title: [CT-based and CT-free navigation in knee prosthesis implantation. Results of a prospective study].
abstract: BACKGROUND
  Accurate leg alignment is one important factor for long-term survival in total knee arthroplasty (TKA). The classical surgeon-controlled technique is associated with a deviation of the leg axis of more than 3 degrees in up to 30% of cases, regardless of the surgeon's experience. The aim of this study was to test the efficiency of a CT-based and CT-free navigation system in restoration of the leg axis.
  
  
  METHODS
  100 TKA (PFC-Sigma, DePuy) were implanted either using the CT-based or CT-free module of the Vector-Vision navigation System (BrainLAB). There were no significant differences between the groups in preoperative leg deformity. Accuracy of implantation was determined on postoperative long-leg coronal and lateral X-rays.
  
  
  RESULTS
  A postoperative leg axis between 3 degrees varus and 3 degrees valgus was obtained in 46 patients (92%) in the CT-based group (A) and in 48 patients (96%) in the CT-free group (B). No significant differences were found for varus / valgus orientation (+/-3 degrees ) of the femoral (A=96%; B=94%) and tibial (A and B each 98%) components.
  
  
  CONCLUSIONS
  The use of the CT-based and CT-free Vector-Vision system allows a significant improvement in the accuracy of implantation in TKA. The CT-based module has the advantage of precise preoperative planning. On the other hand there are additional costs and time-consuming logistics. The advantages of the CT-free module are the intraoperative visualisation of the leg axis, the ligament balancing and joint kinematics. Cutting errors can be detected and corrected with both modules.
authors.affiliation: Orthopädische Klinik, Universität Regensburg. holger.baethis@klinik.uni-regensburg.de
authors.forename: H
authors.initials: H
authors.lastname: Bäthis
authors.forename: L
authors.initials: L
authors.lastname: Perlick
authors.forename: C
authors.initials: C
authors.lastname: Lüring
authors.forename: T
authors.initials: T
authors.lastname: Kalteis
authors.forename: J
authors.initials: J
authors.lastname: Grifka
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D019645:Arthroplasty, Replacement, Knee / Q000295:instrumentation*; D017760:Bone Malalignment / Q000000981:diagnostic imaging / Q000601:surgery; D004867:Equipment Design; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000295:instrumentation*; D021621:Imaging, Three-Dimensional / Q000295:instrumentation*; D008297:Male; D008432:Mathematical Computing; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000000981:diagnostic imaging / Q000601:surgery*; D011183:Postoperative Complications / Q000000981:diagnostic imaging; D011446:Prospective Studies; D025321:Surgery, Computer-Assisted / Q000295:instrumentation*; D013673:Technology Assessment, Biomedical / Q000706:statistics & numerical data; D036542:Tomography, Spiral Computed / Q000295:instrumentation*; D016896:Treatment Outcome