title: Posterior cruciate ligament recruitment affects antero-posterior translation during flexion gap distraction in total knee replacement. An intraoperative study involving 50 patients.
abstract: OBJECTIVE
  Because of the oblique orientation of the posterior cruciate ligament (PCL), flexion gap distraction could lead to anterior movement of the tibia, which would influence the tibiofemoral contact point. This would affect the kinematics of the TKR. We assessed the flexion gap parameters when the knee is distracted during implantation of a PCL-retaining TKR. Furthermore, the effects of PCL elevation (steep or flat) and collateral ligament releases on the flexion gap parameters were determined.
  
  
  METHODS
  During a ligament-guided TKR procedure in 50 knees, the flexion gap was distracted with a double-spring tensor with 200N after the tibia had been cut. The flexion gap height, anterior tibial translation, and femoral rotation were measured intraoperatively using a CT-free navigation system.
  
  
  RESULTS
  During flexion gap distraction, the greatest displacement was seen in anterior-posterior direction. Mean ratio between increase in gap height and tibial translation was 1 to 1.9, and was highest for knees with a steep PCL (1 to 2.3). Knees with a flat PCL and knees with a ligament release had a larger increase in PCL elevation when the gap was distracted.
  
  
  CONCLUSIONS
  When the PCL is tensioned, every extra mm that the flexion gap is distracted can be expected to move the tibia anteriorly by at least 1.7 mm (flat PCL), or more if there is a steep PCL. This changes the tibiofemoral contact point, which may have consequences for polyethylene wear.
authors.affiliation: Department of Research, Development and Education, Sint Maartenskliniek, Nijmegen, The Netherlands. p.heesterbeek@maartenskliniek.nl
authors.forename: Petra
authors.initials: P
authors.lastname: Heesterbeek
authors.forename: Noël
authors.initials: N
authors.lastname: Keijsers
authors.forename: Wilco
authors.initials: W
authors.lastname: Jacobs
authors.forename: Nico
authors.initials: N
authors.lastname: Verdonschot
authors.forename: Ate
authors.initials: A
authors.lastname: Wymenga
mesh_terms: D000328:Adult; D000368:Aged; D019645:Arthroplasty, Replacement, Knee / Q000379:methods; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000601:surgery; D016119:Posterior Cruciate Ligament / Q000503:physiopathology*; D011446:Prospective Studies; D016059:Range of Motion, Articular; D013977:Tibia / Q000503:physiopathology / Q000601:surgery
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