A navicular stress fracture is a crack or break in the navicular bone, which is a boat-shaped bone in the middle of the foot. These fractures often are due to overuse, ongoing forces, and/or stress on the bone rather than a sudden injury.
Patients with navicular stress fractures usually have gradual onset of aching pain across the top and/or middle of the foot. Pain usually improves with rest and support but then returns when activity resumes.
The navicular bone helps transfer force from the ankle to the forefoot (the ball of the foot). The navicular is covered by cartilage and lacks a rich blood supply, especially at its center. This makes it more susceptible to repetitive forces that can cause damage. The bone may break down because of excess force, underlying bone weakness, or a combination of these two factors.
Repetitive forces that could result in a navicular stress fracture include running/jumping sports (such as basketball) and similar activities, increased exercise, or even walking after a period of inactivity.
There are steps you can take to help prevent navicular stress fractures:
Select supportive footwear before you start an exercise or training routine and replace your shoes after 300-500 miles of use. Supportive shoes typically have a stiff sole with lots of cushioning in the shoe, especially at the arch.
Start your new training routine slowly, especially after a period of relative inactivity. Do not increase your walking or running distance increments by more than 10% per week.
Incorporate stretching, particularly of the calf muscles and Achilles tendon, prior to exercise.
A history and physical exam are important ways for diagnosing a navicular stress fracture. Physical examination will show tenderness across the top of the foot. Standing X-rays may reveal a fracture line. However, X-rays may appear normal in the early
stages of the stress fracture. Imaging beyond X-rays such as CT, MRI, and bone scans can be helpful in showing a stress fracture at the navicular if X-rays can't do this.
Your foot and ankle orthopaedic surgeon may recommend surgical or non-surgical options to treat navicular stress fractures. First, you must stop the activity that results in the pain of the stress fracture. Non-surgical treatment includes wearing a cast or boot without weightbearing for 6-8 weeks. Research shows wearing a cast has an 80-100% success rate.
Certain patients, including professional athletes, may choose surgical treatment to allow them to return to activity more quickly and reduce the risk of developing another stress injury. Surgical treatment involves placement of an internal screw or screws
across the fracture. Recovery after surgical treatment usually requires at least 6-8 weeks of limited weightbearing and foot immobilization in a cast or boot with a gradual return to activities.
The most common complication after treatment of a navicular fracture is a nonunion, or failure of the bone to heal. Continued pain with activity after cast removal is a sign that the bone did not heal. If a nonunion develops, the treatment can be surgery. This often involves using a bone graft in the fracture site can help with navicular bone healing.
Another potential complication is the development of arthritis, resulting from damage to the cartilage that covers the joint connecting the navicular bone to the hindfoot (rear part of the foot).
A less common complication of navicular fracture is avascular necrosis (AVN), which results from a loss of blood supply to the navicular bone. AVN causes a collapse of the navicular bone and affects function of the joints in the middle of the foot. It can be difficult to treat.
Call your surgeon if you have had persistent foot pain for 1-2 weeks when walking or participating in activities.
Original article by Michael Johnson, MD
Contributors/Reviewers: F. Ray Nickel, MD; Jason Ahuero, MD; Jamal Ahmad, MD
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