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Complete validation of plumbline distances as a screening tool for sagittal plane deformities


While for scoliosis screening Scoliometer has been widely validated, there is no validated screening instrument for sagittal plane deformities.


To validate a screening tool for sagittal plane deformities (plumbline distances - PD).

Material and methods

Surface measurements (Formetric) of kyphosis/lordosis were considered the Gold Standard [1]. Correlations between Human PD (HPD), Formetric PD (FPD) and Gold Standard were searched in 129 school screening pupils (age 11.8±0.7): not correlated PD were eliminated. ROC-curve statistical technique was used to determine the best cut-off for remaining PDs.

Final FPD were verified in 7257 Formetric evaluations from the Diers database (3 age groups: 6-9y12m, 10-17y12m, 18-78). Final HPD were verified in 103 scoliosis/hyperkyphosis patients aged 14.3±2.2.


HPDs correlate with FPDs (0.49-0.57), C7+L3 with kyphosis (0.54-0.58), L3 with kyphosis and lordosis (0.42-0.56). To identify 60° kyphosis, a cut-off of 90 mm for C7+L3 demonstrated an overall accuracy range of 75-93%, high specificity (78-95%), variable sensitivity (25-83%). HPDs very well ruled out normals (negative predictive value –PV 93-99%), even if with high numbers of false positives (positive predictive value +PV 8-25%). Similarly, for 55° lordosis, a cut-off of 45 mm for L3 demonstrated a 75-94% overall accuracy, 70-94% specificity and 25-100% sensitivity, with –PV 93-100% and +PV 9-20%.


In all groups evaluated results were similar. Below 90mm C7+L3 (45mm L3) almost all pupils are below 60° kyphosis (55° lordosis); in the remaining 20% a not-ionizing surface evaluation (Formetric) should be proposed to identify real deformities (1 out of 4 to 10).


  1. Weiss HR, Dieckmann J, Gerner HJ: Outcome of the in-patient rehabilitation in patients with M. Scheuermann evaluated by surface topography. Stud Heelth Technol Inform. 2002, 88: 246-9.

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This article is published under license to BioMed Central Ltd. This is an open access article distributed under the terms of the Creative Commons Attribution License (, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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Negrini, S., Donzelli, S., Zaina, F. et al. Complete validation of plumbline distances as a screening tool for sagittal plane deformities. Scoliosis 7 (Suppl 1), O16 (2012).

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