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Navicular and Cuboid Fractures


KEY FACTS

Navicular Fractures

  • Three types of navicular fractures generally occur: Avulsion fractures, high-energy fractures with other associated injuries, and stress fractures.

  • Avulsion fractures can generally be treated nonoperatively, except in those cases in which the fragment is large enough to warrant open reduction and internal fixation. These injuries are by far the least severe of the 3.

  • High-energy injuries will require a plan that takes into account all associated injuries, understanding that many of the joints in the hindfoot and midfoot work in tandem, such that injury to one will directly affect the other. Some joints may need to be temporarily spanned in order to provide sufficient stability for the injury to heal. As a result, stiffness is often a concern after these injuries.

  • Many stress fractures can be managed nonoperatively, although some will require surgery. Vigilance is required either way, as it can be difficult to get long-term nonunions to heal.

Cuboid Fractures

  • There are rarer injuries still, and they will rarely occur in isolation.

  • Injury will not infrequently lead to insufficiency of the lateral column of the foot, such that treatment will often require some distraction to regain that length.

A 23-year-old male patient with a large dorsal avulsion fracture fragment from the navicular is shown. He had simply tripped and sustained a trivial injury. This fragment is much larger than the typical avulsion fracture.

Dorsal avulsion fracture off the navicular is shown. The radiograph shows the fragment to be somewhat large as well. A thorough discussion was had with the patient, and operative treatment was elected, given the large size of the fragment.

Patient had open reduction and internal fixation of the large avulsion fracture. A dorsal approach was used; the fracture was anatomically reduced and fixed with 2 cannulated screws.

Open reduction and internal fixation of the dorsal avulsion fracture is shown. The anatomic reduction can be seen more readily on this lateral image.

Anatomy and Function of Midfoot

  • The midfoot includes 5 tarsal bones: Navicular, cuboid, and 3 cuneiforms (medial, middle, and lateral). It forms the transverse arch of the foot and is also part of the longitudinal arch.

  • The navicular articulates in a mobile relationship with the talus proximally. The articulation distally is with 3 cuneiforms, where stability is more important than flexibility.

  • The cuboid articulates in a mobile relationship with the anterior process of the calcaneus proximally. Articulation distally is with the 4th and 5th metatarsal bases. These joints are more mobile than the more medial midfoot joints, as they are analogous to the ring and little finger of the hand, helping provide some measure of "grip" of the ground.

  • The cuneiforms articulate with the navicular proximally, 1st-3rd metatarsal bases distally, and cuboid laterally (with lateral or 3rd cuneiform). These articulations are rigid.

  • The 2nd metatarsal meets the middle cuneiform in a rigid joint, more proximal than the 1st and 3rd joints, and is referred to as the "keystone" of the midfoot.

  • The transverse tarsal, or Chopart, joint is formed by the talonavicular and calcaneocuboid joints. This complex is stiff with hindfoot varus, as in the toe-off phase of gait, and provides a rigid lever for ambulation. Hindfoot valgus "unlocks" the transverse tarsal joint.

  • Mobility at the transverse tarsal joint is necessary for normal gait, and fusions are not well tolerated. Temporary spanning fixation of the talonavicular and calcaneocuboid joint in the setting of trauma will not be durable and is often removed once healing of the traumatized foot has occurred.

  • Fixation from the 4th or 5th metatarsals into the cuboid also restricts normal foot motion and is not well tolerated. Fixation across these joints is often removed once healing has occurred in the traumatized foot. The remaining midfoot joints (naviculocuneiform and medial 3 metatarsocuneiform) are relatively stable and nonmobile articulations and tolerate permanent fixation well, although hardware that spans those joints will often be removed as well.

Navicular Fractures

Introduction

  • Navicular injuries include avulsion fractures of the tuberosity and fractures of the body, either extra- or intraarticular.

  • Avulsion fractures most commonly occur dorsally, although they can occur anywhere around the navicular. Medial avulsions may be caused by the posterior tibial tendon or the plantar calcaneonavicular (spring) ligament, while most others will be capsular avulsion fractures. An avulsion fracture typically involves a low-energy twisting injury with pain at the medial midfoot and an inability to bear weight afterward.

  • Navicular body fractures are less common than avulsion fractures, although they are often greater in severity. They can result from a direct mechanism ("crush") or an indirect mechanism (axial load through foot). Navicular body fractures may present with similar complaints, although a higher energy mechanism may result in a more diffuse midfoot injury in addition to the navicular fracture, and symptoms may correspond to the extent of the injury.

  • Physical examination will reveal varying degrees of edema, ecchymosis, and tenderness over the proximal midfoot. Patients will often have significant pain with resisted adduction of the foot. Diffuse edema and ecchymosis about the foot do not negate the possibility of navicular injury; rather, they may be indicative of multiple midfoot injuries.

  • Radiographs should include anteroposterior, oblique, and lateral foot radiographs. Navicular avulsion fractures will demonstrate a fleck of avulsed cortex, which is sometimes visualized on only 1 view (increasing the possibility of the injury being missed). This should be differentiated from an accessory navicular, which will be well corticated. Computed tomography (CT) scans can be obtained to further delineate anatomy and pick up subtle findings when plain films fail to show adequate detail.

  • Classification of navicular fractures is as follows.

    • Type 1: Transverse coronal plane fracture

    • Type 2: Sagittal plane fracture that often runs dorsolateral to plantarmedial with medial fragment often subluxed and lateral fragment often comminuted

    • Type 3: Fractures with central or lateral comminution and associated with lateral displacement of forefoot &/or occasionally disruption of calcaneocuboid joint or fracture of cuboid

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