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Ankle Varus Deformity

Discussion

  • varus deformity of the ankle may follow distal tibial fracture or distal tibial epiphyseal frx;
    • deformities due to distal tibial epiphyeal injuries are often progressive;
    • deformities due to tibial plafond injuries are usually static (from malreduction at the time of the original procedure);
  • left untreated, the varus deformity may lead to DJD of the ankle;
  • normally the average TAS angle (tibial shaft to tibial joint angle on an AP radiograph) measures 88 deg (in a sample Japanese population);
  • the avgerage TLS angle (tibial shaft to tibial joint line angle on the lateral view) measures 81 deg (in Japanese population);
  • indications for surgery:
    • when the TAS angle is less than 80 deg, and the patient is symptomatic despite non operative treatment;

Technique

(from Takakura, et al (1998).

  • involves a one stage opening wedge valgus osteotomy;
    • since the affected leg is most often short, an opening wedge rather than a closing wedge osteotomy is indicated;
  • fibular osteotomy:
    • performed through a small lateral incision;
  • tibial osteotomy site:
    • use a longitudinal medial incision;
    • make the osteotomy parallel to the joint line, but leave a small posterolateral portion of the distal tibia intact (for stability);
    • in adults attempt to place the osteotomy site at the level of the initial fracture;
      • if this is not possible then make the osteotomy cut 5 cm above the distal end of the medial malleolus;
    • in children, consider making the osteotomy cut about 2-3 cm proximal to the physis;
    • make the opening wedge correction, and then use calipers to determine the necessary width of the bone graft;
    • K wires can be used to stabilize the graft;
  • controversies:
    • physeal bone-bridge resection
    • ipsilateral and contralateral growth plate arrest;
      • in situations in which bone bridge resection is not advisable, growth plate excision is indicated;
      • be sure to arrest the fibular growth plate as well (which contributes to varus deformity);
  • complications: some patients will note a decrease in ROM