title: Does high flexion after total knee replacement really improve our patients' quality of life at a short-term follow-up? : a comparative case-control study with hyperflex PFC Sigma versus a Triathlon knee series.
abstract: OBJECTIVE
  A full range of motion after total knee arthroplasty has become more and more requested by our patients, leading to novel designs of knee implants, the so-called "hyperflex" knees. The aim of the present study was to confirm whether or not hyperflexion of operated knees really improves the patients' quality of life.
  
  
  METHODS
  A retrospective comparative case-control study has been carried out to compare clinical results shown in two types of knee prosthesis, from two homogeneous paired groups of patients including 45 cases of a "hyperflex" model (RP-F), while the control group consisted of 43 cases of a "regular design" model (Triathlon) in terms of expected postoperative flexion.
  
  
  RESULTS
  The hyperflex group demonstrated significant higher mean values of passive flexion at 119.9° in the RP-F group versus 111.1° in the Triathlon group. However, global results in the "regular" control group were significantly better than the "hyperflex" study group, in both IKS knee and functional scores at 84.4 points (RP-F) vs. 89.8 points (Triathlon), and 84.6 points (RP-F) vs. 89.5 points (Triathlon), respectively. Moreover, the self-administered KOOS questionnaire was significantly in favor of the control group, with 73.5 points in RP-F knees versus 86.0 points for Triathlon knees at global KOOS postoperative scores.
  
  
  CONCLUSIONS
  The quality of life of operated patients after TKA obviously would be considered as the main priority, which was better obtained by a "regular design" in our study. Hence "high flexion" cannot be considered as an absolute target when choosing a model for total knee arthroplasty.
authors.affiliation: Orthopaedic and Reconstructive Surgery Department, Hôpital Nord, University Hospital, 80000, Amiens, France.
authors.forename: Maxime L
authors.initials: ML
authors.lastname: Mencière
authors.forename: Jean-Alain
authors.initials: JA
authors.lastname: Epinette
authors.forename: Antoine
authors.initials: A
authors.lastname: Gabrion
authors.forename: Damien
authors.initials: D
authors.lastname: Arnalsteen
authors.forename: Patrice
authors.initials: P
authors.lastname: Mertl
mesh_terms: D000328:Adult; D019645:Arthroplasty, Replacement, Knee / Q000295:instrumentation*; D016022:Case-Control Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007719:Knee Joint / Q000601:surgery*; D007720:Knee Prosthesis; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000601:surgery*; D011474:Prosthesis Design; D011788:Quality of Life; D016059:Range of Motion, Articular; D012189:Retrospective Studies