Table of Contents
International Scholarly Research Notices
Volume 2015, Article ID 439095, 9 pages
Research Article

Design, Repeatability, and Comparison to Literature Data of a New Noninvasive Device Called “Rotameter” to Measure Rotational Knee Laxity

1Research Unit in Engineering Science, University of Luxembourg, 1359 Kirchberg, Luxembourg
2Fachhochschule Bingen, 55411 Bingen am Rhein, Germany
3Laboratoire de Biomécanique Appliquée, Université de la Méditerranée, 13916 Marseille, France
4Chirurgisch-Orthopädisches MVZ, 66557 Illingen, Saarland, Germany
5Klinik für Orthopädie und Orthopädische Chirurgie, Universitätsklinikum des Saarlandes, 66424 Homburg, Saarland, Germany

Received 30 January 2015; Accepted 17 June 2015

Academic Editor: Vassilios S. Nikolaou

Copyright © 2015 Simon Neumann et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


The present paper deals with the design, the repeatability, and the comparison to literature data of a new measuring device called “Rotameter” to characterize the rotational knee laxity or the tibia-femoral rotation (TFR). The initial prototype P1 of the Rotameter is shortly introduced and then modified according to trials carried out on a prosthetic leg and on five healthy volunteers, leading therefore to an improved prototype P2. A comparison of results obtained from P1 and P2 with the same male subject shows the enhancements of P2. Intertester and intratester repeatability of this new device were shown and it was observed that rotational laxities of left and right knees are the same for a healthy subject. Moreover, a literature review showed that measurements with P2 presented lower TFR values than other noninvasive devices. The measured TFR versus torque characteristic was quite similar to other invasive devices, which are more difficult to use and harmful to the patient. Hence, our prototype P2 proved to be an easy-to-use and suitable device for quantifying rotational knee laxity. A forthcoming study will validate the Rotameter thanks to an approach based on computed tomography in order to evaluate its precision.