Annals of Biomedical Engineering

, Volume 37, Issue 11, pp 2337–2359

Development and Validation of a Predictive Bone Fracture Risk Model for Astronauts

  • Emily S. Nelson
  • Beth Lewandowski
  • Angelo Licata
  • Jerry G. Myers
Article

DOI: 10.1007/s10439-009-9779-x

Cite this article as:
Nelson, E.S., Lewandowski, B., Licata, A. et al. Ann Biomed Eng (2009) 37: 2337. doi:10.1007/s10439-009-9779-x
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Abstract

There are still many unknowns in the physiological response of human beings to space, but compelling evidence indicates that accelerated bone loss will be a consequence of long-duration spaceflight. Lacking phenomenological data on fracture risk in space, we have developed a predictive tool based on biomechanical and bone loading models at any gravitational level of interest. The tool is a statistical model that forecasts fracture risk, bounds the associated uncertainties, and performs sensitivity analysis. In this paper, we focused on events that represent severe consequences for an exploration mission, specifically that of spinal fracture resulting from a routine task (lifting a heavy object up to 60 kg), or a spinal, femoral or wrist fracture due to an accidental fall or an intentional jump from 1 to 2 m. We validated the biomechanical and bone fracture models against terrestrial studies of ground reaction forces, skeletal loading, fracture risk, and fracture incidence. Finally, we predicted fracture risk associated with reference missions to the moon and Mars that represented crew activities on the surface. Fracture was much more likely on Mars due to compromised bone integrity. No statistically significant gender-dependent differences emerged. Wrist fracture was the most likely type of fracture, followed by spinal and hip fracture.

Keywords

Monte Carlo method Probabilistic modeling Biomechanical model Risk assessment Fracture risk index Lumbar spine Femoral neck Wrist Gravitational physiology Bone loss 

Nomenclature

Abbreviations

AL

Applied load (N)

BFxRM

Bone fracture risk model

BM

Body mass (kg)

BMC

Bone mineral content (g/cm3)

BMD

Bone mineral density (g/cm2)

CoM

Center of mass

DXA

Dual energy X-ray absorptiometry, a means of quantifying BMD

EVA

Extra-vehicular activity

F

Female

FL

Fracture load (N)

FN

Femoral neck

FOR

Factor of risk

FRI

Fracture risk index

LS

Lumbar spine

LSAH

Longitudinal Study of Astronaut Health

M

Male

n

Sample size

p

Probability

QCT

Quantitative computed tomography, a means of quantifying BMC

Variables

a

A general empirical coefficient

b

Damping coefficient (kN s/m)

F

Force (N)

h

Height (cm)

k

Stiffness coefficient (kN/m)

l

Length (cm)

m

Mass (kg)

x

Displacement (cm)

VO2max

O2 capacity during maximum aerobic exercise (mL/(kg min))

β

Posterolateral angle of impact (°)

ϕ

Slope factor

μ

Position factor

σ

Standard deviation

θ

Trunk flexion angle (°)

Subscripts

a

Active response

A

Arm

BL

Bone loss

CM

Center of mass of the torso

e

Earth

eff

Effective

F

Feet

G

Ground

GR

Ground reaction (force)

H

Hip

HAT

Head, arms and torso

LS

Lumbar spine

O

Object

PL

Pelvis and legs

PM

Postural muscles

s

Suit

S

Shoulder

T

Torso

tot

Total body

UB

Upper body

W

Wrist

Wa

Waist

WaS

Waist to shoulder

Copyright information

© Biomedical Engineering Society 2009

Authors and Affiliations

  • Emily S. Nelson
    • 1
  • Beth Lewandowski
    • 1
  • Angelo Licata
    • 3
  • Jerry G. Myers
    • 2
  1. 1.Bioscience and Technology BranchNASA Glenn Research CenterClevelandUSA
  2. 2.Human Research ProgramNASA Glenn Research CenterClevelandUSA
  3. 3.Cleveland ClinicClevelandUSA

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