The Case: A 54-year-old woman presented to the ED with pain in his right foot after twisting it while climbing back down a ladder. On exam, she had pain to palpation over the lateral aspect of the forefoot. A radiograph was obtained.
Interpretation: Tuberosity Avulsion Fracture of the 5th metatarsal (Pseudo-Jones)
Why it matters:
A fracture at the base of the 5th metatarsal is one of the most common foot fractures ED physicians will encounter, and based on where the fracture is located guides management of the fracture. The base of the 5th metatarsal is divided into three anatomic fracture zones. Zone 1 is a tuberosity avulsion (Pseudo-Jones or Dancer’s fracture) where the fracture line does not extend into the articulation between the 4th metatarsal. The mechanism is plantar flexion and hindfoot inversion. Zone 2 involves a fracture at the metaphyseal-diaphyseal junction (Jones fracture) where the fracture extends into the articulation of the 4th metatarsal. Jones fractures are likely secondary to forefoot adduction. Lastly, zone 3 is classified by a fracture distal to the metaphyseal-diaphyseal junction usually secondary to repetitive microtrauma (i.e. stress fracture) (1).
As stated earlier, the location of the fracture determines how it is managed in the ED. Zone 1 or Pseudo-Jones fractures may be treated with protected weight-bearing in a hard-soled shoe or walking boot and the patient is instructed to bear weight as tolerated (2). Typically, they heal well (over a period of 8-12 weeks) and prompt follow up is not necessary.
Zone 2 (Jones) fractures are believed to have a higher rate of poor healing due to a “watershed area” of the blood supply to the proximal 5th metatarsal at the metaphyseal-diaphyseal junction (1). The rate of nonunion is controversial, but has been reported to be as high as 30% of all zone 2 fractures. As such, they may require operative intervention (2). Given this potential increased risk, Jones fractures are best treated in the emergency department with a posterior ankle splint, non-weight bearing status, and more timely follow up with a specialist (2). The ED treatment of zone 3 fractures is the same as Zone 2 fractures since they are also at an increased risk of nonunion (2).
Written by:
Yonathan Debessai, MD
Cook County Health, PGY-2
Reviewed by:
Scott Sherman, MD
Associate Program Director
Cook County Health
References:
Den Hartog, Bryan D. "Fracture of the proximal fifth metatarsal." JAAOS-Journal of the American Academy of Orthopaedic Surgeons 17.7 (2009): 458-464.
Smidt KP, Massey P. 5th Metatarsal Fracture. [Updated 2020 Aug 10]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2020 Jan-.