Kohler’s disease of the navicular is a condition in which the navicular bone loses its blood supply. This causes pain in the front of the foot. It occurs mostly in boys aged 4 to 7.
The disease is self-limiting, and symptoms generally disappear after several months. Treatment includes taking non-steroidal anti-inflammatory medication, using arch supports and wearing a short leg cast.
Symptoms
Kohler’s disease is a condition in which the bone in front of the ankle (navicular) loses its blood supply and dies. The condition occurs in children, typically between the ages of three and seven years. It is a common cause of foot pain in boys and often affects the left side more than the right.
The navicular bone is small but important for the function of the foot and ankle. Several ligaments and tendons connect to the bone, which allows for effective walking by helping control the position of the arch of the foot. It is susceptible to stress fractures and can also be affected by repetitive stress such as in running or jumping.
Symptoms of the condition are tenderness of the arch area of the foot and a painful sensation with weight bearing, particularly while walking or running. Children may begin to favor the lateral (outside) of the foot for walking, and may also develop a limp. In more severe cases, the navicular bone can become flat and fragmented. Diagnosis is made with a physical examination and x-ray imaging of the foot. X-rays will show a flattening, and a comparison of the navicular on the affected and unaffected sides will demonstrate that the bone has changed shape and consistency.
Treatment of Kohler’s disease is typically non-operative. Over-the-counter non-steroidal anti-inflammatory medications such as ibuprofen can help relieve pain and reduce swelling. Resting the foot, changing footwear, avoiding activities that aggravate the condition, and physical therapy focused on calf stretching and strengthening can also help. Occasionally, a short leg walking cast can provide immobilization for the irritated bone and can significantly decrease symptoms.
The condition usually resolves with conservative management and does not recur, but children with this problem should be encouraged to participate in balanced physical activity that promotes healthy feet and legs. It is particularly important to limit high-impact sports like running, jumping, and contact sports that put significant stress on the feet and ankles. Encouragement to participate in low-impact activities that promote cardiovascular fitness, such as swimming and biking, is also appropriate.
Diagnosis
Affected children complain of pain and tenderness in the arch area of the foot when walking. They tend to walk with a limp and will often compensate by placing weight on the outer edge of their foot. This is because the middle part of the arch (navicular bone) is painful to bear weight on.
This condition is a form of avascular necrosis, where the blood supply to the tissue dies due to limited oxygen and nutrients to the bone tissue. The navicular bone is unique in this condition because it lacks the vascular foramina found in other bones, and is not protected by surrounding hard tarsal bones. This makes the navicular bone vulnerable to injuries, especially when it is squished between the harder, already ossified talus and cuneiform bones.
X-rays show the affected navicular bone to be flattened, sclerotic and fragmented. The diagnosis is made by a physical examination, excluding any other causes of the child’s symptoms such as infection. The child is placed in a below-knee weight bearing cast and treated conservatively. Typically the child will be able to return to all normal activities with a full recovery within six weeks of treatment.
Pediatric orthopedics commonly see Kohler disease in children between the ages of 5 and 7 with boys being five times more likely to be affected than girls. It is believed that Kohler disease is due to an injury to the navicular bone in early childhood, which disrupts the blood vessels supplying the bone before it has completely ossified. This disruption results in a temporary loss of blood supply, which leads to tissue damage and delayed ossification of the bone.
A specialized short leg cast, ibuprofen and supportive shoes usually improve the symptoms of Kohler disease. The patient should be encouraged to rest and use ice on the area of the foot that is painful. If the symptoms persist, an MRI or CT scan should be considered in order to exclude a different problem such as tarsal coalition. The prognosis is excellent for Kohler disease patients. The symptoms should resolve within six months and radiographic resolution will occur in 18 to 24 months.
Treatment
Kohler’s disease of the navicular occurs when the navicular bone loses its blood supply temporarily and sustains a state of bone death (avascular necrosis). This condition primarily affects young boys, however it can occur in girls as well. Symptoms include pain in the foot over the arch or inside aspect of the foot, warmth in the area, tenderness to touch and an antalgic limp. The limp is most prominent when putting weight on the affected side of the foot and may become worse with activity.
X-ray imaging typically confirms the diagnosis by showing characteristic changes in the navicular bone, including flattening and fragmentation. The navicular bone also shows patchy sclerosis and increased radiodensity on x-ray. CT and MRI are rarely used to diagnose Kohler’s disease of the navicular, but they can help in planning treatment.
It is not known what causes Kohler’s disease of the navicular, although it is suspected that there are multiple factors that combine to make the navicular bone susceptible to avascular necrosis. This may include mechanical stress or repetitive strain during sports that aggravate the navicular’s dual blood supply, delayed ossification and possible genetic predispositions.
Children with Kohler’s disease usually see significant improvement with conservative management, which often includes NSAIDs (such as ibuprofen) and rest. Arch supports and short-term cast immobilization can also help reduce symptoms and improve function.
Kohler’s disease is a self-limiting condition, and most patients will resolve within several months to a year as the navicular bone heals and returns to normal. This will lead to a return of normal walking without any long-term problems.
Surgical treatment of Kohler’s disease involves decompression and reconstruction of the blood circulation to the navicular bone. We performed navicular decompression and vascular implantation in 3 patients with Kohler’s disease between October 2013 and July 2015. In all 3 cases, the procedure was successful and there were no recurrent symptoms. This approach offers a simple, cost-effective, and minimally invasive method for treating Kohler’s disease of the navicular. Further research is needed to evaluate the effectiveness of this technique and its effect on prognosis.
Prognosis
Kohler’s disease is a rare condition of avascular necrosis in the navicular bone, located right in front of the ankle on the inside foot. It primarily affects young boys and occurs between the ages of 4 and 7. The cause is unknown but we suspect it can be due to poor blood flow to this area of the foot. Since the navicular bone is an area that develops later than most bones in the body, it tends to have poorer vascularity and therefore can be more susceptible to developing this type of osteonecrosis.
The prognosis is excellent with proper treatment. This includes resting the foot, application of a short leg walking cast to provide support and to help reduce pressure on the navicular bone and non-steroidal anti-inflammatory medications (such as Motrin, Advil and Naproxen) for pain relief.
Occasionally, the navicular bone may need to be removed (navicular osteotomy). This is usually done by making a small incision on the bottom of the foot and then using a drill to create a hole. This allows the surgeon to place a graft and restore the blood supply to the navicular bone. This typically helps relieve symptoms and prevents recurrence of the navicular disease in the future.
A careful history and physical examination is the first step in diagnosing Kohler’s disease of navicular. Often, x-rays will reveal the bone deformities and abnormalities associated with Kohler’s disease. Basic labs, including WBC and CRP (C-reactive protein), can also be helpful in confirming the diagnosis. Often, pediatric patients with Kohler’s disease do not have elevated inflammatory markers and therefore will not be diagnosed as having an infection of the bone.