Dual-Energy X-ray Absorptiometry Assessment of Tibial Mid-third Bone Mineral Density in Young Athletes

Abstract 

We suggested a new reproducible method to measure densitometric values at mid-third part of the tibia by dual-energy X-ray absorptiometry (DXA; Delphi, Hologic^®, Waltham, MA) in a population of young adults. Our population was composed of 170 subjects aged 22.7±4.0yr: athlete men (n=67) and women (n=40); control men (n=33) and women (n=30). Athletes practiced collective sports, judo or weightlifting for 10.0±3.6h/wk. We measured bone area (cm²), bone mineral content (BMC, g), and bone mineral density (BMD,g/cm²) at the left total hip and the mid-third part of the tibia with DXA. For the tibia scan, we used the whole body mode. To ensure the reproducibility of the method, both legs were extended and the feet were maintained on a support in an internal rotation of 35°. The region of interest of the lumbar spine from the whole body scan was positioned around the mid-third part of the tibia. Area, BMC, and BMD values were significantly higher in athletes compared with those of controls. The intra- and interobserver variability of the image analysis were 0.38% and 1.01%, respectively. For BMD measurements, the short-term (4 scans/d) and mid-term (4 scans/mo) reproducibility were 1.33% and 1.94%, respectively. DXA is a suitable tool to evaluate densitometric measurements at the mid-third part of the tibia and the influence of physical activity on that bone site.

Key Words: BMD, DXA, Mid-third part of the tibia, Young adults