Development of a Workflow for Wear And Functional Simulation of Total Knee Replacements
Translated title
Udvikling af et workflow til slid og funktionel simulering af kunstige knæ
Author
Stoltze, Jonas Stensgaard
Term
4. term
Education
Publication year
2014
Submitted on
2014-06-03
Abstract
Formålet med projektet er at udvikle en samlet arbejdsgang til at simulere funktion og slid af total knæalloplastik (TKR) under gang. Belastninger og den styrede bevægelse i knæleddet beregnes først i muskuloskeletprogrammet AnyBody gennem en hel gangcyklus. Via MATLAB overføres disse data til en numerisk finite element (FE) model, som løses i FEBio. Modellen omfatter lårbens- og skinnebensimplantater samt de vigtigste omgivende ledbånd, og den tillader bevægelse i alle seks frihedsgrader (tre oversættelser og tre rotationer). FE-analysen forudsiger både ledkinematik og intern kontakt i leddet. Kinematikken sammenlignes med fluoroskopiske data og resultaterne fra AnyBody. Der ses god overensstemmelse i oversættelserne, mens overensstemmelsen i rotationerne varierer. Det lineære slid estimeres ud fra den beregnede kontakttrykfordeling ved hjælp af en MATLAB-algoritme, som verificeres mod publicerede eksperimentelle resultater. Algoritmen forudsagde en meget lav maksimal sliddybde (76,3 % afvigelse) i forhold til litteraturen, men den overordnede slidkontur stemte godt overens. Den muskuloskeletale model kan løse både en idealiseret hængselsbegrænset model og en kontaktbaseret knæledsmodel. I projektet undersøges sliddet gennem en gangcyklus for begge metoder for at vurdere forskellene i sliddybde. Den kontaktbaserede metode, der bruger en kraftafhængig kinematikløser, forudsagde den største sliddybde af de to metoder.
This project develops a workflow to simulate the function and wear of total knee replacements (TKR) during walking. Joint loads and prescribed motions are first computed with the musculoskeletal modeling program AnyBody over a full gait cycle. These data are transferred via MATLAB to a finite element (FE) model solved in FEBio. The model includes the femoral and tibial implants and the major surrounding ligaments, and it allows motion in all six degrees of freedom (three translations and three rotations). The FE analysis predicts joint kinematics and internal contact. The predicted kinematics are compared with fluoroscopic data and with the AnyBody results, showing good agreement in translational directions, while agreement in rotations varies. Linear wear is estimated from the computed contact pressure using a MATLAB algorithm verified against published experimental results. The algorithm predicted a very low maximum wear depth (76.3% deviation) compared with the literature, but the overall wear pattern was in good agreement. The musculoskeletal model can handle both an idealized hinge-constrained model and a contact-based knee joint model. Wear over a gait cycle is evaluated for both to compare wear depth, and the contact-based approach, which uses a force-dependent kinematic solver, predicted the higher wear depth of the two.
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