Navicular stress fractures are most frequently seen in patients who participate in demanding athletics involving sprinting and jumping or long distance running. These injuries require a high level of suspicion, as the presenting symptoms are nonspecific and have an insidious onset.^1,2 Patients present with a host of foot symptoms, from vague arch “cramping” to prolonged swelling and midfoot tenderness. The symptoms are quite difficult to localize and initially are troublesome only during the provocative activity. Ultimately, they progress to more debilitating and consistent pain.¹

There is frequently a delay in diagnosis and initiation of appropriate treatment, ranging from 4 to 7.2 months.³ This delay is attributed to the nonspecific symptoms as well as initial misdiagnosis. The clinical findings and history can often be confused with posterior/anterior tibial tendinitis, midfoot sprain, and ankle sprains. Only when patients fail to improve is further imaging performed and the treatment redirected.

To guide treatment of a navicular stress fracture, a classification scheme was developed to identify displaced versus nondisplaced and complete versus incomplete fracture patterns.⁴ This is important in the discussion with the patient regarding options and potential surgical intervention. Nonsurgical management is frequently offered to patients with nondisplaced or incomplete fractures of the navicular.⁵ This involves a minimum of 6 to 8 weeks of dedicated time in a non-weight-bearing cast before advancing activities. Multiple studies have consistently shown that immobilization with weight bearing leads to treatment failure, nonunion, and inability to return to preinjury activity.^1,3,6 However, in the compliant patient population, studies have reported successful outcomes with non-weight-bearing immobilization for a minimum of 6 weeks. Torg et al³ showed 100% fracture union, and Fowler et al’s⁶ pooled analysis showed no difference in time to return to activity between operatively treated patients and those treated with cast immobilization and non-weight bearing. Patients with displaced fractures, those who cannot tolerate prolonged immobilization, or persons in whom nonunion develops despite immobilization are offered surgical intervention.^3,7,8,9

On initial evaluation, the patient undergoes a standard weight-bearing radiographic series of the foot, including AP, oblique, and lateral views. Often, these provide little information because a stress injury is difficult to visualize on radiographs. Several studies have confirmed the significantly low rate of detection on radiographs, ranging from 67% to 82%.^3,5 However, weight-bearing radiographs are low-cost initial screening instruments that can show displacement of a complete navicular stress fracture and cystic change or progressive arthritic change of the talonavicular joint, as well as overall foot alignment, which may be important in a discussion of reconstruction and may eliminate the need for further costly imaging modalities (Figure 1).

The next stage of imaging is often dependent on the initial radiographs. If the fracture is identified on radiographs or if they show reactive bone formation suggestive of further pathology, the patient is sent for a CT scan to further delineate the fracture pattern, any associated arthritic change, and any degenerative cyst development² (Figure 2). When the initial radiographs are not diagnostic but the history and examination are consistent with a potential stress injury, a bone scan or an MRI can be used to identify bony uptake or edema and fracture lines, respectively^1,5 (Figures 3 and 4). Bone scans are 100% sensitive for injury, but positive findings are unfortunately nonspecific.^3,4 MRI reduces radiation exposure and shows additional soft-tissue detail but has limited capability to accurately identify
all navicular stress fractures.¹⁰ MRI may be most beneficial in the early stage of diagnosis to identify a stress reaction before fracture. Therefore, these patients still require a conclusive CT scan following a positive result.⁵ The most typical navicular stress fracture pattern on CT is an incomplete fracture in the central third of the bone extending from dorsal-medial to plantarlateral.¹ The CT scan is the most critical imaging modality for fracture classification and surgical planning with navicular stress fractures.⁴