Spaceflight and Fractures: 5-Year-Fracture Incidence Upon Return From Spaceflight

Area of Science:

• Space Medicine
• Astronaut Health
• Bone Physiology

Background:

• Spaceflight and microgravity cause significant bone mineral density (BMD) loss in astronauts.
• Low BMD is a known risk factor for fractures, yet in-flight and post-flight fracture data are scarce.

Purpose of the Study:

• To determine the incidence of fractures in astronauts within five years after returning from spaceflight.
• To identify demographic and spaceflight-related factors associated with post-flight fractures.

Main Methods:

• A retrospective cohort study using NASA's Lifetime Surveillance of Astronaut Health database.
• Included astronauts with at least 5 years of post-flight medical data.
• Compared demographics between astronauts who sustained fractures and those who did not.

Main Results:

• Seven out of 242 (2.9%) astronauts experienced fractures within 5 years post-flight.
• Three fractures involved the hip or spine, and six occurred within 2 years of return.
• No statistically significant association was found between fracture risk and spaceflight duration, age, or time since spaceflight.

Conclusions:

• Post-flight fractures pose a significant risk to astronaut health and mission success.
• Hip and spine fractures are linked to decreased BMD and have serious implications, including mortality.
• Optimizing bone health and fracture treatment protocols is crucial for astronaut safety.