USEFULNESS OF MEASUREMENT OF LOWER LIMB PARAMETERS BY THREE-DIMENSION RECONSTRUCTION SYSTEM EOS®

Abstract

To date, no technique has proved to be reliable and reproducible in order to precisely calculate radiological lower limb parameters.

EOS^® system allows from two bi-dimensional orthogonal radiographies in standing position to obtain a tridimensional reconstruction. A computerized system achieves the parameters calculation.

The aim of the study was first to evaluate the inter and intraobserver reproducibility of the EOS^® system, secondly to compare EOS^® measures with X-ray orthoroentgenograms.

Twenty-five patients about to receive total hip arthroplasty were included (fifty lower limbs). Two independent performers have carried out twice the measures either on standard X-rays and using three-dimensional reconstructions (femoral parameters (length, offset, collo-diaphy-seal angle, neck length, and head diameter), tibiae length, limb length, HKA, HKS). The reproducibility was estimated by intraclass correlation coefficients.

The inter and intraobserver reproducibility of the EOS^® measures have been respectively of 0.881 and 0.916 and more specifically of 0,997 and 0,997 for femoral length, of 0.996 and 0.997 for tibiae, of 0.999 and 0.999 for limb length, of 0.893 and 0.890 for HKS, of 0.993 and 0.994 for HKA, of 0.892 and 0.914 for femoral offset, of 0.765 and 0.850 for collo-diaphyseal angle.

The inter and intraobserver reproducibility using orthoroentgenograms reached 0.854 and 0.902.

Our results show the EOS^® is a tool allowing reproducible measures. Furthermore 3D EOS^® reconstructions offer better reproducible measures for all parameters that the orthoroentgenograms.

Its use prior to the decision of surgery and during surgery planning for lower limb arthroplasty is for us essential for adjusting surgical procedure accordingly.