Anne Schmitz

Development of an Open-Source, Discrete Element Knee Model

Objective: Biomechanical modeling is an important tool in that it can provide estimates of forces that cannot easily be measured (e.g., soft tissue loads). The goal of this study was to develop a discrete element model of the knee that is open source to allow for utilization of modeling by a wider audience of researchers. Methods: A six degree-of-freedom tibiofemoral and one degree-of-freedom patellofemoral joint were created in OpenSim. Eighteen ligament bundles and tibiofemoral contact were included in the model. Results: During a passive flexion movement, maximum deviation of the model from the literature occurred at the most flexed angle with deviations of 2° adduction, 7° internal rotation, 1-mm posterior translation, 12-mm inferior translation, and 4-mm lateral translation. Similarly, the overall elongation of the ligaments agreed with literature values with strains of less than 13%. Conclusion: These results provide validation of the physiological relevance of the model. Significance: This model is one of the few open source, discrete element knee models to date, and has many potential applications, one being for use in an open-source cosimulation framework.

Development of an open-source cosimulation method of the knee

Rigid body dynamics and soft tissue loads are solved simultaneously in a cosimulation framework to couple musculoskeletal dynamics and tissue mechanics. The goal of this work was to implement a validated, open-source cosimulation framework of the knee to determine how this coupling affects computed cartilage loads. The kinematic knee joint of a generic whole body model in the open-source software OpenSim was replaced by a previously developed discrete element knee model that consisted of a six degree of freedom (dof) tibiofemoral joint and one dof patellofemoral joint. A serial approach was initially used to estimate muscle forces and cartilage contact loads for a simple flexion movement. Then, a cosimulation framework was implemented for a simple knee flexion movement in which neuromusculoskeletal dynamics and knee mechanics were simultaneously solved using a computed muscle control (CMC) algorithm. This work highlights that the choice of computation method and the precise acquisition of all the dofs of the knee are important factors to consider when estimating soft tissue loads.

Using external business plan competitions to drive innovation and effective cross-disciplinary collaboration

The integration of entrepreneurial aspects in biomedical engineering undergraduate programs is still at its infancy. It is difficult to integrate business specific classes in engineering program due to curriculum constraints and often student do not have any exposure to entrepreneurship. We present the result of two case studies which leveraged an alternative approach. An inter-universities business plan regional competition was utilized to establish and integrated collaboration between the biomedical and entrepreneurship program at Gannon University. The activity focused on a series of seminars in different classes where students were exposed the creation of a marketing plan, pricing model, organizational design and go-to-market strategies, which are common aspects of a business plan. The active interaction between Engineering and Business fostered innovation that resulted in a positive outcome in the “Shark-Tank” style competition.

Is Race Walking Lower Impact Than Running

Race walking has grown over the past decade because it provides exercise without the high impact loads of running. However, whether race walking is truly a lower impact sport remains to be tested. Fifteen competitive race walkers ran and race walked over a force plate. The loading rate of the vertical ground reaction force was 46% lower for race walking in comparison to running. This suggests race walking is a lower impact exercise safer for the joints. This may be advantageous for people who would like to exercise at a higher intensity that walking provides but have joint problems, e.g. those with osteoarthritis.Copyright

Association Between Impact Peak and Hip Flexor Activity During Running

Gait retraining techniques to reduce impact forces during running is of significant interest to clinicians interested in reducing running injury risk. Increased peak rectus femoris activity during swing was significantly correlated with decreased impact peak during running (r = −0.654, p = 0.01) due to the muscle’s large hip flexion moment arm (43 to 54 mm). Gluteus medius (r = −0.204, p = 0.466) and adductor longus (r = 0.104, p = 0.714) activity were not significantly correlated with impact peak. These results suggest that gait retraining programs aimed at reducing the impact peak during running should focus on increased rectus femoris activity during swing.Copyright