<unk>  (also spelled "Kohler") is a rare bone disorder of the foot found in children between six and nine years of age. It was first described in 1908 by Alban<unk>  (1874-1947), a German radiologist. 
It is caused when the navicular bone temporarily loses its blood supply. As a result, tissue in the bone dies and the bone collapses.  When treated, it causes no long term problems. As the navicular bone gets back to normal, symptoms typically abate.
Köhler disease
Haff disease
Cyberchondria
Aguecheek disease
Upington disease
Bartholin's cyst
Bornholm disease
Grover's disease