What is the diagnosis?

The patient is diagnosed with an oblique fracture of the distal 5th metatarsal.

Image 2. Plain lateral radiograph of the right foot. Author’s image.

What is the mechanism of injury?

A distal 5th metatarsal oblique fracture is typically the result of a forceful and sudden inversion of the foot, paired with axial loading on the lateral side of the foot [1]. This injury pattern is commonly associated with activities that entail abrupt changes in direction, pivoting, or jumping. The peroneus brevis tendon, which anchors to the base of the 5th metatarsal, exerts a pulling force on the bone during the foot's inversion. This interplay of lateral impact and tendon tension generates a substantial load on the bone. Such fractures typically manifest in the midshaft or distal diaphysis of the bone. The fracture line tends to run diagonally across the bone, originating from the distal lateral aspect and extending towards the proximal medial side [1,2]. 

How is it diagnosed, and what are some other differential diagnoses to be aware of?

Plain radiograph. Beyond the diagnosis, consider a transverse fracture of the metadiaphyseal junction of the 5th metatarsal (Jones fracture) or avulsion fracture at the base of the 5th metatarsal (Pseudo-Jones fracture) in patients with foot pain. 

See Table 1 in the Appendix for a summary of the differentials.

What is the management in the ED?

In the emergency department setting, these patients can generally be placed in a walking CAM boot with outpatient sports medicine or orthopedic follow up. Emergent orthopedic consultation is generally not needed. They can be instructed to bear weight as tolerated. Consider operative management if there is severe displacement or open fracture. If there is more than 3 mm of displacement or angulation exceeds 10 degrees, 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 a consideration [1].

• Pearl: Conservative management often takes 6 to 8 weeks. Assessing for secondary causes such as vitamin D deficiency and osteoporosis is important to consider in elderly female patients such as this case.