OpenSim Workshop March 2013 Simulation of Obese Locomotion Biomechanics Workshop Goals: -Investigate...

OpenSim Workshop March 2013

Simulation of Obese Locomotion Biomechanics


Modeling Static Knee Alignment: Motivation

• Obese children have ~3X greater prevalence of knee malalignment vs. NO

• Malalignement as Obese adult >> much greater risk for development and progression of OA

• We want to quantify both the magnitude and the distribution of the knee joint contact force


Modeling Static Knee Alignment

What is the correct anatomical alignment?

?



• For this exercise, we kept the tibiofemoral joint parallel to the ground

• Added two bodies (femoral condyles, tibial plateau)

• Updated joint definitions (articulations)

θ

Varus alignment



• Also made a model with valgus alignment


Check: Make sure muscles aren’t passively stretched i.e. musculo-tendon unit is the same between a neutral and malaligned knee


e.g. Semitendinosus



• Reran IK>RRA>SO>JR for Valgus, Varus, and Neutral Alignment



• Axial Force

• Largest with Varus alignment (Not Expected, I expected neutral)

Result of forcing alignment on neutral subject



• Knee Abd/Add Moment

• Largest with Varus alignment (Expected, Obvious)

Add

Abd


Proof of Concept: Can incorporate radiographic knee alignment to better understand loading in future childhood obesity study

Take home message: Critical to incorporate frontal plane knee alignment if you intend to calculate medial-lateral distribution!

Future:

• Balance forces and moments to resolve *approximate* medial-lateral distribution

• Incorporate med-lat calculation in a JR plugin



Thank you, OpenSim Team!

OpenSim Workshop March 2013 Simulation of Obese Locomotion Biomechanics Workshop Goals: -Investigate...

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