Test 13

Navicular osteonecrosis (eponymously known as Köhler’s disease) is an uncommon condition whereby mechanical compression of the developing navicular is thought to result in ischaemia, osteonecrosis, and osteochondrosis (defined as aseptic ischaemic necrosis from focal disruption of endochondral ossification which usually involves epiphyseal ossification centres). It is typically visualised between the ages of 3 and 7 years and affects boys more often than girls. Radiographs may demonstrate sclerosis, rarefaction (thinner, reduced density), collapse or fragmentation of the navicular, as in the case above. Management is usually conservative.