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Proceedings Paper

LORENZ: a system for planning long-bone fracture reduction
Author(s): Wolfgang Birkfellner; Wolfgang Burgstaller; Joachim Wirth; Bernard Baumann; Augustinus Ludwig Jacob; Kurt Bieri; Stefan Traud; Michael Strub; Pietro Regazzoni; Peter Messmer
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Paper Abstract

Long bone fractures belong to the most common injuries encountered in clinical routine trauma surgery. Preoperative assessment and decision making is usually based on standard 2D radiographs of the injured limb. Taking into account that a 3D - imaging modality such as computed tomography (CT) is not used for diagnosis in clinical routine, we have designed LORENZ, a fracture reduction planning tool based on such standard radiographs. Taking into account the considerable success of so-called image free navigation systems for total knee replacement in orthopaedic surgery, we assume that a similar tool for long bone fracture reposition should have considerable impact on computer-aided trauma surgery in a standard clinical routine setup. The case for long bone fracture reduction is, however, somewhat more complicated since not only scale independent angles indicating biomechanical measures such as varus and valgus are involved. Reduction path planning requires that the individual anatomy and the classification of the fracture is taken into account. In this paper, we present the basic ideas of this planning tool, it's current state, and the methodology chosen. LORENZ takes one or more conventional radiographs of the broken limb as input data. In addition, one or more x-rays of the opposite healthy bone are taken and mirrored if necessary. A most adequate CT model is being selected from a database; currently, this is achieved by using a scale space approach on the digitized x-ray images and comparing standard perspective renderings to these x-rays. After finding a CT-volume with a similar bone, a triangulated surface model is generated, and the surgeon can break the bone and arrange the fragments in 3D according to the x-ray images of the broken bone. Common osteosynthesis plates and implants can be loaded from CAD-datasets and are visualized as well. In addition, LORENZ renders virtual x-ray views of the fracture reduction process. The hybrid surface/voxel rendering engine of LORENZ also features full collision detection of fragments and implants by using the RAPID collision detection library. The reduction path is saved, and a TCP/IP interface to a robot for executing the reduction was added. LORENZ is platform independent and was programmed using Qt, AVW and OpenGL. We present a prototype for computer-aided fracture reduction planning based on standard radiographs. First test on clinical CT-Xray image pairs showed good performance; a current effort focuses on improving the speed of model retrieval by using orthonormal image moment decomposition, and on clinical evaluation for both training and surgical planning purposes. Furthermore, user-interface aspects are currently under evaluation and will be discussed.

Paper Details

Date Published: 30 May 2003
PDF: 4 pages
Proc. SPIE 5029, Medical Imaging 2003: Visualization, Image-Guided Procedures, and Display, (30 May 2003); doi: 10.1117/12.479580
Show Author Affiliations
Wolfgang Birkfellner, Univ. Hospital Basel (Switzerland)
Vienna General Hospital (Austria)
Wolfgang Burgstaller, Univ. Hospital Basel (Switzerland)
Joachim Wirth, Univ. Hospital Basel (Switzerland)
Bernard Baumann, Univ. Hospital Basel (Switzerland)
Augustinus Ludwig Jacob, Univ. Hospital Basel (Switzerland)
Kurt Bieri, Fachhochschule beider Basel Nordwestschweiz (Switzerland)
Stefan Traud, Fachhochschule beider Basel Nordwestschweiz (Switzerland)
Michael Strub, Fachhochschule beider Basel Nordwestschweiz (Switzerland)
Pietro Regazzoni, Univ. Hospital Basel (Switzerland)
Peter Messmer, Univ. Hospital Basel (Switzerland)

Published in SPIE Proceedings Vol. 5029:
Medical Imaging 2003: Visualization, Image-Guided Procedures, and Display
Robert L. Galloway Jr., Editor(s)

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