New research has found that the rate of hip fractures among astronauts after spaceflights lasting more than 90 days was higher than after shorter spaceflights or among people who were not astronauts. The findings of the study in Mayo Clinic Proceedings, underscore the need for expanded assessment of astronauts’ long-term skeletal health.
The National Aeronautics and Space Administration (NASA) is planning multiple missions lasting more than six months in space, including commercial low Earth orbit activity, completing Artemis IV’s first human mission to the lunar south pole in 2028, and developing sustainable surface capabilities on the moon in preparation for Mars. More people spending more time in extraterrestrial exploration could harm the long-term skeletal health of astronauts selected for their physical fitness and optimal health.
Muscle and bone loss caused by the microgravity environment of space is common among astronauts and suggests a risk of skeletal fragility as the body adapts to disuse.
Jean D. Sibonga, Ph.D., lead investigator of the study “Increased Rates of Hip Fractures Associated With Longer Spaceflight Durations” at NASA’s Johnson Space Center, noted that people do not feel the effects of bone loss. After returning from space and feeling stable or recovered, astronauts may resume physically demanding activities despite underlying skeletal changes caused by prolonged disuse. A better understanding of bone health after spaceflight could help astronauts, patients and clinicians assess long-term health concerns, determine appropriate care and reduce the risk of injury.
Longer missions, earlier hip fractures
Matthew T. Drake, M.D., Ph.D., of the Endocrinology and Metabolic Bone Disease Service at the Hospital for Special Surgery in New York, is a co-author of the accompanying editorial “Bone Loss in Astronauts.” He notes, “While data to date on bone loss associated with spaceflight are consistent, a major limitation is accuracy, as astronaut cohort sample sizes are small and spaceflights are rare.”
To overcome this statistical limitation, investigators surveyed a cohort of U.S.-based astronauts about all fractures reported during annual clinical exams and analyzed the data using Bayesian probabilistic modeling. They did not find a higher incidence rate for all fractures, but the rate of hip fractures among astronauts was higher after spaceflights lasting more than 90 days.
The hip fractures occurred at a younger age than would be expected in a population of people who were not astronauts, and the rate was higher than before a long-duration mission or among astronauts with no spaceflight exposure.
“Taken together, the finding of hip fracture occurrence at an age earlier than expected after long-duration spaceflight is clinical evidence that spaceflight-induced bone loss can lead to real long-term fracture consequences, which should be addressed accordingly,” says Moshe Gertzulin, M.D., of the Endocrinology and Metabolic Bone Disease Service at the Hospital for Special Surgery in New York and a co-author of the accompanying editorial.
More detailed scans for safer recovery
Sibonga emphasized the need to expand NASA’s current bone surveillance program beyond dual-energy X-ray absorptiometry measurements of bone mineral density to better evaluate astronauts’ long-term fracture risk. NASA has recently begun ordering quantitative computed tomography scans before and after spaceflight. The scans can provide more detailed information about different areas of the bone and whether astronauts have fully recovered. Without that insight, astronauts could risk placing too much strain on bones that have not yet regained their preflight condition.
To mitigate these risks, the investigators advocate preventive measures that would preserve astronauts’ baseline, preflight skeletal health. A fuller characterization of spaceflight-induced changes to bone mass, density, structure and microarchitecture will help determine which interventions—whether drugs, exercise or dietary adjustments—are most beneficial for astronauts’ long-term skeletal health.
Publication details
Increased Rates of Hip Fractures Associated With Longer Spaceflight Durations, Mayo Clinic Proceedings (2026). DOI: 10.1016/j.mayocp.2026.06.025
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90-plus-day spaceflights linked to higher rates of hip fractures in astronauts (2026, October 1)
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