[Clinical and physiological evaluation of bone changes among astronauts after long-term space flights]

Area of Science:

• Space medicine
• Bone physiology
• Skeletal adaptations to microgravity

Context:

• Astronauts experience prolonged exposure to microgravity during long-duration space missions.
• Understanding bone tissue changes is critical for crew health and safety.
• Previous studies have indicated bone loss, but detailed topographical analysis is needed.

Purpose:

• To investigate the effects of microgravity on bone mineral density (BMD) and mineral content (BMC) in different skeletal regions of astronauts.
• To quantify bone loss in specific body segments and assess overall skeletal changes.
• To evaluate the potential of densitometric data for predicting trauma risk in cosmonauts.

Summary:

• Joint Russian/US studies analyzed BMD and BMC in 18 cosmonauts after 4.5- to 14.5-month missions using dual-energy x-ray gamma-absorptiometry.
• Significant BMD losses were observed in the lower body skeleton, including pelvic bones (-11.99%), lumbar vertebrae (-5.63%), and the femoral neck (-8.17%).
• Upper body bones showed minimal changes or a positive trend, with overall skeletal mass loss of -1.41% over ~6 months, suggesting local osteopenia.

Impact:

• Findings highlight the significant impact of microgravity on lower body bone health, necessitating targeted countermeasures.
• The study proposes a biological basis for microgravity-induced bone changes and discusses the predictive value of densitometry for trauma risk.
• Results contribute to understanding skeletal adaptations in space and inform future mission planning and astronaut health protocols.