Catalyzing Clinically Driven Undergraduate Design Projects at the Nexus of Engineering, Medicine, and Business.

Design projects, particularly those related to assistive technology, offer unparalleled educational opportunities for undergraduate students to synthesize engineering knowledge with a clinically driven need to produce a product that can improve quality of life. Such projects are most effective when engineering, clinical, and business perspectives are considered throughout. However, the logistics of successfully implementing such interdisciplinary projects can be challenging. This paper presents an auto-ethnography of 12 undergraduate design team projects in assistive technology performed by 87 students from five majors (including engineering, business, and clinical students) over the course of 5 years. The overarching goal of our work was to establish an undergraduate integrated design experience at a university in the absence of a dedicated biomedical engineering major. The focus of this experience was to foster the creation of student-led prototypes to address real-world problems for people with disabilities while keeping commercialization potential at the forefront throughout. Student participation demonstrated a clear enthusiasm for completing biomedical engineering-themed projects. To encourage the implementation of similar approaches at universities where a biomedical engineering major does not exist, we identify common obstacles that can arise and present strategies for mitigating these challenges, as well as effective approaches for catalyzing cross-disciplinary collaborations. High impact practices include close involvement of end-users in the design process; cross-disciplinary team composition (e.g., engineering, business, and health sciences students); and choosing cross-disciplinary leads for project management. Teams experienced a high degree of success with all 12 teams producing functional prototypes. We conclude that at universities that do not offer a biomedical engineering major, health-focused integrated design experiences offer students important interdisciplinary perspectives, including a holistic approach to project implementation. Furthermore, for many students, these projects ultimately served as a gateway to subsequent careers and graduate study in biomedical engineering.

Bridging the Gap: Science and Technology Policy in the (Bio)Engineering Classroom.

Engineers and scientists have a key role to play in the creation and implementation of government policy. Policymakers need access to the technical expertise that is critical to our national progress and security; however, this need is often overlooked by engineering students, faculty, and professionals. Even though a substantial fraction of scientists and engineers end up pursuing jobs in government, engineering curricula do not usually provide any background in policy and for many, the policy-making process remains a black box. The good news is that there are some simple ways to make it more accessible and to encourage increased involvement. In this paper, we provide a brief overview of the federal policy-making process and present a collection of classroom learning activities that link policy-making and implementation to science and engineering. These can easily be added to existing courses without wholesale curricular changes. We also suggest professional development activities for engineers at all stages of their careers and discuss ways for engineers to become involved in the policy process. Introducing learning and career development activities focused on science and engineering policy will better prepare engineers to provide needed technical expertise to policymakers. It may also encourage engineers to consider careers in local, state, and federal government.

Bad to the Bone: Multifaceted Enrichment of Open-Ended Biomechanics Class Projects.

Equipping engineering students for career success requires more than technical proficiency; mindset and contextual interpretation also matter. Entrepreneurial mindset learning (EML) is one framework that faculty can use to systematically enrich course projects to encourage development of these important career skills. We present the thought process behind enriching two biomechanics class projects to foster both the entrepreneurial mindset and the technical proficiency in undergraduate engineering students. One project required students to analyze a court case surrounding vertebral fracture in an elderly woman diagnosed one year after a fall in an elevator. In addition to technical analysis, students had to make a recommendation about the likelihood that the injury occurred due to the fall, and contextualize the results within economic and societal terms-how much should the plaintiff sue for and how could such injuries be prevented through design and regulation? The second project asked students to evaluate cervine cancellous bone as a suitable laboratory model for biomechanics research. In addition to technical analysis, students considered the value of cervine vertebrae as a laboratory model within the context of societal and economic benefits of ex vivo animal models, including the relevant policy and regulatory issues. In both projects, implemented at different institutions with similar student demographics, students performed well and enjoyed the "real-world" nature of the projects, despite their frustrations with the open-ended nature of the questions posed. These and other similar projects can be further enhanced to foster the entrepreneurial mindset in undergraduate engineering students without undue burden on the instructor.

Proteoglycans contribute locally to swelling, but globally to compressive mechanics, in intact cervine medial meniscus.

Loss of charged proteoglycans in the knee meniscus, which aid in the support of compressive loads by entraining water, is an effect of degeneration and is often associated with osteoarthritis. In healthy menisci, proteoglycan content is highest in the inner white zone and decreases towards the peripheral red zone. We hypothesized that loss of proteoglycans would reduce both osmotic swelling and compressive stiffness, spatially localized to the avascular white zone of the meniscus. This hypothesis was tested by targeted enzymatic digestion of proteoglycans using hyaluronidase in intact cervine medial menisci. Mechanics were quantified by creep indentation on the femoral surface. Osmotic swelling changes were assessed by measuring collagen fiber crimp period in the radial-axial plane in the lamellar layer along both the tibial and femoral contacting surfaces. All measurements were made in the inner, middle, and outer zones of the anterior, central, and posterior regions. Mechanical measurements showed variation in creep behavior with anatomical location, along with spatially uniform decreases in viscosity (average of 21%) and creep stiffness (average of 15%) with hyaluronidase treatment. Lamellar collagen crimp period was significantly decreased (average of 27%) by hyaluronidase, indicating a decrease in osmotic swelling, with the largest decreases seen in locations with the highest proteoglycan content. Taken together, these results suggest that while proteoglycans have localized effects on meniscus swelling, the resulting effect on compressive properties is distributed throughout the tissue.

Increased lumbar spinal column laxity due to low-angle, low-load cyclic flexion may predispose to acute injury.

Lumbar spinal column laxity contributes to instability, increasing the risk of low back injury and pain. Until the laxity increase due to the cyclic loads of daily living can be quantified, the associated injury risk cannot be predicted clinically. This work cyclically loaded 5-vertebra lumbar motion segments (7 skeletally-mature cervine specimens, 5 osteoporotic human cadaver specimens) for 20 000 cycles of low-load low-angle (15°) flexion. The normalized neutral zone lengths and slopes of the load-displacement hysteresis loops showed a similar increase in spinal column laxity across species. The intervertebral kinematics also changes with cyclic loading. Differences in the location and magnitude of surface strain on the vertebral bodies (0.34% ± 0.11% in the cervine specimens, and 3.13% ± 1.69% in the human cadaver specimens) are consistent with expected fracture modes in these populations. Together, these results provide biomechanical evidence of spinal column damage during high-cycle low-load low-angle loading.

White-Tailed Deer as an Ex Vivo Knee Model: Joint Morphometry and ACL Rupture Strength.

Animal joints are valuable proxies for those of humans in biomechanical studies, however commonly used quadruped knees differ greatly from human knees in scale and morphometry. To test the suitability of the cervine stifle joint (deer knee) as a laboratory model, gross morphometry, ACL cross section, and ACL rupture strength were measured and compared to values previously reported for the knees of humans and commonly studied animals. Twelve knee joints from wild white-tailed deer were tested. Several morphometry parameters, including bicondylar width (53.5 ± 3.0 mm) and notch width (14.7 ± 2.5 mm), showed a high degree of similarity to those of the human knee, while both medial (16.7 ± 2.1°) and lateral (17.6 ± 4.7°) tibial slopes were steeper than in humans but less steep than other quadrupeds. The median ACL rupture force (2054 N, 95% CI 2017-2256 N), mean stiffness (260 ± 166 N/mm), mean length (33 ± 7 mm), and mean cross sectional area (44.8 ± 18.3 mm2) were also comparable to previously reported values for human knees. In our limited sample size, no significant sexual dimorphism in strength or morphometry was observed (p ≥ 0.05 for all parameters), though female specimens generally had steeper tibial slopes (lateral: p = 0.52, medial: p = 0.07). Our results suggest that the deer knee may be a suitable model for ex vivo studies of ACL rupture and repair.

Pain Management After Total Joint Arthroplasty.

Controlling pain after total joint arthroplasty (TJA) is critical to minimizing complications, decreasing costs, and expediting patients' return to function. We implemented a TJA multimodal pain management protocol at a Level III trauma center in a small, rural community in New York. We retrospectively reviewed 266 patient charts and collected patient demographics, pain management information, and discharge data. Our primary goals were to quantify the total number of narcotic medication doses used and length of hospital stay. The multimodal pain management protocol significantly reduced the number of narcotic doses used (P < .01). Hospital length of stay decreased slightly; although not statistically significant (P = .25), this may be clinically significant. Gender, age, and type of arthroplasty (ie, knee, hip) were not significant factors. A multimodal approach to pain management after TJA can reduce narcotic use and hospital length of stay, thereby also reducing the incidence of side effects from narcotics.

Ring apophysis fractures induced by low-load low-angle repetitive flexion in an ex-vivo cervine model.

Ring apophysis fractures of the spine occur in physically-active adolescents causing low back pain and the potential for chronic pain. Many of these fractures occur without memorable trauma, suggesting that the fractures occur during everyday movements and activities. The benign nature of this poorly understood potential mechanism of injury hampers appropriate diagnosis and early treatment. The purpose of this study was to establish an ex-vivo model of ring apophysis fracture and demonstrate that these fractures can be initiated by repetitive non-traumatic loading. Six 5-vertebra cervine lumbar (L1-L5) motion segments were cyclically loaded in low-angle low-load flexion (to 15° flexion, with peak load of 230±50N), a representative movement component of daily activities for both human and deer lumbar spines. Pinned end conditions replicated physiologically realistic loading. Ring apophysis fractures were created under low-load low-angle conditions in healthy vertebrae of similar bone mineral density and a similar degree of skeletal maturity to adolescent humans. All specimens developed ring apophysis fractures, some as early as 1400 cycles. The load-displacement data, and hysteresis loops during the cyclic loading, suggest that the fractures occurred gradually, i.e., without trauma. The ease at which these fractures were created suggests that ring apophysis fractures may be more prevalent than current diagnosis rates. Therefore, clinically, healthcare providers should include the potential for ring apophysis fracture in the differential diagnosis of all physically-active adolescents who present with back pain.

Classroom Journal Club: Collaborative Study of Contemporary Primary Literature in the Biomechanics Classroom.

Current engineering pedagogy primarily focuses on developing technical proficiency and problem solving skills; the peer-review process for sharing new research results is often overlooked. The use of a collaborative classroom journal club can engage students with the excitement of scientific discovery and the process of dissemination of research results, which are also important lifelong learning skills. In this work, a classroom journal club was implemented and a survey of student perceptions spanning three student cohorts was collected. In this collaborative learning activity, students regularly chose and discussed a recent biomechanics journal article, and were assessed based on specific, individual preparation tasks. Most student-chosen journal articles were relevant to topics discussed in the regular class lecture. Surveys assessed student perceptions of the activity. The survey responses show that, across all cohorts, students both enjoyed the classroom journal club and recognized it as an important learning experience. Many reported discussing their journal articles with others outside of the classroom, indicating good engagement. The results demonstrate that student engagement with primary literature can foster both technical knowledge and lifelong learning skills.

The Odocoileus virginianus Femur: Mechanical Behavior and Morphology.

Biomechanical research relies heavily on laboratory evaluation and testing with osseous animal structures. While many femora models are currently in use, including those of the European red deer (Cervus elaphus), the Odocoileus virginianus femur remains undocumented, despite its regional abundance in North America. The objective of this study was to compare biomechanical and morphological properties of the Odocoileus virginianus femur with those of the human and commonly used animal models. Sixteen pairs of fresh-frozen cervine femora (10 male, 6 female, aged 2.1 ± 0.9 years) were used for this study. Axial and torsional stiffnesses (whole bone) were calculated following compression and torsion to failure tests (at rates of 0.1 mm/sec and 0.2°/sec). Lengths, angles, femoral head diameter and position, periosteal and endosteal diaphyseal dimensions, and condylar dimensions were measured. The results show that the cervine femur is closer in length, axial and torsional stiffness, torsional strength, and overall morphology to the human femur than many other commonly used animal femora models; additional morphological measurements are comparable to many other species' femora. The distal bicondylar width of 59.3mm suggests that cervine femora may be excellent models for use in total knee replacement simulations. Furthermore, the cervine femoral head is more ovoid than other commonly-used models for hip research, making it a more suitable model for studies of hip implants. Thus, with further, more application-specific investigations, the cervine femur could be a suitable model for biomechanical research, including the study of ballistic injuries and orthopaedic device development.

Winning the war on surgical site infection: evidence-based preoperative interventions for total joint arthroplasty.

Postoperative surgical site infections (SSIs) are the most common cause of expensive and debilitating revision surgeries. The Institute for Healthcare Improvement has introduced a three-intervention package, titled Project JOINTS, which attempts to control preoperative and perioperative factors contributing to postoperative SSI in patients undergoing total joint arthroplasty (TJA). The three interventions are preoperative screening for Staphylococcus aureus, decolonizing the skin and nares, and intraoperative administration of combined antimicrobial and alcohol agents to the skin. Canton-Potsdam Hospital was an early adopter of the Project JOINTS protocol, and this quality improvement project has demonstrated a reduced SSI rate throughout the two years of implementation. Before implementation, 596 TJAs were performed with an S aureus SSI rate of 1.8%. During Project JOINTS, 305 TJAs were conducted with a significantly (P = .050) lower S aureus SSI rate of 0.66%. Thus, Project JOINTS is effective at reducing the postoperative incidence of S aureus SSIs in patients undergoing TJA.

Unique model evokes the supination/pronation deficits found after Mason II fractures.

A rapid prototyping model of Mason II fracture was used to investigate baseline recommendations for surgical intervention founded on kinematic forearm rotational blockage. Exact replicas of the radial heads in nine cadaveric specimens were produced and specimens were tested in a physiologic elbow simulator. After testing supination/pronation, the rotations were repeated with native replicas and with replicas modeling 3 mm depressed Mason II fractures with and without a gap of 1 mm between the body and fragment. The fragments were located circumferentially around the radial head at 10, 2 and 6 o'clock positions. There was no statistical difference between the range of motion of the native case and the native replica without fracture. After inclusion of the fracture, seven of the nine specimens showed rotational blockages. A two-way ANOVA found no statistical difference due to type of Mason II fracture (p > 0.87) or fracture location (p > 0.27). A χ-square analysis showed that presence of a kinematic deficit with a fractured radial head was significant (p < 0.03). The results support continued surgical intervention for a 3 mm depressed fracture and also establish the use of the rapid prototype as a model for kinematic investigation of fractures in a cadaveric model when ligamentous attachments are preserved.

Cervine tibia morphology and mechanical strength: a suitable tibia model?

Animal models for orthopaedic implant testing are well-established but morphologically dissimilar to human tibiae; notably, most are shorter. The purpose of this study was to quantitatively evaluate the morphology and mechanical properties of the cervine tibia, particularly with regard to its suitability for testing orthopaedic implants. Two endosteal and eleven periosteal measurements were made on 15 cervine tibiae. The mechanical strength in axial compression and torsion was measured using 11 tibiae. The cervine tibia is morphologically similar to the human tibia and more closely matches the length of the human tibia than current tibia models (ovine, porcine, and caprine). The distal epiphysis dimensions are notably different, but no more so than the current tibia models. The torsional stiffness of the cervine tibia is within the range of previously reported values for human tibiae. Furthermore, in many regions, cervine tibiae are abundant and locally available at a low cost. Given these mechanical and morphological data, coupled with potential cost savings if regionally available, the cervine tibia may be an appropriate model for orthopaedic implant testing.

Cyclic cryopreservation affects the nanoscale material properties of trabecular bone.

Tissues such as bone are often stored via freezing, or cryopreservation. During an experimental protocol, bone may be frozen and thawed a number of times. For whole bone, the mechanical properties (strength and modulus) do not significantly change throughout five freeze-thaw cycles. Material properties at the trabecular and lamellar scales are distinct from whole bone properties, thus the impact of freeze-thaw cycling at this scale is unknown. To address this, the effect of repeated freezing on viscoelastic material properties of trabecular bone was quantified via dynamic nanoindentation. Vertebrae from five cervine spines (1.5-year-old, male) were semi-randomly assigned, three-to-a-cycle, to 0-10 freeze-thaw cycles. After freeze-thaw cycling, the vertebrae were dissected, prepared and tested. ANOVA (factors cycle, frequency, and donor) on storage modulus, loss modulus, and loss tangent, were conducted. Results revealed significant changes between cycles for all material properties for most cycles, no significant difference across most of the dynamic range, and significant differences between some donors. Regression analysis showed a moderate positive correlation between cycles and material property for loss modulus and loss tangent, and weak negative correlation for storage modulus, all correlations were significant. These results indicate that not only is elasticity unpredictably altered, but also that damping and viscoelasticity tend to increase with additional freeze-thaw cycling.

Creating physiologically realistic vertebral fractures in a cervine model.

Approximately 50% of women and 25% of men will have an osteoporosis-related fracture after the age of 50, yet the micromechanical origin of these fractures remains unclear. Preventing these fractures requires an understanding of compression fracture formation in vertebral cancellous bone. The immediate research goal was to create clinically relevant (midvertebral body and endplate) fractures in three-vertebrae motion segments subject to physiologically realistic compressional loading conditions. Six three-vertebrae motion segments (five cervine, one cadaver) were potted to ensure physiologic alignment with the compressive load. A 3D microcomputed tomography (microCT) image of each motion segment was generated. The motion segments were then preconditioned and monotonically compressed until failure, as identified by a notable load drop (48-66% of peak load in this study). A second microCT image was then generated. These three-dimensional images of the cancellous bone structure were inspected after loading to qualitatively identify fracture location and type. The microCT images show that the trabeculae in the cervine specimens are oriented similarly to those in the cadaver specimen. In the cervine specimens, the peak load prior to failure is highest for the L4-L6 motion segment, and decreases for each cranially adjacent motion segment. Three motion segments formed endplate fractures and three formed midvertebral body fractures; these two fracture types correspond to clinically observed fracture modes. Examination of normalized-load versus normalized-displacement curves suggests that the size (e.g., cross-sectional area) of a vertebra is not the only factor in the mechanical response in healthy vertebral specimens. Furthermore, these normalized-load versus normalized-displacement data appear to be grouped by the fracture type. Taken together, these results show that (1) the loading protocol creates fractures that appear physiologically realistic in vertebrae, (2) cervine vertebrae fracture similarly to the cadaver specimen under these loading conditions, and (3) that the prefracture load response may predict the impending fracture mode under the loading conditions used in this study.

Dependence of elbow joint stiffness measurements on speed, angle, and muscle contraction level.

Elbow joint stiffness is critical to positioning the hand. Abnormal elbow joint stiffness may affect a person's ability to participate in activities of daily living. In this work, elbow joint stiffness was measured in ten healthy young adults with a device adapted from one previously used to measure stiffness in other joints. Measurements of elbow stiffness involved applying a constant-velocity rotational movement to the elbow and measuring the resultant displacement, torque, and acceleration. Elbow stiffness was then computed using a previously-established model for joint stiffness. Measurements were made at two unique elbow joint angles, two speeds, and two forearm muscle contraction levels. The results indicate that the elbow joint stiffness is significantly affected by both rotational speed and forearm muscle contraction level.

Subsidence in two uncemented femoral stems: an in vitro study.

Many aspects of the performance of different implant designs remain as open questions in total hip arthroplasty. Despite the increased survivorship of each hip replacement, the amount of bone removed during surgery remains an important factor because of the potential need for revision surgery. Given that a smaller implant will have less surface area over which to transfer load, constructs that preserve more bone stock may be susceptible to mechanical complications related to the fixation of the implant in the femur. To assess mechanical fixation, this study compared the fiber metal taper and Mayo conservative hip stems in subsidence, frontal plane rotation and failure load. After dual-energy x-ray absorptiometry scans, pairs of cadaveric femurs received implants of each type and were loaded for 10,000 cycles. The subsidence and rotation were measured. Finally, specimens were loaded to failure. The subsidence and rotation after cyclic loading were -0.73 mm and 0.1°, respectively, for the Mayo implants and -0.87 and 0.52°, respectively, for the fiber metal taper implants, but no significant differences between implant types were found. There was also no significant relationship to bone mineral density. A power analysis revealed that 914 specimens would have been required to achieve a power of 0.8.

A continuous method to compute model parameters for soft biological materials.

Developing appropriate mathematical models for biological soft tissues such as ligaments, tendons, and menisci is challenging. Stress-strain behavior of these tissues is known to be continuous and characterized by an exponential toe region followed by a linear elastic region. The conventional curve-fitting technique applies a linear curve to the elastic region followed by a separate exponential curve to the toe region. However, this technique does not enforce continuity at the transition between the two regions leading to inaccuracies in the material model. In this work, a Continuous Method is developed to fit both the exponential and linear regions simultaneously, which ensures continuity between regions. Using both methods, three cases were evaluated: idealized data generated mathematically, noisy idealized data produced by adding random noise to the idealized data, and measured data obtained experimentally. In all three cases, the Continuous Method performed superiorly to the conventional technique, producing smaller errors between the model and data and also eliminating discontinuities at the transition between regions. Improved material models may lead to better predictions of nonlinear biological tissues' behavior resulting in improved the accuracy for a large array of models and computational analyses used to predict clinical outcomes.

Effects of camera switching on fine accuracy in a motion capture system.

When using optical motion capture systems, increasing the number of cameras improves the visibility. However, the software used to deal with the information fusion from multiple cameras may compromise the accuracy of the system due to camera dropout, which can vary with time. In cadaver studies of radial head motion, increasing the number of cameras used by the motion capture system seemed to decrease the accuracy of the measurements. This study investigates the cause. The hypothesis was that errors in position can be induced when markers are obscured from and then restored to a camera's viewable range, as can happen in biomechanical studies. Accuracy studies quantified the capabilities of the motion capture system with precision translation and rotation movements. To illustrate the effect that abrupt perceived changes in a marker's position can have on the calculation of radial head travel, simulated motion experiments were performed. In these studies, random noise was added to simulated data, which obscured the resultant path of motion. Finally, camera-blocking experiments were performed in which precise movements were measured with a six-camera Vicon system and the errors between the actual and perceived motion were computed. During measurement, cameras were selectively blocked and restored to view. The maximum errors in translation and rotation were 3.7 mm and 0.837 deg, respectively. Repeated measures analysis of variance (ANOVAs) (alpha=0.05) confirmed that the camera-blocking influenced the results. Taken together, these results indicate that camera-switching can affect the observation of fine movements using a motion analysis system with a large number of cameras. One solution is to offer opportunity for user interaction in the software to choose the cameras used for each instant of time.

Proprioception after total ankle arthroplasty.

BACKGROUND: Total ankle arthroplasty (TAA) is becoming an effective treatment for end-stage ankle arthritis. It is unknown if TAA alters the patient's ability to sense ankle joint position. MATERIALS AND METHODS: Thirteen unilateral TAA patients with a minimum of 2-years followup completed proprioceptive testing of the TAA and the contralateral side. The task was to reproduce a given ankle angle using a joystick-driven device while the lower limb was obscured from view. Nine angles were tested, including two angles in dorsiflexion, three in plantarflexion, two in inversion, and two in eversion. A repeated-measures ANOVA was used to evaluate the results. RESULTS: No statistically significant differences between the TAA ankle and the contralateral side were found. CONCLUSION: TAA does not cause a change in proprioceptive abilities in arthritis patients when compared to the contralateral, unaffected side in a small sample of unilateral patients. Surgeons and rehabilitation professionals may use this information when designing rehabilitation plans following the insertion of a TAA.