title: High-flexion total knee arthroplasty improves flexion of stiff knees.
abstract: OBJECTIVE
  High-flexion knee prosthesis designs are generally thought to be of benefit only in patients with a satisfactory preoperative flexion angle. The aim of the study was to evaluate whether high-flexion designs were indeed worthless in osteoarthritis patients with severe preoperative flexion limitation.
  
  
  METHODS
  The postoperative maximum flexion was compared in osteoarthritis patients with a preoperative maximum flexion of 100° or less, using LPS and LPS-flex implants (NexGen®; Zimmer, Warsaw, IN) in total knee arthroplasties. Data on 39 knees in the LPS group and 41 in the LPS-flex group, with a minimum of 2 years of follow-up, were reviewed retrospectively, focused on the postoperative maximum flexion.
  
  
  RESULTS
  Two years after operation, the LPS-flex group had a mean postoperative maximum flexion of 131±10° (range, 105-140°), which was significantly higher than the 121±12° (range, 95-140°) in the LPS group (P<0.001). In the LPS-flex group, about half of the knees (n=18, 44%) could achieve a maximum flexion of 140° postoperatively, but in the LPS group only five knees (13%) achieved a maximum flexion of 140°.
  
  
  CONCLUSIONS
  Despite a different period of the operation between groups, this study suggested that osteoarthritis patients with severe preoperative flexion limitation could achieve more postoperative gain in flexion when a high-flexion prosthesis was used, compared to the flexion obtained using a standard prosthesis.
authors.affiliation: Department of Orthopaedic Surgery, Asan Medical Center, College of Medicine, Ulsan University, and Ulsan University Hospital, 388-1, Pungnap-2-dong, Songpa-gu, Seoul, 138-736, South Korea.
authors.forename: Bum-Sik
authors.initials: BS
authors.lastname: Lee
authors.forename: Jong-Min
authors.initials: JM
authors.lastname: Kim
authors.forename: Sang-Jin
authors.initials: SJ
authors.lastname: Lee
authors.forename: Kwang-Hwan
authors.initials: KH
authors.lastname: Jung
authors.forename: Dae-Hee
authors.initials: DH
authors.lastname: Lee
authors.forename: Eun-Jong
authors.initials: EJ
authors.lastname: Cha
authors.forename: Seong-Il
authors.initials: SI
authors.lastname: Bin
mesh_terms: D000368:Aged; D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects / Q000379:methods* / Q000534:rehabilitation; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007593:Joint Instability / Q000517:prevention & control; D007720:Knee Prosthesis; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000175:diagnosis / Q000601:surgery*; D011183:Postoperative Complications / Q000503:physiopathology; D011300:Preoperative Care / Q000379:methods; D011474:Prosthesis Design; D016059:Range of Motion, Articular / Q000502:physiology*; D012189:Retrospective Studies; D012720:Severity of Illness Index; D018709:Statistics, Nonparametric; D013997:Time Factors; D016896:Treatment Outcome