title: Subject-specific modeling of muscle force and knee contact in total knee arthroplasty.
abstract: Understanding the mechanical loading environment and resulting joint mechanics for activities of daily living in total knee arthroplasty is essential to continuous improvement in implant design. Although survivorship of these devices is good, a substantial number of patients report dissatisfaction with the outcome of their procedure. Knowledge of in vivo kinematics and joint loading will enable improvement in preclinical assessment and refinement of implant geometry. The purpose of this investigation was to describe the mechanics of total knee arthroplasty during a variety of activities of daily living (gait, walking down stairs, and chair rise/sit). Estimates of muscle forces, tibial contact load, location, and pressure distribution was performed through a combination of mobile fluoroscopy data collection, musculoskeletal modeling, and finite element simulation. For the activities evaluated, joint compressive load was greatest during walking down stairs; however, the highest contact pressure occurred during chair rise/sit. The joint contact moment in the frontal plane was mainly varus for gait and walking down stairs, while it was valgus during chair rise/sit. Excursion of the center of pressure on the tibial component was similar during each activity and between the medial and lateral sides. The main determinants of center of pressure location were internal-external rotation, joint load, and tibial insert conformity. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:1576-1587, 2016.
authors.affiliation: Department of Mechanical and Materials Engineering, University of Denver, Denver, Colorado.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Navacchia
authors.affiliation: Department of Mechanical and Materials Engineering, University of Denver, Denver, Colorado.
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Rullkoetter
authors.affiliation: Institute for Biomechanics, ETH Zurich, Zurich, Switzerland.
authors.forename: Pascal
authors.initials: P
authors.lastname: Schütz
authors.affiliation: Institute for Biomechanics, ETH Zurich, Zurich, Switzerland.
authors.forename: Renate B
authors.initials: RB
authors.lastname: List
authors.affiliation: Department of Mechanical and Materials Engineering, University of Denver, Denver, Colorado.
authors.forename: Clare K
authors.initials: CK
authors.lastname: Fitzpatrick
authors.affiliation: Department of Mechanical and Materials Engineering, University of Denver, Denver, Colorado.
authors.forename: Kevin B
authors.initials: KB
authors.lastname: Shelburne
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019645:Arthroplasty, Replacement, Knee; D020342:Finite Element Analysis; D006801:Humans; D007719:Knee Joint / Q000502:physiology*; D008954:Models, Biological; D018482:Muscle, Skeletal / Q000502:physiology*; D057285:Precision Medicine
keywords: TKR; fluoroscopy; knee osteoarthritis; musculoskeletal modeling