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Erschienen in:
01.04.2016 | Original Article
A fast, accurate and closed-form method for pose recognition of an intramedullary nail using a tracked C-arm
Erschienen in: International Journal of Computer Assisted Radiology and Surgery | Ausgabe 4/2016
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Purpose
The main challenge of intramedullary nail (IM-nail) fixation surgery is to achieve the X-ray shot in which the distal holes of the IM-nail appear as circles (desired view); screw insertion is then performed. Although C-arm X-ray devices are routinely used in IM-nail fixation procedures, the surgeons or radiation technologists (rad-techs) usually utilize them in a trial-and-error manner. This increases both radiation exposure and surgery time. This study addresses the problem by presenting a C-arm-based IM-nail pose recognition method.
Methods
The specific purpose of this study was to develop and validate an automated technique for identifying the current pose of the IM-nail relative to the C-arm. An accuracy assessment is performed to test the reliability of the navigation results. The algorithm starts with a sequential biplanar set of X-ray imagery (acquired from a tracked C-arm) of the distal part of an inserted IM-nail. The image-processing module then extracts features of interest, and a mathematical model incorporates them to calculate the six degree-of-freedom position and orientation parameters of the nail.
Results
Translational accuracy was demonstrated to be better than 0.5 mm, rotational accuracy for roll and pitch to be better than \(2^{\circ }\) and for yaw to be better than \(2.5^{\circ }\) depending on the separation angle. Computation time was less than 0.5 s.
Conclusion
An IM-nail distal locking navigation technique is introduced in this study that leads to more accurate and faster screw placement with a lower consumption of radiation dose and a minimum number of added steps to the operation.