External Fixation Systems

Pin CharacteristicsIn external fixation the global stiffness, stability and elasticityof frames is strongly influenced by the configuration i.e. thenumber of rods, pin placement, pin diameter and the numberof pins.Pin PlacementAbigger distance between pins induces a higher frame stabilityi.e. it is recommended to place the pins in the extreme holes ofthe clamps when it is possible.Pin DiameterThe choice of pin diameter should be determined by takinginto account all the following parameters:StabilityAnatomical locationRigidity / elasticitySize of boneSoft tissuesPin BiomechanicsThe effect of pin diameter on axialframe stiffness. †N/m 10 -32’000When comparing axial frame stiffness a 1mm increase in pindiameter will approximately double frame stiffness.However, as a general rule, we can consider that:Minimum pin shaft diameter = Cortical bone thickness / 2364.8860.05 mm1,675.46 mm2’0002’0002’000Number of PinsThe number of pins is dependent on4 mm2’000Efforts on the frame (lengthening)The frame stiffness to be reachedBy adding pins, the frame stiffness will be increased.InstrumentationDrill sleeves are imperative in order to protect soft tissues.Don’t tap the trocar. Turn anticlockwise for a few turnsto create an insertion point and then proceed clockwise.Drill sleeves can be utilised together with the clampsor with the insertion guide.Use Stryker ® Trauma Drill Brace!!Apex ® Pins have an integrated safety feature to reducepotential breakage of the pin tip. Apex Pins must be usedwith a Stryker ® Trauma drill brace to effect this feature.Increased drilling sensitivity.Better feeling of the second cortex.Integrated safety featurereduces potential tip breakageunder high insertion forces7