Number of paired measure ments (n) | Mean of measured supine length 1 and 2 (SD) | Mean of estimated length 1 and 2 (SD) | Difference between measured and estimated Mean (95% CI) | P values | 95% Limits of agreement | |

Estimated* length from upper arm length | 22 | 124.7 (19.7) | 140.2 (24.5) | −15.5 (−20.2 to −10.7) | <0.001 | −36.5 to 5.5 |

Estimated* length from tibial length | 25 | 126.0 (19.4) | 126.3 (19.9) | −0.26 (−2.15 to 1.64) | 0.8 | −9.2 to 8.7 |

Estimated* length from knee height | 25 | 126.0 (19.4) | 124.8 (19.8) | 1.3 (−1.1 to 3.7) | 0.3 | −10.0 to 12.5 |

Estimated* length from TL<12 years | 15 | 116.1 (17.1) | 116.3 (18.09) | −0.13 (−2.7 to 2.4) | 0.5 | −9.2 to 8.9 |

Estimated* length from KH<12 years | 15 | 116.1 (17.1) | 113.95 (17.22) | 2.19 (0.02 to 4.36) | 0.02 | −5.5 to 9.9 |

KH, knee height; TL, tibial length.

* Based on Stevenson’s method

^{11}using the following equations to estimate supine length: (4.35 x upper arm length) + 21.8, (3.26 x tibial length) + 30.8, (2.69 x knee height) + 24.2.; difference in means and significance (P value) assessed by paired t-test.