Freiberg infraction

2nd metatarsal head osteonecrosis or osteochondral fracture

Mottled sclerosis and lucency

flattening of head

bone marrow edema

Smillie classification

Stage I: epiphyseal fissure surrounded by sclerosis

Stage II: mild subchondral collapse

Stage III: prominent medial and lateral projection of MT head

Stage IV: MT head projection fracture, central area of collapse

Stage V: extensive articular surface collapse, osteoarthritis