• Michael Hoffmann, Jan Philipp Petersen, Malte Schröder, Maximillian Hartel, Michael Kammal, Johannes Maria Rueger, and Andreas Hermann Ruecker.
• Department of Trauma, Hand and Reconstructive Surgery, University Medical Center Hamburg-Eppendorf, Hamburg, Germany. mihoffma@uke.uni-hamburg.de
• Am J Sports Med. 2012 Apr 1;40(4):920-6.

BackgroundRetrograde drilling for osteochondritis dissecans (OCD) remains a challenging operation.PurposeA novel radiation-free electromagnetic navigation system (ENS)-based method was developed and its feasibility and accuracy for retrograde drilling procedures evaluated and compared with the standard freehand fluoroscopic method in an experimental setting.Study DesignControlled laboratory study.MethodsA controlled laboratory study with 16 standard freehand fluoroscopically and 16 electromagnetically guided retrograde drilling procedures was performed on 8 cadaveric human knees. Four artificial cartilage lesions (2 on each condyle) were set per knee. Drilling accuracy was determined by final distance from the tip of the drill bit to the tip of the probe hook (D1) and distance between the tip of the drill and the marked lesion on the cartilage surface (D2). Intraoperative fluoroscopy exposure times were documented, as were directional readjustments or complete restarts. All procedures were timed using a stopwatch.ResultsSuccessful retrograde drilling was accomplished in all 16 cases using the novel ENS-based method and in 11 cases using the standard fluoroscopic technique. The overall mean time for the fluoroscopy-guided procedures was 10 minutes 55 seconds ± 3 minutes 19 seconds and for the ENS method was 5 minutes 34 seconds ± 38 seconds, providing a mean time benefit of 5 minutes 35 seconds (P < .001). Mean D1 was 3.8 ± 1.6 mm for the standard and 2.3 ± 0.6 mm using the ENS technique (P = .021), and mean D2 was 2.5 ± 1.3 mm for the standard and 0.9 ± 0.7 mm for the ENS-based method (P < .001).ConclusionCompared with the standard fluoroscopic technique, the novel ENS-based method used in this study showed superior accuracy, required less time, and utilized no radiation.Clinical RelevanceThe novel method improves a standard operating procedure in terms of accuracy, operation time for the retrograde drilling procedure, and radiation exposure.

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