- 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 thru 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;
Results of opening wedge osteotomy for the treatment of a post traumatic varus deformity of the ankle.
Y. Takakura et al.
JBJS. Vol 80-A. No 2. Feb 1988. p 213.
Low tibial osteotomy for osteoarthritis of the ankle.
Results of a new operation in 18 patients.
Y Takakura et al.
JBJS Vol 77-B. (1). 1995. p 50-54.
