Bone-specific Physical Activity Questionnaire (BPAQ) Score Associations with Proximal Femur Geometry from DXA-derived 3D Analysis

The bone-specific physical activity questionnaire (BPAQ) was developed to account for the lifetime influence of habitual mechanical loading on the skeleton. We have previously shown that BPAQ scores predict DXA-derived bone mass at clinically important sites and exhibit high inter- and intra-rater reliability. Recently, software was developed to determine three dimensional (3D) parameters of the proximal femur from standard DXA scans, from which the influence of physical activity on bone geometry can be examined.

PURPOSE: The aim of the current study was to determine the relationship of lifetime bone-relevant physical activity to morphometric parameters of the proximal femur from novel 3D analysis of standard DXA scans.

METHODS: Healthy men and women from the local community underwent proximal femur DXA scans (Medix DR, Medilink) and completed the BPAQ. Scans were analysed using the novel 3D software (DMS Group, France) to derive cortical and trabecular volume and cortical thickness at the femoral neck (FN) and total hip (TH). Lifetime bone-relevant physical activity was determined from the BPAQ and group tertiles were compared using one-way ANOVA.

RESULTS: A total of 234 participants were recruited (53.6 ± 19.1 yrs, 167.7 ± 9.3 cm, 71.5 ± 15.2 kg), of whom 33.3% were men (n = 78). Participants in the highest BPAQ tertile exhibited more robust parameters of bone geometry than the lowest BPAQ tertile for trabecular volume (FN = 12.78 ± 3.38 cm3 vs. 10.95 ± 2.46 cm3; TH = 75.36 ± 18.66 cm3 vs. 63.43 ± 14.43 cm3, p < 0.001), cortical volume (FN = 2.14 ± 0.58 cm3 vs. 1.73 ± 0.44 cm3; TH = 13.57 ± 3.42 cm3 vs. 11.06 ± 2.54 cm3, p < 0.001), total volume (FN = 14.90 ± 3.85 cm3 vs. 12.69 ± 2.77 cm3; TH = 88.92 ± 21.60 cm3 vs. 74.63 ± 16.55 cm3, p < 0.001) and total cortical thickness (FN = 1.11 ± 0.20 mm vs. 0.99 ± 0.19 mm, p < 0.001).

CONCLUSIONS: Lifetime bone-relevant physical activity is associated with more robust bone geometry at the proximal femur; in particular, bone volume and cortical thickness. Those properties are typically associated with greater bone strength, and thereby reduced fracture risk. These findings emphasize the importance of lifelong bone-relevant exercise for maintaining a healthy skeleton and confirm the sensitivity of the BPAQ to exercise-related geometric adaption.