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Ankle Arthrodesis

(see also: Sub-Talar Fusion, Tibial-Talar-Calcaneal Fusion

Discussion and Outcomes:


Exam:

  • perform an Allen test for the foot vasculature;
  • note function of posterior tibial pulse while the dorsalis pedis pulse is occluded and vice versa;
  • check external rotation of ipsilateral hip, since ankle fusion patients tend to hold their lower limb in external rotation in order to
    progress through stance phase of gait;
  • note amount of subtalar and transtalar mobility, since this correlates with better postoperative functional scores and satisfaction;

Radiographic Studies:


Non Operative Treatment Options:

  • prior to ankle arthrodesis, the patient should be given the option of wearing either a below knee cast or CAM walker;
    • a good candidate for ankle arthrodesis is a patient with documented ankle arthritis, who has obtained pain relief from a CAM
      walker, and who does not wish to wear a CAM walker for a lifetime;
    • patients can use a double upright AFO w/ a patellar tendon bearing support which partially unload ankle joint during gait;
      • adding a rocker bottom orthosis to the shoe will improve transition throughout stance phase;

Open Exposure for Ankle Fusion:


Arthroscopic Arthrodesis:


Internal Fixation w/ Cannulated Screws


External Fixation:


Bone Grafting


Post operative management:

  • note that even rigid fixation, 8 deg of flexion-dorsiflexion and 7 deg of torsional motion may occur;
  • avg immobilization time until all casts are removed is 7-8 months;
  • allow unprotected wt-bearing only after bone trabeculation is seen across osteotomy site;
    • anteromedial portion of distal tibia undergoes cyclic tension and compression during walking;
    • tension in anteromedial tibia occurs after heel strike, & compression occurs after heel off;
    • reverse of this cycle would be expected to occur in the posterolateral aspect of the tibia;
    • walking does not provide uniform compression across an ankle arthrodesis site, and probably should be avoided until there is
      trabeculation across frx site;
  • SACH will cushion impact of initial ground contact and help permit initiation for rocker bottom type action during ground contact
    in pts who have lost ability to plantar flex from heel strike to foot flat;

    • rocker sole helps tibia pass over foot w/ platar flexion from foot flat to liftoff;
  • patients with greater tarsal mobility will have better postoperative foot mobility and higher satisfaction;
  • Heel-to-toe Rocker Sole
    • sole is shaped with an accentuated rocker angle at both the heel and toe
    • increase propulsion at toe-off, decrease pressure on heel strike, and reduce the need for ankle motion;
    • this type of heel is also useful for patients with severe claw toes, and those with heel ulcers

- Complications of Ankle Arthrodeses:

 


References: