Fracture Risk in Spaceflight and Potential Treatment Options

INTRODUCTION: Understanding the effects of microgravity on bone is essential, since humans are now considering long-distance spaceflight missions. It is well known that bone mineral density (BMD) decreases during long-duration spaceflight. While the risk of fracture in a microgravity environment is believed to be low, the potential risk for fracture increases upon re-entering a gravity environment. The objective of this study was to determine skeletal regions of high-risk for fracture after long-duration spaceflight and identify management protocols for those fractures.METHODS: A literature search was conducted on current fracture risk predictive models and suggestions for treatment.RESULTS: Exercise with the Advanced Resistance Exercise Device (ARED), T2 treadmill, and cycle ergometer with vibration isolation and stabilization (CEVIS) on the International Space Station (ISS) is part of a fundamental long-duration spaceflight strategy to mitigate BMD loss. Additionally, studies have shown that bisphosphonates have an additive effect for preventing bone loss. However, if a fracture were to occur, treatments that improve bone healing in space (in addition to standard management modalities such as splinting) include the use of low-intensity pulsed ultrasound, electromagnetic field therapy, and intermittent subcutaneous injections of parathyroid hormone. In the event of a complicated fracture, surgical intervention with a universal external fixation device could be a viable option for management.CONCLUSION: In conclusion, the best strategy for mitigating musculoskeletal injuries for deep-space missions will be a combination of BMD loss reduction coupled with improvements in management protocols for potential fractures.Swaffield TP, Neviaser AS, Lehnhardt K.