Fractures around the base of the 5th metatarsal

Clinical History

We present three cases outlining the normal variants and trauma to the base of the 5th metatarsal.

Imaging Findings

We present a case of a fracture through the base and apophysis of the 5th metastarsal in a 13-year-old boy following an ankle trauma. Further examples of the normal anatomy and fractures are given, to draw attention to the possibility of confusion of the normal findings with pathology in this region.

Discussion

The mechanism for fracture in this region is usually a forced inversion causing an avulsion of the base of the 5th metatarsal. A clinical assessment is often made using the Ottawa rules (Steill et al.), which were more recently discussed in a systematic review (Bachmann et al.). Midfoot views are only generally requested when there is a specific concern, like tenderness of the base of the 5th metatarsal. Nevertheless, the 5th metatarsal is generally included on the lateral ankle view, so that an obvious fracture can be identified even when it is clinically not suspected. Our case is one of an unusual fracture through the apophysis and base of the 5th metatarsal. The subsequent film shows a simple base fracture as a clear transverse break in the cortex and an accompanying soft tissue swelling. The final film demonstrates a normal apophysis with the longitudinal lucent line at the base. The important radiological feature is that fractures tend to run transversely across the base while the physeal line is longitudinal. The fractures are generally related to the peroneus brevis tendon coming under stress. It is important to note that these fractures are not "Jones" fractures. Jones fractures involve the proximal shaft of the metatarsal and not the base, and do not relate to avulsion by the peroneus brevis tendon (Rodgers). Jones fractures should be properly distinguished, as they can often require surgical intervention. Avoiding misdiagnoses in this region is extremely important to avoid unnecessary treatment and to provide follow-up as guided, in the case of a Jones fracture.

Differential Diagnosis List

Final Diagnosis

Fracture through the apophysis of the 5th metatarsal base.

URL:	https://www.eurorad.org/case/2868
DOI:	10.1594/EURORAD/CASE.2868
ISSN:	1563-4086