• Mark Lenz, Stephan Marcel Perren, Boyko Gueorguiev, Dankward Höntzsch, and Markus Windolf.
• AO Research Institute Davos, Clavadelerstrasse 8, CH-7270 Davos-Platz, Switzerland; Dept. of Trauma, Hand and Reconstructive Surgery, University Hospital Jena, Erlanger Allee 101, D-07747 Jena, Germany. Electronic address: mark.lenz@med.uni-jena.de.
• Clin Biomech (Bristol, Avon). 2013 Nov 1;28(9-10):988-93.

BackgroundReliable periprosthetic fracture treatment needs detailed knowledge on the mechanical behavior of the fixation components used. The holding capacity of three conventional fixation components for periprosthetic fracture treatment was systematically investigated under different loading directions.MethodsLocking compression plates were fixed to a 7 cm long part of diaphyseal fresh frozen human femur with either a single 1.7 mm cerclage cable, a 5.0mm monocortical or a bicortical locking screw (n=5 per group). Constructs were loaded in lateral, torsional and axial direction with respect to the bone axis in a load-to-failure test. Corresponding stress distribution around the screw holes was analyzed by finite element modeling.FindingsBoth screw fixations revealed significantly higher stiffness and ultimate strength in axial compression and torsion compared to the cerclage (all P<0.01). Ultimate strength in lateral loading and torsion was significantly higher for bicortical screws (mean 3968 N SD 657; mean 28.8 Nm SD 5.9) compared to monocortical screws (mean 2748 N SD 585; mean 14.4 Nm SD 5.7 Nm) and cerclages (mean 3001N SD 252; mean 3.2 Nm SD 2.0) (P≤0.04). Stress distribution around the screw hole varied according to the screw type and load direction.InterpretationFixation components may be combined according to their individual advantages to achieve an optimal periprosthetic fracture fixation.© 2013.

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