title: Patients achieved greater range of movement when using high-flexion implants.
abstract: OBJECTIVE
  NexGen Legacy Posterior Stabilized high-flexion prostheses (LPS-Flex) have been popularized as an alternative to NexGen standard prostheses (LPS) in total knee arthroplasty (TKA). Advocates of this new generation prosthesis suggest improved postoperative knee flexion. The purpose of this study was to summarize the best evidence for comparing the range of motion (ROM) and functional outcomes of LPS-Flex prostheses and LPS in TKA.
  
  
  METHODS
  Electronic databases were systematically searched to identify relevant randomized controlled trials (RCTs). The last date for our research was July 2014. Our search strategy was followed the requirements of the Cochrane Library Handbook. The methodological quality was assessed, and the data were extracted independently by two authors.
  
  
  RESULTS
  Nine studies that included 978 knees met our inclusion criteria for review. The results showed that there was larger postoperative ROM (1.62, 95% CI 0.52-2.72) in the LPS-Flex group than in the LPS group. There was not a statistically significant difference in the clinical functional scores and complications between the LPS-Flex group and the LPS group in TKA. The pooled mean differences were as follows: total KSS, -0.64 (95% CI -1.41 to 0.13); functional KSS, -0.53 (95% CI -1.51 to 0.45); HSS, 0.23 (95% CI -0.87 to 1.33); complications, 0.49 (95% CI 0.20-1.24); and radiolucent lines, 1.56 (95% CI 0.68-3.55).
  
  
  CONCLUSIONS
  The preliminary results indicate that the NexGen LPS-Flex prosthesis provides an alternative to the NexGen LPS prosthesis, with greater range of motion and without severe complications or radiographic outcomes. The clinical advantages were not shown in the KSS or the HSS. Thus, the selection of a high-flexion prosthesis should depend on the characteristics of the patient, particularly high motivation and poor preoperative ROM. The potential benefits in the medium- and long-term outcomes require confirmation by larger, multicenter and well-conducted RCTs.
  
  
  METHODS
  Therapeutic study, Level I.
authors.affiliation: The Orthopedic Department, West China Hospital, Sichuan University, Chengdu, China.
authors.forename: Canfeng
authors.initials: C
authors.lastname: Li
authors.forename: Yi
authors.initials: Y
authors.lastname: Zeng
authors.forename: Bin
authors.initials: B
authors.lastname: Shen
authors.forename: Jing
authors.initials: J
authors.lastname: Yang
authors.forename: Zongke
authors.initials: Z
authors.lastname: Zhou
authors.forename: Pengde
authors.initials: P
authors.lastname: Kang
authors.forename: Fuxing
authors.initials: F
authors.lastname: Pei
mesh_terms: D019645:Arthroplasty, Replacement, Knee / Q000295:instrumentation*; D006801:Humans; D007720:Knee Prosthesis; D011474:Prosthesis Design; D016059:Range of Motion, Articular