title: Using navigation intraoperative measurements narrows range of outcomes in TKA.
abstract: Computer-assisted technology creates a new approach to total knee arthroplasty (TKA). The primary purpose of this technology is to improve component placement and soft tissue balance. We asked whether the use of navigation techniques would lead to a narrow range of implant alignment in both coronal and sagittal planes and throughout the flexion-extension range. Using a prospective consecutive series of 57 navigated TKAs, we assessed intraoperative knee measurements, including alignment, varus-valgus stress angles in extension, and varus-valgus angles from 0 degrees to 90 degrees of flexion comparing postimplant with preimplant. We found fewer outliers with coronal (100% of TKAs within +/-2 degrees) and sagittal (0% of TKAs with fixed flexion greater than 5 degrees) alignment, soft tissue balancing (mean varus and valgus stress angles -3.2 degrees and 2.3 degrees; range, -5 degrees to 5 degrees), and mean femorotibial angle over flexion range 0 degrees (-0.2 degrees; range, -1 degrees to 2 degrees), 30 degrees (-0.2 degrees; range, -5 degrees to 4 degrees), 60 degrees (-0.5 degrees; range, -5 degrees to 7 degrees), and 90 degrees (-0.2 degrees; range, -5 degrees to 10 degrees). This technology allows a narrow range of implant placement and soft tissue management in extension. We anticipate improved ultimate patient outcomes with less tissue disruption.
  
  
  METHODS
  Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.
authors.affiliation: Department of Orthopaedics, Golden Jubilee National Hospital, Beardmore Street, Clydebank, Glasgow, UK. frederic.picard@gjnh.scot.nhs.uk
authors.forename: Frederic
authors.initials: F
authors.lastname: Picard
authors.forename: Angela H
authors.initials: AH
authors.lastname: Deakin
authors.forename: Jon V
authors.initials: JV
authors.lastname: Clarke
authors.forename: John M
authors.initials: JM
authors.lastname: Dillon
authors.forename: Alberto
authors.initials: A
authors.lastname: Gregori
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects*; D001696:Biomechanical Phenomena; D005260:Female; D006801:Humans; D007593:Joint Instability / Q000503:physiopathology / Q000517:prevention & control; D007719:Knee Joint / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D007720:Knee Prosthesis; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000379:methods*; D011183:Postoperative Complications / Q000503:physiopathology / Q000517:prevention & control*; D011446:Prospective Studies; D017755:Prosthesis Fitting; D011859:Radiography; D016059:Range of Motion, Articular; D013314:Stress, Mechanical; D025321:Surgery, Computer-Assisted