Metatarsal Fractures
Metatarsal Fractures
Traumatic and Stress-Related Injuries
Lawrence and Botte (5th MT)
Critical Must-Knows
- Zone 2 (Jones) is a vascular watershed area prone to nonunion
- Zone 1 (Pseudo-Jones) heals well with protected weight-bearing
- Lisfranc injury must be excluded with weight-bearing views if subtle
- 1st Metatarsal requires zero displacement tolerance due to load bearing
- Smoking significantly increases the risk of Jones fracture nonunion
Examiner's Pearls
- "Jones fracture entry point: 'High and Inside' (High-Dorsal, Inside-Medial)
- "Fleck sign: Pathognomonic for Lisfranc avulsion (Base of 2nd MT)
- "Stress fractures: 2nd MT (Good) vs 5th MT (Poor) prognosis
- "Early fixation in athletes improves time to union and return to play
Clinical Imaging
Imaging Gallery
Exam Warning
The exam favourite is the Zone 2 (Jones) fracture of the 5th metatarsal. It is a vascular watershed area (metaphyseal-diaphyseal junction) and prone to nonunion. Do not confuse it with Zone 1 (Pseudo-Jones) which is a tuberosity avulsion and heals universally. Zone 3 is a diaphyseal stress fracture and has the highest nonunion rate.
At a Glance
Metatarsal Fractures: Key Features
| Feature | Detail |
|---|---|
| Most Common | 5th Metatarsal (70%) |
| Most Critical | 1st Metatarsal (Load bearing) |
| High Risk | Zone 2/3 (Watershed nonunion) |
| Lisfranc Sign | Plantar ecchymosis |
| Lisfranc Pathognomonic | Fleck sign (Base of 2nd MT) |
| Lisfranc Radiology | Gap >2mm between 1st/2nd MT |
Essential Mnemonics
5th Metatarsal Zones
Memory Hook:1-2-3: The further down the bone (distal), the worse it heals
Lisfranc Stability
Memory Hook:M-M-L: Medial, Middle (the key), Lateral
Jones Entry Point
Memory Hook:Stay 'HI' (High and Inside) to avoid the lateral cortex
Overview and Epidemiology
Metatarsal fractures are common foot injuries, representing approximately 35% of all foot fractures. The fifth metatarsal is the most frequently injured, accounting for nearly 70% of metatarsal fractures. These injuries range from simple avulsion fractures to complex stress reactions and traumatic Lisfranc disruptions.
- 5th Metatarsal: Most common (Zones 1-3). Zone 1 (Avulsion) is the most frequent.
- Central Metatarsals (2-4): Often fractured together. Isolated fractures are rare and should raise suspicion of Lisfranc involvement.
- 1st Metatarsal: Least common but most critical for weight-bearing (carries 1/3 of body weight).
- Stress Fractures: "March fracture" classically involves the 2nd or 3rd metatarsal shaft. 5th metatarsal stress fractures (Zone 3) are high-risk.
Anatomy and Biomechanics
The foot's structural integrity depends on the metatarsals' role in the longitudinal and transverse arches.
Structural Anatomy
- The Columns:
- Medial Column: 1st Metatarsal + Medial Cuneiform (Flexible).
- Middle Column: 2nd/3rd Metatarsals + Middle/Lateral Cuneiforms (Rigid, "Keystone").
- Lateral Column: 4th/5th Metatarsals + Cuboid (Mobile).
- Ligamentous Support: The Lisfranc ligament (oblique) connects the medial cuneiform to the base of the 2nd metatarsal. There is no ligamentous connection between the 1st and 2nd metatarsal bases.
Blood Supply of the 5th Metatarsal
The 5th metatarsal base has a dual blood supply:
- Metaphyseal Arteries: Supply the tuberosity (Zone 1).
- Nutrient Artery: Enters the mid-diaphysis and travels proximally. The Junction: The area between these two supplies (Zone 2 - Jones fracture site) is a vascular watershed area, leading to high nonunion rates. [1]
Biomechanics
- Weight Distribution: During gait, the 1st metatarsal takes double the load of the lesser metatarsals.
- Load Sharing: The metatarsal heads follow a parabolic curve. Shortening of one metatarsal (e.g., malunion) leads to transfer metatarsalgia under adjacent heads.
Classification Systems
Divides the 5th metatarsal base into three zones based on anatomy and healing potential.
Classification
| Grade/Type | Description | Management |
|---|---|---|
| Pseudo-Jones | Tuberosity avulsion. Involves the cancellous bone. Heals universally. | Boot and weight-bear as tolerated. Excellent prognosis. |
| Jones Fracture | Metaphyseal-diaphyseal junction. Extends into the 4th-5th intermetatarsal joint. Watershed area. | NWB cast 6-8 weeks OR intramedullary screw fixation (athletes). |
| Stress Fracture | Proximal diaphyseal fracture. Distal to the 4th-5th intermetatarsal joint. Very poor biology. | Intramedullary screw fixation strongly recommended. High nonunion risk. |
Clinical Assessment
A high degree of clinical suspicion for Lisfranc injury is required for all midfoot trauma.
- Mechanism: Direct blow (crush) vs. Indirect twisting (Lisfranc).
- Pain: Inability to weight-bear is a significant indicator of instability.
- Training History: Recent increase in load (military recruits, marathon runners) for stress fractures.
Investigations
Radiographic assessment is the gold standard, but subtle injuries may require advanced imaging.
Plain Radiographs
Standard Views AP, Lateral, and 30° Oblique views. Lisfranc Signs:
- Gap greater than 2mm between 1st/2nd MT bases.
- Fleck Sign: Bony avulsion in the 1st intermetatarsal space.
Weight-Bearing Views
Stability Assessment Essential for subtle Lisfranc injuries. If painful, consider stress radiographs under anesthesia.
CT Scan
Pre-op Planning Superior for identifying small avulsion fractures (Fleck sign) and assessing articular involvement.
MRI
Stress Fractures The most sensitive test for early stress reactions (bone marrow edema) before cortical changes appear on X-ray.
Management Algorithm
- Zone 1: Symptomatic weight-bearing in boot.
- Zone 2 (Jones): NWB cast (6-8 weeks) OR Screw fixation in athletes.
- Zone 3 (Stress): Aggressive surgical fixation recommended.
Surgical Technique
Setup & Approach
- Positioning: Patient supine with a bolster under the ipsilateral hip to rotate the foot medially.
- Imaging: Enables optimal lateral foot C-arm view.
- Entry Point: Establish a 'High and Inside' (dorsomedial) entry point on the tuberosity.
- Significance: Avoids splitting the lateral cortex and aligns with the intramedullary canal.
Surgical Technique
- Guidewire: Pass a 1.6mm or 2.0mm guidewire down the intramedullary canal.
- Confirmation: Confirm central placement on AP and Lateral views.
- Drilling: Drill over the wire cautiously.
- Screw: Insert a 4.5mm - 5.5mm partially threaded screw.
- Compression: Confirm compression across the watershed zone on C-arm.
Technical Pearls
- Screw Selection: Use the largest diameter solid screw (4.5-5.5mm).
- Thread Engagement: Ensure all threads cross the fracture site.
- Length: Screw tip should reach within 5mm of the distal MT head.
- Bone Graft: Consider for delayed unions (greater than 6 months).
Common Pitfalls
- Undersized screw: Leads to persistent nonunion.
- Lateral entry point: Risks splitting the lateral cortex.
- Eccentric wire: Leads to distal cortical perforation.
- Sural Nerve: Avoid excessive lateral dissection.
Complications
Metatarsal fractures, particularly the 5th, are prone to specific long-term issues.
Complications of Metatarsal Trauma
| Complication | Risk Site / Cause | Management / Sign |
|---|---|---|
| Nonunion | Zone 2/3 (5th MT) | ORIF + Bone Graft (ICBG) |
| Metatarsalgia | Malunion (Plantar angulation) | Transfer lesion to adjacent heads |
| Sural Neuropathy | Lateral approach to 5th MT base | Numbness on lateral foot border |
| Hardware Prominence | Pain over screw head | Hardware removal after union |
| Refracture | Premature return to sport | Occurs in 10-15% of athletes |
| Compartment Syndrome | High-energy crush injury | RARE but emergent fasciotomy required |
| Post-traumatic Arthritis | Lisfranc injury (50% rate) | May require fusion at 2-5 years |
| Complex Regional Pain | Prolonged immobilization | Early mobilization, physio, pain clinic |
Detailed Complication Management
Nonunion (Zone 2/3 - Fifth Metatarsal)
- Incidence: 30-50% without surgery for Jones fractures.
- Risk Factors:
- Smoking (most significant).
- Delayed presentation (>6 weeks).
- Premature weight-bearing.
- Undersized screw fixation (<4.5mm).
- Management:
- Revision: Larger diameter screw (5.5mm+).
- Biology: Debridement + Bone Graft (ICBG/BMAC).
- Stimulation: External bone stimulator.
Postoperative Care
Recovery depends on the stability of the construct and the biology of the fracture.
Phase 1 (0-2 weeks)
Protection Splint/Backslab. Strictly Non-Weight Bearing. Elevation to manage edema.
Phase 2 (2-6 weeks)
Mobilization Transition to a CAM walking boot. Gentle ROM of toes. Weight-bearing status per surgeon/topic protocol.
Phase 3 (6-12 weeks)
Rehabilitation Gradual weight-bearing as tolerated. Physical therapy for intrinsic foot muscle strengthening.
Outcomes and Prognosis
Overall prognosis for metatarsal fractures is good, provided structural alignment is maintained.
Zone 1 & Central MTs
Excellent Predictable healing within 6-10 weeks. Functional return to baseline is standard.
Zone 2 & 3 (5th MT)
Guarded Highest rate of secondary intervention (up to 30%). Return to high-impact sport may take 4-6 months if nonunion develops.
Long-term Prognosis
- Arthritis: Post-traumatic arthritis is common following Lisfranc injuries, even with anatomical reduction.
- Deformity: Malunion (plantar angulation) leads to chronic metatarsalgia.
Evidence Base
Surgical vs Cast for Jones
- RCT: Surgery vs Cast
- Surgery: 95% union, faster return to sport
- Cast: 44% failure rate
Screw Diameter Matters
- Larger screws (>4.5mm) = Higher union rates
- Solid screws biomechanically superior to cannulated
Zone 1 (Pseudo-Jones) Outcomes
- Prospective study of tuberosity avulsions
- Soft elastic dressing vs Cast
- Soft dressing: Faster return to baseline & full union
Exam Viva Scenarios
Practice these scenarios to excel in your viva examination
"A 19-year-old elite basketball player presents with sudden lateral foot pain after a pivot. X-ray shows a transverse fracture at the 5th MT base, 2cm distal to the tuberosity tip. How would you proceed?"
MCQ Practice Points
Exam Pearl
Q: What are the three zones of 5th metatarsal base fractures and their significance?
A: Zone 1 (tuberosity avulsion): Peroneus brevis insertion, excellent healing, weight-bear as tolerated. Zone 2 (Jones fracture): Metaphyseal-diaphyseal junction, poor blood supply, high nonunion risk - consider early fixation in athletes. Zone 3 (diaphyseal stress): Chronic, requires intramedullary screw fixation.
Exam Pearl
Q: What associated injury must be excluded with any metatarsal fracture?
A: Lisfranc injury - tarsometatarsal joint complex disruption. Check for: 2nd MT base alignment with middle cuneiform on AP, medial border of 4th MT aligns with medial cuboid on oblique. Fleck sign (avulsion between 1st/2nd MT bases) pathognomonic. Weight-bearing radiographs if subtle. Missed injury leads to painful flatfoot.
Exam Pearl
Q: What are the indications for surgical fixation of metatarsal shaft fractures?
A: Surgical indications: greater than 10° sagittal angulation, greater than 3-4mm shortening, displacement greater than 3-4mm in transverse plane, multiple metatarsal fractures (disrupts transverse arch), open fractures, compartment syndrome. Central metatarsals (2-4) tolerate less displacement than 1st or 5th due to load distribution.
Exam Pearl
Q: What is the mechanism and treatment of first metatarsal stress fractures?
A: First MT stress fractures occur in runners with forefoot varus or hypermobility. Located at proximal metaphysis or diaphysis. Treatment: Activity modification, rigid-soled shoe/boot for 6-8 weeks. Surgical fixation for nonunion or elite athletes. Risk factors include vitamin D deficiency, female athlete triad, training errors.
Exam Pearl
Q: What is the "March fracture" and its typical location?
A: March fracture = stress fracture of metatarsal shaft, classically 2nd or 3rd metatarsal neck/shaft. Named for military recruits. Caused by repetitive stress exceeding bone remodeling capacity. X-ray may be negative initially; periosteal reaction or callus appears 2-3 weeks later. MRI/bone scan for early diagnosis if needed.
Australian Context
Epidemiology in Australia:
Metatarsal fractures are common in Australian sports medicine, particularly in high-intensity contact sports such as AFL, rugby league, rugby union, and netball. The fifth metatarsal accounts for approximately 70% of metatarsal injuries in athletic populations. Jones fractures (Zone 2) represent a particular challenge in professional AFL and NRL athletes, where rapid return to play is prioritized. The incidence of stress fractures has increased in military recruits and distance runners, with second metatarsal stress fractures ("March fractures") comprising the majority of overuse injuries in Australian Defence Force training programs.
Management Principles in Australian Trauma and Sports Medicine:
Australian foot and ankle surgeons follow evidence-based protocols emphasizing early surgical fixation for Jones fractures in elite athletes, consistent with Level I evidence demonstrating superior union rates and faster return to sport. Specialist foot and ankle services are concentrated in major metropolitan trauma centers and sports medicine clinics. The Australian Orthopaedic Foot and Ankle Society (AOFAS) provides guidelines supporting intramedullary screw fixation for Zone 2 and 3 fractures in active individuals. VTE prophylaxis protocols follow RACS guidelines, with low-molecular-weight heparin or direct oral anticoagulants prescribed for immobilized patients undergoing lower limb surgery.
Access to Care and Rehabilitation:
Public hospital services provide comprehensive metatarsal fracture management, though elective surgical fixation for stress fractures may have extended waiting periods in non-urgent cases. Sports medicine clinics and private orthopaedic practices offer expedited surgical intervention. Rehabilitation is typically coordinated through titled sports physiotherapists (members of Sports Medicine Australia) who specialize in progressive weight-bearing protocols and return-to-sport clearance. The Australian Institute of Sport (AIS) has established evidence-based return-to-play criteria for metatarsal injuries that are widely adopted by state sports institutes and professional sporting codes.
Exam Cheat Sheet
High-Yield Exam Summary
5th MT Base Zones
- •Zone 1: Avulsion → Boot and weight-bear as tolerated
- •Zone 2: Jones → Watershed, NWB Cast or Screw (Athlete)
- •Zone 3: Stress → Diaphyseal, High risk of nonunion
Lisfranc Pearls
- •Plantar ecchymosis (Pathognomonic sign)
- •Gap greater than 2mm between 1st/2nd MT bases
- •Fleck sign is a pathognomonic avulsion fragment
Management Limits
- •1st MT: Zero displacement tolerance
- •2-4 MT: less than 10° angulation, less than 3mm shortening
- •5th MT: Zone 2 always requires non-operative protection or ORIF