title: Use of a Computed Tomography Based Approach to Validate Noninvasive Devices to Measure Rotational Knee Laxity.
abstract: The purpose of this study is to validate a noninvasive rotational knee laxity measuring device called "Rotameter P2" with an approach based on Computed Tomography (CT). This CT-approach using X-rays is hence invasive and can be regarded as a precise reference method that may also be applied to similar devices. An error due to imperfect femur fixation was observed but can be neglected for small torques. The most significant estimation error is due to the unavoidable soft tissues rotation and hence flexibility in the measurement chain. The error increases with the applied torque. The assessment showed that the rotational knee angle measured with the Rotameter is still overestimated because of thigh and femur displacement, soft tissues deformation, and measurement artefacts adding up to a maximum of 285% error at +15 Nm for the Internal Rotation of female volunteers. This may be questioned if such noninvasive devices for measuring the Tibia-Femoral Rotation (TFR) can help diagnosing knee pathologies and investigate ligament reconstructive surgery.
authors.affiliation: Research Unit in Engineering Science, University of Luxembourg, 1359 Kirchberg, Luxembourg.
authors.forename: Simon
authors.initials: S
authors.lastname: Neumann
authors.affiliation: Research Unit in Engineering Science, University of Luxembourg, 1359 Kirchberg, Luxembourg.
authors.forename: Stefan
authors.initials: S
authors.lastname: Maas
authors.affiliation: Research Unit in Engineering Science, University of Luxembourg, 1359 Kirchberg, Luxembourg.
authors.forename: Danièle
authors.initials: D
authors.lastname: Waldmann
authors.affiliation: Research Unit in Engineering Science, University of Luxembourg, 1359 Kirchberg, Luxembourg.
authors.forename: Pierre-Louis
authors.initials: PL
authors.lastname: Ricci
authors.affiliation: Fachhochschule Bingen, 55411 Bingen am Rhein, Germany.
authors.forename: Arno
authors.initials: A
authors.lastname: Zürbes
authors.affiliation: Laboratoire de Biomécanique Appliquée, Université de la Méditerranée, 13916 Marseille, France.
authors.forename: Pierre-Jean
authors.initials: PJ
authors.lastname: Arnoux
authors.affiliation: Clinique d'Eich, Centre Hospitalier de Luxembourg, 1460 Eich, Luxembourg.
authors.forename: Frédéric
authors.initials: F
authors.lastname: Walter
authors.affiliation: Chirurgisch-Orthopädisches Zentrum, Illingen, 66557 Saarland, Germany; Klinik für Orthopädie und Orthopädische Chirurgie, Universitätsklinikum des Saarlandes, 66424 Homburg/Saar, Germany.
authors.forename: Jens
authors.initials: J
authors.lastname: Kelm