ABSTRACT
EDUCATIONAL CHALLENGE: Electronic dance music (EDM) festivals - crowded, loud, low-resource environments - pose unique challenges to event medical teams. Simulation can prepare teams to manage clinical presentations in this unconventional context. Without access to simulation infrastructure, a low-technological, low-fidelity simulation modality is warranted. SOLUTION: Draw & Doodle Simulation (D&D SIM) is a low-fidelity simulation where patients are hand-drawn (i.e. on paper, whiteboard, or digitally) instead of utilizing manikins or live actors. Facilitators draw all patient findings, while participants doodle any possible interventions. SOLUTION IMPLEMENTATION: Two D&D SIM cases (serotonin toxicity and refractory anaphylaxis) were piloted in classrooms. Participants included paramedics, medical students, lifeguards, and first aiders. Facilitators conducted simulations using chart paper, with each participant doodling contributions using differently colored markers. LESSONS LEARNED: Participants responded positively, rating the serotonin toxicity case 4.31/5 (n = 13) and refractory anaphylaxis case 4.53/5 (n = 15). Participants appreciated the 'low-stakes', useful 'visual' representation of progress, 'fun and [interactivity]', and appropriate '[realism]' of D&D SIM. However, D&D SIM was perceived as 'less life threatening', would not be appropriate for physical skills (e.g. CPR), required everyone to be 'oriented in the same direction to see the drawing', and the chart paper risked becoming cluttered. NEXT STEPS: Next steps include writing new cases, implementing D&D SIM in other teaching contexts, exploring its use in digital platforms, and studying its effectiveness against higher-fidelity simulation.
ABSTRACT
Total knee arthroplasty (TKA) is an end-stage treatment for knee osteoarthritis that relieves pain and loss of mobility, but patient satisfaction and revision rates require improvement. One cause for TKA revision is joint instability, which may be due to improper ligament balancing. A better understanding of the relationship between prosthesis design, alignment, and ligament engagement is necessary to improve component designs and surgical techniques to achieve better outcomes. We investigated the biomechanical effects of ligament model complexity and ligament wrapping during laxity tests using a virtual joint motion simulator. There was little difference in kinematics due to ligament complexity or ligament wrapping.
ABSTRACT
Component alignment accuracy during total knee arthroplasty (TKA) has been improving through the adoption of image-based navigation and robotic surgical systems. The biomechanical implications of resulting component alignment error, however, should be better characterized to better understand how sensitive surgical outcomes are to alignment error. Thus, means for analyzing the relationships between alignment, joint kinematics, and ligament mechanics for candidate prosthesis component design are necessary. We used a digital twin of a commercially available joint motion simulator to evaluate the effects of femoral component rotational alignment. As anticipated, the model showed that an externally rotated femoral component results in a knee which is more varus in flexion, with lower medial collateral ligament tension compared to a TKA knee with a neutrally aligned femoral implant. With the simulation yielding logical results for this relatively simple test scenario, we can have more confidence in the accuracy of its predictions for more complicated scenarios.
ABSTRACT
BACKGROUND: Posterior-stabilized (PS)-total knee arthroplasty (TKA) arose as an alternative to cruciate-retaining (CR)-TKA in the 1970s. Since then, it has become a popularly utilized TKA design with outcomes comparable to CR-TKA. The post-cam mechanism is unique to PS-TKA as it substitutes the function of the posterior cruciate ligament (PCL). The study aimed to understand the kinematic and laxity changes in PS-TKA with under- and overstuffing of the tibiofemoral joint space with the polyethylene (PE) insert. METHODS: This study employed a hybrid computational-experimental joint motion simulation on a VIVO 6 degrees of freedom (6-DoF) joint motion simulator (AMTI, Watertown, MA, USA). Physical prototypes of a virtually-performed TKA in mechanical alignment (MA) and kinematic alignment (KA) based on cadaveric CT scans and a virtual ligament model were utilized. The reference, understuffed (down 2 mm) and overstuffed (up 2 mm) joint spaces were simulated, neutral flexion and laxity testing loads and motions were performed for each configuration. RESULTS: The PE insert thickness influenced post-cam engagement, which occurred after 60º in the overstuffed configurations, after 60º-75º in the reference configurations and after 75º in the understuffed configurations. The understuffed configurations, compared to the reference configurations, resulted in a mean 2.0º (28%) and 2.0º (31%) increase in the coronal laxity in MA and KA respectively. The overstuffed configurations, compared to the reference configuration, resulted in an increase in the mean joint compressive forces (JCFs) by 73 N (61%) and 77 N (62%) in MA and KA models, respectively. CONCLUSIONS: The under- and overstuffing in PS-TKA alter the kinematics with variable effects. Understuffing decreases the stability, JCFs and inverse with overstuffing. Subtle changes in the PE insert thickness alter the post-cam mechanics.
