Table 3

Limits of agreement between mean measured supine length (1 and 2) and mean estimated supine length from segmental measures (1 and 2), with measures 1 and 2 taken 2–4 weeks apart

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 values95% Limits of agreement
Estimated* length from upper arm length22124.7 (19.7)140.2 (24.5)−15.5 (−20.2 to −10.7)<0.001−36.5 to 5.5
Estimated* length from tibial length25126.0 (19.4)126.3 (19.9)−0.26 (−2.15 to 1.64)0.8−9.2 to 8.7
Estimated* length from knee height25126.0 (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 years15116.1 (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 years15116.1 (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 method11 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.