Unilateral below-knee amputees commonly experience asymmetrical gait patterns and develop comorbidities in their intact (non-amputated) and residual (amputated) legs, with the mechanisms leading to these asymmetries and comorbidities being poorly understood. Prosthetic feet have been designed in an attempt to minimize walking asymmetries by utilizing elastic energy storage and return (ESAR) to help provide body support, forward propulsion and leg swing initiation. However, identifying the influence of walking speed and prosthetic foot stiffness on amputee gait mechanics is needed to develop evidence-based rationale for prosthetic foot selection and treatment of comorbidities. In this research, experimental and modeling studies were performed to identify the influence of walking speed and prosthetic foot stiffness on amputee walking mechanics. The results showed that when asymptomatic and relatively new amputees walk using clinically prescribed prosthetic feet across a wide range of speeds, loading asymmetries exist between the intact and residual knees. However, knee intersegmental joint force and moment quantities in both legs were not higher compared to non-amputees, suggesting that increased knee loads leading to joint disorders may develop in response to prolonged prosthesis usage or the onset of joint pathology over time. In addition, the results showed that decreasing ESAR foot stiffness can increase prosthesis range of motion, mid-stance energy storage, and late-stance energy return. However, the prosthetic foot contributions to forward propulsion and swing initiation were limited due to muscle compensations needed to provide body support and forward propulsion in the absence of residual leg ankle muscles. A study was also performed that integrated design optimization with forward dynamics simulations of amputee walking to identify the optimal prosthetic foot stiffness that minimized metabolic cost and intact knee joint forces. The optimal stiffness profile stiffened the toe and mid-foot while making the ankle less stiff, which decreased the intact knee joint force during mid-stance while reducing the overall metabolic cost of walking. These studies have provided new insight into the relationships between prosthetic foot stiffness and amputee walking mechanics, which provides biomechanics-based rationale for prosthetic foot prescription that can lead to improved amputee mobility and overall quality of life. / text

published_or_final_version / Orthopaedics and Traumatology / Master / Master of Medical Sciences

published_or_final_version / Zoology / Master / Master of Philosophy

Background: Low performance rate of comprehensive diabetic foot examinations (CDFEs) causing health care disparity. Objective: Increasing performance of CDFEs at Phoenix Indian Medical Center, an Indian Health Service (IHS) facility. Design: Before-after design, convenience sample. Setting: An IHS adult ambulatory care clinic in urban Phoenix, Arizona. Target: Four primary care providers (PCPs).Interventions: Utilizing the PDSA framework, a multidisciplinary group of clinical staff developed a process to increase the performance rate of CDFEs. Brainstorming, use of the Ishikawa diagram, and root cause analysis led to identification of factors contributing to low rates of CDFEs in the clinic. The QI intervention addressed multiple aspects of activities related to the CDFE performance, including pre-visit planning, enhanced communication, making equipment for CDFEs accessible to healthcare providers, and requesting patients to remove shoes and socks. Measurement: Weekly performance rate of CDFEs. Results: The results, analyzed with a run chart, showed an upward trend in performance for some providers. The median aggregate performance rates for pre and post intervention were 82.6% and 80.2%, respectively. Limitations: This study should be replicated over a longer time frame with more participants. Two significant weaknesses were identified in this study. The required provider de-identification prevented provider feedback. The data collection method provided CDFE performance data based on provider empanelment. This method of data collection reflects composite team care rather than specific provider behaviors. Conclusions: This multidisciplinary approach to improving the performance rates of CDFEs showed an upward trend for some providers but was not statistically significant. Post intervention CDFE performance rates were not improved. Significance: This study highlights the role of the doctorally prepared advanced practice nurse (DNP) in designing, facilitating and evaluating a practice change project to address the rate of provider performance of CDFE for their AI/NA patients. An exemplar, this QI intervention can be replicated for quality improvement initiatives targeting improved healthcare outcomes, crucial to the national effort of addressing healthcare disparities.

The byssal adhesion mechanism of the biofouling species Dreissena polymorpha was investigated using a combination of studies on synthetic peptide mimics of tandem repeat sequences from byssal component Dreissena polymorpha foot protein 1 (Dpfp-1) and characterization of the regions of the byssus. A 20-residue fusion peptide incorporating two Dpfp-1 repeat sequences adopts a random coil and β-turn conformation in solution, and spontaneously forms a film at the solid-liquid interface in the presence of iron (III) cations. Infrared characterization of the byssus Amide I region showed that β-sheets dominate its secondary structure, although the proportion of different secondary structures varies between regions. Matrix-assisted laser desorption ionization (MALDI) mass spectrometry of intact byssal regions identified previously unknown differences in the composition of byssal threads, plaques, and the adhesive interface, which are believed to correlate to the different roles of these components in the overall structure.

The byssal adhesion mechanism of the biofouling species Dreissena polymorpha was investigated using a combination of studies on synthetic peptide mimics of tandem repeat sequences from byssal component Dreissena polymorpha foot protein 1 (Dpfp-1) and characterization of the regions of the byssus. A 20-residue fusion peptide incorporating two Dpfp-1 repeat sequences adopts a random coil and β-turn conformation in solution, and spontaneously forms a film at the solid-liquid interface in the presence of iron (III) cations. Infrared characterization of the byssus Amide I region showed that β-sheets dominate its secondary structure, although the proportion of different secondary structures varies between regions. Matrix-assisted laser desorption ionization (MALDI) mass spectrometry of intact byssal regions identified previously unknown differences in the composition of byssal threads, plaques, and the adhesive interface, which are believed to correlate to the different roles of these components in the overall structure.

Research shows miners can be exposed to foot-transmitted vibration (FTV) when operating various pieces of underground mining equipment, and case reports suggest workers are experiencing symptoms similar to those of hand-arm vibration syndrome in their feet. A field study was conducted to measure and document FTV exposure associated with operating underground mining equipment, and probable health risks were determined based on both ISO 2631-1 (1997) for WBV and ISO 5349-1 (2004) for HAV. Seventeen participating operator’s also reported musculoskeletal discomfort. Seventeen male participants ranging between 24-61 years of age, with an average height and mass of 175.0cm and 88.2kg volunteered for the study. Seventeen pieces of equipment were tested; 1 locomotive, 1 crusher, 9 bolter drills (4 scissor platforms, 2 Maclean, 2 Boart/basket, and 1 RDH), and 6 jumbo drills. Including all seventeen pieces of underground mining equipment, the vibration acceleration ranged from 0.13-1.35m/s2 with dominant frequencies between 1.25-250Hz according to ISO 2631-1. According to ISO 5349-1 vibration acceleration ranged from 0.14-3.61m/s2 with dominant frequencies between 6.3-250Hz. Furthermore, the magnitude of FTV measured on the jumbo drills with grated platforms (#5 and #6) was less than FTV measured from the jumbo drills with, solid metal surfaces. Additionally, twelve of the seventeen equipment operators indicated a complaint of discomfort in their lower body (specifically at the level of the knee or lower). The health risk analysis based on ISO 2631-1 indicated that one operator (bolter drill #9) was exposed to vibration above the criterion value, while the health risk analysis based on ISO 5349-1 indicated iv that two operators (jumbo drill #1 and bolter drill #1) were exposed to vibration above the criterion value. Operators reported very severe or severe discomfort; however, the same operators were not the operators of the equipment with FTV exposure levels above the ISO standards, leaving evidence to suggest that the standards are not properly assessing injury risk to vibration exposure via the feet. Future research is needed to develop a standard specific for FTV and to determine the link between early musculoskeletal injury reporting and the onset of vibration white foot. To do so, a better understanding of the biodynamic response of the foot to FTV is needed. A laboratory study was conducted to 1) measure and document transmissibility of FTV from (a) floor-to-ankle (lateral malleolus), and (b) floor-to-metatarsal, during exposure to six levels of vibration (25Hz, 30Hz, 35Hz, 40Hz, 45Hz, and 50Hz) while standing, and 2) to determine whether independent variables (vibration exposure frequency, mass, arch type) influence transmissibility (dependent variable) through the foot. A two-way repeated measures analysis of variance (ANOVA) was conducted. There was a significant interaction between transmissibility location and exposure frequency (λ = 0.246, F (5,25) = 15.365, p = 0.0001). There were significant differences in mean transmissibility between the ankle and metatarsal at 40Hz [t(29) = 4.116, p = 0.00029], 45Hz [t(29) = 6.599, p = 0.00000031], and 50Hz [t(29) = 8.828, p = 0.000000001]. The greatest transmissibility at the metatarsal occurred at 50Hz and at the ankle (lateral malleolus) transmissibility was highest from 25-30Hz, indicating the formation of a local resonance at each location. v Future research should focus on identifying resonance frequencies at different locations on the feet. This information is needed to develop an exposure guideline to help protect workers from exposure to FTV, and to develop personal protective equipment capable of attenuating harmful FTV exposure frequencies.

This study describes the biomechanics of the foot and ankle during the transitional and steady state skating strides using kinematic, kinetic, and myoelectric measures. A data set for five collegiate hockey players was completed (mean +/- SD: age = 21.8 +/- 1.9 years, height = 1.81 +/- 0.05 m, mass = 83.3 +/- 8.0 kg). Three acceleration strides and a constant velocity stride were examined on ice. An electrogoniometer at the ankle was used to measure angular displacement and velocity values. Myoelectric activation patterns were measured at the vastus medialis, tibialis anterior, peroneus longus, and medial gastrocnemius of the right lower limb. Kinetic pressure profiles were measured using piezo resistive fabric sensors providing accurate pressure measurement within the narrow confines of the skate boot-to-foot/ankle interface. Sixteen flexible piezo-resistive sensors (1.2 cm x 1.8 cm x 0.2 cm thick) were taped to discrete anatomical surfaces of the plantar, dorsal, medial and lateral surface of the foot, as well as to the posterior aspect of heel and leg. Repeated measures ANOVAs and Tukey post hoc tests found few significant differences among stride variables; however insights into the mechanics of ice hockey skating at the foot and ankle are given.

Purpose: To highlight the histopathological characteristics of the skin in congenital clubfoot and correlate the clinical findings in clubfoot with the changes in the dermal layers. Materials and methods: One hundred skin specimens, from 77 infants (6 to 12 months), were studied between 2004 and 2008. Using the Pirani scoring system, the clinical severity was recorded. The mobility of the skin and the correctability of the medial ray were assessed clinically. A skin specimen (1cm x 1mm) was taken from the medial side of the foot at surgery following failed plaster treatment. The layers were studied under light microscopy. The thickness of the dermis and the histopathological features of clubfoot skin were compared with 10 normal skin specimens. Results: The dermis of clubfoot skin showed significant fibrosis with thick bundles of collagen fibres (P = .001) on Haematoxylin and Eosin staining (H&E). The dermal thickness ranged between 1.0mm and 5.2mm in clubfoot skin, compared with controls (0.64-1.28mm). Fibrosis extended into the subcutis in a septolobular fashion in 95% of the cases. Significant atrophy of eccrine glands was seen in 98% (P = .001). Hair follicles were absent in 78%. The elastic fibres of clubfoot skin, stained with Elastic van Gieson staining (EVG), showed hypertrophy in varying degrees in all skin specimens. They were fragmented, with loss of their parallel arrangement. There was no significant inflammatory reaction in the dermis. The Pirani score was significantly increased (mean 7.8). Discussion: Fibrosis and thickening of the dermis were the most significant histopathological features of the clubfoot skin. The elastic fibres were also abnormal. There was atrophy of the skin appendages due to the fibrosis. There was a strong correlation between the Pirani score and the severity of the deformity(P 0.016). The cases with poor outcome had a higher score than those with a satisfactory outcome.Lack of a significant inflammatory reaction suggests that neither the serial manipulations of the foot, nor the repeated plaster cast changes, were responsible for the dermal fibrosis, which is probably present from birth and contributes to the deformity. / Thesis (Ph.D.)-University of KwaZulu-Natal, Durban, 2012.

Foot and mouth disease (FMD) is regarded as one of the greatest biological threats to the U.S. livestock industry because of its potential to cause catastrophic economic damages and massive livestock depopulation. Current U.S. contingency plans call for "stamping out" of FMD. An integral component of a "stamping out" policy is movement restrictions. The main purpose for movement restrictions is to stop the spread of disease, but they also disrupt the agribusiness sector. Welfare slaughter, the depopulation of healthy quarantined animals, is a possibility if movement restrictions are kept in place for prolonged periods of time. Many studies have analyzed the economic consequences of alternative mitigation strategies, but generally these studies have ignored the costs that might arise because of movement restrictions affecting uninfected premises located within the quarantine zone. Ultimately this study seeks to improve preparedness in the event of a FMD outbreak. It does this by developing information for those formulating plans on the costs associated with movement restrictions regarding quarantined, uninfected large feedlots located in the Texas High Plains Region. To accomplish this objective two strategies were compared: an unrestricted feed strategy, where feed is allowed to be brought onto uninfected premises and finished cattle are sold; and a welfare slaughter strategy, where feed isn't allowed to be brought onto the uninfected premises so animals are depopulated. In addition, seasonal differences in total costs were examined. This study expanded on the High Plains Study conducted by M. Ward, L. Highfield, P. Vongseng, and M. Garner by using their epidemiological data combined with a cost accounting framework to estimate the total cost of each strategy. This study examined direct disease management costs (indemnity payments, feed costs, marketing costs, surveillance costs, cleaning and disinfecting costs, appraisal cost, euthanasia costs, and disposal costs). Overall, the unrestricted feed strategy was less expensive than the welfare slaughter strategy, costing on average $22.6 million compared to $48.5 million, respectively. Disease outbreak timing did impact the overall cost of both strategies. The results suggest the policy makers should strongly consider creating movement policies that address feed supply and finished cattle movement for uninfected large feedlots in prolonged quarantine zones; as such policies appear to reduce outbreak related costs for stakeholder and the U.S. government.