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Overview

Effect of Microgravity on Fracture Healing/Ultrasound as a Possible Countermeasure

Principal Investigator:
Mark E. Bolander, M.D.

Organization:
Mayo Clinic Rochester - Rochester

The space environment can severely weaken the bones. Consequently, there is concern that even relatively short periods in space will leave astronauts prone to fractures. Because fractures need motion from weight bearing for normal healing, astronauts may also be at risk for abnormal fracture healing. A non-healing fracture would be serious for the astronaut and could potentially affect the astronaut’s mission or safety.

Dr. Mark Bolander is evaluating fracture healing in a hindlimb elevation model. This technique approximates the weightless environment of space. The experiments have shown that the fracture callus in this model is much smaller than under normal conditions. In the future, Bolander’s project will investigate if ultrasound treatment, an artificial way of inducing mechanical stimulation into the bone, will increase the strength of fracture healing.

NASA Taskbook Entry


Technical Summary

The NSBRI Conference convened in Clear Lake, Texas, identified fracture healing during spaceflight as an area where further information would be required to appropriately prepare for long-term space missions, and developing countermeasures to restore normal fracture healing was identified as a priority for current research.

Our current understanding of bone physiology suggests that fracture healing will be abnormal in the microgravity environment. This hypothesis is supported by two published studies, the first an abstract reporting abnormal healing in rats undergoing hindlimb unloading, the second a manuscript (in Russian) that describes abnormal fracture healing in five rats with fibula fractures flown on Cosmos-2044. This latter study reports that abnormalities seen in fracture healing after spaceflight were duplicated in the hindlimb-unloading model.

The goals of the experiments are 1) to confirm the previous reports that microgravity adversely affects fracture healing, and 2) to determine if ultrasound treatment, which has been shown to accelerate fracture healing in clinical studies, will reverse the impaired cellular events in fracture healing that are related to microgravity. If ultrasound does not act as an effective countermeasure, we will undertake detailed evaluation of our histologic samples to identify potential targets for other countermeasures.


This project's funding ended in 2004