FIGURE 6-36. Middle talocalcaneal coalition: “C sign” (continuity between sustentaculum and talar posteromedial process, marked by arrowheads); associated findings are also seen (rounded lateral talar process and talar head beak).
FIGURE 6-37. Variant decreased densities. A: Hallux proximal phalanx diaphysis. B: Medial aspect of navicular. C: Calcaneal neutral triangle. D: Fifth metatarsal head medially and the geographic decreased density in the second metatarsal head (a bilateral presentation).
FIGURE 6-39. Variant increased densities in cancellous bone: Bone island. A: Hallux distal phalanx (arrowhead). B: Second metatarsal head (arrowhead). C: Central calcaneus (arrowhead). The semicircular increased density (arrow) in the medial tubercle is the superimposed lateral tubercle; it continues to the Achilles tendon enthesis posterosuperiorly as prominent trabeculations.
FIGURE 6-30. Interphalangeal joint synostosis: Third-, fourth-, and fifth toe DIPJs.
FIGURE 6-31. Intermediate cuneiform–metatarsal coalition. This finding was bilateral and symmetrical.
FIGURE 6-32. Rare intertarsal synostoses. Talonavicular coalition: A: Lateral view. B: Medial oblique view. Lateral cuneiform–cuboid coalition: C: Medial oblique view; there also is a fibrocartilaginous calcaneonavicular coalition.
FIGURE 6-33. Incomplete medial cuneiform–navicular coalition. Fibrocartilaginous (arrow): A: DP view. B: Lateral oblique view. Synostosis (in a different patient): C: DP view. D: Lateral oblique view.
FIGURE 6-34. Calcaneonavicular coalition. A: Osseous (arrowheads) (medial oblique view). B: Fibrocartilaginous (arrowheads) (medial oblique view). C: “Anteater” calcaneus (arrowheads) (lateral view).
FIGURE 6-35. Middle talocalcaneal coalition (obliquely oriented) calcaneal axial view. A: Osseous (arrowhead). B: Fibrocartilaginous (arrowhead).
FIGURE 6-36. Middle talocalcaneal coalition: “C sign” (continuity between sustentaculum and talar posteromedial process, marked by arrowheads); associated findings are also seen (rounded lateral talar process and talar head beak).
FIGURE 6-37. Variant decreased densities. A: Hallux proximal phalanx diaphysis. B: Medial aspect of navicular. C: Calcaneal neutral triangle. D: Fifth metatarsal head medially and the geographic decreased density in the second metatarsal head (a bilateral presentation).
FIGURE 6-38. Variant “punched-out” radiolucent densities (arrowheads). A: Second and third toe proximal phalanx distal diametaphyses. B: Calcaneal body, central location. C: Calcaneal lateral tuberosity, small.
FIGURE 6-39. Variant increased densities in cancellous bone: Bone island. A: Hallux distal phalanx (arrowhead). B: Second metatarsal head (arrowhead). C: Central calcaneus (arrowhead). The semicircular increased density (arrow) in the medial tubercle is the superimposed lateral tubercle; it continues to the Achilles tendon enthesis posterosuperiorly as prominent trabeculations.