Navicular fractures, along with cuboid fractures, form the most common isolated mid-foot fractures.
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Epidemiology
Navicular fractures are responsible for approximately 5% of all foot fractures and 35% of all midfoot fractures 7.
Clinical presentation
May present with pain, swelling or hematoma directly over the mid-foot. Stress fractures in athletes and construction workers may present with vague pain and swelling over the mid-foot, which worsens with exercise. Patients generally have a normal range of motion and a normal neurovascular examination 1.
Pathology
The fracture occurs via two main mechanisms:
chronic overuse injuries causing a stress fracture (often in athletes)
acute high-energy trauma where the head of the talus impacts the concavity of the navicular bone
Classification
The Sangeorzan classification is used to assess the severity of isolated navicular fractures and to determine management:
type I: the fracture line is in the coronal plane, and there is no angulation of the forefoot
type II: the fracture line is dorsal-lateral to plantar-medial, and the forefoot is medially displaced
type III: there is a comminuted fracture in the sagittal plane, and the forefoot is displaced laterally 4
Radiographic features
Plain radiograph
Plain radiographs are the best initial test in a suspected navicular fracture. Their sensitivity for identifying navicular fracture is low; however, lateral and oblique radiographs provide the greatest chance of identifying a fracture. Rarely fractures of an accessory navicular bone (if present) are also possible and may be visible.
CT
CT is more sensitive for identifying navicular fractures. It also allows for the assessment of the extent of the fracture line and the degree of comminution.
MRI
T2: may demonstrate areas of hyperintensity over the fracture site indicating bone edema
It should be noted that MRI is more sensitive than CT; however, in identifying stress fractures 3.
Treatment and prognosis
Management may be operative 5 or non-operative 6.
Non-operative management consists of cast immobilization and non-weight bearing. Most undisplaced fractures can be managed conservatively in a cast 3. Other indications for non-operative management include:
acute avulsion fractures
most tuberosity fractures
minimally displaced type I and type II body fractures
Operative management may either be fragment excision or ORIF +/- external fixation / primary fusion.
Fragment excision is indicated in those patients where avulsed fragments have failed to improve clinically despite non-operative management as well as symptomatic non-union of tuberosity fractures.
Displaced/intra-articular type I and II navicular body fractures typically require open reduction and internal fixation. ORIF is also indicated when avulsion fractures involve more than 25% of the articular surface or when tuberosity fractures have more than 5 mm of diastasis or have a large intra-articular fragment.
Type III fractures require open reduction and internal fixation, followed by external fixation. This is also required when there is evidence of navicular avascular necrosis.