng
authors.affiliation: Department of Orthopaedic Surgery, West China Hospital, West China Medical School, Sichuan University, Chengdu, Sichuan Province, 610041, China. Electronic address: hb.si@163.com.
authors.forename: Haibo
authors.initials: H
authors.lastname: Si
authors.affiliation: Department of Orthopaedic Surgery, West China Hospital, West China Medical School, Sichuan University, Chengdu, Sichuan Province, 610041, China. Electronic address: licanfeng87@163.com.
authors.forename: Canfeng
authors.initials: C
authors.lastname: Li
authors.affiliation: Department of Orthopaedic Surgery, West China Hospital, West China Medical School, Sichuan University, Chengdu, Sichuan Province, 610041, China. Electronic address: shenbin71@hotmail.com.
authors.forename: Bin
authors.initials: B
authors.lastname: Shen
mesh_terms: D019645:Arthroplasty, Replacement, Knee; D001803:Blood Transfusion / Q000706:statistics & numerical data; D006801:Humans; D007719:Knee Joint / Q000502:physiology; D020370:Osteoarthritis, Knee / Q000601:surgery; D056888:Patient Positioning; D011182:Postoperative Care; D019106:Postoperative Hemorrhage / Q000517:prevention & control; D016032:Randomized Controlled Trials as Topic; D016059:Range of Motion, Articular / Q000502:physiology
keywords: Blood loss; High-flexion; Mild-flexion; Total knee arthroplasty