Introduction: Degenerative osteoarticular conditions of the lower limb comprise of the most common orthopedic diseases requiring implants surgery. Biomechanical factors have an important role in the development of the degenerative process. Radiological diagnostics prominently rely on bidirectional 2D X-ray images, CT and MRI also being employed in the assessment process. However, these diagnostic tools usually cover a single joint, mostly unilaterally, rarely if ever providing a chance to simultaneously examine each members of the closed kinetic chain of both limbs under normal postural loads in a standing position. Classification and measurements of anatomical conditions are carried out in a 2D environment only and measured values are projected to real-life circumstances.
EOS, a new 2D/3D digital imaging system based on Nobel-prize winning ultra low-dose X-ray radiation detection and a unique 3D toolbox with 3D reconstruction module offers a truly groundbreaking option in this field. We present results obtained during the first year of clinical use of our EOS 2D/3D system.
Methods: 20 patients with coxarthrosis and 20 patients with gonarthrosis have been examined with traditional 2D X-ray and EOS 2D/3D system. Clinical parameters (femoral and tibial length, mechanical angle of the femur and tibia, anatomical and mechanical femorotibial angle, etc.) have been determined for both diagnostic methods and results were compared. 3D measurements available within EOS 3D toolbox were determined including femoral and tibial torsion and femorotibial rotation. For visualization of the lower limbs EOS 3D reconstructions were made.
Results: Using EOS built-in 3D toolbox, comparison of numerical data for 2D and 3D measurements of clinical parameters showed a significant difference whereby 3D measurements always represented more valid, more accurate values. Differences between 2D and 3D measurement values were as much as 5–10 mm in length or 5–8 degrees in angles. This was particularly true for conditions where torsion and rotation of the bones were present.
EOS 3D reconstruction module provided a surface reconstructed 3D model of the examined limbs and automatically displayed every clinically relevant parameters measured in the 3D toolbox. This proved to be an important feature for pre-operative planning and postoperative evaluations.
Conclusion: EOS 2D/3D system provides a ground-breaking new tool for length and angle measurements of the lower limb in 3D, providing distortion-free clinical parameters that are accurate and true-to-life values, avoiding artefactual effects from projection, torsion and rotation and positioning of the patient, which usually concomitantly affect the accuracy and reproducibility of conventional 2D measurements.
