title: The relationship between the survival of total knee arthroplasty and postoperative coronal, sagittal and rotational alignment of knee prosthesis.
abstract: OBJECTIVE
  Our study sought to address four issues: (1) the relationship between postoperative overall anatomical knee alignment and the survival of total knee prostheses; (2) the relationship between postoperative coronal alignment of the femoral and tibial component and implant survival; (3) the relationship between postoperative sagittal alignment of the femoral and tibial components and implant survival; and (4) the relationship between postoperative rotational alignment of the femoral and tibial component and implant survival.
  
  
  METHODS
  We reviewed 1,696 consecutive patients (3,048 knees). Radiographic and computed tomographic examinations were performed to determine the alignment of the femoral and tibial components. The mean duration of follow-up was 15.8 years (range, 11-18 years).
  
  
  RESULTS
  Thirty (1.0%) of the 3,048 total knee arthroplasties failed for a reason other than infection and periprosthetic fracture. Risk factors for failure of the components were: overall anatomical knee alignment less than 3° valgus, coronal alignment of the femoral component less than 2.0° valgus, flexion of the femoral component greater than 3°, coronal alignment of the tibial component less than 90°, sagittal alignment of the tibial component less than 0° or greater than 7° slope, and external rotational alignment of the femoral and tibial components less than 2°
  
  
  CONCLUSIONS
  In order to improve the survival rate of the knee prosthesis, we believe that a surgeon should aim to place the total knee components in the position of: overall anatomical knee alignment at an angle of 3-7.5° valgus; femoral component alignment, 2-8.0° valgus; femoral sagittal alignment, 0-3°; tibial coronal alignment, 90°; tibial sagittal alignment, 0-7°; femoral rotational alignment, 2-5° external rotation; and tibial rotational alignment, 2-5° external rotation.
authors.affiliation: Joint Replacement Center, Ewha Womans University School of Medicine, Seoul, Republic of Korea, younghookim@ewha.ac.kr.
authors.forename: Young-Hoo
authors.initials: YH
authors.lastname: Kim
authors.forename: Jang-Won
authors.initials: JW
authors.lastname: Park
authors.forename: Jun-Shik
authors.initials: JS
authors.lastname: Kim
authors.forename: Sang-Doo
authors.initials: SD
authors.lastname: Park
mesh_terms: D000328:Adult; D000368:Aged; D019645:Arthroplasty, Replacement, Knee / Q000295:instrumentation*; D017760:Bone Malalignment / Q000000981:diagnostic imaging* / Q000453:epidemiology*; D005260:Female; D005269:Femur / Q000000981:diagnostic imaging; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D007719:Knee Joint / Q000000981:diagnostic imaging; D007720:Knee Prosthesis; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000601:surgery*; D011184:Postoperative Period; D011475:Prosthesis Failure; D012189:Retrospective Studies; D013977:Tibia / Q000000981:diagnostic imaging; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome