Essential Insights On Treating Fifth Metatarsal Fractures

Author(s): 
By Nicholas Romansky, DPM, and Todd Becker, DPM

Podiatric physicians commonly see fifth metatarsal fractures when treating active patients. The actual rate of occurrence is unknown but some estimate the rate at somewhere between 0.7 and 1.9 percent of all foot fractures. Fractures of the fifth metatarsal can occur at a number of locations and while some of these respond well to conservative treatment, other fractures have been notoriously hard to heal with high rates of nonunion and other complications.
Proper classification of these fractures and a strong understanding of the mechanism of injury will help guide the podiatric physician in establishing a proper prognosis and treatment. It is also helpful to have a thorough understanding of fifth metatarsal anatomy (see “A Primer On Fifth Metatarsal Anatomy” below).

How To Ensure An Appropriate Diagnosis
The accurate diagnosis of fifth metatarsal fractures begins with a thorough history and physical exam. In many cases, the patient may not relate a specific traumatic event during the history portion of the exam, making the physical exam and subsequent studies imperative to an accurate diagnosis. In the acute setting, the patient may present with symptoms of localized pain on the outside or bottom of the midfoot. These symptoms can be insidious in nature or exacerbated by weightbearing. The physical exam may reveal ecchymosis, edema, point tenderness and/or pain against resistance.
Radiographs are invaluable in the diagnosis. It is important to get multiple views of the affected foot, including AP, lateral and medial oblique views for proper assessment of the fracture for location, the amount of displacement, angulation and comminution. One should also obtain radiographs after the patient’s affected extremity has been immobilized for two to three weeks. Fracture healing is dependent on location of the fracture and the specific blood supply to that area of violation.

Open reduction with internal fixation is generally indicated when the fracture is non-reducible and one notes residual displacement of 3 to 4 mm or 10 degrees of angulation in the sagittal plane. When these fractures go unrecognized, a painful plantar keratosis might develop anywhere along the fifth metatarsal. Cortical disruption or thickening, periosteal callus formation and the presence of intramedullary sclerosis may all be visible on X-rays.
Other modalities one may employ for diagnosing fifth metatarsal fractures include CT, MRI, bone scan, ultrasound and tuning fork.
The differential diagnosis for lateral foot pain should include stress fracture, apophysitis in adolescents, accessory bones (i.e., os vesalianum or os peroneum), herniated disc, neoplasm and tendonitis.

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