A recent study of spinal cord injury (SCI) patients at the Rehabilitation Institute of Chicago revealed a 2% loss in leg bone mass each month, correlating with a 6.9% drop in leg bone strength. The findings suggest a decrease in mechanical strength in the legs occurs more rapidly and to a greater degree than what was previously believed. This, according to the research team at Worcester Polytechnic Institute (WPI), Worcester, Mass, puts SCI patients at an increased risk of fractures from minor stresses.
Senior author of the study, Karen Troy, PhD, assistant professor of biomedical engineering at WPI, says the study discovered that bone loss occurred sooner in mechanically important areas and significantly increased the risk of fracture.
For patients with spinal cord injuries, this dramatic decline in bone strength often causes broken legs or knees from otherwise minor impact or stresses. “Their bones are so fragile, that just the act of rolling over in bed can snap their knee or leg,” Troy says.
As part of the study, each patient received two standard scans (a DXA bone mineral density scan and a CT scan) of their leg bones at specified time intervals for nearly 4 months after the original injury. The scans documented the change in bone mass over time. The researchers subsequently used sophisticated computer modeling systems to process the scan data and simulate how the amount and distribution of bone loss would affect the ability to sustain mechanical loads and movements.
The study is available in the Journal of Bone and Mineral Research.
[Source: Worcester Polytechnic Institute]