title: Enclosed electronic system for force measurements in knee implants.
abstract: Total knee arthroplasty is a widely performed surgical technique. Soft tissue force balancing during the operation relies strongly on the experience of the surgeon in equilibrating tension in the collateral ligaments. Little information on the forces in the implanted prosthesis is available during surgery and post-operative treatment. This paper presents the design, fabrication and testing of an instrumented insert performing force measurements in a knee prosthesis. The insert contains a closed structure composed of printed circuit boards and incorporates a microfabricated polyimide thin-film piezoresistive strain sensor for each condylar compartment. The sensor is tested in a mechanical knee simulator that mimics in-vivo conditions. For characterization purposes, static and dynamic load patterns are applied to the instrumented insert. Results show that the sensors are able to measure forces up to 1.5 times body weight with a sensitivity fitting the requirements for the proposed use. Dynamic testing of the insert shows a good tracking of slow and fast changing forces in the knee prosthesis by the sensors.
authors.affiliation: Microsystems Laboratory (LMIS4), École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland. david.forchelet@epfl.ch.
authors.forename: David
authors.initials: D
authors.lastname: Forchelet
authors.affiliation: Laboratory of Microengineering for Manufacturing (LPM), École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland. matteo.simoncini@epfl.ch.
authors.forename: Matteo
authors.initials: M
authors.lastname: Simoncini
authors.affiliation: Laboratory of Movement Analysis and Measurement (LMAM), École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland. arash.arami@epfl.ch.
authors.forename: Arash
authors.initials: A
authors.lastname: Arami
authors.affiliation: Microsystems Laboratory (LMIS4), École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland. arnaud.bertsch@epfl.ch.
authors.forename: Arnaud
authors.initials: A
authors.lastname: Bertsch
authors.affiliation: Laboratory of Microengineering for Manufacturing (LPM), École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland. eric.meurville@epfl.ch.
authors.forename: Eric
authors.initials: E
authors.lastname: Meurville
authors.affiliation: Laboratory of Movement Analysis and Measurement (LMAM), École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland. kamiar.aminian@epfl.ch.
authors.forename: Kamiar
authors.initials: K
authors.lastname: Aminian
authors.affiliation: Laboratory of Microengineering for Manufacturing (LPM), École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland. peter.ryser@epfl.ch.
authors.forename: Peter
authors.initials: P
authors.lastname: Ryser
authors.affiliation: Microsystems Laboratory (LMIS4), École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland. philippe.renaud@epfl.ch.
authors.forename: Philippe
authors.initials: P
authors.lastname: Renaud
mesh_terms: D019645:Arthroplasty, Replacement, Knee / Q000295:instrumentation*; D001696:Biomechanical Phenomena / Q000502:physiology; D004867:Equipment Design / Q000295:instrumentation*; D006801:Humans; D007719:Knee Joint / Q000502:physiology; D007720:Knee Prosthesis; D025321:Surgery, Computer-Assisted / Q000295:instrumentation*; D016474:Weight-Bearing / Q000502:physiology