title: Smart instrumentation for determination of ligament stiffness and ligament balance in total knee arthroplasty.
abstract: Ligament balance is an important and subjective task performed during total knee arthroplasty (TKA) procedure. For this reason, it is desirable to develop instruments to quantitatively assess the soft-tissue balance since excessive imbalance can accelerate prosthesis wear and lead to early surgical revision. The instrumented distractor proposed in this study can assist surgeons on performing ligament balance by measuring the distraction gap and applied load. Also the device allows the determination of the ligament stiffness which can contribute a better understanding of the intrinsic mechanical behavior of the knee joint. Instrumentation of the device involved the use of hall-sensors for measuring the distractor displacement and strain gauges to transduce the force. The sensors were calibrated and tested to demonstrate their suitability for surgical use. Results show the distraction gap can be measured reliably with 0.1mm accuracy and the distractive loads could be assessed with an accuracy in the range of 4N. These characteristics are consistent with those have been proposed, in this work, for a device that could assist on performing ligament balance while permitting surgeons evaluation based on his experience. Preliminary results from in vitro tests were in accordance with expected stiffness values for medial collateral ligament (MCL) and lateral collateral ligament (LCL).
authors.affiliation: École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland; Microsystems Laboratory - LMIS4, Lausanne, Switzerland. Electronic address: hasenkamp@gmail.com.
authors.forename: W
authors.initials: W
authors.lastname: Hasenkamp
authors.affiliation: Klinikum rechts der Isar, Technische Universität München, Munich, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Villard
authors.affiliation: Centre Hospitalier Universitaire Vaudois and University of Lausanne, Lausanne, Switzerland.
authors.forename: J R
authors.initials: JR
authors.lastname: Delaloye
authors.affiliation: École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland; Laboratory of Movement Analysis and Measurements - LMAM, Lausanne, Switzerland.
authors.forename: A
authors.initials: A
authors.lastname: Arami
authors.affiliation: École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland; Microsystems Laboratory - LMIS4, Lausanne, Switzerland.
authors.forename: A
authors.initials: A
authors.lastname: Bertsch
authors.affiliation: Centre Hospitalier Universitaire Vaudois and University of Lausanne, Lausanne, Switzerland.
authors.forename: B M
authors.initials: BM
authors.lastname: Jolles
authors.affiliation: École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland; Laboratory of Movement Analysis and Measurements - LMAM, Lausanne, Switzerland.
authors.forename: K
authors.initials: K
authors.lastname: Aminian
authors.affiliation: École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland; Microsystems Laboratory - LMIS4, Lausanne, Switzerland. Electronic address: philippe.renaud@epfl.ch.
authors.forename: P
authors.initials: P
authors.lastname: Renaud
mesh_terms: D019645:Arthroplasty, Replacement, Knee / Q000295:instrumentation* / Q000379:methods; D001696:Biomechanical Phenomena; D002138:Calibration; D017885:Collateral Ligaments / Q000503:physiopathology; D004548:Elasticity; D004867:Equipment Design; D005269:Femur; D006801:Humans; D007432:Intraoperative Period; D007719:Knee Joint / Q000503:physiopathology* / Q000601:surgery*; D008022:Ligaments / Q000503:physiopathology* / Q000601:surgery*; D017888:Medial Collateral Ligament, Knee / Q000503:physiopathology; D009068:Movement / Q000502:physiology; D015203:Reproducibility of Results; D013977:Tibia
keywords: Ligament balance; Ligament stiffness; Load monitoring; Soft-tissue balance; Strain sensors; Total knee arthroplasty