[Bone mineral density in cosmonauts after flights lasting 4.5-6 months on the Mir orbital station]

Abstract

A technique of quantitative digital roentgenography (QDR) being a current modification of dual photon absorptiometry (DPA) was used to measure bone mineral density (BMD) in the crewmembers of the 6-9th expeditions onboard Mir orbital station after space missions of 132 to 176 days in duration. Total mineral losses were, on average, 0.4% of a preflight level, and in the most test subjects the postflight BMD of the skull, ribs and arms increased and that of lumbar vertebrae, pelvis and legs decreased. The most marked local postflight mineral losses occurred in the proximal femur bone (the femoral neck and the greater trochanter--up to 14%). The observed changes did not depend on flight duration. These findings are being compared to the results of similar studies conducted during the 120-day (NASA) and 370-day (IBMP) hypokinesia experiments. The possibility of existing the general mechanism of modifying mineral status of the skeleton due to different situation related deficiency of musculoskeletal load.