E-Poster Presentation 30th Australian and New Zealand Bone and Mineral Society Annual Scientific Meeting 2020

Mid-thigh bone, lean and fat mass are reliable indices of tissue mass in predicting osteosarcopenia-associated outcomes – a validation study (#102)

Ebrahim Bani Hassan 1 2 , Fernan Munandar Putra 1 2 , Sara Vogrin 1 2 , Julie A Pasco 2 3 4 , Mark A Kotowicz 2 3 4 , Gustavo Duque 1 2
  1. Australian Institute for Musculoskeletal Science (AIMSS), ), The University of Melbourne and Western Health, St. Albans, Victoria , Australia
  2. Department of Medicine-Western Health, The University of Melbourne, St. Albans, Victoria , Australia
  3. University Hospital Geelong, Barwon Health, Geelong, Victoria , Australia
  4. School of Medicine, Deakin University, Geelong , Victoria , Australia

Background: Mid-thigh has been recognized as a surrogate to assess bone, muscle and fat. Mid-thigh tissue measures associate well with both strength and adverse outcomes. In this study, we further investigated mid-thigh region of interest (ROI)’s ability to assess musculoskeletal health in a large cohort of community-dwelling participants.

Methods: Whole body DXA scans from 1322 participants of the Geelong Osteoporosis Study were analysed for bone, lean and fat mass in five ROIs: 2.6 cm mid-thigh, 13 cm mid-thigh, whole thigh, whole calf and forearm. Tissue masses in these ROIs were compared to conventional indices of musculoskeletal assessment (hip, spine and femoral neck BMD; appendicular lean mass adjusted for BMI or height2; gynoid and android fat) using Pearson’s correlation coefficient. Their associations with physical performance (timed-up-and-go [TUG] test), 1-year retrospective falls history and 5-year retrospective fractures was compared using regression.

Results: Mid-thigh tissue masses were moderately to highly correlated with their counterpart conventional indices: bone (r=0.4–0.49, p<0.001), muscle (corrected for BMI, r=0.86–0.94, p<0.001) and fat (r=0.57–0.94, p<0.001). For every 10% change in the tissue masses of mid-thigh, TUG changed between 0.5%–3.5% (p<0.01). Other ROIs were variable and mostly did not show significant associations with TUG (0.06–1.75, p=0.01 to 0.767). Mid-thigh BMD had comparable association with fractures vs neck of femur, hip and spine BMD (0.84% vs 0.80-0.86% difference in fracture rate per 10% difference in BMD, p<0.034). Whole-thigh and mid-thigh lean mass were also comparable to ALM/BMI (0.87–0.91 vs 0.90% difference in falls rate per 10% change in lean mass, p<0.027).

Conclusions: Data suggest that the mid-thigh is the best potential ROI out of selected regions to study muscle while whole thigh is better for bone. Both ROIs are equivalent or better than conventional indices when assessing concurrent physical performance (including falls) and fractures.