Analysis of cancellous bone turnover by multiple slice analysis at distal radius: a study using peripheral...

We compared the results of peripheral quantitative computed tomography (pQCT) measurements (XCT-900; Stratec) at the 4% site of the distal radius (section 1; slice thickness of 2 mm) and in two proximally adjacent sections (sections 2 and 3). The study population consisted of 138 ambulatory patients (age 16.4 +/- 5.6 yr; mean +/- SD; 71 female) who were referred to a pediatric densitometry unit. Total volumetric bone mineral density (BMD) increased, whereas the area of the radial cross-section decreased in a proximal direction. There was a decrease in bone mineral content between sections 1 and 3, which was more pronounced in subjects under age 16. Cancellous BMD significantly decreased from section 1 to 3 only under the age of 16. In 12 patients under age 17 who suffered from increased bone fragility, cancellous BMD decreased about 2.5 times more between sections 1 and 3 than in age-matched patients who received anticonvulsant therapy but had a normal neurologic and musculoskeletal status (-21.4% +/- 16.9 vs -8.1% +/- 6.3; p = 0.02). This suggests that in the bone fragility group, trabeculae were removed faster during longitudinal growth of the radius. In conclusion, multiple slice analysis may provide information on the dynamic turnover of metaphyseal trabeculae during growth.