title: Asian-specific total knee system: 5-14 year follow-up study.
abstract: BACKGROUND
  Knee size and body size differ in Asians compared with Caucasians. Nevertheless, many total knee arthroplasty (TKA) prostheses used worldwide are made for Western Caucasian subjects. As a result, an Asian's knee might not fit these prostheses. We studied the Flexible Nichidai Knee (FNK) system, a new model of TKA for Asian patients. The purpose of this report is to investigate the outcomes of this prosthesis retrospectively.
  
  
  METHODS
  We investigated 1055 primary TKAs in 595 patients who underwent FNK for osteoarthritis (OA) in Japan and were followed for > 5 years. The knee score and function score were used for clinical evaluation. We examined the range of motion (ROM) preoperatively and at final follow-up and radiographic assessments. In addition, postoperative complications were investigated. A survivorship analysis was also conducted using two endpoints: revision for any reason and aseptic failure.
  
  
  RESULTS
  890 knees in 502 patients were available for study (follow-up rate of 96.0%). The mean follow-up term was 8.3 years (range, 5.0-14.1 years). The knee and function score significantly improved from 41.3 to 90.3 and from 39.1 to 76.2 points, respectively (p < 0.001). The mean ROM in FNK posterior cruciate retaining (CR) type and FNK posterior-stabilized (PS) type ameliorated significantly from 107.8° and 95.6° to 110.7° and 110.4°, respectively (p < 0.01). Ten knees underwent revision surgery (infection in 3 cases, instability in 2, loosening in 2, and non-union of femoral supracondylar fracture, severe pain, and recurrent hemarthrosis in 1 each). The survivorship rate was 99.4% (95% CI, 99.0-99.8) at 5 years (n = 952 patients at risk) and 96.2% (95% CI, 91.9-100) at 12.5 years (n = 49 patients at risk).
  
  
  CONCLUSIONS
  The FNK prosthesis for Asians achieved excellent mid- to long-term survivorship and clinical results.
authors: Department of Orthopedic Surgery, Nihon University School of Medicine, 30-1 Oyaguchi, Kamimachi, Itabashi-ku, Tokyo 173-8610, Japan. kunihiro619@hotmail.com
authors: Kunihiro
authors: K
authors: Hosaka
authors: Shu
authors: S
authors: Saito
authors: Takao
authors: T
authors: Ishii
authors: Sei
authors: S
authors: Mori
authors: Takanobu
authors: T
authors: Sumino
authors: Yasuaki
authors: Y
authors: Tokuhashi
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects* / Q000379:methods / Q000401:mortality; D044466:Asian People; D049628:Body Size / Q000502:physiology; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007564:Japan / Q000453:epidemiology; D007720:Knee Prosthesis / Q000639:trends*; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications / Q000401:mortality*; D011475:Prosthesis Failure / Q000009:adverse effects* / Q000639:trends*; D012189:Retrospective Studies; D012307:Risk Factors; D016896:Treatment Outcome