[Dynamics of changes in bone mineral density and structural organization in cosmonauts following space flight of 6 months in duration]

Abstract

Microgravity effect on bone tissue of cosmonauts was evaluated following space flights of 6 months in duration. Peripheral quantitative computed tomography (pQCT) was used to determine volumetric bone mineral density (VBMD) and structure of distal parts of the leg and forearm. Changes in VBMD were found to correlate with bone position relative to the vector of gravity. In the forearm, reversible hypermineralization was bound together with compact bone thickening. Reversible osteopenia in the lower leg was accompanied with plausible losses both in compact and trabecular bone. Irrespective of position relative to the vector of gravity, bone microarchitecture tended to reduce the number of trabecules and to increase heterogeneity of the trabecular network. Pre-flight structural dynamics showed a complex character with linear time dependence.