Mechanical Characterization of Fourth Generation Composite Humerus

Mechanical data on upper extremity surrogate bones, supporting use as biomechanical tools, is limited. The objective of this study was to characterize the structural behaviour of the fourth-generation composite humerus under simulated physiologic bending, specifically, stiffness, rigidity, and mid-diaphysial surface strains. Three humeri were tested in four-point bending, in anatomically defined anteroposterior (AP) and mediolateral (ML) planes. Stiffness and rigidity were derived using load–displacement data. Principal strains were determined at the anterior, posterior, medial, and lateral surfaces in the humeral mid-diaphysial transverse plane of one specimen using stacked rosettes. Linear structural behaviour was observed within the test range. Average stiffness and rigidity were greater in the ML (918 ± 18 N/mm; 98.4 ± 1.9 Nm2) than the AP plane (833 ± 16 N/mm; 89.3 ± 1.6 Nm2), with little inter-specimen variability. The ML/AP rigidity ratio was 1.1. Surface principal strains were similar at the anterior (5.41 µε/N) and posterior (5.43 µε/N) gauges for AP bending, and comparatively less for ML bending, i.e. 5.1 and 4.5 µε/N, at the medial and lateral gauges, respectively. This study provides novel strain and stiffness data for the fourth-generation composite humerus and also adds to published construct rigidity data. The presented results support the use of this composite bone as a tool for modelling and experimentation

The role of eye tracking technology in assessing older driver safety

A growing body of literature is focused on the use of eye tracking (ET) technology to understand the association between objective visual parameters and higher order brain processes such as cognition. One of the settings where this principle has found practical utility is in the area of driving safety. METHODS: We reviewed the literature to identify the changes in ET parameters with older adults and neurodegenerative disease. RESULTS: This narrative review provides a brief overview of oculomotor system anatomy and physiology, defines common eye movements and tracking variables that are typically studied, explains the most common methods of eye tracking measurements during driving in simulation and in naturalistic settings, and examines the association of impairment in ET parameters with advanced age and neurodegenerative disease. CONCLUSION: ET technology is becoming less expensive, more portable, easier to use, and readily applicable in a variety of clinical settings. Older adults and especially those with neurodegenerative disease may have impairments in visual search parameters, placing them at risk for motor vehicle crashes. Advanced driver assessment systems are becoming more ubiquitous in newer cars and may significantly reduce crashes related to impaired visual search, distraction, and/or fatigue

Hand transplants, daily functioning, and the human capacity for limb regeneration

Unlike some of our invertebrate and vertebrate cousins with the capacity to regenerate limbs after traumatic loss, humans do not have the ability to regrow arms or legs lost to injury or disease. For the millions of people worldwide who have lost a limb after birth, the primary route to regaining function and minimizing future complications i

Socioecological model-based design and implementation principles of Lower Limb Preservation Programs as partners for Limb-loss Rehabilitation Programs- A mini-review

People with lower limb loss, especially of dysvascular etiology, are at substantial risk for both ipsilateral and contralateral reamputation. Additionally, while not as well documented for reamputation, there is recognition that amputation incidence is influenced by not only sociodemographic factors such as sex, race, socioeconomic status, but also by system factors such as service access. A systems strategy to address this disparity within the field of limb-loss rehabilitation is for Limb-loss Rehabilitation Programs (LRP) to partner with medical specialists, mental health professionals, and Limb Preservation Programs (LPP) to provide comprehensive limb care. While LPPs exist around the nation, design principles for such programs and their partnership role with LRPs are not well established. Using a socioecological model to incorporate hierarchical stakeholder perspectives inherent in the multidisciplinary field of limb care, this review synthesizes the latest evidence to focus on LPP design and implementation principles that can help policymakers, healthcare organizations and limb-loss rehabilitation and limb-preservation professionals to develop, implement, and sustain robust LPP programs in partnership with LRPs

Implications of Arm Restraint on Lower Extremity Kinetics During Gait

Background Literature indicates the importance of the upper extremities in providing stability and propulsion for the body during ambulation. However, the kinetic implications of upper extremity restraint during gait are not as well documented. Aim The objective of this study was to examine the effect of arm restraint (unilateral and bilateral) on lower extremity joint kinetics during walking. Methods Twenty-three healthy young participants were instrumented for three dimensional motion analysis, and tested in four randomly ordered upper extremity restraint conditions (unrestrained, bilateral restraint, right side restraint, and left side restraint). Temporal spatial parameters and gait/phase-specific lower extremity kinetics and kinematics were measured. For each restraint condition, pointwise differences from the unrestrained condition were compared using a two-way ANOVA model of restraint condition (“Condition”) and gait cycle phase (“Timing”). Results Decreases in walking speed and stride length were observed for all restraint conditions. Differences in kinetic demands were also noted, primarily at the hip and knee. Conclusion Upper extremity restraint in healthy young adults leads to significant changes in temporal-spatial parameters and proximal joint kinetics, most prominently during periods of load accommodation and balance

Quantitative biomechanical evaluation of upper extremity-strain behavior of the humerus diaphysis under loading

While mechanical behavior of the adult human lower extremity long bones under loading has been studied extensively, the same is not true for the adult human humerus. Mechanical data reported for cadaveric humeri and anatomic humerus models are limited to stiffness and rigidity. Strain characteristics of the humerus diaphysis as a function of loading provide a valuable addition to the currently limited knowledge. The objective of this dissertation was to accomplish this goal, using numerical/finite element (FE) methods applied to a standard anatomic humerus model (Reference-Humerus) that was developed from the NIH Visible Human Project for this purpose. Four phases were defined, namely, (a) experimental strain (and stiffness and rigidity) characterization of structural properties of an existing humerus model, HS4 (Model 3404, Pacific Research Labs, USA), in four-point bending (under physiologic magnitude loads), (b) anatomic characterization of the Reference-Humerus model, and (c) development and experimental (four-point bending) validation of an FE model of the Reference-Humerus (under physiologic magnitude loads), followed by (d) study of strain characteristics of the humerus diaphysis under simplified physiologic loading, modeled using Deltoid and Supraspinatus action during shoulder abduction. (a) The HS4 demonstrated linear mechanical behavior under physiologic magnitude loads. The bending stiffness, rigidity, and mean principal strain data pointed to a stiffer medio-lateral plane compared with the antero-posterior plane for this specimen. (b) The Reference-Humerus's measured osteoanatomic characteristics lay near/within respective ranges for cadaveric humeri, thus establishing anatomic validity. (c) Experimental validation of the Reference-Humerus FE model that incorporated the cortex-simulation material's experimentally-derived elastic modulus range established its validity for biomechanical applications. (d) Reference-Humerus FE modeling of simplified physiologic loading demonstrated changes in maximum and minimum principal strain magnitudes and distribution in the humerus diaphysis as a function of shoulder abduction, external load, and Supraspinatus weakness. This dissertation provides novel insight into strain behavior of the humerus under loading as well as its surgical osteoanatomic characteristics. In addition, the anatomically characterized Reference-Humerus developed as part of this dissertation is a biomechanical tool with future biomechanical and research applications such as humeral fracture risk evaluation in musculoskeletal pathology, presurgical planning/surgical simulation, and implant design

The state of pulmonary rehabilitation in latin america during the COVID-19 pandemic

Background: In December 2019, China reported a severe upper respiratory failure syndrome caused by a new virus identified as coronavirus COVID-19. Aims and Objectives: The aim of this exploratory study is to outline the current state of pulmonary rehabilitation in Latin American (LA) countries during the COVID-19 pandemic. Materials and Methods: A total of 1162 rehabilitation professionals (rehabilitation medicine specialists and residents, physiotherapists, occupational therapists, and speech therapists) from 20 countries in LA answered a 34-question online survey related to the current state of pulmonary rehabilitation in LA during the COVID-19 pandemic. Results: More than half of the professionals reported the absence of pulmonary rehabilitation services in their work centers, limited or non-existent pulmonary rehabilitation materials or equipment, and little or no training by their multidisciplinary team and themselves. Regarding COVID-19, 49.2% of the respondents indicated not receiving the necessary material for the protection against COVID-19, and more than half reported limited equipment to perform interventions in patients hospitalized by this disease, and not to have clear about the recommendations to prescribe pulmonary physiotherapy in these patients. Moreover, almost all the professionals did not feel capable of treating patients with lung disease from COVID-19 and felt anxiety doing it. Conclusion: Pulmonary rehabilitation is vital for providing optimal care for respiratory impairments, and this relationship has been magnified by the COVID-19 pandemic. This manuscript highlights the limited professional training and resource availability in LA and provides recommendations to improve the current situation