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dc.contributor.advisorMaletsky, Lorin
dc.contributor.authorFitzwater, Fallon Gray
dc.date.accessioned2015-09-07T21:08:14Z
dc.date.available2015-09-07T21:08:14Z
dc.date.issued2014-12-31
dc.date.submitted2014
dc.identifier.otherhttp://dissertations.umi.com/ku:13771
dc.identifier.urihttp://hdl.handle.net/1808/18387
dc.description.abstractDynamic in-vitro knee simulator's ability to achieve physiological compression and A-P loads is dependent on the chosen axes of applied loads in the sagittal plane. Anterior-posterior (A-P) and compressive forces generated at the tibia during dynamic activities have a large influence on the joint kinematics and soft tissue loads. Simulating accurate physiological joint forces during in-vitro testing is essential for evaluating the performance of total knee replacements and determining the effects of pathologies and injuries. Instrumented tibia trays have measured joint forces for a variety of activities. Most activities generate compressive loads that range from 2-3.5 times body weight (BW). A-P forces range between a .40 BW posterior to a .20 BW anterior. The objective of this study is to determine the relationship between hamstring force and ankle load, which cause a flexion-extension moment at the ankle, and A-P and compressive tibia forces in a dynamic knee simulator. A set of posterior stabilized total knee prostheses attached to custom fixtures was mounted on the Kansas Knee Simulator. A non-physiological deep knee bend, ranging from 20-120° flexion, was performed while applying constant ankle load and hamstring forces independently. Joint forces were measured using a six degree-of-freedom load cell placed directly below the tibia tray. A-P translations of the femur relative to the tibia were calculated for each cycle. In addition, a rigid body computational model with either a hamstring force or ankle loads (ADAMS.MSC software 2011) was used to determine the five loading profiles for the Kansas Knee Simulator needed to simulate a physiological walk compression and A-P loads obtained from instrumented tibia data. The addition of hamstring forces increased the anterior forces at the tibia while increasing compression. A posteriorly directed ankle load, which causes an extension moment at the ankle, caused a decrease in anterior forces but did not have the capability to generate a posterior directed tibia force. Posterior ankle loads decreased quadriceps loads and compression. In the computational model, the hamstrings were not able to achieve posterior tibia loads while an anterior ankle load is required to achieve posterior joint force during the walk simulations. Dynamic knee simulators in which the hip positioned directly over the ankle during the entire simulation can easily achieve anterior tibia loads but will have difficulties generating a posteriorly directed tibia load. The hamstrings have shown to only contribute to anterior tibia loads and will not be necessary to include in this type of knee simulator. Anterior ankle loads can create posterior tibia loads; however, it is highly coupled with the quadriceps axis which is typically run in position control. The anterior ankle loads, used to create a posterior tibia load will increase quadriceps loads and compression. The results from this study show that ankle loads, which cause flexion-extension moments at the ankle, are a robust way to achieve a physiological ratio of A-P to compressive load at the tibia.
dc.format.extent45 pages
dc.language.isoen
dc.publisherUniversity of Kansas
dc.rightsCopyright held by the author.
dc.subjectEngineering
dc.subjectBiomechanics
dc.subjectKnee Joint
dc.subjectKnee Loading
dc.subjectSimulator
dc.titleQuantifying the Effect of Sagittal Plane Loading on Anterior-Posterior and Compressive Knee Loads during Dynamic Simulations
dc.typeThesis
dc.contributor.cmtememberLuchies, Carl
dc.contributor.cmtememberFischer, Ken
dc.thesis.degreeDisciplineMechanical Engineering
dc.thesis.degreeLevelM.S.
dc.rights.accessrightsopenAccess


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