Schnitzer, T. | bioRxiv Science

bioRxiv2021

Dominant and nondominant distal radius microstructure: predictors of asymmetry and effects of a unilateral mechanical loading intervention

Most information about distal radius microstructure is based on the non-dominant forearm, with little known about the factors that contribute to bilateral asymmetries in the general population, or what factors may influence bilateral changes over time. Here, we analyzed bilateral longitudinal high resolution peripheral quantitative computed tomography (HRpQCT) data collected over a 12-month period as part of a clinical trial that prescribed a well-controlled, compressive loading task to the nondominant forearm. Baseline data from 102 women age 21-40, and longitudinal data from 66 women who completed the 12-month trial, were examined to determine factors responsible for side-to-side asymmetries in bone structure and change in structure over time. Cross-sectionally, the dominant radius had 2.4%-2.7% larger cross-sectional area, trabecular area, and bone mineral content than the nondominant radius, but no other differences were noted. Those who more strongly favored their dominant arm had significantly more, thinner, closely spaced trabecular struts in their dominant versus nondominant radius. Individuals assigned to a loading intervention had significant bilateral gains in total bone mineral density (2.0% and 1.2% in the nondominant versus dominan sides), and unilateral gains in cortical area (3.1%), thickness (3.0%), bone mineral density (1.7%) and inner trabecular density (1.3%). Each of these gains were significantly predicted by loading dose, a metric that included bone strain, number of cycles, and strain rate. Within individuals, change was negatively associated with age, meaning that women closer to age 40 experienced less of a gain in bone versus those closer to age 21. We believe that dominant/nondominant asymmetries in bone structure reflect differences in habitual loads during growth and past ability to adapt, while response to loading reflects current individual physiologic capacity to adapt.

physiology↗

bioRxiv2019

Prognostics for pain in osteoarthritis: Do clinical measures predict pain after total joint replacement?

A significant proportion of osteoarthritis (OA) patients continues to experience moderate to severe pain after total joint replacement (TJR). So far, preoperative factors related to pain persistence have been mainly studied using individual predictor variables and distinct pain outcomes, thus leading to lack of consensus in the field. In this prospective observational study, we evaluated knee and hip OA patients before, 3 and 6 months post-TJR searching for clinical predictors of pain persistence. We assessed multiple measures of quality, mood, affect, health and quality of life, together with radiographic evaluation and performance-based tasks, modeling four distinct pain outcomes. Multivariate regression models were built, and a network analysis was applied to pain related biopsychosocial measures and their change with surgery. A total of 106 patients completed the study. Pre-surgical pain levels were not related to post-surgical residual pain. Distinct pain scales were associated with different aspects of the pain experience. Multi-factorial models did not reliably predict post-surgical pain in knee OA across four distinct pain scales and did not generalize to hip OA; however, network analysis of pain related biopsychosocial measures showed significant changes post-surgery in both groups. Our results show that although tested clinical and biopsychosocial variables are reorganizing after TJR in OA, they do not present as a robust markers for post-surgery pain outcomes. A better understanding of mechanisms underlying pain persistence after TJR is necessary to derive clinical prognostic factors.

neuroscience↗