What is Kohler's Disease of the Navicular Bone?

The arch of the foot is an important structure thats integrity is needed for good biomechanics of the foot. Like any engineering structure such as an arch, the element that is at the top of the arch bears a lot of loads. In the foot, the element that is at the top of the arch is the navicular bone. This means that when we are bearing weight that navicular bone is subject to a lot of loads. In normal circumstances that bone is made and built to take that load and can adapt to increased loads if given time. However, sometimes things can go wrong, and the bone breaks down. In an athlete that could be something like a stress fracture of the navicular bone. A particular problem of the navicular bone that happens in children is a condition known as Kohler’s Disease. This more often affects boys than girls and affects children between the ages of 3 to 9 with around age 5 being the most common age. For some reason the navicular is temporarily ‘softened’ and gets compressed by weightbearing forces coming from the bone being at the top of the arch.

Typically, only one foot is affected, and it is very unusual to have both feet affected at the same time. There is a vague pain over the top of the foot in the midfoot area and a tenderness can be localised over navicular on palpation. It is quite common for the child to limp because of the pain and they can avoid trying to turn the foot inwards as that can be painful. Classically and typically on x-ray there is a characteristic narrowing of navicular bone with an irregular increase in the density appearance of the bone. This is often obvious and quite pronounced. In the early acute stages of Kohler’s Disease, it is important to get weight off the foot. They need to stop all sport and running around at school in the short term as the loads on the bone needs to be reduced to a minimum. Things like a moon boot can be used to help restrict activity. Sometimes crutches may be needed to get all weight off the foot. If the initial symptoms are not too bad or things have settled down from that acute phase, limited weightbearing can be used and foot orthotics are very helpful to support the arch of the foot and decrease loads on the bone to permit increased levels of activity over time. If the problem is more serious, then a lower limb cast is often needed to protect the foot. The structural alignment of the arch really does need to be protected with the use of foot orthotics to prevent a reoccurrence of the Kohler’s Disease or the development of any sort of deformity from damage to the bone while the condition was active. The long-term prognosis of most cases is usually pretty good and most have no long-term problems. Those who did have Kohler’s disease when they were young do need to be conscious of any arch problems developing over time.