Navigierte Osteosynthese des proximalen Femurs

ZusammenfassungEine wichtige Ursache für das sekundäre Implantatversagen bei der Osteosynthese proximaler Femurfrakturen ist eine Fehllage der Gleitschraube. In der konventionellen Technik wird die Implantation mit 1 oder 2 simultanen Bildwandlern kontrolliert. Problematisch ist die Strahlenbelastung des Operationspersonals. In einer experimentellen Studie überprüften wir die Präzision und Strahlenbelastung bei der navigierten Implantation der dynamischen Hüftschrauben. Drei Versuchsreihen wurden durchgeführt: 1. Bohrung und Schraubenimplantation mit der konventionellen Technik (Führungsdraht, Stufenbohrer), 2. navigierte Bohrung mit einem 3,2-mm-Bohrer, Einschieben des Führungsdrahtes und Überbohren mit dem Stufenbohrer, 3. navigierte Bohrung mit 3,2 mm, dann Röntgenkontrolle und dann Korrektur oder Überbohren. Bezüglich der Operationszeit, Präzision der Schraubenlage („tip-apex distance“ nach Baumgaertner und 135°-Winkel) ergab sich kein signifikanter Unterschied. Jedoch war mit Navigation die Röntgenzeit um bis zu 93% vermindert. Navigation kann mit derselben Präzision die Röntgenbelastung erheblich vermindern.AbstractScrew position in femoral head has been considered the most important predictive factor for mechanical failure in pertrochanteric osteosynthesis, and correct positioning is assisted by fluoroscopic control. Although fluoroscopy leads to precise and reproducible results, it is associated with scattered radiation to the patient and surgical staff. Computer-assisted surgery (CAS) may be an alternative in means of achieving precise screw insertion with a low radiation dose. We designed a laboratory study in which artificial proximal femora were submitted to insertions of a dynamic hip screw (DHS) and an anti-rotational screw (ARS). Three set-ups were tested: (1) conventional implantation with two simultaneous C-arms using a guide wire; (2) drilling and implantation controlled by CAS solely with a 3.2-mm drill bit, then insertion of a guide wire and drilling for the dynamic hip screw; (3) after navigated drilling (3.2 mm) a fluoroscopic control was performed. Five variables were used comparing methods and surgeons: operation time, radiation time, tip–apex distance (TAD), and the insertion neck–shaft angles of DHS and ARS. Considering TAD as a precision parameter, CAS led to screw insertion as accurate as with fluoroscopic control, with a reduction of radiation time up to 93%.

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