The central objective of this investigation is to quantify the dynamic strength changes in the cervical, thoracic, and lumbar vertebrae incurred following long-duration microgravity exposure. Specific objectives are to:
Subjects for this study will be ISS crewmembers who have previously flown as well as nine crewmembers who have yet to fly.
Retrospective data will include pre- and postflight qCT scans and MRI scans archived with NASA’s Life Sciences Data Archive. The lumbar spine (L1 and L2) were the focus of the qCT scans. MRIs focused on the cervical and lumbar areas.
Data collection from prospective subjects is planned to occur once preflight between L-180 and L-45 days and once postflight between R+0 and R+14 days. Each data collection will include a qCT scan of the C3, T3, and L1 vertebrae. Each data collection will also include MRI scans of the cervical, thoracic, and lumbar spine regions. qCT scanning and MRI scanning need not occur on the same day, but must occur within 30 days of each other. There will be no inflight data collection.
Tissue degradation will be measured from retrospective and prospective qCT and MRI pre- and postflight scans. Image segmentation, registration, cortical thickness, and vBMD analysis techniques will be applied to quantify morphological and material property changes that occur in the vertebrae (cervical, thoracic, and lumbar) and spinal musculature when exposed to long-duration microgravity.
Geometric, volumetric, cortical thickness, and vBMD data will be used to morph and scale a finite element (FE) HBM to represent the pre- versus postflight spinal anatomy of individual crewmembers. Dynamic loads representing launch, pad or launch abort, and landing will be simulated with each altered HBM to assess individual and group strength decrement and injury risk with stress, strain, force, moment, and acceleration-based metrics.
This investigation is in progress and results are not yet available. However, this study is expected to provide a greater understanding of spaceflight-induced bone and muscle degradation of the vertebral column and the resulting risk of vertebral fracture. Knowledge gained will inform the development and evaluation of countermeasures to prevent or reduce the effects of microgravity.