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Metatarsal fractures

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Most fractures of a single metatarsal are non-displaced due to the support from the surrounding ligaments and muscle attachments. The chance of displacement increases with multiple fractures or fractures of the head neck of the metatarsal. Displaced fractures of the metatarsals can alter the normal distribution of weight in the forefoot leading to pain and disability. The first metatarsal is larger than the others and most important for weight-bearing and balance; therefore, malunion or malignment at this location is especially poorly tolerated.

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The fifth metatarsal is further divided into 3 zones, numbered 1 to 3 from proximal to distal. Zone 1 is at the base of the metatarsal and contains the cancellous (styloid) tuberosity, the insertion site of the peroneus brevis and lateral band of the plantar fascia. Zone 2 is at the metaphyseal-diaphyseal junction, distal to the cancellous (styloid) tuberosity, and zone 3 is on the diaphysis, distal to the peroneus tertius. Avulsion fractures commonly occur in zone 1. Fractures involving Zone 2, called Jones fractures, are particularly susceptible to nonunion and malunion because this diaphyseal bone is a watershed region between two blood supplies . In addition, the various tendons and muscles attached to the bone may pull the fracture apart and prevent healingand because like zone 3 it is often subject to significant repetitive forces. Zone 3 fractures are commonly stress fractures. It is important to specify location of injury involving the fifth metatarsal because different types of fractures require different management in the 3 zones.

Figure 1. Metatarsals 1-5 and zones 1-3 of 5th metatarsal

Patient presentation  

Patients suffering from a metatarsal(s) fracture present with acute onset of pain, swelling, ecchymosis, and tenderness to palpation in the forefoot, along with difficulty bearing weight. Gross deformities are only seen with displaced fractures, complex injuries involving serial fractures, and concomitant toe dislocations. Most metatarsal shaft fractures are caused by direct or indirect trauma to the foot. Direct impact causes a transverse or comminuted fracture pattern, while an indirect twisting-type injury causes an oblique or spiral fracture pattern with soft-tissue swelling. Common direct trauma mechanisms include a heavy object dropped on the foot or a forceful blow to the foot as may occur in sports injuries, falls, and motor vehicle accidents. Indirect trauma occurs with body torque when the leg and hind foot are twisted around a fixed forefoot. 

Assessment of each metatarsal can be performed by palpating the shaft, tarsometatarsal (TMT) joint, and the plantar metatarsal heads to evaluate for elevation or depression of the head. It is important critical to maintain good alignment of the each metatarsophalangeal (MP) joint. Assessment of neurovascular status should be performed. 

Avulsion fractures at the base of the fifth metatarsal, in Zone 1 where the peroneus brevis and plantar fascia insert, may occur during forced inversion of the foot and ankle while plantar flexed. This injury, commonly termed a pseudo-Jones or dancer’s fracture, can happen after landing awkwardly from a jump or inverting the ankle while running. On exam, the patient is asked to evert the foot to assess for continuity of the tendons. If the patient is able to evert the foot, the injury will likely heal with non-operative treatment. Weakness is in eversion is often noted as the pull of the peroneus brevis tendon displaces fracture fragments. 

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True Jones fractures occur in Zone 2 of the fifth metatarsal and the fracture line extends through the proximal articulation with the fourth metatarsal. This fracture is a result of tensile stress along the lateral border of the metatarsal during adduction or inversion of the forefoot. An athlete can sustain this injury with a sudden change in direction while the heel is off the ground. Injuries can range from simple isolated fractures of a single metatarsal to severe crush injuries with several fractures and soft tissue compromise. 

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In isolated foot injuries obtain weight-bearing radiographs in the anteroposterior (AP), oblique, and lateral planes . Except should be obtained. If possible the radiographs should be performed with weight-bearing to help assess displacement and instability. Except in the case of an isolated direct blow to the foot, initial films should include the entire foot to rule out associated injuries that may require treatment. The lateral view is important for judging sagittal plane displacement of the metatarsal heads, and the oblique view can help detect minimally displaced fractures. To detect Lisfranc injuries, it is important to carefully examine the radiographs for widening between the 1st and 2nd metatarsal space, fleck fractures at the base of the 1st metatarsal, and loss of alignment between the medial edge of the 2nd cuneiform and medial edge of the 2nd metatarsal base. Weight-bearing x-rays can be particularly helpful when trying to rule out of assess Lisfranc injuries.

Figure 3. Radiograph demonstrating a Lisfranc fracture by black circle (Credit: http://en.wikipedia.org/wiki/File:Lisfranc_fracture.jpg)

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The goal of treatment is to restore alignment of the 5 metatarsals in order to preserve the transverse and longitudinal arch of the foot and the normal weight distribution over the metatarsal heads. Management varies widely depending on the location of the injury. Most isolated central (2nd - 4th) metatarsal fractures can be treated with a walking boot and progressive weight bearing as tolerated. Reduction and surgical intervention may be required if the fracture displays more than 10 degrees of deviation in the dorsal plantar plane or 3 to 4 mm translation in the dorsal or plantar plane. Single metatarsal shaft fractures with medial or lateral displacement typically heal well without correction. 

For 1st metatarsal fractures, the best way to determine operative versus non-operative management is with stress radiographs. Displacement of the first metatarsal through the joint or fracture site represents an unstable fracture that requires surgical fixation. Options include closed reduction with percutaneous K-wire fixation or ORIF (open reduction internal fixation). Severely In rare instances severely comminuted fractures which are unable to be fixed with lag screws may be treated with external fixation. If there are no signs of instability and no associated injuries to the midfoot or other metatarsals, these fractures can be managed with a short leg cast or removable boot with weight bearing as tolerated for 4-6 weeks.

Three distinct fractures occur in the proximal fifth metatarsal and they are all treated differently. Cancellous .  Zone 1 injuries are treated very differently than Zone 2 and 3 injuries. Cancellous (styloid) tuberosity avulsion fractures (Dancer's Fractures or Zone 1 injuries ) require only symptomatic therapy with a walking boot for 6 weeks unless .  In very rare instances where there is a significant articular step-off , in which ORIF should be considered. Non-weight-bearing is advised for 3-4 weeks or until symptoms dissipate enough to allow weight-bearing. Jones fractures in Zone 2 require more aggressive treatment but management is controversial. Options include non-weight bearing in a cast for 6-8 weeks, weight-bearing orthosis for 8-12 weeks, and surgical fixation in athletes. A fracture in Zone 3 is typically a stress fracture treated with cessation of causative activity for 4-8 weeks. There has been some controversy in their treatment as well, whether it be operative or non-operative. Recent studies advocate the use of electromagnetic stimulation in treatment of these fractures. 

Most metatarsal fractures will go on to heal uneventfully with appropriate treatment, but complications do occur. Malunion, nonunion, or arthritic degeneration of the TMT and MP joints can lead to metatarsalagia and significant disability, especially in the 1st metatarsal.  In addition, malunion can cause plantar keratoses from significant plantar deviation of the metatarsal heads and dorsal keratoses from uncorrected dorsal angulation. In Zone 1 fractures, asymptomatic nonunion can occur, but this usually does not require intervention. Sural nerve entrapment can occur. Although not commonly recognized, displaced intra-articular fractures can result in a chronically painful joint. Tarsometatarsal joint pain can occur with nonunion. Nonunion of Zones 2 and 3 are due to inadequate treatment, poor blood supply, and cavus alignment of the foot , placing which places increase stress on the 5th metatarsal base. Failure of operative treatment is often due to resumption of activity too early, poor compression at the fracture site, inadequate bone grafting, or incomplete debridement of the sclerotic medullary canal.

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Miscellany

The metatarsal bone become became infamous with soccer fans when David Beckham was tackled by Aldo Duscher breaking his 2nd metatarsal bone and jeopardizing his ability to play in the 2002 World Cup. Luckily, Beckham was able to make it back in time to represent England in the 2002 World Cup.
  
The most common location for a stress fracture is the metatarsal bone, especially the 2nd. They are commonly called “march” fractures owing to their prevalence in military recruits.

The metatarsal bones are often broken by football players. These and other recent cases have been attributed to the modern lightweight design of football boots, which give less protection to the foot. 

Key terms 

Metatarsal fracture, Lisfranc joint, Jones fracture, cancellous (styloid tuberosity), metatarsalagia

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