Die atypische Femurfraktur als Sonderfall der Alterstraumatologie

Zusammenfassung

Atypische Femurfrakturen (AFF) stellen einen Sonderfall in der Alterstraumatologie dar und machen im Hinblick auf die Gesamtzahl der Femurfrakturen nur einen geringen Anteil aus. Im Gegensatz zur klassischen Fraktur des proximalen Femurs sind AFF subtrochantär bzw. im Schaftbereich lokalisiert, entstehen häufig ohne adäquates Unfallereignis und zeigen charakteristische Merkmale im Röntgenbild. In vielen Fällen kommt es zu einem bilateralen Auftreten von AFF. Klinisch besteht oftmals Tage bis Monate vor der Diagnose einer AFF ein Prodromalschmerz im entsprechenden Bein bzw. der Leistengegend. Durch die American Society for Bone and Mineral Research (ASBMR) wurden Haupt- und Nebenkriterien zur Definition einer atypischen Femurfraktur erstellt. Diese sollen die Diagnosestellung erleichtern. Zu den Hauptkriterium zählen u. a. die peri- oder endostale Verdickung der lateralen Kortikalis sowie das Fehlen einer Frakturtrümmerzone. Um eine Fraktur als AFF zu definieren, müssen mindestens 4 der 5 Hauptkriterien erfüllt sein. Es gibt Evidenz für eine Korrelation zwischen AFF und der (Langzeit-)Einnahme von Bisphosphonaten. Atypische Femurfrakturen können jedoch auch ohne Bisphosphonateinnahme auftreten. Ist eine AFF diagnostiziert, sollte die Bisphosphonattherapie pausiert werden. Für die Therapie unterscheidet man zwischen kompletter und inkompletter Fraktur. Komplette AFF werden operativ zumeist mit einer Marknagelosteosynthese stabilisiert. Inkomplette Frakturen können konservativ therapiert werden – es gibt jedoch eine hohe Versagerrate mit Progress in eine komplette Fraktur, sodass bei persistierenden Schmerzen eher die prophylaktische Marknagelosteosynthese empfohlen wird. Der Behandlungsverlauf nach bisphosphonatassoziierten AFF ist häufiger mit perioperativen Komplikationen vergesellschaftet als die Behandlung von „typischen“ Femurfrakturen. Somit ist die Kenntnis der Pathophysiologie und der Therapieoptionen der Schlüssel zur erfolgreichen Behandlung dieser Verletzung.

Abstract

Atypical femur fractures (AFF) are a special case in geriatric traumatology and with regard to all femur fractures they are really rare events. In contrast to typical fractures of the proximal femur, AFF are located in the subtrochanteric region or the femoral shaft. They occur after minimal trauma and have a distinct configuration and radiographic appearance. Bilateral AFF are not uncommon. Patients often suffer from prodromal pain in the corresponding leg or groin long before the AFF is diagnosed. The American Society for Bone and Mineral Research (ASBMR) has created major and minor criteria for helping to diagnose an AFF. Major features include e.g. the localized perosteal or endosteal thickening of the lateral cortex and the lack of a comminution zone. Four of five major features are needed to define a fracture as “atypical”. There is some evidence for an association between AFF and the long-term bisphosphonate use but they can also occur without any bisphosphonate therapy. After diagnosis of an AFF, you should stop bisphosphonate medication immediately. To choose the appropriate therapy, itʼs necessary to distinguish complete and incomplete fractures. Complete atypical femur fractures are treated surgically – intramedullary nailing is the method of choice. Incomplete fractures can be treated conservatively but this is often associated with high failure quote and progress to complete fracture. In case of persisting pain, prophylactic nailing is recommended. Overall the therapy, especially of the AFF with bisphosphonate history is associated with a high rate of complications. Therefore, the knowledge of the pathophysiology and treatment options is essential for a successful treatment in these cases.

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