Maximilian Faschingbauer1, Hinrich J D Heuer1, Klaus Seide1,2, Robert Wendlandt3, Matthias Münch2, Christian Jürgens1,4, Rainer Kirchner4. 1. Berufsgenossenschaftliches Unfallkrankenhaus (Trauma Hospital) Hamburg, Department for Trauma Surgery, Orthopaedics and Sportstraumatology, Hamburg, Germany. 2. Berufsgenossenschaftliches Unfallkrankenhaus (Trauma Hospital) Hamburg, Laboratory for Biomechanics, Hamburg, Germany. 3. University Medical Center Schleswig-Holstein, Campus Luebeck, Biomechanics Laboratory, Luebeck, Germany. 4. University Medical Center Schleswig-Holstein, Campus Luebeck, Clinic for Musculoskeletal Surgery, Luebeck, Germany.
Abstract
BACKGROUND: Different hexapod-based external fixators are increasingly used to treat bone deformities and fractures. Accuracy has not been measured sufficiently for all models. METHODS: An infrared tracking system was applied to measure positioning maneuvers with a motorized Precision Hexapod® fixator, detecting three-dimensional positions of reflective balls mounted in an L-arrangement on the fixator, simulating bone directions. By omitting one dimension of the coordinates, projections were simulated as if measured on standard radiographs. Accuracy was calculated as the absolute difference between targeted and measured positioning values. RESULTS: In 149 positioning maneuvers, the median values for positioning accuracy of translations and rotations (torsions/angulations) were below 0.3 mm and 0.2° with quartiles ranging from -0.5 mm to 0.5 mm and -1.0° to 0.9°, respectively. CONCLUSIONS: The experimental setup was found to be precise and reliable. It can be applied to compare different hexapod-based fixators. Accuracy of the investigated hexapod system was high.
BACKGROUND: Different hexapod-based external fixators are increasingly used to treat bone deformities and fractures. Accuracy has not been measured sufficiently for all models. METHODS: An infrared tracking system was applied to measure positioning maneuvers with a motorized Precision Hexapod® fixator, detecting three-dimensional positions of reflective balls mounted in an L-arrangement on the fixator, simulating bone directions. By omitting one dimension of the coordinates, projections were simulated as if measured on standard radiographs. Accuracy was calculated as the absolute difference between targeted and measured positioning values. RESULTS: In 149 positioning maneuvers, the median values for positioning accuracy of translations and rotations (torsions/angulations) were below 0.3 mm and 0.2° with quartiles ranging from -0.5 mm to 0.5 mm and -1.0° to 0.9°, respectively. CONCLUSIONS: The experimental setup was found to be precise and reliable. It can be applied to compare different hexapod-based fixators. Accuracy of the investigated hexapod system was high.