Kohler Disease (Navicular Osteochondrosis)

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Kohler disease is a self-limiting avascular necrosis of the tarsal navicular occurring in children aged 3-7 years with a strong male predominance (5:1). The navicular is the last tarsal bone to ossify, making it vulnerable to vascular insufficiency during this period. Children present with antalgic gait, limping, and medial midfoot pain. Radiographs show the classic coin on edge appearance with sclerosis, fragmentation, and flattening of the navicular. The condition is bilateral in 25% of cases. Treatment is entirely conservative with a short leg walking cast or firm-soled shoe for 4-8 weeks. The prognosis is excellent with complete clinical and radiographic resolution expected within 6-18 months. No surgery is ever required.

Kohler disease (also known as navicular osteochondrosis or Kohler I disease) is a self-limiting avascular necrosis affecting the tarsal navicular in young children. First described by Alban Kohler in 1908, it represents a temporary disruption of blood supply to the developing navicular bone during a critical period of ossification.

Epidemiology

The condition predominantly affects boys aged 3-7 years with a peak incidence at 4-5 years. The male-to-female ratio is approximately 5:1. The navicular is the last tarsal bone to ossify (typically between ages 2-4 years), which is believed to be a key factor in its susceptibility. Bilateral involvement occurs in approximately 25% of cases, though often asymmetrically. There is no clear racial or ethnic predisposition, and the condition is relatively uncommon compared to other pediatric osteochondroses.

Pathophysiology

The navicular bone occupies a central position in the medial longitudinal arch, making it subject to significant compressive forces during weight-bearing. The etiology involves a combination of factors including delayed ossification, mechanical compression, and vascular insufficiency. During the ossification period (ages 2-4 years), the navicular is particularly vulnerable as its blood supply is tenuous. The developing bone must support the mechanical loads of walking while its vascular supply is establishing. This mismatch between mechanical demand and vascular capacity leads to ischemia, osteonecrosis, and the characteristic radiographic changes. The condition is self-limiting because once ossification completes and vascular supply matures, normal bone architecture is restored.

History

Children present with an insidious onset of limping and medial midfoot pain. Parents typically notice their child has developed a limp over days to weeks. The child may refuse to walk long distances or complain of foot pain with activity. Pain is localized to the medial midfoot and worsens with weight-bearing. Unlike septic arthritis or acute fractures, there is no history of trauma and the child remains systemically well. Some children may walk on the lateral border of their foot to offload the painful navicular.

Examination

Inspection: The child demonstrates an antalgic gait pattern, often favoring the lateral border of the foot. There may be mild swelling over the dorsomedial midfoot, though this is often subtle or absent.

Palpation: Point tenderness is present over the navicular bone on the medial aspect of the midfoot. The navicular is located approximately 2-3 cm distal to the medial malleolus.

Range of Motion: Midfoot motion is typically preserved but may be painful at extremes. Subtalar and ankle motion should be normal.

Gait: Classic antalgic gait with shortened stance phase on the affected side. Some children adopt a supinated foot posture to reduce pressure on the navicular.

Neurovascular: Normal - any neurovascular compromise should prompt consideration of alternative diagnoses.

Epidemiology and Presentation

Kohler disease presents similarly in Australian children as described internationally, predominantly affecting boys aged 3-7 years with medial midfoot pain and limp. The condition is relatively uncommon in Australian paediatric orthopaedic practice, representing a small proportion of referrals for the limping child. There are no specific Australian epidemiological data, but clinical experience suggests the incidence mirrors international reports.

Management Approach

Australian paediatric orthopaedic practice follows conservative management principles consistent with international evidence. Initial assessment typically occurs in paediatric emergency departments or general practice, with referral to paediatric orthopaedics for confirmation and management. Treatment with short leg walking casts or supportive footwear is standard, with excellent access to paediatric casting services at major children's hospitals including Royal Children's Hospital Melbourne, Children's Hospital Westmead, Queensland Children's Hospital, and Perth Children's Hospital.

Access and Follow-Up

Most children with Kohler disease can be managed in the community following initial specialist assessment and parent education. Public hospital outpatient departments provide follow-up as needed, though many children are discharged after one or two visits given the excellent prognosis. No specific PBS medications are required beyond over-the-counter analgesics. Custom orthotics, if needed, are available through private podiatry services or hospital-based orthotist clinics, though are rarely necessary for this self-limiting condition.