The reliability of computed tomography scanograms in the measurement of limb length discrepancy

This study determined the intrarater and interrater reliabilities of measurements of paediatric limb length discrepancy on anteroposterior scout computed tomography scanograms. Seven physicians measured 26 films at two measuring sessions, separated by at least 8 weeks. High intraclass correlation coefficients above 0.96 were observed for measures by different raters within one session and also for repeat measures by the same raters across sessions. The intrarater, intersessional 95% limits of agreement were +/-6 mm for tibial length, +/-5 mm for femoral length and +/-7 mm for total limb length. These errors are similar to those seen with the use of orthoroentgenograms.