title: In vivo anteroposterior translation after meniscal-bearing total knee arthroplasty: effects of soft tissue conditions and flexion angle.
abstract: OBJECTIVE
  Anteroposterior (AP) joint translation is an important indicator of good clinical outcome following total knee arthroplasty (TKA). This study evaluated the in vivo relationship between changes in the degree of voluntary soft tissue tension and flexion angle versus simultaneous AP translation after TKA.
  
  
  METHODS
  A posterior cruciate ligament (PCL)-retaining meniscal-bearing design was investigated in 20 knees of 20 patients. AP translation was measured at 30° and 75° flexion with the KT-2000 arthrometer while patients were anesthetized and non-anesthetized.
  
  
  RESULTS
  The mean translations at 30° and 75° were 10.5 and 10.4 mm, respectively, in non-anesthetized patients and 13.8 and 12.7 mm, respectively, in patients under anesthesia. AP translation showed a significant positive correlation with soft tissue tension (p < 0.001), but not with flexion angle (p = 0.366). No interaction was observed between soft tissue tension and the flexion angle in terms of AP translation (p = 0.431).
  
  
  CONCLUSIONS
  Surgeons should recognize that AP translation is greater in anesthetized patients than in non-anesthetized patients, regardless of the flexion angle, with no significant correlation between flexion angle and translation, regardless of the level of consciousness. Because conformity between the tibial insert and femoral component decreases with flexion, whereas the opposing effects of supporting structures, such as muscles, ligaments, and capsules, increases, proper soft tissue tension, particularly retention of a functional PCL, could have an important role in determining AP translation in the current prosthesis design.
authors.affiliation: Ishii Orthopaedic and Rehabilitation Clinic, 1089 Shimo-Oshi, Gyoda, Saitama, 361-0037, Japan, ishii@sakitama.or.jp.
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Ishii
authors.forename: Hideo
authors.initials: H
authors.lastname: Noguchi
authors.forename: Mitsuhiro
authors.initials: M
authors.lastname: Takeda
authors.forename: Junko
authors.initials: J
authors.lastname: Sato
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Sakurai
authors.forename: Shin-Ichi
authors.initials: S
authors.lastname: Toyabe
mesh_terms: D000368:Aged; D000768:Anesthesia, General; D053587:Arthrometry, Articular; D019645:Arthroplasty, Replacement, Knee; D003243:Consciousness; D005260:Female; D006801:Humans; D007593:Joint Instability / Q000503:physiopathology; D007719:Knee Joint / Q000502:physiology*; D007720:Knee Prosthesis; D008297:Male; D008875:Middle Aged; D009068:Movement; D018482:Muscle, Skeletal / Q000502:physiology; D016119:Posterior Cruciate Ligament / Q000502:physiology; D011474:Prosthesis Design