Three-Dimensional Reconstruction of Foot in the Weightbearing Position From Biplanar Radiographs: Evaluation of Accuracy and Reliability

Abstract

The initial assessment and postoperative monitoring of patients with various abnormalities of the foot in clinical routine practice is primarily based on the analysis of radiographs taken in the weightbearing position. Conventional x-ray imaging, however, only provides a 2-dimensional projection of 3-dimensional (3D) bony structures, and the clinical parameters assessed from these images can be affected by projection biases. In the present work, we addressed this issue by proposing an accurate 3D reconstruction method of the foot in the weightbearing position from low-dose biplanar radiographs with clinical index measurement assessment for clinical routine practice. The accuracy of the proposed reconstruction method was evaluated for both shape and clinical indexes by comparing 3D reconstructions of 6 cadaveric adult feet from computed tomographic images and from biplanar radiographs. For the reproducibility study, 3D reconstructions from the biplanar radiographs of the foot of 6 able-bodied subjects were considered, with 2 observers repeating each measurement of anatomic landmarks 3 times. Baseline assessment of important 3D clinical parameters was performed on 17 subjects (34 feet; mean age 27.7, range 20 to 52 years). The average point to surface distance between the 3D stereoradiographic reconstruction and the computed tomographic scan-based reconstruction was 1 mm (range 0mm to 6mm). The selected radiographic landmarks were highly reproducible (95% confidence interval <2.0 mm). The greatest interindividual variability for the clinical parameters was observed for the twisting angle (mean 87°, range 73° to 100°). Such an approach opens the way for routine 3D quantitative analysis of the foot in the weightbearing position.

Understanding the foot's functional anatomy in physiological and pathological conditions: The calcaneopedal unit concept

“…4) resulting in cavovarus foot. 9,15,23,24 Conversely, a pronation twist of the lamina pedis relaxes the plantar fascia and is followed by a push and pull intersegmental movement at the tarsal and tarsometatarsal joints, as if playing the accordion. In mechanical terms, this is called a loose pack situation, and leads to an increase in medial arch height.…”

Definition of a Global Coordinate System in the Foot for the Surgical Planning of Forefoot Corrections

“…The availability of CT scanners can also differ from hospital to hospital or country to country. Although this is outside the scope of this study, some initiatives have been set up to transfer data from 2D radiographic images to a 3D digital model [31,32]. This might be a future solution to avoid the need for a CT scan for patients with minor pathologies.…”

Reconstruction tridimensionnelle de la main à partir de radiographies biplanes : évaluation de la précision et de la fiabilité

“…Le principe général de cette méthode de reconstruction 3D personnalisée de la main était le repositionnement et la déformation semi-automatique d'un modèle 3D générique à partir des contours osseux de la main et du poignet d'une radiographie biplane. La méthode proposée a été adaptée des travaux antérieurs sur le pied et le membre inférieur [19,21].…”

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