Cited by 302Spaceflight effects on biologyBone health and osteoporosis researchEffects of Vibration on Health

Adaptation of the proximal femur to skeletal reloading after long-duration spaceflight

Lang, Thomas F, Leblanc, Adrian D, Evans, Harlan J, Lu, Ying·2006·Journal of Bone and Mineral Research

Abstract

We studied the effect of re-exposure to Earth's gravity on the proximal femoral BMD and structure of astronauts 1 year after missions lasting 4–6 months. We observed that the readaptation of the proximal femur to Earth's gravity entailed an increase in bone size and an incomplete recovery of volumetric BMD. Introduction: Bone loss is a well-known result of skeletal unloading in long-duration spaceflight, with the most severe losses occurring in the proximal femur. However, there is little information about the recovery of bone loss after mission completion and no information about effect of reloading on the structure of load-bearing bone. To address these questions, we carried out a study of the effect of re-exposure to Earth's gravity on the BMD and structure of the proximal femur 1 year after missions lasting 4–6 months. Materials and Methods: In 16 crew members of the International Space Station (ISS) making flights of 4.5–6 months, we used QCT imaging to measure the total, trabecular, and cortical volumetric BMD (vBMD) of the proximal femur. In addition to vBMD, we also quantified BMC, bone volume, femoral neck cross-sectional area (CSA), and femoral neck indices of compressive and bending strength at three time-points: preflight, postflight, and 1 year after mission. Results: Proximal femoral bone mass was substantially recovered in the year after spaceflight, but measures of vBMD and estimated bone strength showed only partial recovery. The recovery of BMC, in the absence of a comparable increase in vBMD, was explained by increases in bone volume and CSA during the year after spaceflight. Conclusions: Adaptation of the proximal femur to reloading entailed an increase in bone size and an incomplete recovery of vBMD. The data indicate that recovery of skeletal density after long-duration space missions may exceed 1 year and supports the evidence in the aging literature for periosteal apposition as a compensatory response for bone loss. The extent to which this compensatory effect protects against fracture remains to be seen.

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Crossref · 10.1359/jbmr.060509

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  • Long-duration spaceflights induce bone mineral density (BMD) loss in weight-bearing bones, with considerable individual variability.

    “It is well known that long-duration spaceflights induce BMD loss in weight-bearing bones although there is considerable individual variability [6–12].”
  • The person-to-person variability of BMD loss observed in the available data is large.

    “An additional limitation of our model is that the person-to-person variability of BMD loss observed in the available data [19,32,33] is large (see Fig 1).”

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Authors
Lang, T. F., Leblanc, A. D., Evans, H. J., & Lu, Y.
Affiliations
  • University of California, San Francisco (US)
  • Universities Space Research Association (US)
  • Wyle (United States) (US)
  • Department of Radiology, University of California, San Francisco, California, USA
Corresponding author
Lang, Thomas F
Venue
Journal of Bone and Mineral Research
Published
2006-08-01
Volume
21
Issue
8
Pages
1224-1230
ISSN
  • 0884-0431 (ISSN-L)
  • 1523-4681
OpenAlex
W2083991002
Cited by
302
References
37
Citations by year
2026: 7 · 2025: 11 · 2024: 9 · 2023: 18 · 2022: 10 · 2021: 10 · 2020: 16 · 2019: 22 · 2018: 11 · 2017: 10 · 2016: 12 · 2015: 17 · 2014: 17 · 2013: 23 · 2012: 20
FWCI
9.50
Type
journal article
Language
en
Open access
closed
Locations
  • Journal of Bone and Mineral Research (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
  • Health Sciences › Medicine › Orthopedics and Sports Medicine › Effects of Vibration on Health
Keywords
spaceflight, bone loss, skeletal unloading, proximal femur, volumetric bone mineral density, trabecular bone, cortical bone, bone volume, bone strength, periosteal apposition, astronauts, International Space Station
MeSH terms
Adaptation, Physiological, Adult, Bone Regeneration, Femur Neck, Gravitation, Humans, Organ Size, Skeleton, Space Flight, Tomography, X-Ray Computed, Bone Density, Weight-Bearing, Astronauts

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