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Scaphoid Nonunion: 3.5 mm Cannulated Screw Insertion

- Discussion:
    - indicated for patients w/ delayed unions or non unions of scaphoid waist;
    - cautions: distal-waist fractures may not be amenable to this form of fixation if the screw threads cross the fracture site;

- Technique:
    - see: volar surgical approach:
    - may result in shorter healing times than the Herbert screw;
    - scew will be inserted from distal to proximal;
    - trapezoidal shaped cortico-cancellous iliac crest bone graft is
           - the inner surface of the scaphoid is notched to allow insertion of the graft;
           - the dorsal surface is left intact and acts as a hinge as the scaphoid hump-back deformity is corrected;
    - consider using a rongeur to remove a small portion of non articulating portion of trapezium inorder to allow a more dorsal insertion of guide wire;
    - K wire is then passed w/ care to place it in the central 1/3 of the proximal pole of the scaphoid on both AP and lateral radiographs;
           - as pointed out by Trumble, et al (1996), key to a successful result is placement of guide wire in central third of proximal pole of scaphoid;
           - these authors emphasized that the guide wire needs to be placed in the central third of proximal scaphoid on both PA, lateral, and oblique radiographs;
    - once this K wire is measured, drive it across the radiocarpal joint for stabilization;
    - 2nd K wire is inserted into radial aspect of the scaphoid for stabilization;
    - carefully measure the depth of the cannulated screw guide wire (it is important for the screw threads to completely cross the frx site);
    - cannulated screw is inserted in the usual manner;
    - in some cases, there will be partial scaphoid collapse during screw insertion;
    - Trumble et al 1996, left the second stabilizing K wire in place for 6-8 weeks postop;
    - post operatively, below elbow spica cast is worn for 6-8 weeks;
    - average time to union should be about 3-4 months

Non-union of the scaphoid. Treatment with cannulated screws compared with treatment with Herbert screws.

Corticocancellous grafting and an AO/ASIF lag screw for nonunion of the scaphoid. A retrospective analysis.

A technical note on percutaneous scaphoid fixation using a hybrid technique.