The MRSD of the selleck inhibitor various bone indices are displayed for the Sjælland data as a contour plot in Fig. 2. The three classical indices have MRSD between 7.4% and 7.9%. The lowest value of MRSD is 6.66%, and it is obtained with the following a and b values, here quoted ± their 95% confidence limits: $$ a = \text1.\text35 \pm 0.0\text5 $$ $$ b = 0.\text28 \pm 0.0\text7 $$ The true optimal index is somewhere within this confidence range, and we choose eFT-508 in vitro to define the Paediatric Bone Index, PBI = A/(W 1.33 L 0.33) to represent the preferred index; it has the aesthetic quality of being the geometric mean of the three classical indices. We adopt the measurement unit μm0.33 because it leads to PBI values in the convenient range 3–7. Using the approximation A ≈ πTW, we have $$ \textPBI \approx \pi \text T/\left( WL \right)^0.\text33 $$ The MRSD values for the Erasmus study are generally larger than for the Sjælland study, but their relative sizes are very similar, and MRSD is 7.5% for Temsirolimus clinical trial PBI in the Erasmus data.

Figures 3 and 4 show the Sjælland and Erasmus data for PBI. The solid curves are smoothed ADAMTS5 versions of the average PBI as a function of bone age Although the Sjælland study is very large, it is not well suited as a reference database for clinical use because the images are 43 years old, and they are of the right hand, whereas the left hand is used for bone age radiographs today. Instead, the recent Erasmus study of the left hand is

used, so the average curves in Fig. 4 constitute the recommended PBI reference database for Caucasian children in Western Europe, and they are also listed in Table 1. The data do not show any significant variation in relative SD with bone age or sex, so a constant of 7.5% is used. Table 1 The mean PBI at each bone age value, as derived from the Erasmus study Bone age (years) PBI boys (μm0.33) PBI girls (μm0.33) 6.0 4.24 4.35 6.5 4.31 4.39 7.0 4.35 4.44 7.5 4.38 4.49 8.0 4.40 4.53 8.5 4.43 4.55 9.0 4.46 4.57 9.5 4.48 4.61 10.0 4.49 4.67 10.5 4.50 4.74 11.0 4.51 4.82 11.5 4.52 4.88 12.0 4.55 4.94 12.5 4.63 5.01 13.0 4.78 5.10 13.5 4.95 5.20 14.0 5.12 5.29 14.5 5.26 5.36 15.0 5.38 5.41 15.5 5.51 5.44 16.0 5.65 5.46 16.5 5.76 5.48 17.0 5.83 5.50 17.5 5.87 5.53 18.0 5.92 5.56 18.5 5.99 5.58 19.0 6.10 5.59 The standard deviation score (SDS) of a PBI measurement is computed as in the following example: A girl with BA = 10 years receives a measurement of PBI = 5.00 μm0.33.