Whole Knee Joint Finite Element (FE) Modeling
The results from motion analysis studies can be used to determine knee cartilage stress distribution using finite element analysis (FEA). FEA is an advanced computer simulation tool used in a wide range of engineering disciplines for analyzing output variables such as stress and strain in a body. Knee joint models are developed by using MRI scans to generate solid bodies of the bone and soft tissues. Ligaments, tendons, and cartilage are assembled into anatomically correct positions and assigned mechanical properties. The motion analysis results are then used to define load and boundary conditions for the knee joint FE models. Outcomes include predicted magnitudes of cartilage contact pressure and contact area that can be used to study how different exercises may increase risk for cartilage injury and, ultimately, the development of osteoarthritis (OA).
From 2016-2020, graduate students Jonathon Stearns (ME), Michael Rumery (ME) and Greg Lane (ME) created several participant-specific whole knee joint FE models to compare knee joint cartilage tissue stresses during gait (i.e. walking), cycling, and elliptical training exercises. Generally, their results showed that cartilage tissue loads are much lower in cycling than gait and elliptical training, suggesting that cycling is a preferred exercise for populations that are at high risk for knee OA.
From 2014-2015, graduate students Meghan Sylvia (ME) and Nick Czapla (ME) developed a whole knee joint FE model from MRIs. Meghan's research addressed the hypothesis that cartilage tissue loading during the stance phase of gait would depend on body weight and varus/valgus knee alignment angles. Nick's research addressed the hypothesis that cartilage tissue loading during the stance phase of gait would depend on the severity and type of injury to the anterior cruciate ligament (ACL).
From 2013-2014, graduate student Spencer Wangerin (ME) added a patella (i.e. kneecap) and patellar ligament to complete the OpenKnee, an open-source FE model available from OpenKnee (Project Director Dr. Erdemir, Cleveland Clinic). A solid model of the patellar structures was created from 175 Magnetic Resonance Images (MRIs) and a finite element mesh of the complete knee was created for use in the FE solver ABAQUS. Spencer used this FE model to predict cartilage tissue loading during the stance phase of gait.