Intervertebral Disc Elastography to Relate Shear Modulus and Relaxometry in Compression and Bending.

Intervertebral disc degeneration is the most recognized cause of low back pain, characterized by the decline of tissue structure and mechanics. Image-based mechanical parameters (e.g., strain, stiffness) may provide an ideal assessment of disc function that is lost with degeneration but unfortunately remains underdeveloped. Moreover, it is unknown whether strain or stiffness of the disc may be predicted by MRI relaxometry (e.g. T1 or T2), an increasingly accepted quantitative measure of disc structure. In this study, we quantified T1 and T2 relaxation times and in-plane strains using displacement-encoded MRI within the disc under physiological levels of compression and bending. We then estimated shear modulus in orthogonal image planes and compared these values to relaxation times and strains within regions of the disc. Intratissue strain depended on the loading mode, and shear modulus in the nucleus pulposus was typically an order of magnitude lower than the annulus fibrosis, except in bending, where the apparent stiffness depended on the loading. Relative shear moduli estimated from strain data derived under compression generally did not correspond with those from bending experiments, with no correlations in the sagittal plane and only 4 of 15 regions correlated in the coronal plane, suggesting that future inverse models should incorporate multiple loading conditions. Strain imaging and strain-based estimation of material properties may serve as imaging biomarkers to distinguish healthy and diseased discs. Additionally, image-based elastography and relaxometry may be viewed as complementary measures of disc structure and function to assess degeneration in longitudinal studies.

Oral Health: Opportunities for Lifestyle Medicine Highlighted by the SARS-CoV-2 Pandemic.

A significant amount of illness has origins in oral microorganisms. The current SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) pandemic has reduced the general population's access to and use of routine and nonemergency dental care. This creates a dangerous situation in which oral bacteria, fungi, and viruses may remain unchecked and allowed to flourish, which in turn increases risks for several systemic diseases as well as negative outcomes for pregnancies and surgical patients. This situation presents opportunities for health maintenance and disease prevention by individuals as well as for dental health professionals to use anti-infective treatments and procedures. Lifestyle medicine professionals have a chance to encourage behaviors that individuals can undertake to promote good oral health outside of the dentist's office as well as shaping public perceptions about and reinforcing the importance of resuming dental visits as governmental restrictions allow.

Urinary Tract Infection after Total Hip Arthroplasty: A Retrospective Cohort Study.

Perioperative urinary tract infections (UTI) are a relatively common occurrence after total hip arthroplasty (THA). The purpose of this study was to assess demographics, outcomes and trends in the development of UTI's after THA using the National Hospital Discharge Survey (NHDS). All patients undergoing THA were divided based on whether or not they developed a UTI, and data regarding demographics, outcome and complications were gathered and analyzed. No significant trend in rate of UTI after THA was found. Patients who developed a UTI were more likely to be female, have more comorbidities and receive a transfusion. They had a longer hospitalization, lower rate of discharge directly home and an increased rate of discharge to a rehabilitation facility. Orthopaedists should identify those patients at increased risk who according to this study appear to be older, female patients with multiple co-morbidities who received a blood transfusion. (Journal of Surgical Orthopaedic Advances 29(3):162-164, 2020).

Comparison of intervertebral disc displacements measured under applied loading with MRI at 3.0 T and 9.4 T.

The purpose of this study was to compare displacement behavior of cyclically loaded cadaveric human intervertebral discs as measured noninvasively on a clinical 3.0 T and a research 9.4 T MRI system. Intervertebral discs were cyclically compressed at physiologically relevant levels with the same MRI-compatible loading device in the clinical and research systems. Displacement-encoded imaging was synchronized to cyclic loading to measure displacements under applied loading with MRI (dual MRI). Displacements from the two systems were compared individually using linear regression and, across all specimens, using Bland-Altman analysis. In-plane displacement patterns measured at 3.0 T and 9.4 T were qualitatively comparable and well correlated. Bland-Altman analyses showed that over 90% of displacement values within the intervertebral disc regions of interest lay within the limits of agreement. Measurement of displacement using dual MRI using a 3.0 T clinical system is comparable to that of a 9.4 T research system. Additional refinements of software, technique implementation, and image processing have potential to improve agreement between different MRI systems. Despite differences in MRI systems in this initial implementation, this work demonstrates that dual MRI can be reliably implemented at multiple magnetic field strengths, permitting translation of dual MRI for a variety of applications in the study of tissue and biomaterial biomechanics.