IRVINE, Calif. -- A study of 13 astronauts who spent up to six months in space found that on average, they lost 14 percent in hipbone strength, while three lost up to 30 percent, UC Irvine, which conducted the study, reported Monday.
For decades, researchers have tried to determine why the microgravitational environment of space makes bones more fragile.
The UCI study is the first to specifically evaluate bone strength, said study leader Joyce Keyak, a biomedical engineering professor at UC Irvine. Previous studies focused on bone mineral density.
"If preventive measures are not taken, some of our astronauts may be at increased risk for age-related fractures decades after their mission," Keyak said.
Using a computer program she developed over the past 20 years to identify hipbone fracture risk in people with osteoporosis, the team analyzed the hipbone CT scans of one female and 12 male International Space Center crew members, she said.
Bone strength decreased between 0.6 percent and 5.0 percent for each month of service on the station, Keyak said.
The hip experiences the greatest rate of bone loss in space, and researchers also look at the effects of long-duration spaceflight on the spine, she said.
