title: Design modifications of high-flexion TKA do not improve short term clinical and radiographic outcomes.
abstract: BACKGROUND
  The prosthesis of contemporary total knee arthroplasty (TKA) has been modified to provide a more familiar environment for higher flexion angle of the replaced knee. The design modifications continue based on evidence reported in the literature. However, whether these modifications of the prosthesis design lead to improvements in clinical results needs further investigation. We determined whether the prosthesis modifications based on recent evidence improve clinical and radiographic results following high flexion TKA.
  
  
  METHODS
  524 patients who underwent primary TKA using two different high flexion prostheses were divided to Group 1 (HF-1) using a high flexion prosthesis, group 2 (HF-2) using the more recently devised high flexion prosthesis, which claims to be adopted from evidence proposed in the literature. Clinical outcomes included ranges of motion (ROM), the Knee Society knee and function score (KSKS and KSFS), the Western Ontario and McMaster Universities Arthritis Index (WOMAC) score, radiologic evaluation, and complication related to surgery.
  
  
  RESULTS
  No differences in terms of clinical and radiographic results were observed between the groups at the 2 year follow-up. The mean ROM was 123°and 124° in the HF-1 and HF-2 groups, respectively. KSKS were 90 and 89.1, KSFS were 76.6 and 81.8, and total WOMAC scores were 23.1 and 24.9 in the HF-1 and HF- 2 groups. No differences of the incidences of radiolucency on radiographs (1.4% in HF-1, 2.1% in HF-2) and dislocation (1 case in HF-1 only) was observed.
  
  
  CONCLUSIONS
  Even if recent modifications in the design of high flexion TKA prosthesis were based on evidence in the literature, they did not provide meaningful improvements in short-term clinical and radiographic outcomes after TKA. Surgeons should consider our findings when choosing a prosthesis for their patients.
authors.forename: Jai Gon
authors.initials: JG
authors.lastname: Seo
authors.forename: Young-Wan
authors.initials: YW
authors.lastname: Moon
authors.forename: Moon Jong
authors.initials: MJ
authors.lastname: Chang
authors.forename: Byung Chul
authors.initials: BC
authors.lastname: Jo
authors.forename: Yong Beom
authors.initials: YB
authors.lastname: Park
authors.forename: Deuk Soo
authors.initials: DS
authors.lastname: Lim
authors.affiliation: Department of Orthopaedic Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, 81 Irwon-ro, Gangnam-gu, Seoul 135-710, South Korea. oselite@naver.com.
authors.forename: Byung Hoon
authors.initials: BH
authors.lastname: Lee
mesh_terms: D000368:Aged; D019645:Arthroplasty, Replacement, Knee / Q000295:instrumentation* / Q000639:trends*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007720:Knee Prosthesis / Q000639:trends*; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000000981:diagnostic imaging* / Q000601:surgery*; D011474:Prosthesis Design / Q000639:trends*; D011859:Radiography; D016059:Range of Motion, Articular / Q000502:physiology; D012189:Retrospective Studies; D013997:Time Factors; D016896:Treatment Outcome