Ankle and Foot Imaging Atlas

1. Navicular-cuneiform (first cuneiform is medial)
   
2. Cuboid is lateral
   
3. Boehler's angle 28-40 degrees (ant and post superior surface of the calcaneus)
   

1. Sesamoids
1. Two sesamoids at the volar aspect of the first metatarsal head
1. May be bifid
2. May be seen at the 1IP, 2MTP, 5 MTP
2. Os tibiale externum
3. Os intermetatrsium
4. Os peroneum => in the peroneus longus tendon
   
5. Talar beak
6. Radiolucent defect  in the epiphysis of proximal phalanx of great toe may be a normal variant
7. Nutrient artery canal => usually seen in one projection only (as opposed to fracture).

1. Talocalcaneal coalition
1. Obliteration of the middle facet joint
2. C sign
3. Beaking of the talus
   
2. Calcaneonavicular coalition
1. Anteater sign
2. Tapering of navicular
3. Articulating surface of navicular is larger then articulating surface of talus
3. Club foot
1. Hindfoot equinus
2. Hindfoot varus (talocalcaneal angle < 15 degrees)
   
3. Forefoot varus
   

1. Axial view => patient supine, tube angled 45 to the head and centered on calcaneonavicular joint.
2. Calcaneal fractures are associated with thoracolumbar spine fractures in 10% of the cases.
3. Beak fracture of calcaneal tuberosity => avulsion from pull by Achilles tendon

1. Jones fracture => base of 5th metatarsal, results from twisting and inversion of the foot
2. Lisfranc fracture/dislocation
1. Homolateral vs divergent
1. Homolateral => lateral dislocation of lateral four metatarsals
2. Partial incongruity
   
3. Divergent => lateral dislocation of lateral four metatarsals and medial dislocation of first metatarsal
4. Therapy
1. If displacement is < 2mm, closed reduction is performed
2. If displacement is > 2mm, ORIF is performed
   
1. Lisfranc ligament
1. If torn => may not have fracture of 1st cuneiform and 2nd metatarsal
2.  Complications: cuboid fracture from impaction by dislocated fifth metatarsal, fractures of bases of lateral four metatarsals, first cuneiform fracture from impaction in divergent Lisfranc injury
3. Stress fracture is most common in 3rd metatrsal
4. Metatarsal - tarsal dislocation is usually lateral

1. Dislocations are usually dorsal or volar
2. On frontal view, joint space loss may suggest dilocation

1. Most commonly develops between third and fourth toes

1. Fungal or actinomyces infection
2. Sinus tracts
3. Bone involvement