Köhler's Disease

Köhler's disease is a self-limiting osteochondrosis of the tarsal navicular in young children, in which the bone passes through a phase of avascular necrosis (AVN) and then reossifies to a normal shape.

It is uncommon, classically affects boys aged around 4 to 7, and usually involves 1 foot. It presents as a painful limp with tenderness over the midfoot. The radiographs can look alarming, but the long-term outcome is excellent.

The priorities are to exclude the serious causes of a painful limp, avoid over-calling a normal ossification variant, and reassure the family while managing symptoms.

The navicular sits at the apex of the medial longitudinal arch, between the talus and the 3 cuneiforms, and carries high compressive load. It is the last tarsal bone to ossify, earlier in girls than boys. A late-ossifying bone under high load is central to the disease.

Its central third is a relative vascular watershed. Compression of the immature bone between the talus and the cuneiforms is thought to compromise small perforating vessels, causing transient ischaemia of the ossific nucleus. The bone becomes sclerotic, flattened and sometimes fragmented, then reossifies and remodels as the surrounding cartilage keeps growing.

Köhler's disease is distinct from Müller-Weiss disease, a separate navicular osteonecrosis seen mainly in adults.