, Francois Lintz2, Cesar de Cesar Netto3, Alexej Barg4, Arne Burssens5 and Scott Ellis6
(1)
Department for Foot and Ankle Surgery, Hospital Rummelsberg, Schwarzenbruck, Germany
(2)
Foot and Ankle Surgery Centre, Clinique de l’Union, Toulouse, France
(3)
Department of Orthopedics and Rehab, University of Iowa, Iowa City, IA, USA
(4)
University Orthopedic Center, University of Utah, Salt Lake City, UT, USA
(5)
Department of Orthopedics and Trauma, University Hospital of Ghent, Ghent, OVL, Belgium
(6)
Department of Orthopedic Surgery, Hospital for Special Surgery, New York, NY, USA
Keywords
Weight bearing cone beam computed tomographyWeight Bearing CT International Study Group (WBCT ISG)International WBCT Society
Introduction
The standard for diagnostic radiographic imaging in foot and ankle surgery until 2012 was radiographs with full weight bearing without any useful alternative [1–3]. The three-dimensional position of bones and relationships between bones in the foot (e.g., angles) are difficult to assess with standard radiographs due to superimposition of the different bones [2, 4]. The reason is the “reduction” of a three-dimensional body (foot) to a two-dimensional image (conventional radiograph). Angle measurements with conventional radiographs could be inaccurate due to inaccuracies of the projection (orientation of (central) beam) and/or foot orientation (Fig. 1.1) [2, 5–7]. 3D imaging with conventional computed tomography (CT) allows for exact analysis within the 3D data that is not influenced by projection and/or foot orientation but lacks weight bearing (Fig. 1.2) [2, 4, 8]. Weight bearing cone beam computed tomography (WBCT) was introduced in 2012 for foot and ankle use as a new technology that allows 3D imaging with full weight bearing which should be not influenced by projection and/or foot orientation [2]. The cone beam technology as such (Chap. 19) is similar to previous applications, for example, intraoperative 3D imaging (Fig. 1.3) or maxillofacial 3D imaging (Fig. 1.4) [9, 10]. Different devices from different companies became available (Chap. 20). Several measurement possibilities had been provided with different software solutions (Chap. 21). Many clinical application possibilities have been shown (Chap. 22). From the very beginning of the device availability, scientific studies have been employed. Most of the studies investigated the accuracy of the bone position assessment, i.e., different measurement of angles between bones and position of bones (Chaps. 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, and 18). Shortly after, additional measurements, for example, pedography, were added (Chaps. 19, 20, 21, 22, and 23).
Fig. 1.1
Conventional radiographs for measurement of hindfoot alignment in a patient with healed tibio-talo-calcaneal arthrodesis with retrograde nail. The healed arthrodesis ensures uniform hindfoot position during repetitive radiographic assessment. Radiographs with different internal rotations (0–40°) of the foot in relation to the central beam were obtained, and the hindfoot angle is measured. The measured hindfoot angles ranged from 5.8° to 21.2°. The different angles are not influenced by the “real” hindfoot angle (healed arthrodesis plus nail) but only be different orientation (internal rotation) of the foot and ankle during radiographic assessment
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