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Synthes Uniplanar External Fixator for Tibial Frx



- See: Synthes Hybrid Fixator

- Discussion and Initial Considerations

- Operative Technique:
    - may be combined w/ circular wire fixators;
    - reduction:
          - in most cases, the fracture should be reduced prior to fixator application;
    - planning the configuration:
          - enhancement of fixator stability;
          - safe zones for pin insertion:
          - plane of the fixator:
                - consider the need for soft tissue coverage and position the fixator in way that not to interfere with free flap coverage;
                - because major bending moments on tibia during gait are in saggital plane, placment of fixator pins and frame near the saggital plane improves stability;
                        - rigid quadrilateral frames w/ transfixation pins in coronal plane are somewhat flexible in the saggital plane;
          - use external fixator tube assembly to confirm the position of the proximal and distal pins;
                 - it is embarrassing to find out midway thru the case that the fixation bars are not long enough to span the proximal and distal pins;
          - first pin is inserted into proximal fragment close to the joint;
          - second pin is inserted into distal frag in same plane, close to distal joint;
          - placing this in cortical bone may provide better purchase, but sometimes dense cancellous bone of tibial pilon must be used;
          - fixator tube is assembled to both proximal and distal half pins;
          - frx is reduced & connecting devices are tightened;
    - incision:
          - Schanz Screw and Insertion Pins:
          - all pins are placed through stab wounds
          - 10 mm incision is made at chosen site using soft tissue guide;
          - if cancellous site is chosen, hole is drilled only with the 3.5 mm drill, and a 5.0 mm Schanz screw is used;
    - drilling technique:
          - all half pins are predrilled using fresh, sharp drills
          - predrilling reduces bone temperature by approximately 50%;
          - hand drilling or low speed drilling is preferred;
          - all drilling and pin application is done thru sleeve trochar units to prevent winding and necrosis of subcutaneous tissues;
          - 3.2 mm drill is used for 5 mm half pin (Synthes System)
          - drill through both cortices;
          - tented skin is released so no skin pressure is exerted near pin site;
    - final fixation
          - w/ triple drill guide placed thru inner clamps, & inner two 5.0 mm cortical half pins are inserted at least 1 cm proximal or distal to frx site;
          - ensure that pins are well away from areas of comminution;
          - clamps are placed close to skin for frame strength, but at least one inch away to permit wound access