title: Intraoperative navigation of patient-specific instrumentation does not predict final implant position.
abstract: The purpose of this study was to determine if intraoperative navigation predicted final implant position of total knee arthroplasties (TKAs) performed with patient-specific instrumentation (PSI). We retrospectively reviewed 60 TKAs performed with PSI and imageless navigation. These values were compared to postoperative coronal alignment based on long-leg radiographs, as well as rotation and tibial slope based on CT scans. The intraoperative coronal position of the tibia as measured by the intraoperative navigation indicated a significantly higher deviation from the neutral mechanical axis than the actual final position (P=0.03). Similarly, tibial slope and femoral component rotation measured by intraoperative navigation significantly deviated from the final slope and femoral component rotation (P<0.0001). In conclusion, intraoperative navigation of PSI position showed a significantly high deviation from the true final implant position.
  
  
  METHODS
  Level III, therapeutic. See Instructions to Authors for a complete description of levels of evidence.
authors.affiliation: Department of Orthopedic Surgery, Mayo Clinic, Rochester, Minnesota.
authors.forename: Matthew P
authors.initials: MP
authors.lastname: Abdel
authors.affiliation: Center for Musculoskeletal Surgery - Orthopedic Department, Charité - Universitätsmedizin Berlin, Berlin, Germany.
authors.forename: Philipp
authors.initials: P
authors.lastname: von Roth
authors.affiliation: Orthopedic Department, Hospital Märkisch Oderland, Section Wriezen, Wriezen, Germany.
authors.forename: Hagen
authors.initials: H
authors.lastname: Hommel
authors.affiliation: Center for Musculoskeletal Surgery - Orthopedic Department, Charité - Universitätsmedizin Berlin, Berlin, Germany.
authors.forename: Carsten
authors.initials: C
authors.lastname: Perka
authors.affiliation: Center for Musculoskeletal Surgery - Orthopedic Department, Charité - Universitätsmedizin Berlin, Berlin, Germany.
authors.forename: Tilman
authors.initials: T
authors.lastname: Pfitzner
mesh_terms: D000368:Aged; D019645:Arthroplasty, Replacement, Knee / Q000295:instrumentation* / Q000379:methods*; D005260:Female; D005269:Femur / Q000601:surgery; D006801:Humans; D007432:Intraoperative Period; D007720:Knee Prosthesis; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D012399:Rotation; D025321:Surgery, Computer-Assisted / Q000295:instrumentation*; D013977:Tibia / Q000601:surgery; D014057:Tomography, X-Ray Computed
keywords: femoral rotation; intraoperative navigation; mechanical axis; patient-specific instrumentation (PSI); total knee arthroplasty (TKA)