Precision of bone mineral density scans at the proximal tibia in osteoarthritic subjects

This study was conducted to assess the precision of dual-energy X-ray absorptiometry (DXA) measurements at the proximal tibia and compare it with precision at other skeletal sites. Precision at the proximal tibia was determined in two groups: 14 subjects with knee osteoarthritis (OA) and 14 normal subjects who were scanned bilaterally four times each, with repositioning. Precision of femoral neck, trochanter, and total hip was also determined in both groups. Group mean bone mineral density (BMD), standard deviation (SD), and root mean squared coefficient of variation (%CV) were determined for both tibias and hips, lumbar spine (L2-L4) and total body. The %CV of the proximal tibia ranged from 1.01% to 1.24% and did not differ significantly in the two groups. The %CV of the hips, spine, and total body ranged from 0.79% to 2.28%. We conclude that DXA scans at the proximal tibia are highly reproducible and that precision at the proximal tibia is comparable to that of the hip, spine, and total body. A larger study is needed to determine whether proximal tibia BMD measurements have research or clinical application for osteoarthritis or other conditions.