It is well known that bone adapts to chronic mechanical loading, such as physical activity. The bone-specific physical activity questionnaire (BPAQ) was designed to provide an estimate of lifetime (tBPAQ) musculoskeletal loading. The true influence of physical activity on bone is difficult to assess from standard aBMD as subtle changes in bone morphology that can markedly influence bone strength cannot be detected. Recently, software was developed to determine 3D parameters of the proximal femur from standard DXA scans; including total volume, as well as cortical and trabecular compartments. The purpose of the current study was to determine the relationship of lifetime physical activity to morphometric parameters of the proximal femur from novel 3D analysis of standard DXA scans.
Healthy men and women from the local community underwent DXA scans (Medix DR, Medilink) and completed the BPAQ. Scans were analysed using the novel software (DMS Group, France) to derive 3D bone parameters at the femoral neck (FN) and total hip (TH). Lifetime physical activity was estimated from the BPAQ and group tertiles were compared using one-way ANOVA.
A total of 234 participants were recruited (53.6±19.1yrs, 167.7±9.3cm, 71.5±15.2kg), of whom 33.3% were men (n=78). Participants in the highest tBPAQ tertile exhibited significantly more robust parameters of bone geometry than the lowest tBPAQ tertile for trabecular volume (FN=12.78±3.38cm3 vs. 10.95±2.46cm3; TH=75.36±18.66cm3 vs. 63.43±14.43cm3, p<0.001), cortical volume (FN=2.14±0.58cm3 vs. 1.73±0.44cm3; TH=13.57±3.42cm3 vs. 11.06±2.54cm3, p<0.001), total volume (FN=14.90±3.85cm3 vs. 12.69±2.77cm3; TH=88.92±21.60cm3 vs. 74.63±16.55cm3, p<0.001) and total cortical thickness (FN=1.11±0.20mm vs. 0.99±0.19mm, p<0.001).
Using novel 3D analysis of DXA scans, lifetime 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 increased bone strength, and thereby a reduced risk of fracture.