• C Rivière, F Iranpour, S Harris, E Auvinet, A Aframian, P Chabrand, and J Cobb.
• Department of joint replacement, the MSK Lab, Charing Cross Campus, Laboratory Block, Fulham Palace Rd, W6 8RP London, UK. Electronic address: rivierech@gmail.com.
• Orthop Traumatol Sur. 2017 Nov 1; 103 (7): 1069-1073.

IntroductionKinematic alignment (KA) technique is an alternative technique for positioning a TKA, which aims a patient-specific implant positioning in order to reproduce the pre-arthritic knee anatomy. Because reliability in implant positioning is of interest to obtain reproducible good functional results, our study tests the hypothesis that the medial and lateral distal and posterior positions of the planned and surgically implanted kinematically aligned femoral component are similar.MethodsPreoperative knee magnetic resonance imaging (MRI) and postoperative knee computed tomography (CT) of 13 patients implanted with a KA Persona® TKA (Zimmer, Warsaw, USA) using manual instrumentation (kinematically-aligned TKA procedure pack®, Zimmer Biomet, Warsaw, USA) were segmented to create 3D femoral models. The kinematic alignment position of the femoral component was planned on the 3D model created from the preoperative MRI. Differences in the positions of the planned and surgically implanted kinematically-aligned femoral component were determined with in-house analysis software.ResultsThe average differences between the medial and lateral distal and posterior positions of the planned and surgically implanted kinematically-aligned femoral component were inferior to 1mm and no statistically significant. In terms of variability, 62% (8/13) of performed implants matched all four positions within 1.5mm, and the maximum difference was 3mm.ConclusionIn this small series, intraoperative kinematic positioning of the femoral component with the specific manual instrumentation closely matched the planned position, which suggests that this technique reliably aligned the flexion-extension axis of the femoral component to the cylindrical axis.Level Of EvidenceLevel 3.Copyright © 2017 Elsevier Masson SAS. All rights reserved.

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