Navicular stress fractures occur in athletes who participate in running and jumping sports. They present with gradual onset of aching pain in the middle of the foot and get worse during and after physical activity.
The navicular bone helps transfer force from the ankle to the ball of the foot. The middle part of the bone has a poor blood supply and is more susceptible to repetitive forces that can cause a stress injury.
Symptoms
The navicular bone helps transfer force from the ankle to the forefoot (the ball of the foot). It is covered by cartilage and has a poor blood supply. Therefore, it is sensitive to repetitive overload. The stress fracture develops when the navicular bone experiences stresses that are greater than it can handle, or when the navicular bone is already weak due to previous injury or biomechanical abnormalities.
The initial symptoms of a navicular stress fracture include pain when running, jumping or loading the foot. The pain may become constant and aggravated by repetitive activities. If the injury is not diagnosed and treated quickly, the break can worsen, becoming a chronic injury with a more difficult time to heal.
Navicular stress fractures are often difficult to diagnose because the pain is not caused by direct trauma and the initial X-rays can appear normal. The diagnostic test of choice is a triple-phase bone scan, which typically provides excellent results and localizes the lesion well. A CT scan is also useful to demonstrate the degree of displacement and help guide therapy.
The treatment of navicular stress fractures is non-surgical, with a period of immobilization in a cast or CAM boot and gradual return to activity. Surgical management is usually reserved for patients with significant nonunion or displaced fractures, elite athletes or those who have a history of repeated stress injuries in the navicular area.
Diagnosis
The injury is typically a vague aching pain in the dorsal midfoot that radiates into the medial arch. The pain becomes worse during and after physical activity (particularly sprinting and jumping), and can last well into postactivity rest periods. The injury usually develops slowly over time and may be triggered by a change in training intensity, shoe wear, or foot posture.
X-rays have a low sensitivity for this type of injury, and routine weight bearing radiographs can miss the stress fracture if it is present. MRI is the imaging modality of choice, as it is very sensitive for bone stress injuries and is particularly good at detecting bone edema and stress reactions which can precede fractures [5].
Navicular stress fractures are complicated by a poor blood supply to the area, leading to delayed healing and rates of nonunion as high as 20%.[1] In some cases, the fractures may be displaced and require surgical management.
Ideally, surgery should be considered as an option only after conservative treatment has failed to provide relief. In this setting, the goal is to return athletes to their sport as soon as it is safe. This includes a period of 6 weeks of nonweight bearing in a CAM boot, followed by a gradual increase in activities over the next week. In select difficult cases, teriparatide can be administered to accelerate healing and allow for early weight bearing.
Treatment
In young athletes, navicular stress fractures can occur due to chronic overload of the bone that doesn’t allow it time to recover between training and sport sessions. The navicular bone has a poor blood supply, and this makes it more vulnerable to these overuse injuries.
Treatment starts with resting your feet and stopping the activity that’s causing the pain. Your foot and ankle orthopaedic surgeon may recommend a period of non-weight bearing in a cast or boot, with gradual return to activities.
For patients who are not able to tolerate non-invasive treatments, surgery can be recommended. Surgery for navicular stress fractures includes placing a bone graft in the area of the navicular bone to help it heal. Surgical techniques are evolving to allow definitive healing shown on cross-sectional imaging and earlier return to sports with a lower risk of reinjury.
It’s important to evaluate for underlying issues that can predispose patients to developing this type of injury. A poor training regimen that results in overloading, inadequate recovery between sessions, a vitamin D deficiency, and excessive pronation are all associated with increased risk of navicular stress fractures. Specific anatomic variants, such as a short first metatarsal, limited subtalar motion, medial narrowing of the talonavicular joint, and pes cavus, are also associated with a higher risk of navicular stress fractures [15]. Your foot and ankle orthopaedic specialist will help you address these issues to reduce your chance of developing this overuse injury in the future.
Prevention
A navicular stress fracture usually occurs when repetitive, high-impact activity exceeds the foot’s ability to absorb shock. The bone breaks down faster than it can be replaced, leading to a gradual deterioration of the bone. If not stopped, this can lead to a complete stress fracture that takes longer to heal.
Affected individuals typically describe a vague, aching pain that’s difficult to pinpoint and is worse with weightbearing and physical activities such as sprinting and jumping. The pain usually doesn’t improve during rest, and it may increase when activity is resumed.
In general, it takes 6 to 8 weeks for a stress fracture to heal. However, some bones, such as those in the base of the fifth metatarsal, have less blood supply and can take a little longer. For this reason, it’s important not to return to normal activity too quickly.
Our podiatrists recommend a slow increase in exercise intensity to allow the foot to adapt and to avoid a sudden change in training conditions that can place too much strain on the foot. They also recommend working out on softer surfaces, like grass, that provide more cushioning.
Athletes who experience a navicular stress fracture often develop the injury as a result of training errors, such as a sudden increase in training intensity or inadequate recovery between workouts. Other risk factors for the condition include a pes cavus (high arch), an excessive amount of pronation, and restricted ankle dorsiflexion.