BONE MICROARCHITECTURE DECLINE AND RISK OF FALL AND FRACTURE IN MEN WITH POOR PHYSICAL PERFORMANCE – THE STRAMBO STUDY

Context: High fracture risk in subjects with low muscle strength is attributed to high risk of fall.

Objective: To study the association of muscle mass and physical performance with bone microarchitecture decline and risk of fall and nonvertebral fracture in men.

Design: Prospective 8-year follow-up of a cohort.

Setting: General population.

Participants: 821 volunteer men aged ≥60.

Interventions: Hip areal bone mineral density (aBMD) and appendicular lean mass (ALM) were assessed at baseline by DXA. Lower limb relative ALM (RALM-LL) is ALM-LL/(leg length)². The physical performance score reflects ability to perform chair stands and static and dynamic balance. Bone microarchitecture was assessed by high resolution peripheral QCT (HR-pQCT) at baseline, after 4 and 8 years. Statistical analyses were adjusted for shared risk factors.

Outcomes: Rate of change in the HR-pQCT indices, incident falls and fractures.

Results: Cortical bone loss and estimated bone strength decline were faster in men with low vs. normal RALM-LL (failure load: -0.74±0.09 vs. -0.43±0.10%/year; p<0.005). Differences were similar between men with poor and those with normal physical performance (failure load: -1.12 ±0.09 vs. -0.40±0.05%/year; p<0.001). Differences were similar between men having poor performance and low RALM-LL and men having normal RALM-LL and performance (failure load: -1.40±0.17 vs. -0.47±0.03%/year; p<0.001). Men with poor physical performance had higher risk of fall (HR=3.52, 95%CI: 1.57–7.90, p<0.05) and fracture (HR=2.68, 95%CI: 1.08–6.66, p<0.05).

Conclusion: Rapid decline of bone microarchitecture and estimated strength in men with poor physical performance and low RALM-LL may contribute to higher fracture risk.