Fractures of the 5th metatarsal are a common injury that must be recognized and treated appropriately to avoid poor clinical outcomes for the patient. Since orthopedic surgeon Sir Robert Jones first described these fractures in 1902, there has been an abundance of literature focused on the proximal aspect of the fifth metacarpal due to its tendency towards poor bone healing. Nevertheless, it is critical that the physician recognizes all injury patterns of the fifth metatarsal and initiate the appropriate treatment plan or referral process to avoid potential complications.
Classified by Lawrence and Bottle, the base, or proximal aspect, of the 5th metatarsal is broken up into three anatomical zones: zone 1, the tuberosity; zone 2, the metaphyseal-diaphyseal junction; and zone 3, the diaphyseal area within 1.5 cm of the tuberosity. Fractures through zone 1 have the name to as pseudo-Jones fractures, and fractures through zone 2 are referred to as Jones fractures. Additionally, a patient may sustain a shaft fracture greater than 1.5 cm distal to the tuberosity, a long spiral fracture extending into the distal metaphyseal area, the so-called dancer's fracture, or a stress fracture of the metatarsal.
Classification of these fractures is crucial to making management decisions. Metaphyseal arteries and diaphyseal nutrient arteries provide the blood supply to the fifth metatarsal base. A vascular watershed area exists in zone 2, contributing to the high nonunion rates seen with these fractures.
Fractures of the fifth metatarsal are the most prevalent metatarsal fractures. These fractures peak during the third decade of life for men and the seventh decade of life for women. There is a strong correlation between female gender and zone 1 fractures and dancer's fractures. Zone 1 injuries are typical of a twisting injury and are the most common fracture of the base of the 5th metatarsal.
These patients typically present with pain about the lateral aspect of the forefoot that is worse with weight-bearing activity. This pain may occur in the setting of acute trauma or repetitive microtrauma over weeks to months. One should be suspicious for stress fracture with antecedent pain or pain of worsening quality or duration over time. The examiner must obtain a thorough past medical history and social history to make treatment decisions and optimize patients with surgical indications. It is important to evaluate the skin for open injuries that may require more urgent debridement. Physical examination may reveal tenderness to palpation, swelling, and ecchymosis at the site of injury. Patients will also have pain with resisted foot eversion. It is critical to evaluate the patient for other injuries, including injury to the lateral ankle ligamentous structures and Lisfranc injury.
Radiographs are the initial imaging of choice used to evaluate for these injuries. AP, lateral, and oblique images of the foot are essential to making the diagnosis. In zone 1 injuries, the medial fracture line lies proximal to the fourth to the fifth intermetatarsal joint. In zone 2 injuries, the medial fracture line extends towards or even into the fourth and/or fifth intermetatarsal joint. In zone 3 injuries, the medial fracture line will typically exit distal to the fourth and/or fifth intermetatarsal joint, but some may be more proximal. The usual fracture pattern seen in dancer fractures is an oblique spiral fracture beginning distal and lateral and extending proximal and medial. Other distal diaphyseal fractures are generally seen on radiographs running in the transverse plane.
The radiographic appearance of fifth metatarsal base stress fractures classify into three types based on the Torg classification system:
Other imaging modalities such as CT and MRI may be considerations in the setting of delayed healing, nonunion, or high index of suspicion for a stress fracture in the setting of a normal radiograph, but these are not routine studies.
Treatment decisions are based on the anatomic zone of injury, the social and medical history of the injured patient, and evidence of radiographic signs of healing.
Nondisplaced zone 1 injuries can be treated conservatively with protected weight bearing in a hard-soled shoe, walking boot or walking cast. Progression to weight bearing as tolerated is initiated as pain and discomfort subside over a period of 3 to 6 weeks. Fractures involving 30% of the articular surface or with an articular step off over 2 mm may be treated with open reduction and internal fixation, closed reduction, and percutaneous pinning, or excision of the fragment.
Nondisplaced zone 2 injuries, or Jones fractures, may also be treated conservatively with 6 to 8 weeks of non-weight bearing in a short leg cast. The physician may advance weight bearing status as radiographic evidence of bone healing appears. Surgical interventions are indicated in the high-performance athlete, the informed patient who elects to proceed with surgical treatment, or displaced fractures. There are many forms of surgical interventions including intramedullary screw fixation, tension band constructs, and low profile plates and screws. Surgical management of high-performance athletes minimizes the risk of nonunion and prevents prolonged restriction from physical activity.
Diaphyseal zone 3 stress fractures paint a more complicated picture for the patient and physician. A trial of conservative management with non-weight bearing in a short leg cast may be initiated, however, immobilization for up to 20 weeks may be required before radiographic union is observed and even then nonunion development is not uncommon. In high-performance athletes or individuals with Torg Type II or III fractures, surgical interventions may be indicated. Surgical options include intramedullary screw fixation, bone grafting procedures, or a combination of the two.
The bone grafting inlay technique requires removing a 0.7 by 2.0 cm rectangular section of bone at the fracture site and replacing it with an autogenous corticocancellous bone graft of the same dimensions taken from the anteromedial distal tibia. The medullary cavity must be curetted or drilled until all of the sclerotic bone has been removed and the medullary canal reestablished prior to inserting the donor graft.
Nondisplaced dancer’s fractures and other fractures of the fifth metatarsal shaft and neck are treated the same as nondisplaced zone 1 injuries. Advance weight bearing status as tolerated by pain. If evidence of delayed union or nonunion exists, surgical interventions may be required. If there is more than 3 mm of displacement or angulation > 10° the fracture should be reduced and splinted. If the fracture remains malreduced or there is evidence of loss of reduction on follow-up radiographs, surgical interventions with percutaneous pinning or plate and screw fixation should be considered.
Patients treated with intramedullary screw fixation or bone graft inlay technique are made non-weight bearing in a plaster splint or short leg cast for 6 weeks with a gradual return to sport or activity.
The majority of acute, nondisplaced fractures of the 5th metatarsal heal with conservative treatment by 6 to 8 weeks. Zones 2 and 3 injuries have a higher rate of nonunion due to the vascular watershed area mentioned earlier, with zone 2 injuries having a nonunion rate as high as 15 to 30%. Diaphyseal stress fractures may have a prolonged course of healing of up to 20 weeks.
There is an increased risk of nonunion with zones 1 and 2 injuries, as discussed earlier. There is also a risk of nonunion associated with using an intramedullary screw with a diameter under 4.5 mm or the use of a screw that is too long, causing fracture distraction or malreduction. Fixation failure rates are higher in individuals who do not abide by non-weight bearing restrictions or who return to sport or activity before evidence of radiographic union.
Patients, especially high-level athletes, should be educated regarding the risk of nonunion in specific fracture patterns and a thorough discussion of operative and nonoperative management should be initiated.
A multidisciplinary team, including the orthopedic nurse, is most effective in the appropriate management of fifth metatarsal fractures. Generally, the patient will present to their primary care physician or the emergency department complaining of typical signs and symptoms. Appropriate diagnosis directs the treatment and triage of these patients. Prompt referral to an orthopedic surgeon is paramount as appropriate treatment can lead to union rates as high as 97%. [Level 4] Mismanagement of these fractures may lead to poor clinical outcomes and lifestyle alterations. Emergent referral to orthopedic surgery is necessary for an open fracture. Traditionally, intramedullary screw fixation has been an option when surgery is warranted, but newer techniques with planar plating have resulted in successful outcomes in elite athletes.
With proper identification of fracture and interprofessional communication with an orthopedic referral, outcomes of this difficult to treat fracture can stand a better chance of full recovery, but this requires an interprofessional team approach, including physicians, specialists, specialty-trained nurses, physical and occupational therapists, and pharmacists, all collaborating across disciplines to achieve optimal patient results. [Level V]
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