Claudio Carrara1, Claudio Belvedere2, Paolo Caravaggi2, Stefano Durante3, Alberto Leardini2. 1. Movement Analysis Laboratory, IRCCS Istituto Ortopedico Rizzoli, Bologna, Italy. Electronic address: clacar.92@gmail.com. 2. Movement Analysis Laboratory, IRCCS Istituto Ortopedico Rizzoli, Bologna, Italy. 3. Nursing, Technical and Rehabilitation Assistance Service, IRCCS Istituto Ortopedico Rizzoli, Bologna, Italy.
Abstract
BACKGROUND: For the diagnosis and treatment of foot and ankle disorders, objective quantification of the absolute and relative orientation angles is necessary. The present work aims at assessing novel techniques for 3D measures of foot bone angles from current Cone-Beam technology. METHODS: A normal foot was scanned via weight-bearing CT and 3D-model of each bone was obtained. Principal Component Analysis, landmark-based and mid-diaphyseal axes were exploited to obtain bone anatomical references. Absolute and relative angles between calcaneus and first metatarsal bone were calculated both in 3D and in a simulated sagittal projections. The effects of malpositioning were also investigated via rotations of the entire foot model. RESULTS: Large angle variations were found between the different definitions. For the 3D relative orientation, variations larger than 10 degrees were found. Foot malposition in axial rotation or in varus/valgus can result in errors larger than 5 and 3 degrees, respectively. CONCLUSIONS: New measures of foot bone orientation are possible in 3D and in weight-bearing, removing operator variability and the effects of foot positioning.
BACKGROUND: For the diagnosis and treatment of foot and ankle disorders, objective quantification of the absolute and relative orientation angles is necessary. The present work aims at assessing novel techniques for 3D measures of foot bone angles from current Cone-Beam technology. METHODS: A normal foot was scanned via weight-bearing CT and 3D-model of each bone was obtained. Principal Component Analysis, landmark-based and mid-diaphyseal axes were exploited to obtain bone anatomical references. Absolute and relative angles between calcaneus and first metatarsal bone were calculated both in 3D and in a simulated sagittal projections. The effects of malpositioning were also investigated via rotations of the entire foot model. RESULTS: Large angle variations were found between the different definitions. For the 3D relative orientation, variations larger than 10 degrees were found. Foot malposition in axial rotation or in varus/valgus can result in errors larger than 5 and 3 degrees, respectively. CONCLUSIONS: New measures of foot bone orientation are possible in 3D and in weight-bearing, removing operator variability and the effects of foot positioning.
Authors: Eli Schmidt; Thiago Silva; Daniel Baumfeld; Kevin N Dibbern; Hee Young Lee; John Femino; Nacime Salomao Barbachan Mansur; Cesar de Cesar Netto Journal: Iowa Orthop J Date: 2021