- See: - Radiographic Features of Talocalcaneal Coalition
- Discussion:
- demonstrates the body of the calcaneus, middle facet of the sub-talar Joint and the sustenaculum tali;
- Talocalcaneal Coalition:
- x-ray appearance of two facets either in same plane or at an angle greater than 20 deg to each other suggests coalition;
- angulation of middle facet by more than 20 deg off the horizontal is consistent with a coalition, even if the joint space is open;
- Technique:
- patient is erect;
- sole of the foot is flat on the cassette;
- central beam angled 45 deg toward the midline of the heel;
- 35 or 55 deg is used to better visualize other facets of sub-talar joint;
- since nl posterior and middle facets are in parallel planes at approx 45 deg to the sole of the foot, these two areas are identified on Axial (Harris, or ski jump) view (described by Korvin in 1933);
- effectiveness of Harris View for visualizing subtalar joint is enhanced by measuring angle of posterior facet on lateral radiograph and then adjusting Harris View to this inclination