AP of Ankle 

- Discussion:
    - is taken in line with the long axis of the foot;
    - entire fibula should be included if there is lateral joint tenderness above the joint line;
    - this view is used to evaluate medial & lateral malleolus anterolateral tibia and proximal fibula;
    - osteochondral frx of distal tibia and talus;
    - articular congruity & measurements of relative mallellar length, syndesmotic integrity, and talar shift;

- TibioFibular overlap:
    - on AP view indicates a proper syndesmotic relationship;
    - space between medial wall of fibula & incisural surface of tibia should be less than 5 mm;
    - anterior tubercle of tibia should overlap the fibula by at least 6 mm or 42% of fibular width;

- Stress Views:
    - routine AP radiographic may show no lateral displacement of the talus, but an x-ray made when the ankle is stressed into supination and external rotation will show displacment and tilting of the talus in the mortise;

- External Rotation Stress Test:
    - evaluates syndesmotic & deep deltoid ligament;
    - on AP view differnece in width of superior clear space between medial and lateral side of the joint should be < 2 mm;
    - these are static measurements of the talar position;
    - in normal ankle, talus may tilt up to 5 deg w/ inversion stress;
    - measurements of talar tilt using stress x-rays are used to evaluate lateral ligament stability;

- Technique:
    - patient is supine with the heel resting on the cassette;
    - foot is in neutral position, sole is perpendicular to leg & cassette;
    - central beam is directed vertically to the ankle at the midpoint between the malleoli

Original Text by Clifford R. Wheeless, III, MD.

Last updated by Data Trace Staff on Monday, October 29, 2012 9:48 pm