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Metatarsal Fractures


KEY FACTS

  • Toe and metatarsal fractures are the most common fractures of the foot with an incidence of 140 per 100,000 per year.

  • The 5th metatarsal is the most frequently fractured metatarsal (23%).

  • The metatarsals are affected by stress fractures more commonly than all other sites in the body.

  • A majority of metatarsal fractures are low-energy injuries suitable for closed treatment.

    • The intact soft tissues splint the fracture.

  • A low-energy metatarsal shaft fracture typically does not disrupt proximal or distal stabilizing soft tissue structures.

    • The metatarsal head remains in the appropriate location for weight bearing.

  • A high-energy injury, with disruption of the stabilizing soft tissues proximally or distally, will elevate or depress the metatarsal head.

    • Thus, this may disrupt the normal distribution of weight in the forefoot.

    • Altered weight distribution may lead to metatarsalgia and painful plantar keratosis.

  • Displacement, shortening, or angulation of the 1st metatarsal in any plane anywhere along the bone can significantly alter the weight-bearing distribution of the foot and is therefore an indication for operative management.

  • An isolated, nondisplaced metatarsal base fracture may be stable, but if any uncertainty exists, further evaluation of the midfoot with stress x-rays is necessary.

  • High-energy injuries, even when closed, have extensive soft tissue disruption and may require operative treatment.

  • Lawn mower injuries are common with an incidence of between 50,000-160,000 each year.

    • They can cause significant morbidity and, rarely, even death.

This young man’s foot was crushed by a large garage door. The 1st metatarsal (MT) shaft is widely displaced.

There is not much vertical displacement of the MT head, suggesting that some of the soft tissue connections were intact between the 1st and 2nd MT heads.

Open reduction was performed through a medial incision with a lag screw and neutralization plate.

After 6 weeks of non-weight bearing, he went on to a full recovery.

Forefoot Structure

  • The metatarsals are the major weight-bearing structure of the forefoot.

  • The 1st metatarsal head and its 2 associated sesamoids bear ~ 1/3 of the body weight.

    • The remainder is distributed among the lesser 4 metatarsals.

    • The 2nd and 3rd frequently bear more than the 4th and 5th.

  • The metatarsal bases are rigidly stabilized to the cuneiforms and cuboid in the midfoot.

  • The proximal transverse metatarsal ligament runs from the 5th metatarsal base to the 4th, to the 3rd, then the 2nd, and then to the medial cuneiform.

  • The distal transverse intermetatarsal ligament runs from the 5th metatarsal head to the 4th, then the 3rd, then 2nd, and then finally to the lateral sesamoid.

  • There are no ligaments connecting the 1st metatarsal to the others.

  • A low-energy metatarsal shaft fracture does not disrupt these proximal or distal stabilizers, so the metatarsal head remains in the appropriate location for weight bearing.

  • A higher energy injury, with disruption of the stabilizing soft tissues proximally or distally, will elevate or depress the metatarsal head.

    • Thus, this may disrupt the normal distribution of weight in the forefoot.

    • Altered weight distribution may lead to metatarsalgia and painful plantar keratosis.

  • The 1st metatarsal is intimately associated with the sesamoids, which are held fixed in relation to the lesser metatarsals by attachments to the intermetatarsal ligaments and the 2 heads of the adductor hallucis.

    • Displacement of the 1st metatarsal head in any direction can alter the balance of the entire forefoot.

  • The tibialis anterior works to elevate the 1st metatarsal, while the peroneus longus plantar flexes.

    • Either of these muscles may act to deform a 1st metatarsal fracture.

  • The flexor digitorum longus, flexor hallucis longus, and intrinsic muscles place plantar flexion stress on the metatarsal heads in distal fractures and can cause plantar flexion deformities.

  • The 5th metatarsal, like the 1st, has less soft tissue coverage than the middle metatarsals and has extrinsic muscle attachments, the peroneus brevis and tertius, which attach at its base.

    • It also has a strong attachment to the lateral band of the plantar fascia.

    • It is the most mobile of the metatarsals.

Metatarsal Fractures

Mechanism

  • Metatarsal fractures result from a wide variety of mechanisms and may range from an isolated single bone fracture to multiple fractures with severe soft tissue compromise.

  • Direct trauma with a heavy falling object is common in industrial workers.

  • Many low-energy injuries arise from indirect trauma, a twisting force with a fixed forefoot.

  • Fractures of the 5th metatarsal base result from avulsion by the lateral band of the plantar aponeurosis.

  • Stress fractures occur as a result of repetitive force on the metatarsals and occur frequently in athletes, soldiers, and dancers.

Physical Examination

  • Patients with metatarsal fractures present with pain on ambulation or difficulty with weight bearing on the affected foot, swelling, deformity, and ecchymosis.

  • Dorsal swelling is typical, because the plantar skin allows little swelling due to the thick fibrous septa within the skin pad.

  • Each metatarsal and toe should be carefully and sequentially evaluated.

  • Palpation of each digit and each metatarsal shaft usually will elicit point tenderness at the fracture site.

  • Subungual hematoma is a hallmark of distal phalangeal fractures and may be associated with open fractures of the distal phalanx.

Imaging

  • Radiographs should include anteroposterior, lateral, and oblique views of the foot.

  • Metatarsal head alignment can be evaluated further with anteroposterior and lateral weight-bearing views of the whole foot and a tangential view of the metatarsal heads.

    • Unfortunately, these views are difficult to obtain in a patient with a new injury.

  • Stress fractures frequently do not appear initially on plain x-ray.

    • Follow-up films 3-4 weeks later will usually demonstrate periosteal reaction or, in the 5th metatarsal, a resorption gap, that confirms the diagnosis.

  • Magnetic resonance imaging can identify a stress fracture immediately but is not often needed, because the diagnosis can be made clinically.

  • Bone scans also will detect a stress fracture after a few days of symptoms.

Classification

  • Metatarsal fractures can be classified according to the location, and thus include head, neck, shaft, and base fractures.

  • It is useful to classify 1st and 5th metatarsal fractures separately from the rest, because the treatment options differ widely for these types.

  • Second, third, and fourth metatarsal fractures can be grouped together, as the treatment options are similar.

  • Proximal 5th metatarsal fractures can be categorized by zone.

  • Metatarsal base fractures can occur in isolation.

    • However, it is important to recognize that many, perhaps all, such fractures represent an injury to the midfoot.

  • An isolated, nondisplaced metatarsal base fracture may be stable, but if any uncertainty exists, then further evaluation of the midfoot with stress x-rays is necessary.

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