Summary

Fractures of the metatarsals are the most common traumatic foot injuries. Management depends entirely on the specific bone and zone involved. The 5th Metatarsal Base is the most notorious due to its variable blood supply; fractures in the vascular watershed (Zone 2 / Jones Fracture) have a high non-union rate (30-50%) and require aggressive management (Cast or Screw), whereas avulsions (Zone 1 / Pseudo-Jones) heal predictably. Stress Fractures ("March Fractures") of the lesser metatarsal necks are common in runners/military recruits. Lisfranc Injuries involving the 2nd Metatarsal base must always be excluded. [1,2,3]

Key Facts

• Most Common: Zone 1 Avulsion of the 5th Metatarsal (Pseudo-Jones).
• The Watershed: The metaphyseal-diaphyseal junction of the 5th MT (Zone 2) receives blood from both proximal and distal sources, creating a zone of poor perfusion. Fractures here struggle to heal.
• The Keystone: The 2nd Metatarsal base is the keystone of the arch. Fractures here suggest a Lisfranc dislocation.
• March Fracture: A stress fracture of the 2nd/3rd metatarsal neck due to repetitive loading (Army recruits).

Clinical Pearls

"Zone 2 is the Danger Zone": Draw a line between the 4th and 5th metatarsal bases.

• If the fracture enters this joint -> Zone 2 (Jones) -> BAD (Requires Cast/Screw).
• If the fracture is proximal to this joint -> Zone 1 (Avulsion) -> GOOD (Shoe/Boot).

"Respect the 1st Ray": The 1st Metatarsal bears 50% of body weight. It usually requires fixation for even minimal displacement to prevent load transfer metatarsalgia.

"The Black Line": In chronic stress fractures, a transverse black radiolucent line indicates a non-union ("Dreaded Black Line"). Surgery is almost always needed.

                 METATARSAL FRACTURE
                        ↓
             WHICH BONE? WHICH ZONE?
             ┌──────────┴──────────┐
          1st-4th               5th METATARSAL
             ↓                     ↓
       DISPLACED >3mm?            ZONE?
       OR ANGULATED?        ┌──────┼──────┐
       ┌─────┴─────┐      ZONE 1 ZONE 2 ZONE 3
      NO          YES       ↓      ↓      ↓
      ↓            ↓       BOOT   CAST   SURGERY
    BOOT         SURGERY  (WBAT)  (NWB)  (Screw)
   (WBAT)       (Wire/Plate)     (6-8w)

Zone 1 (Avulsion / Pseudo-Jones)

• Treatment: Symptomatic. Stiff-soled shoe or Walking Boot.
• Weight Bearing: As tolerated (WBAT).
• Prognosis: Excellent. Union in 6-8 weeks. Non-union is rare and usually painless.

Zone 2 (True Jones Fracture)

• Conservative: Non-Weight Bearing Cast for 6-8 weeks. (Success ~75%).
• Surgical: Intramedullary Screw Fixation (e.g., 4.5mm Cannulated Screw).
  • Indication: Athletes, High-demand patients, delayed diagnosis.
  • Benefit: Faster return to sport (8 weeks vs 14+ weeks) and lower non-union rate (<5% vs 25-40%).

Zone 3 (Proximal Diaphysial Stress)

• Treatment: Surgery (IM Screw + Bone Graft) is routinely recommended due to extremely high rate of non-union with casting.

Stress Fractures (March Fracture)

• Phase 1: Rest. Boot. Stop running.
• Phase 2: Cross-train (Swim/Bike) until pain-free.
• Phase 3: Gradual return to run (10% rule).
• Surgery: Rarely needed unless frank displacement occurs.

Shaft Fractures (Traumatic)

• Check: Are the heads aligned in the "Cascade"? Is there plantar angulation (pebble in shoe)?
• Surgery: Indicated for shortening >3mm, angulation >10 deg plantar, or multiple fractures.
  • Technique: K-wires (retrograde) or Plates.

The Mologne Trial (Am J Sports Med 2005)

• RCT comparing Cast vs Screw for Acute Jones Fractures.
• Result:
  • Cast: 44% treatment failure (non-union / refracture).
  • Screw: 5% failure. Median time to return to sport was significantly faster.
• Conclusion: Surgical fixation is the gold standard for active individuals.

Early Weight Bearing for Zone 1

• Multiple studies confirm that Zone 1 fractures are benign. Immobilization in a cast is unnecessary and harmful (stiffness/atrophy). "Treat the patient, not the X-ray."

The "Dancer's Fracture" (Zone 1)

You have pulled a chip of bone off the side of your foot. It feels like a sprain and looks bad on X-ray, but it heals very well. You can walk on it in a boot as pain allows.

The "Jones Fracture" (Zone 2)

This break is in a specific "bad blood supply" area. If you walk on it, it will not heal. You have two choices:

1. Cast: No weight for 6-8 weeks. (75% chance of healing).
2. Surgery: A screw down the definitive of the bone. (95% chance of healing, faster recovery).

The "March Fracture"

You have marched/run too much. The bone has microscopic cracks. If you stop running now, it will heal. If you continue, it will snap.

Q1: What are the 3 zones of the 5th Metatarsal base (Lawrence & Botte)? A: Zone 1: Tuberosity Avulsion. Zone 2: Metaphyseal-Diaphyseal Junction (Jones). Zone 3: Proximal Diaphysis (Stress).

Q2: Why is the blood supply to Zone 2 precarious? A: It is a watershed area supplied by the nutrient artery (distal) and metaphyseal vessels (proximal). The fracture disrupts the flow, leaving the area ischemic.

Q3: What complication arises from fracture of the Metatarsal Neck with plantar angulation? A: The metatarsal head becomes prominent in the sole of the foot, acting like a "pebble in the shoe". It alters the weight-bearing mechanics, leading to intractable plantar pain and callosity formation.

Q4: How do you treat a Zone 1 injury? A: Symptomatically. Protected weight bearing in a stiff-soled shoe or boot. It does not require a cast.

(End of Topic)