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Supination – Adduction Injuries of the Ankle

 

- Discussion:
    - equivalent to Weber type A fracture;
    - transverse avulsion type fracture of the fibula (short oblique or transverse) below the level of joint or tear of the lateral collateral
             ligaments and vertical fracture of the medial malleolus;
    - mechanism:
          - supination of foot is combination of inward rotation at ankle, adduction of the hindfoot, and inversion of the forefoot;
          - as foot supinates the lateral structures tighten;
          - continued supination & adduction force may rupture portions of lateral collateral ligaments or may avulse distal fibula,
                  resulting in transverse frx below the level of intact syndesmotic ligaments;
          - subsequently, adduction forces talus against the medial side of the joint, resulting in vertical frx of medial malleolus;
    - associated injuries:
          - osteochondral frx of talus or injury to its articular surface;
          - marginal impaction fractures:
                   - in the report by McConnell and Tornetta, the authors searched through 800 ankle fractures seen at the authors' institution,
                           and identified 44 (5 percent) of which were of the supination-adduction pattern;
                           - 19 of these injuries had displaced vertical medial malleolus fractures, of which eight (42%) showed marginal
                                      impaction of the tibial plafond;
                           - all 8 patients underwent ORIF with elevation of impacted articular component and had good to excellent functional
                                      outcome with no arthritis on radiograph at the time of the most recent follow-up;

- Radiographs:

- Non Operative Treatment:
    - frequently does well w/ closed reduction;

- Operative Treatment:
    - may be fixed w/ 2 malleolar screws & single fibular screw;
    - fibula:
            - K wires, 1.6 mm & figure of 8 tension band wires;
            - for larger frag use one third tubular plate;
    - operative treatment of vertical malleolar frx;
            - medial surface is inspected for articular crush of tibial surface or talar dome;
            - if frx is w/o comminution, then consider screw fixation (usually w/ two screws);
            - 4.0 mm cancellous bone screws, or 4.5 mm cannulated screws as lag screws for medial malleolus;
            - w/ severe displacement and/or comminution of the verticle medial malleolar fragment, consider need for a medial butress
                      plate, esp if there is a varus deformity of talus



Supination-adduction injuries of the ankle in children--radiographical classification and treatment.

Marginal Plafond Impaction in Association With Supination-Adduction Ankle Fractures: A Report of Eight Cases