Fifth Metatarsal Stress Fractures

Akash Gupta

Martin O’Malley

Introduction

In the elite athlete, recognition of fifth metatarsal stress fractures is key to early treatment.
Fracture occurs because of overuse and lateral overload. Furthermore, there is increased motion of the fifth metatarsal with a base that is anchored by the tendon and ligaments.
Operative intervention for these patients allows for more aggressive rehabilitation and earlier return to sport.
Risk factors for this injury include a cavus foot and metatarsus adductus (Figure 21-1). The alignment does not need to be corrected initially; however, the metatarsus adductus may limit the screw size able to be placed.
In larger athletes, metatarsus adductus is seen along with a prominent base of the fifth metatarsal (Figure 21-2)

Figure 21-1. Three-dimensional computed tomography reconstruction demonstrating metatarsus adductus.

Figure 21-2. Professional basketball player’s foot demonstrating a prominent fifth metatarsal base.

Imaging

X-rays: Routine weight-bearing radiographs (anteroposterior, lateral, and oblique) are typically the initial imaging modality of choice (Figure 21-3). X-rays can allow for assessment of medullary sclerosis and the morphology of the fracture. In addition, measurements can be made such as the fourth-to-fifth intermetatarsal angle, the fifth metatarsal lateral deviation angle, and the calcaneal pitch as described by Lee et al, as well as the metatarsus adductus angle as described by Sgarlato et al.
Magnetic resonance imaging (MRI): MRI is best at detecting bone edema and stress reaction, which may occur before stress fracture (Figure 21-4). Fifth metatarsal stress reactions present
with symptoms similar to those of stress fractures, but lack an obvious fracture line on computed tomography (CT). By detecting such stress reactions early, steps may be taken to prevent the stress reaction from progressing into a full-blown stress fracture. MRI has the additional advantage of avoiding radiation exposure.

Figure 21-3. Oblique radiograph of the foot demonstrating a proximal fifth metatarsal fracture.

Figure 21-4. T2 magnetic resonance imaging demonstrating bone marrow edema and a stress reaction in the base of the fifth metatarsal.
CT: CT plays an important role in preoperative planning, because it provides the best visualization of the fracture line. It allows the surgeon to determine whether the fracture line is complete, and whether there is a plantar gap. Furthermore, CT can also be used to monitor healing. Of note, repeat CT and MRI scans are often recommended to ensure positive signs of healing before return to sports.

Treatment Algorithm

The standard method of treatment is percutaneous internal fixation with solid partially threaded screws and with bone marrow aspirate concentrate added to the fracture site.
In fractures that have a higher risk of nonunion, open bone grafting of the fracture site can also be added to the treatment plan.
CT scan is performed at 10 weeks, with a goal of 100% union.