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Astronauts
traveling and working in hypo-gravity environments experience
unique risks to their skeletal structures (Credit: NASA). |
What will happen if an astronaut falls during
a spacewalk on the moon? Is a bone fracture likely to occur? Can
this injury be treated effectively? What if the same event occurs
on Mars? What will be the consequences?
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Astronauts
traveling and working in hypo-gravity environments experience
unique risks to their skeletal structures (Credit: NASA). |
In addition to the bone fracture and renal stone
simulations, Glenn is also developing a module predicting the likelihood
that an astronaut will need a sleep aid due to sleep schedule disruptions.
Glenn is also beginning a model quantifying the likelihood and severity
of a head injury, and will conduct additional analyses quantifying
the expected incidence rate of glaucoma, stroke, and seizure. The
IMM is an ongoing effort to quantify risks to astronauts, guide
mission planners in improving safety, and helping improve fitness
for duty standards.
Bone Fracture
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Ex vivo
test of Femoral Neck bone fracture strength in a bone exhibiting
reduced levels of bone mineral density (Credit: Bonnaire,
et al, INJURY, 2002). |
Treating medical conditions in space can be especially
challenging. The absence of gravity can make stabilizing an injured
body very difficult. The limited space within the spacecraft does
not allow for excess equipment to be stored for possible medical
treatment if the risk of injury is low. Decisions must be made quickly
using the available resources to preserve an astronaut’s life.
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Falling
during extravehicular activity results in a unique risk
of leg (Femoral Neck) fracture (Credit: NASA). |
Glenn is using clinical and biomechanical analyses
of bone fractures that occur on Earth to develop a bone fracture
risk module. Using this computer model, the data from the analyses
on Earth will then be translated to conditions on the moon and Mars.
A significant effect of microgravity is the reduction
of an astronaut’s bone mineral density and bone strength,
which can make his/her bones more susceptible to fracture. Though
gravity is reduced in space, an astronaut could still fall and injure
him/her self during a space walk on the moon or Mars. Space suits
used for extra-vehicular activity (outside the spacecraft) are very
heavy and dramatically increase the overall mass of the astronaut.
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The
IMM bone fracture risk module predicts the skeletal loading potential
during regular astronaut activities (graph1) and estimates
the probability that these will result in a fracture (graph2).
(Data shown represents a Mars mission with 6 month travel
to Mars and 500 days on the surface.) |
Glenn is using clinical and biomechanical analyses
of bone fractures that occur on Earth to develop a bone fracture
risk module. Based on current flight experience and the best Earth-based
clinical evidence, this model is designed to estimate the likelihood
and health impact of fractures during exploration missions. Using
this computer model, the data from the analyses on Earth will then
be translated to conditions on the moon and Mars.
Glenn recently extended this module to quantify
the probability of wrist fractures on the International Space Station
(ISS). Additionally, Glenn used a space suit simulator to quantify
the attenuation likely to be provided to the hip by the suit in
the case of a fall to the side.
Kidney Stones
As another part of the Integrated Medical Model,
Glenn is also developing a model to assess the risk of renal (kidney)
stone formation during long duration exploration missions as well
as after an astronaut has returned to Earth. This condition can
occur due to an increase of calcium in the blood, which is a result
of bone loss during space flight. As an additional complication,
astronauts become dehydrated in microgravity, which may also increase
the risk for kidney stone formation.
As part of the integrated model, the bone fracture
wrist and renal stone models will help NASA predict the likelihood
of occurrence as well as the outcome of treatment. In the future,
Glenn plans to create a simulation model to help predict behavioral
health changes in astronauts during and after a mission. The complete
integrated model will establish improved safety guidelines and fitness
for duty standards for astronauts.
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