It is diagnosed both by clinical and radiological findings, only occurring in young children with an approximate mean age of 4.5, although the exact age range and mean is debated in the literature. This is not the case in a navicular which becomes visible on x-ray later on here the navicular usually has an irregular outline, increased density and is often fragmented or flattened. There is usually one main artery and vein supplying the navicular nucleus while many other arteries partially contribute to it in a lesser manner in essence, an anastomosis network. Later-appearing naviculars tend to ossify from multiple ossification centres and as a result of the overlap occurring between these ossification centres, the navicular produces a false perception of increased bone density. The exact cause of Kohler s disease is unknown and subject to debate.
Young boys do, however, seem to be affected more than young girls.
Other likely factors include altered function of hypophyseal, thymus, or thyroid glands, ie. similar to the bony lesions occurring at the epiphyses eg. It does not have a tendency to occur in particular foot types ie. It is at this time where the nucleus of the navicular is subject to greatest stress at times of weightbearing, especially so in a heavier child, predisposing the child to trauma. There will be associated erythema, tenderness, warmth, and swelling in the area of the navicular, although this is not a definite feature. A definite feature is pain since it is this which alerts the patient to a potential problem.