Accuracy of computer-assisted pin placement using a fluoroscopy guided navigation system and a novel targeting device - A phantom study

摘要

Objectives: To determine the accuracy of computer-assisted targeting using a novel fluoroscopy guided navigation system in combination with a novel targeting device. This phantom study serves as an important pre-study for further application in emergency surgery. Materials and Methods: A phantom was built by stepwise arrangement of two different materials (polystyrene foam and aerated concrete) in three steps (5, 10, and 15 cm) and insertion of screws (n=60) serving as target points. The polystyrene foam was considered to simulate soft tissue, the aerated concrete to simulate bony tissue. Four fluoroscopic images were acquired from different directions using a simultaneous tracked c-arm and sent to the Stealth Station navigation system equipped with the FluoroNav navigation software (Medtronic Inc., USA). The tips of the screws were identified on the c-arm images and for every target a drilling path was planned with the navigation system. According to the paths surgical pins with two different diameters (1.0 and 2.5mm) were advanced to the targets using the Vertek targeting device, which was developed by our group in collaboration with Medtronic Inc., USA and Medical Intelligence, Germany. Using the pin with 2.5mm diameter every target was localized once (n=60). 1.0mm pins were advanced into the two lower steps, only (n=40). The accuracy of pin placement was evaluated using CT (1.25mm slice thickness). The distance between the tips of the pin and the screw were determined and the perpendicular distance according to the axis of the surgical pin was calculated (= localization error).