Associations Among Hip Structure, Bone Mineral Density, and Strength Vary With External Bone Size in White Women.

Bone mineral density (BMD) is heavily relied upon to reflect structural changes affecting hip strength and fracture risk. Strong correlations between BMD and strength are needed to provide confidence that structural changes are reflected in BMD and, in turn, strength. This study investigated how variation in bone structure gives rise to variation in BMD and strength and tested whether these associations differ with external bone size. Cadaveric proximal femurs (n = 30, White women, 36-89+ years) were imaged using nanocomputed tomography (nano-CT) and loaded in a sideways fall configuration to assess bone strength and brittleness. Bone voxels within the nano-CT images were projected onto a plane to create pseudo dual-energy X-ray absorptiometry (pseudo-DXA) images consistent with a clinical DXA scan. A validation study using 19 samples confirmed pseudo-DXA measures correlated significantly with those measured from a commercially available DXA system, including bone mineral content (BMC) (R 2  = 0.95), area (R 2  = 0.58), and BMD (R 2  = 0.92). BMD-strength associations were conducted using multivariate linear regression analyses with the samples divided into narrow and wide groups by pseudo-DXA area. Nearly 80% of the variation in strength was explained by age, body weight, and pseudo-DXA BMD for the narrow subgroup. Including additional structural or density distribution information in regression models only modestly improved the correlations. In contrast, age, body weight, and pseudo-DXA BMD explained only half of the variation in strength for the wide subgroup. Including bone density distribution or structural details did not improve the correlations, but including post-yield deflection (PYD), a measure of bone material brittleness, did increase the coefficient of determination to more than 70% for the wide subgroup. This outcome suggested material level effects play an important role in the strength of wide femoral necks. Thus, the associations among structure, BMD, and strength differed with external bone size, providing evidence that structure-function relationships may be improved by judiciously sorting study cohorts into subgroups. © 2022 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Paper towel test as independently self-administered to quantify cough-related urine loss: Compliance and comparisons with survey-only data in SWAN.

AIMS: The epidemiologic Study of Women's Health Across the Nation (SWAN) includes urinary incontinence (UI) questionnaire items. We introduced an independently self-administered paper towel test (PTT-ISA; invention disclosure #2021-347) to objectively demonstrate UI. Aims were to determine: (1) PTT-ISA compliance and (2) relationship to questionnaire results. METHODS: 276 community women were invited to complete both SWAN questionnaire and PTT-ISA. For PTT-ISA, a woman holds a trifold brown paper towel against her perineum while coughing hard three times. She checks the towel for wetness and compares it with pictorial showing wetted area gradations (dry towel through >6 ml/saturated). She then selects the best photo match for her towel. A newly conceptualized variable constructed as PTT-ISA plus questionnaire results was formed. RESULTS: Of 276 women, noncompliance with PTT-ISA was 2.2% (6 women). Four others (1.5%) were missing questionnaires. For the remaining 266 women, conceptual cohesiveness between questionnaire-only and PTT-ISA + questionnaire was demonstrated in 165 (62.0%). Lack of cohesiveness occurred in 101 (38.9%), including 41 women who said "no" to the questionnaire item indicative of stress UI and had leakage on PTT-ISA; leakage degree varied across the full pictorial spectrum from drops to saturated. CONCLUSION: PTT-ISA demonstrates high compliance, with rate comparable to survey compliance. It is a novel measure for objective sign of urine loss when independently self-administered by community women outside of a clinic environment. Further research comparing PTT-ISA with clinician-observed cough test is warranted. As independently self-administered, PTT-ISA is simple, noninvasive, inexpensive, and an acceptable test that adds value to otherwise survey-dependent research.

Performance-based physical functioning in African-American and Caucasian women at midlife: considering body composition, quadriceps strength, and knee osteoarthritis.

In 2000, body composition, x-ray-defined knee osteoarthritis, and self-reported knee pain information from a cross-sectional, community-based study of 211 African-American and 669 Caucasian women in southeast Michigan (mean age, 47 years) was related to performance-based physical functioning measures to characterize development of functional limitations. Body composition was assessed with bioelectrical impedance. Functioning measures were gait assessment, timed walk, timed stair climb with and without videography, and isometric quadriceps strength. Knee osteoarthritis was determined by Kellgren-Lawrence score from radiography, whereas knee pain was self-reported. Almost 31% of mid-aged women walked at functionally inadequate speeds, and over 12% walked at speeds considered typical of frailty in older women. Ten percent of women had skeletal muscle mass levels less than a proposed cutpoint for increased physical disability risk in older adults. Gait measures correlates included increasing age, increasing fat mass (in kilograms), knee joint pain, and reduced quadriceps strength. Stair climbing correlates included skeletal muscle mass (in kilograms) and its change, painful knee osteoarthritis, and reduced quadriceps strength. Race differences in walking measures and stair climbing time diminished when the authors accounted for other factors. Compromised physical functioning began earlier than expected, with indications that approximately 12-31% of women might benefit from interventions to forestall future decline.