The COVID-19 pandemic is causing global morbidity and mortality, straining health systems, and disrupting society, putting individuals with Alzheimer's disease and related dementias (ADRD) at risk of significant harm. In this Special Article, we examine the current and expected impact of the pandemic on individuals with ADRD. We discuss and propose mitigation strategies for: the risk of COVID-19 infection and its associated morbidity and mortality for individuals with ADRD; the impact of COVID-19 on the diagnosis and clinical management of ADRD; consequences of societal responses to COVID-19 in different ADRD care settings; the effect of COVID-19 on caregivers and physicians of individuals with ADRD; mental hygiene, trauma, and stigma in the time of COVID-19; and the potential impact of COVID-19 on ADRD research. Amid considerable uncertainty, we may be able to prevent or reduce the harm of the COVID-19 pandemic and its consequences for individuals with ADRD and their caregivers.

Anticipating and Mitigating the Impact of the COVID-19 Pandemic on Alzheimer's Disease and Related Dementias

Purpose
The acetabular labrum is theorized to be important to normal hip function by creating intra-articular fluid pressurization through the hip fluid seal. However, the effect of a labral tear or partial labral resection, and interventions including labral repair and labral reconstruction, on the hip fluid seal remains to be defined. The purpose of this study was to characterize intra-articular fluid pressurization in six labral conditions: intact, tear, repair (looped vs. through sutures), partial resection, reconstruction with iliotibial band, and complete resection.

The hip fluid seal—Part I: the effect of an acetabular labral tear, repair, resection, and reconstruction on hip fluid pressurization

1 Bone Overview, Pr. David Mitton, Pr. Christian Roux, Dr. Pascal Laugier 2 Introduction to the physics of ultrasound, Dr. Pascal Laugier, Dr. Guillaume Haiat.- 3 Quantitative ultrasound instrumentation for bone in vivo characterization, Dr. Pascal Laugier.- 4 Clinical applications, Dr. Reinhard Barkmann, Pr. C-C Gluer.- 5 Poromechanical Models: Biot's theory - Modified Biot's theory - Multilayer model, Dr. Michal Pakula, Pr. Mariusz Kaczmarek,Dr. Frederic Padilla.- 6 Scattering by trabecular bone, Dr. Frederic Padilla, Dr. Keith Wear.- 7 Guided waves in cortical bone, Dr. Maryline Talmant, Josquin Foiret,Dr. Jean-Gabriel Minonzio.- 8 Numerical methods for ultrasonic bone characterization, Dr. Emanuel Bossy, Dr. Quentin GRIMAL.- 9 Homogenization theories and inverse problems, Prof. Robert P. Gilbert, Dr. Ana Vasilic, Dr. Sandra Ilic.- 10 Linear acoustics of trabecular bone, Prof. Jukka S Jurvelin et al..- 11 The Fast and Slow Wave Propagation in Cancellous Bone -Experiments and Simulations, Prof. Atsushi Hosokawa, Dr. Yoshiki Nagatani, Prof. Mami Matsukawa.- 12 Phase Velocity of Cancellous Bone Negative dispersion arising from fast and slow waves, interference, diffraction, and phase cancellation at piezoelectric receiving elements, Prof. James G. Miller et al..- 13 Linear ultrasonic properties of cortical bone: in vitro studies, Dr. Guillaume Haiat.- 14 Ultrasonic monitoring of fracture healing, Dr. Vasilios Protopappas, Dr. Maria G. Vavva, Dr. Konstantinos N. Malizos, Prof. Dimitrios I. Fotiadis.- 15 Nonlinear acoustics for non-invasive assessment of bone micro-damage, Dr. Marie Muller, Dr. Guillaume Renaud.- 16 Microscopic elastic properties, Prof. Kay Raum.- 17 Ultrasonic Computed Tomography, Dr. Philippe Lasaygues.- Index.

Bone quantitative ultrasound

There is an evolving body of knowledge regarding the acetabular labrum. Labral tears are most frequently anterior and often are associated with sudden twisting or pivoting motions. High clinical suspicion in association with positive physical findings are fundamental for the clinician to properly determine treatment for the suspected tear. Labral tears, especially those present for years, may contribute to the progression of hip osteoarthritis. Patients at risk include those with developmental dysplasia, those with tears greater than 5 years, and those with associated chondral full-thickness lesions. Chondral injuries may occur in association with a multitude of hip conditions including labral tears, loose bodies, osteonecrosis, slipped capital femoral epiphysis, dysplasia, and degenerative arthritis. Labral tears occurring at the watershed zone may destabilize the adjacent acetabular conditions. Arthroscopic observations support the concept that labral disruption, acetabular chondral lesions, or both frequently are part of a continuum of degenerative joint disease.

Anatomy, pathologic features, and treatment of acetabular labral tears : Hip arthroscopy

A Survey on Wearable Technology: History, State-of-the-Art and Current Challenges

Alzheimer’s Disease (AD) represents a major and rapidly growing burden to the healthcare ecosystem. A growing body of evidence indicates that cognitive, behavioral, sensory, and motor changes may precede clinical manifestations of AD by several years. Existing tests designed to diagnose neurodegenerative diseases, while well-validated, are often less effective in detecting deviations from normal cognitive decline trajectory in the earliest stages of the disease. In the quest for gold standards for AD assessment, there is a growing interest in the identification of readily accessible digital biomarkers, which harness advances in consumer grade mobile and wearable technologies. Topics examined include a review of existing early clinical manifestations of AD and a path to the respective sensor and mobile/wearable device usage to acquire domain-centric data towards objective, high frequency and passive digital phenotyping.

/pdf/digital-biomarkers-for-alzheimer-s-disease-the-mobile-1j27cqc6yc.pdf

Digital biomarkers for Alzheimer's disease: the mobile/ wearable devices opportunity.

The use of guided waves has recently drawn significant interest in the ultrasonic characterization of bone aiming at supplementing the information provided by traditional velocity measurements. This work presents a three-dimensional finite element study of guided wave propagation in intact and healing bones. A model of the fracture callus was constructed and the healing course was simulated as a three-stage process. The dispersion of guided modes generated by a broadband 1-MHz excitation was represented in the time-frequency domain. Wave propagation in the intact bone model was first investigated and comparisons were then made with a simplified geometry using analytical dispersion curves of the tube modes. Then, the effect of callus consolidation on the propagation characteristics was examined. It was shown that the dispersion of guided waves was significantly influenced by the irregularity and anisotropy of the bone. Also, guided waves were sensitive to material and geometrical changes that take place during healing. Conversely, when the first-arriving signal at the receiver corresponded to a nondispersive lateral wave, its propagation velocity was almost unaffected by the elastic symmetry and geometry of the bone and also could not characterize the callus tissue throughout its thickness. In conclusion, guided waves can enhance the capabilities of ultrasonic evaluation.

Three-dimensional finite element modeling of guided ultrasound wave propagation in intact and healing long bones.

Articular cartilage friction increases in hip joints after the removal of acetabular labrum

The ubiquity and remarkable technological progress of wearable consumer devices and mobile-computing platforms (smart phone, smart watch, tablet), along with the multitude of sensor modalities available, have enabled continuous monitoring of patients and their daily activities. Such rich, longitudinal information can be mined for physiological and behavioral signatures of cognitive impairment and provide new avenues for detecting MCI in a timely and cost-effective manner. In this work, we present a platform for remote and unobtrusive monitoring of symptoms related to cognitive impairment using several consumer-grade smart devices. We demonstrate how the platform has been used to collect a total of 16TB of data during the Lilly Exploratory Digital Assessment Study, a 12-week feasibility study which monitored 31 people with cognitive impairment and 82 without cognitive impairment in free living conditions. We describe how careful data unification, time-alignment, and imputation techniques can handle missing data rates inherent in real-world settings and ultimately show utility of these disparate data in differentiating symptomatics from healthy controls based on features computed purely from device data.

Developing Measures of Cognitive Impairment in the Real World from Consumer-Grade Multimodal Sensor Streams

An arthroplasty device is provided having an interpenetrating polymer network (IPN) hydrogel that is strain-hardened by swelling and adapted to be held in place in a joint by conforming to a bone geometry. The strain-hardened IPN hydrogel is based on two different networks: (1) a non-silicone network of preformed hydrophilic non-ionic telechelic macromonomers chemically cross-linked by polymerization of its end-groups, and (2) a non-silicone network of ionizable monomers. The second network was polymerized and chemically cross-linked in the presence of the first network and has formed physical cross-links with the first network. Within the IPN, the degree of chemical cross-linking in the second network is less than in the first network. An aqueous salt solution (neutral pH) is used to ionize and swell the second network. The swelling of the second network is constrained by the first network resulting in an increase in effective physical cross-links within the IPN.

Lampros Kourtis

Papers

Digital biomarkers for Alzheimer's disease: the mobile/ wearable devices opportunity.

Three-dimensional finite element modeling of guided ultrasound wave propagation in intact and healing long bones.

Articular cartilage friction increases in hip joints after the removal of acetabular labrum

Developing Measures of Cognitive Impairment in the Real World from Consumer-Grade Multimodal Sensor Streams

Hydrogel arthroplasty device