Developing an Innovative Amputated Limb Simulator to Advance Clinicians’ Skills

Two million people are living with limb loss in the United States and more than 550,000 new amputations occur annually, 50 percent of which involve the lower limb at the transtibial level.^1-3 Most people acquire transtibial amputations from complications of diabetes and vascular disease, which renders the residual limb vulnerable to tissue damage when the limb experiences high forces, particularly during weight bearing activities such as standing, walking, etc.³ This is a concern because the socket of a lower-limb prosthesis is the critical point of force transfer at the residuum and is a major contributor to a prosthesis user’s experiences, quality of life, and clinical outcomes.^4-7

Appropriate socket fit requires clinicians to accurately capture the shape of the residuum. These methods are usually taught by utilizing expensive and variable patient-model learning experiences.⁸ Due to budget and time constraints, educational programs expose students to patient models a few times per course, and they have limited skills practice prior to clinical residency.⁹ Simulation-based training can help students develop skills before they practice on real patients and increase the opportunity to practice these skills independent of a patient model.^10-12 Unfortunately, there is a lack of high-fidelity simulation-based training and an absence of quantified evidence in learning outcomes associated with it in O&P training programs.

To address this gap, a team of clinicians and researchers led by Christopher Hovorka, PhD, CPO, FAAOP, assistant professor at Baylor College of Medicine’s Orthotics and Prosthetics Program, in collaboration with Marcia O’Malley, PhD, director of Rice University’s Mechatronics and Haptic Interfaces Lab, is developing a novel amputated limb simulator with a force-feedback system to enhance clinicians’ skills in prosthetics. The project received funding from multiple agencies including the Huffington Department of Education Innovation and Technology, the Orthotics & Prosthetics Foundation for Education and Research, and the Texas Society of Allied Health Professions. The Rice team will embed an array of force-sensing resistors onto a simulator that replicates a limb with a transtibial amputation. The limb simulator is composed of a silicone matrix and rigid plastic skeletal, and elastic connective tissue structures that emulate the anatomical structures of a conical-shaped amputated limb (Figures 1 and 2). When learners palpate the simulated limb with their hands, a visual display of the limb will include a force profile and wrist vibration to inform their performance of the magnitude and location of force applied to the limb (Figure 3). The system uses low-cost sensors that collect the forces applied to the limb, a graphical user interface projecting the force feedback, and wrist bracelet vibration to inform learners whether the force imposed is within or exceeds a safe threshold.

The Baylor team will evaluate the fidelity of the feedback system and determine the optimal force threshold for feedback. Then the team will evaluate learners’ clinical skills performance before and after participation in a simulation-based training protocol. The goal of the novel force-feedback system and the simulation-based training protocol is to enable students to make errors and informed corrections that reinforce skill acquisition and learning.^12-15 The team at Baylor will evaluate the simulator’s effectiveness to reinforce entry-level student skills in palpation of anatomical landmarks, measurement of limb dimension, and residual-limb shape capture—all essential clinical procedures that determine prosthetic socket fit.

The use of the simulator and the simulation-based training module has the potential to reduce costs and enable student performance in skills that influence clinical outcomes, patient experiences, and quality of life, which are key priorities that align with patient-oriented and values-based care initiatives in US healthcare. The proposed force-feedback system is an advantage over rudimentary amputated limb simulators that are infrequently used for prosthetist training. These rudimentary systems lack a feedback system to inform learners’ performance, which is essential for developing clinical skills.

Significance

Anecdotal reports suggest the use of an amputated limb simulator for skills practice prior to students engaging in patient model learning experiences may enhance student self-confidence.¹⁶ However, it is unknown if student use of the amputated limb simulator translates to improved student performance related to prosthetic socket fit. Additionally, there are several skills that contribute to socket fit, such as identification of anatomical landmarks, limb measurement, and impression taking. Evaluating the acquisition of these skills and the associated outcomes may improve our understanding of the value of simulation-based training in prosthetics.

Hence, the lack of simulation-based training in prosthetics provides an opportunity for developing and evaluating an innovative force-feedback simulator technology to enhance student learning of important clinical skills. This has the potential to provide new knowledge on the utility and effectiveness of a force-feedback system as a teaching tool to advance clinicians’ skills and performance. Specifically, there are two areas of potential impact. First there is opportunity to clarify the optimal force thresholds for safe palpation, measurement, and impression taking as these are currently unknown. Knowledge in this area can inform teaching strategies and learner assessment across all levels of clinician training (e.g., primary entry-level foundational training, residency training, and post-certification continuing education skills assessment). Second, the novel force-feedback simulator has the potential to advance instructional methods for high-stakes clinician skills training by serving as a tool for repeated task practice prior to student engagement with patient models. As such, it could improve the student and patient model learning experience by reinforcing student confidence and skills and reducing errors and harm to patient models.

More broadly, the potential benefits of the novel simulator as a teaching tool are in its measurement capabilities, which can improve our understanding of student learning of complex clinical skills and how these skills translate to improving prosthetic socket fit, patient health, and quality of life.

Christopher Hovorka, PhD, CPO, FAAOP, is an educator and scientist in Baylor College of Medicine’s Orthotics and Prosthetics Program. After a career as an exercise physiologist, he pivoted into O&P first by completing a bachelor’s degree in O&P at the University of Washington and residencies in orthotics (Southern Illinois University School of Medicine) and prosthetics (Connecticut Children’s Medical Center). After several years of clinical practice in O&P and a desire to advance clinician education and evidence to support clinical decision making, he pursued graduate degrees in allied health science (Master of Science at the University of Connecticut) and a doctorate in applied physiology/motor control at Georgia Tech. As an educator and scientist, he was awarded 34 research and development grants, produced 24 peer-reviewed publications, received nearly a dozen national educator excellence awards, developed 101 courses, and taught 51 courses. He is now applying what he has learned in his research and teaching experience to advance health professions education through course instruction and development of simulation-based training for O&P clinical skills reinforcement and competency assessment. He can be reached at chris.hovorka@bcm.edu.

Acknowledgement

The author acknowledges Juan Guzman, business operations coordinator, Baylor College of Medicine Orthotics & Prosthetics, who was instrumental in the photo and video capture and editing for this article and more material that will be used in a simulation-based training program. The program, currently in development, will instruct learners on clinical methods using the amputated limb simulator that are performed in an effective and reproducible manner.

References

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