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Cited by 236Spaceflight effects on biologyBone health and osteoporosis researchSpace Exploration and Technology

Reduction in proximal femoral strength due to long-duration spaceflight

Keyak, J.H., Koyama, A.K., LeBlanc, A., Lu, Y., Lang, T.F.·2009·Bone
DOI 10.1016/j.bone.2008.11.014
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Abstract

Loss of bone mass is a well-known medical complication of long-duration spaceflight. However, we do not know how changes in bone density and geometry ultimately combine to affect the strength of the proximal femur as a whole. The goal of this study was to quantify the changes in proximal femoral strength that result from long-duration spaceflight. Pre-and post-flight CT scan-based patient-specific finite element models of the left proximal femur of 13 astronauts who spent 4.3 to 6.5 months on the International Space Station were generated. Loading conditions representing single-limb stance and a fall onto the posterolateral aspect of the greater trochanter were modeled, and proximal femoral strength (F(FE)) was computed. Mean F(FE) decreased from 18.2 times body weight (BW) pre-flight to 15.6 BW post-flight for stance loading and from 3.5 BW pre-flight to 3.1 BW post-flight for fall loading. When normalized for flight duration, F(FE) under stance and fall loading decreased at mean rates of 2.6% (0.6% to 5.0%) per month and 2.0% (0.6% to 3.9%) per month, respectively. These values are notably greater than previously reported reductions in DXA total femoral bone mineral density (0.4 to 1.8% per month). In some subjects, the magnitudes of the reductions in proximal femoral strength were comparable to estimated lifetime losses associated with aging. Although average post-flight proximal femoral strength is greater than forces expected to occur due to falls or normal activities, some subjects have small margins of safety. If proximal femoral strength is not recovered, some crew members may be at increased risk for age-related hip fractures decades after their missions.

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  • BMD loss is an established fracture risk factor due to bone weakening, as shown by large epidemiological studies correlating BMD with the incidence of fragility fractures.

    “BMD loss is an established fracture risk factor due to bone weakening as measured in large epidemiological studies correlating BMD with the incidence of fragility fractures [2–4].”

    From A human mission to Mars: Predicting the bone mineral density loss of astronauts (2020) · cites this paper as [2]

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Authors
Keyak, J. H., Koyama, A. K., LeBlanc, A., Lu, Y., & Lang, T. F.
Affiliations
  • University of California, Irvine (US)
  • University of California, San Francisco (US)
  • Universities Space Research Association (US)
Corresponding author
Keyak, J.H.
ORCID
Venue
Bone
Publisher
Elsevier BV
Published
2009-03
Volume
44
Issue
3
Pages
449-453
ISSN
  • 1873-2763 (ISSN-L)
  • 8756-3282
DOI
10.1016/j.bone.2008.11.014
OpenAlex
W2119818184
Cited by
236
References
22
Citations by year
2026: 3 · 2025: 8 · 2024: 5 · 2023: 6 · 2022: 14 · 2021: 15 · 2020: 18 · 2019: 19 · 2018: 8 · 2017: 16 · 2016: 8 · 2015: 18 · 2014: 22 · 2013: 24 · 2012: 16
FWCI
8.12
Type
journal article
Language
en
Open access
closed
Licence
www.elsevier.com/tdm/userlicense/1.0/ (tdm)
Locations
  • Bone (publishedVersion)
  • PubMed (publishedVersion)
Funders
National Aeronautics and Space Administration
Topics
  • Health Sciences › Medicine › Physiology › Spaceflight effects on biology
  • Health Sciences › Medicine › Orthopedics and Sports Medicine › Bone health and osteoporosis research
  • Physical Sciences › Engineering › Aerospace Engineering › Space Exploration and Technology
Keywords
long-duration spaceflight, bone loss, astronauts, International Space Station, finite element model, hip fracture risk, bone mineral density, bone geometry, safety margin, aging
MeSH terms
Adult, Computer Simulation, Female, Femur, Humans, Male, Middle Aged, Risk Factors, Space Flight, Time Factors, Bone Density, Weight-Bearing, Compressive Strength, Fractures, Bone

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