Navicular stress fracture

Findings

This presents with an acute or insidious onset of pain over the mid-foot, but clinical examination may or may not produce pain on passive, mid-tarsal joint movements. However, it is usually tender to direct palpation over the navicular.

Cause

A stress fracture of the navicular seems to occur in sprint, jump and interval sprint games, but not in endurance events. Perhaps when the foot is on tiptoe, as in sprinting, the concave surface of the navicular becomes the anvil, to the hammer of the convex surface of the talus, and this impact load produces the vertical fracture in the navicular.

Treatment

A cast brace and non-weight bearing for 1 month, if the scans show no widening or sclerosis of the fracture. Follow this with weight-bearing for 1 month in a cast brace. Later weight-bearing rehabilitation through the Achilles ladders, with caution, for 3-4 months. If there is widening or non-union of the fracture then a compression screw should be inserted.

Sports

a)      Athletics – seems to occur in sprints up to 400 metres, jumps, and hurdles.

b)      Field hockey – has become more common since the advent of the “plastic” surface for hockey pitches.

c)      Non-impact cross-training and local muscle strengthening must be maintained.

d)     Impact should be severely limited until the fracture is healed, but it can be introduced somewhat earlier on rebound trampettes.

This fracture is often missed. Too often, this injury presents months after its onset, frequently when non-union is established. A negative X-ray does not rule out this injury, and if there is any element of doubt concerning the diagnosis then an MRI or bone scan should be ordered. The morbidity of this problem is excessive, and non-union is common, so a CT scan to assess the problem should be undertaken early. If there is a doubt about non-union then the fracture should probably have a compression screw inserted. Occassionally, the palpable tenderness seems to be over the anterior talar surface, but the problem is likely to be navicular.

"Concise guide to sports injuries, 2^nd edition",Churchill Livingstone, Malcolm T.F. Read,  foreword by Bryan English