Low Muscle Strength and Mass Is Associated With the Accelerated Decline of Bone Microarchitecture at the Distal Radius in Older Men: the Prospective STRAMBO Study.

Low muscle mass and strength are associated with poor bone microarchitecture. We studied the association of muscle mass and strength with changes in bone microarchitecture of distal radius in 821 older men during an 8-year prospective follow-up. Bone microarchitecture was assessed by high resolution peripheral quantitative computed tomography (XtremeCT-1, Scanco) at baseline, then after 4 and 8 years. Relative appendicular lean mass of the upper limbs (RALM-u.l.) was calculated as DXA-measured lean mass of upper limbs divided by (height)2 . Relative grip strength was calculated as grip strength divided by height. Decrease in bone mineral content (BMC), total volumetric bone mineral density (Tt.vBMD), cortical thickness (Ct.Th), cortical area (Ct.Ar) and cortical vBMD (Ct.vBMD) accelerated with age. Trabecular area (Tb.Ar) expansion and trabecular bone deterioration accelerated with age. Men in the first RALM-u.l. quartile had more rapid loss of BMC, Tt.vBMD, Ct.Th, Ct.vBMD and Ct.Ar vs. the highest quartile. They had more rapid increase in Tb.Ar. Men in the lowest quartile of grip strength had greater decrease in BMC, Tt.vBMD, Ct.Th, Ct.vBMD, Ct.Ar, and greater increase in Tb.Ar vs. the highest quartile. In the models including ALM-u.l. and grip strength (not corrected for height), both muscle-related variables were associated with more rapid bone microarchitectural deterioration (slightly more so for grip strength). Trabecular vBMD (Tb.vBMD) and Central.Tb.vBMD increased in men having higher muscle mass and strength. Trends in trabecular number and thickness did not differ across the groups in all the analyses. Thus, in men, aging-related deterioration of bone microarchitecture was most rapid after the age of 80. Low grip strength (and slightly more weakly low RALM-u.l.) is associated with the more rapid decrease in Tt.vBMD and cortical variables, and with greater Tb.Ar expansion. In conclusion, dynapenia and sarcopenia contribute to the deterioration of bone microarchitecture in older men.