Cortical and Trabecular Bone Mineral Loss From the Spine and Hip in Long-Duration Spaceflight

In an earlier study, areal BMD (aBMD) measurements by DXA showed that cosmonauts making flights of 4- to 12-month duration on the Soviet/Russian MIR spacecraft lost bone at an average rate of 1%/month from the spine and 1.5%/month from the hip. However, because DXA measurements represent the sum of the cortical and trabecular compartments, there is no direct information on how these bone envelopes are affected by spaceflight.

To address this, we performed a study of crewmembers (13 males and 1 female; age range, 40-55 years) on long-duration missions (4-6 months) on the International Space Station (ISS). We used DXA to obtain aBMD of the hip and spine and volumetric QCT (vQCT) to assess integral, cortical, and trabecular volumetric BMD (vBMD) in the hip and spine. In the heel, DXA was used to measure aBMD, and quantitative ultrasound (QUS) was used to measure speed of sound (SOS) and broadband ultrasound attenuation (BUA). RESULTS AND CONCLUSIONS: aBMD was lost at rates of 0.9%/month at the spine (p