Two-year outcomes of computed tomography-based and computed tomography free navigation for total knee arthroplasties.

UNLABELLED: Optimal component position in all planes and well-balanced soft tissues facilitate a good clinical outcome and long-term survival after total knee arthroplasties. We investigated the accuracy of implantation of navigated total knee arthroplasties at 3 months followup and the influence on the clinical outcome at 2 years followup. Forty-four patients (44 procedures) were enrolled in our prospective study. One half of the surgeries were performed using a computed tomography-based navigation system, and half were performed with imageless navigation. Outcomes were based on the Insall knee score parameters, anterior knee pain, patient satisfaction, feeling of instability, and step test. The radiographic parameters were the mechanical axis, tibial slope, lateral distal femoral angle, and medial proximal tibial angle. The radiographic measurements were similar in both groups (patients within +/- 3 degrees inaccuracy range in computed tomography-based/imageless groups; mechanical axis 86%/81%, tibial slope 95%/91%, lateral distal femoral angle 95%/91%, medial proximal tibial angle 91%/95%). The imageless system provided equal radiographic results, but we found improved ligament balancing in the computed tomography free group. The computed tomography-based approach has a good pre-operative planning procedure, but is more expensive and time consuming. LEVEL OF EVIDENCE: Therapeutic Study, Level II. See the Guidelines for Authors for a complete description of levels of evidence.