Prosthetic Limb Attachment via Electromagnetic Attraction through a Closed Skin Envelope.

OBJECTIVE: Current socket-based methods of prosthetic limb attachment are responsible for many of the dominant problems reported by persons with amputation. In this work, we introduce a new paradigm for attachment via electromagnetic attraction between a bone-anchored ferromagnetic implant and an external electromagnet. Our objective was to develop a design framework for electromagnetic attachment, and to evaluate this framework in the context of transfemoral amputation. METHODS: We first used inverse dynamics to calculate the forces required to suspend a knee-ankle-foot prosthesis during gait. We then conducted cadaveric dissections to inform implant geometry and design a surgical methodology for covering the implant. We also developed an in silico framework to investigate how electromagnet design affects system performance. Simulations were validated against benchtop testing of a custom-built electromagnet. RESULTS: The physical electromagnet matched simulations, with a root-mean-square percentage error of 4.2% between measured and predicted forces. Using this electromagnet, we estimate that suspension of a prosthesis during gait would require 33 W of average power. After 200 and 1000 steps of simulated walking, the temperature at the skin would increase 2.3℃ and 15.4℃ relative to ambient, respectively. CONCLUSION: Our design framework produced an implant and electromagnet that could feasibly suspend a knee-ankle-foot prosthesis during short walking bouts. Future work will focus on optimization of this system to reduce heating during longer bouts. SIGNIFICANCE: This work demonstrates the initial feasibility of an electromagnetic prosthetic attachment paradigm that has the potential to increase comfort and improve residual limb health for persons with amputation.

Advancing Family Presence Policies and Practices in the Canadian Health and Care Context: COVID-19 and Beyond.

With the onset of the COVID-19 pandemic, restrictive visitor policies have curtailed the ability of family caregivers to be present to partner in the care of loved ones. Building on the success of the "Better Together" campaign, Healthcare Excellence Canada - the newly amalgamated organization of the Canadian Foundation for Healthcare Improvement and the Canadian Patient Safety Institute - has co-developed policy guidance and "Essential Together" programming that recognizes the significant role of essential care partners. This work aims to support the safe reintegration of essential care partners into health and care organizations across Canada during the pandemic and beyond.

Molecular underpinnings of integrin binding to collagen-mimetic peptides containing vascular Ehlers-Danlos syndrome-associated substitutions.

Collagens carry out critical extracellular matrix (ECM) functions by interacting with numerous cell receptors and ECM components. Single glycine substitutions in collagen III, which predominates in vascular walls, result in vascular Ehlers-Danlos syndrome (vEDS), leading to arterial, uterine, and intestinal rupture and an average life expectancy of <50 years. Collagen interactions with integrin α2ß1 are vital for platelet adhesion and activation; however, how these interactions are impacted by vEDS-associated mutations and by specific amino acid substitutions is unclear. Here, we designed collagen-mimetic peptides (CMPs) with previously reported Gly → Xaa (Xaa = Ala, Arg, or Val) vEDS substitutions within a high-affinity integrin α2ß1-binding motif, GROGER. We used these peptides to investigate, at atomic-level resolution, how these amino acid substitutions affect the collagen III-integrin α2ß1 interaction. Using a multitiered approach combining biological adhesion assays, CD, NMR, and molecular dynamics (MD) simulations, we found that these substitutions differentially impede human mesenchymal stem cell spreading and integrin α2-inserted (α2I) domain binding to the CMPs and were associated with triple-helix destabilization. Although an Ala substitution locally destabilized hydrogen bonding and enhanced mobility, it did not significantly reduce the CMP-integrin interactions. MD simulations suggested that bulkier Gly → Xaa substitutions differentially disrupt the CMP-α2I interaction. The Gly → Arg substitution destabilized CMP-α2I side-chain interactions, and the Gly → Val change broke the essential Mg2+ coordination. The relationship between the loss of functional binding and the type of vEDS substitution provides a foundation for developing potential therapies for managing collagen disorders.