Fifth metatarsal base fractures

Three zones at the base of the fifth metatarsal behave differently: the tuberosity (zone 1) heals reliably, the metaphyseal–diaphyseal junction (zone 2, the true Jones fracture) lies in a watershed area and heals poorly, and the proximal shaft (zone 3) is usually a stress fracture.

Mechanism

Zone 1: inversion (peroneus brevis and lateral band of the plantar fascia avulse the tip). Zone 2: adduction of the forefoot with the ankle plantarflexed. Zone 3: repetitive load (athletes).

Clinical findings

• Tenderness over the base of the fifth metatarsal (part of the Ottawa foot rules).

Imaging

• AP, oblique and lateral of the foot (Ottawa foot rules).
• Zone matters: avulsion (zone 1), Jones (zone 2) or diaphyseal stress fracture (zone 3).

• AP, oblique and lateral foot. Do not confuse with the apophysis in children (parallel to the shaft) or the os peroneum.

Classification

Zone 1

Tuberosity avulsion.

Zone 2

Jones fracture at the metaphyseal–diaphyseal junction, extends into the 4th–5th intermetatarsal joint.

Zone 3

Proximal diaphyseal stress fracture.

Types shown in 3D

Zone 1

Tuberosity avulsion (pseudo-Jones): heals reliably. Stiff shoe, weight bearing as tolerated.

Zone 2

Jones fracture at the metaphyseal–diaphyseal junction (into the 4th–5th intermetatarsal joint): watershed blood supply, slow healing. Non-weight-bearing cast or screw.

Zone 3

Proximal diaphyseal stress fracture (athletes): screw fixation is often preferred.

Treatment

Zone 1

Symptomatic: stiff-soled shoe or boot, weight bearing as tolerated.

Zone 2–3

Non-weight-bearing cast for 6–8 weeks, or intramedullary screw fixation in athletes and in delayed union.

Aftercare

Gradual return to sport guided by symptoms and healing.

Complications

• Non-union and refracture (zones 2–3)