Long space stay makes bones weak

Washington Jan 27: Astronauts who spend months in space tend to lose bone strength, making them increasingly vulnerable to fractures in later life.Universities of California (UC) Irvine and San Francisco evaluated 13 astronauts who spent four to six months on the International Space Station and found that, on average, their hipbone strength decreased 14 percent.

Three astronauts experienced losses of 20 percent to 30 percent, rates comparable to those seen in older women with osteoporosis. These results alarmed researchers because they revealed a greater rate of bone deterioration than previously measured using less powerful technologies. Orthopaedic researchers looking into the effects of long-duration spaceflight usually study the hipbone or spine. The hip experiences the greatest rate of bone loss in space, and a hip fracture almost always requires hospitalisation and major surgery. It can impair a person`s ability to walk unassisted and may cause prolonged or permanent disability or even death. Fractures of the vertebra also have serious consequences, including loss of height, severe back pain and deformity. "If preventive measures are not taken, some of our astronauts may be at increased risk for age-related fractures decades after their missions," said Joyce Keyak of UC Irvine, biomedical engineering professor, who led the study. For as long as there have been astronauts, researchers have studied why the microgravitational environment of space makes bones more fragile. While previous studies looked at bone mineral density, this study is the first to specifically evaluate bone strength. Keyak and her colleagues used a novel computer programme she developed over the past 20 years to identify hipbone fracture risk in people with osteoporosis. The study team used this programme to analyse structurally the hipbone CT scans of one female and 12 male International Space Centre crewmembers, said an UCI release. These results appear in the online version of the journal Bone. IANS