Screw Fixation for Ankle Arthrodesis:

Discussion:
    - select appropriately sized 6.5 mm or 7.0 mm canulated screw (threads must cross the frx site);
    - consider direction of maximal deformity and displacment;
    - guide wire insertion (for cannulated screw insertion);
          - K wire is inserted from deep w/ in sinus tarsi (talar neck) to enter into the central-anterior aspect of the tibia;
                - this K wire continues onto medial aspect of tibia
                - insertion in this direction will keep screw threads in the tibia rather than the talus;
                - alternative is a K wire inserted from the medial malleolus into the talus (screw threads left in talus); 
          - home-run screw:
                - posterior malleolus into the neck of the talus; 
                - if major deformity is anterior talar displacment (as may be seen with plafond fractures), then first screw should correct displacment (such as screw insertion
                         from the posterior tibia into the talus) inorder to maximize coverage of the talus within the mortise; 
                - note that at level of penetration of this screw through the skin, the sural nerve typically courses along the lateral border of achilles tendon;
                - references:
                        - Risk to Neurovascular Structures Using Posterolateral Percutaneous Ankle Screw Placement: A Cadaver Study 
    - intraoperative x-ray before closing wound to ensures optimal bony contact, alignment, secure fixation, and preservation of sub-talar joint; 
    - controversies: 
          - should the fibula be included in the fixation?

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References: 

          - Ankle arthrodesis using internal screw fixation.
          - Ankle arthrodesis with vertical Steinmann's pins in rheumatoid arthritis.
          - Transarticular cross-screw fixation. A technique of ankle arthrodesis.
          - Arthrodesis of the ankle with cancellous-bone screws and fibular strut graft. Biomechanical analysis.
          - An analysis of talar surface area occupied by screw fixation in ankle fusions.
          - Ankle arthrodesis placement of cannulated screws.
          - Stability of an ankle arthrodesis fixed by cancellous-bone screws compared with that fixed by an ex fixator. A biomechanical study.
          - Outcome after single technique ankle arthrodesis in patients with rheumatoid arthritis.
          - Ankle arthrodesis using internal screw fixation.
          - Wolf blade plate ankle arthrodesis.
          - Use of internal compression in arthrodesis of the ankle.
          - Ankle arthrodesis with an anterior tension plate.
          - Posterior internal compression arthrodesis of the ankle.
          - Ankle arthrodesis placement of cannulated screws.   Kish G.  Foot & Ankle.  14(4):223-4, 
          - Clinical Outcome of Arthrodesis of the Ankle Using Rigid IF w/ Cancellous Screws.  MT Monroe et al.  FAI.  Vol. Vol 20. No 4. Apr 1999. p 228.