Dual X-Ray absorptiometry leg length in youth

Leg length has been found to be a predictor of the risk cardiovascular disease, metabolic disease and type 2 diabetes. Traditional measures of leg-length are conducted by subtracting seated leg length from standing height. We examined whether dual X-ray absorptiometry (DXA) may provide another accurate method to determine leg length. The data were obtained from a study of adolescents. The aims were to examine the relationship between DXA-derived leg length (DXA-LL) and traditionally derived leg length (T-LL) and determine whether the two types of measures yielded similar associations with measures of cardiometabolic health and bone density.

140 adolescents either conceived and reared in their birth families in the United States (BR birth reared, n = 74, 39 female) or internationally adopted prior to age 5 from orphanage-like institutions (PI previously institutionalized, n = 66, 44 female) had their leg length measured using traditional methods and then using whole body DXA scan. DXA-LL was determined using custom regions of interest.

DXA-LL and T-LL measures were nearly perfectly correlated (r (138) =0.96, p < 0.001). However, DXA-LL estimates were less than T-LL estimates (77.75±6.04 vs 78.96±6.00 cm, p < 0.001). The BR group had longer DXA-LL than the PI group (80.67 cm, 74.84 cm) after controlling for age and sex. Controlling for age and sex, longer leg length using DXA-LL was associated with lower glucose, cholesterol, triglycerides, and HDL, and denser bone density. Similar results were obtained with T-LL.

DXA-LL is an accurate and reliable leg length measurement tool.