What is the diagnosis?

Avulsion fracture of the 5th metatarsal styloid, also known as a pseudo-Jones fracture which involves an intra-articular fracture of the base of the 5th metatarsal.

Image 2. Case courtesy of Frank Gaillard, Radiopaedia.org, rID: 12765 [2]. Annotation by author. 

What is the mechanism of injury?

Fractures of the styloid (tuberosity) of the 5th metatarsal are considered avulsion fractures at the insertion site of the peroneus brevis tendon. These can occur during a forced inversion of the hindfoot and plantarflexion of the forefoot, such as a runner inverting their foot while running on an uneven surface or a soccer player landing awkwardly after a jump for a header [1]. It can often occur after repeated stress on the metatarsal styloid; for example a marathoner running 26.2 miles throughout the uneven city streets of Chicago. 

Avulsion fractures are the most common type of fracture involving the 5th metatarsal. Image 3 below demonstrates the other common sites of fracture.

Image 3. Case courtesy of Frank Gaillard, Radiopaedia.org, rID: 7644 [2]

• Pearl: Fractures of the proximal 5th metatarsal are classified into two groups, zone 1 and zone 2.

• Zone 1 fractures involve the styloid of the 5th metatarsal. Zone 1 generally has an abundant collateral blood supply and the risk for malunion is low. 

• Zone 2 fractures involve the intermetatarsal zone and proximal diaphysis. Zone 2 fractures are at higher risk for malunion due to tenuous blood supply. This is typically where Jones fractures occur.

What physical exam findings are expected?

On initial inspection of the foot, swelling and ecchymosis can be present along the lateral or plantar aspect of the foot. There will be point tenderness along the base of the 5th metatarsal in nearly all cases of 5th metatarsal avulsion fractures. 

• Pearl: A thorough ankle exam is critical with foot injuries, even when an injury to the midfoot or forefoot is suspected.

• Pearl: Palpation of the base of the 5th metatarsal is a recommended part of the ankle exam and is included in the Ottawa Ankle Rules.

• Pearl: The Ottawa Ankle Rules were developed to rule out clinically significant foot and ankle fractures as a means to reduce X-ray imaging. It includes five components:

  1. Tenderness to palpation along the distal 6 cm of the posterior edge of fibula or tip of lateral malleolus

  2. Tenderness along distal 6 cm of the posterior edge of tibia/tip of medial malleolus

  3. Tenderness at the base of the 5th metatarsal

  4. Tenderness at the navicular

  5. Inability to bear weight both immediately after injury and for 4 steps during initial evaluation [3]

What is the management in the ED?

Management is typically conservative. Nondisplaced 5th metatarsal styloid fractures only require symptomatic treatment. This general approach includes rest, ice, compression, analgesics (acetaminophen and ibuprofen), and elevation. Patients should be encouraged to weight-bear as tolerated. If weight bearing is painful, crutches can be used until the pain improves. 

• Pearl: Other options for patients include commercially available walking boots, a postoperative hard sole shoe, or compression dressing such as ace wrap. Patients should work with their sports medicine physician to develop a stepwise return to activity plan [1].

When do you consult orthopedic surgery?

Emergent referral is generally not required for fractures of the 5th metatarsal styloid. 

Considerations for referral include:

1. Displacement > 3 mm

2. Step-off greater than 1 to 2 mm at the articular surface with the cuboid

3. Symptomatic malunion

4. Presence of other associated fractures

Patients should seek follow up with an orthopedic surgeon or sports medicine physician in 1-2 weeks after injury [1].