The goal of this research is to comprehensively characterize space flight induced changes in disc morphology, biochemistry, metabolism, and kinematics. These data will be correlated with measures of back pain intensity and disability. The hypothesis is that spontaneous space flight back pain and disc herniation are due to biomechanical and biological pathomechanisms. First, microgravity leads to higher than normal physiologic disc swelling and increased disc height that may stiffen the lumbar motion segment and cause abnormal segmental movement patterns. These biomechanical changes increase risk for annular rupture, vertebral endplate microfracture, and facet joint capsule strain. Second, increased disc swelling may alter nuclear matrix osmotic pressure and nutrient transport from endplate capillaries in adjacent vertebra. These biological changes adversely affect disc cell metabolism, causing pain and inducing disc matrix degradation.
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This investigation uses state-of-the-art imaging technologies to quantify morphology, biochemistry, metabolism, and kinematics for lumbar discs of crewmembers before and after prolonged space flight. These data will be correlated with low back pain that spontaneously arises in space in order to establish pain and disc damage mechanisms that will serve as basis for future countermeasure development. Successful completion of the investigation will include a comprehensive database of microgravity-induced intervertebral disc and vertebral changes (type and magnitude), as well as a prioritization of these changes regarding their deleterious effects and risks for crewmember injury based on clinical findings.
Crewmembers will be imaged twice preflight (over a one-month time frame) to establish baseline data and to characterize measurement repeatability. After long-term microgravity exposure, 180 days on the International Space Station (ISS), crewmembers will be studied while maintaining supine posture as soon as possible after return to Earth in order to quantify the acute effects of prolonged space flight. Also, pre- and postflight, they will don a compression device so that MRI images are obtained before and after 50% axial body weight load. This compression device loads the spine and simulates 50% body weight load (not including loads from muscles) on the lumbar spine in upright posture. Subsequently, crewmembers will be tested after three and six months of readaptation to 1-G in order to distinguish immediate and longer-term recoveries. These measures represent a comprehensive set of tests that evaluate exposure severity, potential injury mechanisms, and pain generator localization.
This experiment is in progress. Results will be available at a later date.
Mao CP, Macias BR, and Hargens AR. Shoulder skin and muscle hemodynamics during backpack carriage. Applied Ergonomics.
2015. November; 51:80-4.
Sayson JV, Lotz J, Parazynski S, and Hargens AR. Back pain in space and post-flight spine injury: Mechanisms and countermeasure development. Acta Astronautica.
2013; 86: 24-38. [DOI]
Berg-Johansen B, Liebenberg EC, Li A, Macias BR, Hargens AR, and Lotz JC. Spaceflight-induced bone loss alters failure mode and reduces bending strength in murine spinal segments. Journal of Orthopaedic Research.
2015, Aug 18.
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Intervertebral disc compressibility, cervical
Intervertebral disc compressibility, lumbar
Intervertebral disc heights, cervical
Intervertebral disc heights, lumbar
Lumbar disc biochemistry
Lumbar disc kinematics
Lumbar disc metabolism
Lumbar disc morphology
Muscle cross-sectional area, cervical
Muscle cross-sectional area, lumbar
Pfirmann grade, cervical
Pfirmann grade, lumbar
Spatial location, cervical
Spatial location, lumbar
Spinal length, cervical
Spinal length, lumbar
Crew health and performance is critical to successful human exploration beyond low Earth orbit.
The Human Research Program (HRP) investigates and mitigates the highest risks to human health
and performance, providing essential countermeasures and technologies for human space exploration.
Risks include physiological and performance effects from hazards such as radiation, altered gravity,
and hostile environments, as well as unique challenges in medical support, human factors,
and behavioral health support. The HRP utilizes an Integrated Research Plan (IRP) to identify
the approach and research activities planned to address these risks, which are assigned to specific
Elements within the program. The Human Research Roadmap is the web-based tool for communicating the IRP content.
The Human Research Roadmap is located at: https://humanresearchroadmap.nasa.gov/
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for information of how this experiment is contributing to the HRP's path for risk reduction.