FIFTH METATARSAL STRESS FRACTURES - DIAGNOSIS and MANAGEMENT
Jones Fracture | Zone Classification | High Non-Union Risk
ZONE CLASSIFICATION (LAWRENCE & BOTTE)
Critical Must-Knows
- Zone 2 (Jones fracture) has watershed blood supply - high non-union risk
- Intramedullary screw fixation is treatment of choice in athletes
- Zone 1 (tuberosity) avulsions heal reliably with conservative treatment
- Delayed union common if conservative treatment of Zone 2
- Return to sport faster with surgical fixation (6-8 vs 12-20 weeks)
Examiner's Pearls
- "Jones fracture is Zone 2 (NOT Zone 1 tuberosity avulsion)
- "Blood supply enters distally - Zone 2/3 is watershed area
- "Athletes with Zone 2 fractures should be offered surgery
- "Zone 1 avulsions rarely need surgery - peroneus brevis attachment
Clinical Imaging
Imaging Gallery
Critical Fifth Metatarsal Exam Points
Zone Classification
Zone 2 = Jones fracture at metaphyseal-diaphyseal junction. Often confused with Zone 1 tuberosity avulsion. Zone 2 has watershed blood supply and high non-union risk.
Blood Supply
Nutrient artery enters distally, retrograde flow to proximal metaphysis. Zone 2/3 is watershed area between nutrient artery and metaphyseal vessels.
Surgical Indications
Athletes with Zone 2/3 fractures should be offered surgery. Intramedullary screw fixation provides faster healing (6-8 weeks vs 12-20 weeks conservative).
Conservative Success
Zone 1 avulsions heal reliably with NWB casting 4-6 weeks. Conservative treatment of Zone 2/3 in non-athletes requires strict NWB 6-8 weeks.
Quick Decision Guide by Zone
| Zone | Location | Mechanism | Non-Union Risk | Treatment |
|---|---|---|---|---|
| Zone 1 | Tuberosity | Avulsion (inversion) | Less than 5% | Conservative - NWB cast 4-6 weeks |
| Zone 2 (Jones) | Metaphyseal-diaphyseal junction | Acute stress/trauma | 25-50% | Surgery for athletes; conservative option for non-athletes |
| Zone 3 | Proximal diaphysis | Repetitive stress | 30-50% | Surgery strongly recommended - bone graft may be needed |
JONES - Jones Fracture Features
Memory Hook:Keep JONES in mind when managing metaphyseal-diaphyseal junction fractures
ZONES - Fifth Metatarsal Zones
Memory Hook:Remember the ZONES from proximal to distal when evaluating 5th metatarsal pain
SCREW - Surgical Indications
Memory Hook:Use a SCREW when any of these indications are present
CAST - Conservative Management Criteria
Memory Hook:Only CAST when all these criteria are met for Zone 2/3 fractures
Overview and Epidemiology
Fifth metatarsal fractures are common foot injuries with significant variation in prognosis based on anatomical zone. The proximal fifth metatarsal is the most commonly fractured metatarsal.
Epidemiology:
- Peak incidence in 20-40 year age group
- Male predominance, especially in athletes
- Common in basketball, football, soccer, and running sports
- Associated with pes cavus foot type
- Increased risk with tight gastrocnemius and varus hindfoot
Historical context:
- First described by Sir Robert Jones in 1902 (his own injury during dancing)
- Original Jones fracture was Zone 2 location
- Term often incorrectly applied to Zone 1 avulsion fractures
- Torg classification (1984) refined understanding of healing potential
Terminology Clarity
A true Jones fracture is a Zone 2 fracture at the metaphyseal-diaphyseal junction - NOT a tuberosity avulsion (Zone 1). Sir Robert Jones sustained his injury while dancing, and it was at the proximal diaphysis, not the tuberosity.
Pathophysiology and Mechanisms
Fifth metatarsal anatomy:
- Most lateral metatarsal, articulates with cuboid proximally
- Styloid process (tuberosity) projects proximally and laterally
- Insertion of peroneus brevis on tuberosity
- Peroneus tertius inserts on dorsal shaft
Zone anatomy (Lawrence and Botte):
Tuberosity (Avulsion Zone):
- Proximal tip of styloid process
- Site of peroneus brevis insertion
- Well-vascularized from metaphyseal vessels
- Cancellous bone - heals readily
- Mechanism: Inversion injury, peroneus brevis avulses fragment
Excellent healing potential due to good blood supply.
Blood supply:
- Nutrient artery enters distal third of metatarsal shaft
- Blood flows retrograde (distally to proximally)
- Metaphyseal vessels supply proximal tuberosity
- Watershed zone at Zone 2 where supplies meet
- Limited periosteal blood supply in proximal diaphysis
Vascular Watershed
The metaphyseal-diaphyseal junction (Zone 2) represents a watershed zone between the nutrient artery and metaphyseal vessels. This explains the high non-union rate despite adequate fracture reduction.
Blood Supply Key
The nutrient artery enters distally and flows retrograde. Zone 2 is the watershed zone where nutrient artery territory meets metaphyseal vessels. This anatomical fact explains why Zone 2/3 fractures have such high non-union rates compared to Zone 1.
Classification Systems
Lawrence and Botte Zone Classification (1993) - Standard for exam
| Zone | Location | Characteristic | Treatment | Prognosis |
|---|---|---|---|---|
| Zone 1 | Tuberosity | Avulsion fracture | Conservative | Excellent |
| Zone 2 | Metaphyseal-diaphyseal junction | Jones fracture | Surgical for athletes | Guarded |
| Zone 3 | Proximal diaphysis | Stress fracture | Surgical | Poor if delayed |
This is the most clinically useful classification system.
History
Key history points:
- Acute trauma vs insidious onset (stress fracture)
- Mechanism: inversion, direct blow, repetitive stress
- Previous foot injuries or fractures
- Training changes (mileage, intensity, surface)
- Shoe wear and orthotics
- Sport and activity level
Risk factors for stress fracture:
- Rapid training increases
- Change in running surface
- Improper footwear
- Pes cavus foot type
- Previous fifth metatarsal fracture
- Female athlete triad
- Vitamin D deficiency
Thorough history helps distinguish acute injury from chronic stress reaction.
Examination
Physical examination:
Inspection:
- Swelling location (lateral midfoot)
- Ecchymosis
- Foot alignment (pes cavus, hindfoot varus)
- Weight-bearing posture
Palpation:
- Point tenderness over base of 5th metatarsal
- Zone 1 vs Zone 2 vs Zone 3 location
- Comparison to contralateral side
Special tests:
- Weight bearing tolerance
- Single leg hop test (stress fracture screening)
- Gastrocnemius/soleus flexibility
- Ankle ROM and stability
Precise localization of tenderness helps determine zone involvement.
Investigations
X-ray:
- AP, lateral, and oblique foot views
- Acute fracture: visible fracture line
- Stress reaction: periosteal reaction, cortical thickening
- Chronic: medullary sclerosis, widened fracture line
- Compare to contralateral foot for subtle findings
CT scan:
- Assess fracture healing
- Evaluate medullary canal sclerosis
- Preoperative planning for screw sizing
- Detect occult stress fractures
MRI:
- Early stress reaction detection (bone marrow edema)
- Soft tissue assessment
- Evaluate for associated injuries
- Most sensitive for occult fractures
Imaging Choice
X-ray is first-line for acute injury. MRI is most sensitive for early stress reaction (before cortical break). CT is useful for assessing healing and preoperative planning.
Management Algorithm
Conservative treatment (standard):
Non-displaced (most common):
- Hard-soled shoe or short leg walking boot
- Weight bearing as tolerated
- 4-6 weeks immobilization
- Activity progression when pain-free
Displaced fractures:
- Short leg non-weight bearing cast 4-6 weeks
- Followed by walking boot 2-4 weeks
- Surgery rarely needed unless significant displacement
Surgical indications (rare):
- Displacement greater than 2mm
- Large fragment with significant articular involvement
- Failed conservative treatment
Zone 1 avulsions heal reliably due to excellent blood supply.
Surgical Technique
Surgical indications:
Absolute:
- Competitive athletes with Zone 2/3 fractures
- Torg Type III non-unions
- Failed conservative management
Relative:
- Torg Type II delayed unions
- High-demand recreational athletes
- Patient preference for faster return
Contraindications:
- Active infection
- Severe peripheral vascular disease
- Medical comorbidities precluding surgery
Surgical treatment offers faster, more reliable healing for active patients.
Complications
Non-union (most common complication):
Risk factors:
- Zone 2/3 location
- Conservative treatment of high-risk fractures
- Torg Type II or III at presentation
- Non-compliance with weight-bearing restrictions
- Smoking
Management:
- Revision surgery with debridement
- Bone grafting (autograft preferred)
- Larger diameter screw
- Consider low-intensity pulsed ultrasound (LIPUS)
Outcomes:
- Union rate 90%+ with bone graft
- Return to sport typically possible
- May require extended rehabilitation
Non-union is common with Zone 2/3 fractures and requires aggressive treatment.
Postoperative Care
Standard postoperative protocol after intramedullary screw fixation:
Immediate postoperative:
- Posterior splint or CAM boot
- Non-weight bearing
- Elevation and ice for swelling
- Wound care at 10-14 days
- Pain management
Activity:
- Upper body and core exercises allowed
- Ankle ROM exercises in boot
- No weight bearing on operative foot
Initial protection allows fracture healing to begin.
Conservative Recovery
Conservative treatment of Zone 2/3 fractures requires 12-20 weeks for return to sport compared to 6-8 weeks with surgical treatment. This significant difference drives the recommendation for surgery in athletes.
Outcomes and Prognosis
Outcomes by zone and treatment:
| Zone | Treatment | Union Rate | Time to Union | Return to Sport |
|---|---|---|---|---|
| Zone 1 | Conservative | 95%+ | 6-8 weeks | 8-10 weeks |
| Zone 2/3 | Conservative | 70-75% | 12-20 weeks | 15-25 weeks |
| Zone 2/3 | Surgical (screw) | 90-95% | 6-8 weeks | 8-10 weeks |
| Non-union | Surgery + graft | 90-95% | 10-14 weeks | 12-16 weeks |
Factors affecting outcome:
- Zone of fracture (Zone 1 best, Zone 3 worst)
- Chronicity at presentation (acute better than chronic)
- Treatment selection (surgery better for athletes)
- Compliance with rehabilitation
- Underlying biomechanical factors
Long-term outcomes:
- Majority return to pre-injury sport level
- Recurrence more common with conservative treatment
- Hardware symptoms may require screw removal
- Addressing biomechanics reduces recurrence
Prognosis Summary
Zone 1 fractures have excellent prognosis with conservative treatment. Zone 2/3 fractures in athletes should have surgical treatment for faster, more reliable union. Established non-unions require bone grafting with 90%+ success.
Evidence Base
Surgical vs Conservative for Jones Fractures
- Surgical group: 7.5 weeks mean return to sport
- Conservative group: 14.5 weeks mean return to sport
- Refracture rate: 0% surgical vs 21% conservative
- Union rate: 100% surgical vs 72% conservative
Screw Diameter and Union
- Screws 4.5mm or smaller had higher failure rate
- Screws 5.0mm or larger had 96% union rate
- Largest screw that fits is recommended
- Screw should extend to distal metaphysis
Bone Grafting for Non-Unions
- Union rate 94% with autograft and screw
- Average time to union 10 weeks
- Return to sport in 12-16 weeks
- Calcaneal autograft as effective as iliac crest
Torg Classification Prognostic Value
- Type I (acute): 89% union with conservative treatment
- Type II (delayed): 62% union with conservative treatment
- Type III (non-union): 10% union without bone graft
- Classification guides treatment selection
Risk Factors for Refracture
- Premature return to sport increased refracture risk 3-fold
- Conservative treatment had higher refracture than surgery
- Pes cavus and varus hindfoot associated with recurrence
- Orthotics reduced refracture risk in high-risk patients
Exam Viva Scenarios
Practice these scenarios to excel in your viva examination
Scenario 1: Professional Footballer with Jones Fracture
"A 25-year-old professional footballer presents with an acute Jones fracture (Zone 2) after a twisting injury. X-ray shows a sharp fracture line without sclerosis. He has an important match in 8 weeks. How would you manage this patient?"
Scenario 2: Zone 1 Avulsion in Recreational Athlete
"A 40-year-old recreational tennis player presents after an inversion injury with pain at the base of the fifth metatarsal. X-ray shows a 4mm displaced avulsion of the tuberosity (Zone 1). How would you manage this?"
Scenario 3: Non-Union After Conservative Treatment
"A 28-year-old amateur footballer was treated conservatively for a Jones fracture 4 months ago. He continues to have pain and X-ray shows a widened fracture line with medullary sclerosis. How would you manage this non-union?"
MCQ Practice Points
MCQ Focus: Nerve Injury
Q: Which nerve is most commonly injured during the approach for 5th metatarsal screw fixation? A: Dorsolateral Branch of the Sural Nerve. It runs along the lateral aspect of the foot and is at risk with lateral dissection or drill guide placement.
MCQ Focus: Watershed Area
Q: Which arterial supply is deficient at the Zone 2/3 junction? A: The area is a watershed vascular zone between the intramedullary nutrient artery (diaphyseal) and the metaphyseal/periosteal vessels.
MCQ Focus: Screw Position
Q: What is the optimal starting point for an intramedullary screw in the 5th metatarsal? A: High and Inside (Dorsal and Medial) on the base. This aligns the screw with the straight distal segment of the canal.
MCQ Focus: Torg Classification
Q: What defines a Torg Type II fracture? A: Widened fracture line with intramedullary sclerosis. Type I has no sclerosis. Type III has complete canal obliteration.
MCQ Focus: Healing Time
Q: How long does conservative treatment typically take for union in a Zone 3 stress fracture? A: 12-20 weeks (3-5 months). This prolonged time is why surgical fixation (6-8 weeks) is preferred for athletes.
Australian Context
Epidemiology in Australia:
- Common in Australian Rules Football, rugby, soccer, basketball
- High incidence during pre-season training periods
- State and national level athletes frequently affected
- Similar presentation patterns to international data
Management approach:
- Sports medicine physicians and orthopaedic surgeons collaborate
- High rate of surgical intervention for elite athletes
- Good access to MRI for stress fracture detection
- Established return to sport protocols in AFL and NRL
Prevention strategies:
- Bone health screening for at-risk athletes
- Training load monitoring programs
- Footwear assessment and orthotic prescription
- Education on early reporting of foot pain
Australian Sport Context
Fifth metatarsal stress fractures are common in Australian Rules Football due to the cutting, pivoting, and rapid acceleration demands. AFL medical teams have structured protocols for early detection and often proceed directly to surgical treatment for in-season fractures.
Fifth Metatarsal Stress Fractures
High-Yield Exam Summary
Zone Classification
- •Zone 1: Tuberosity avulsion - excellent prognosis
- •Zone 2: Jones fracture (metaphyseal-diaphyseal junction) - high non-union
- •Zone 3: Proximal diaphyseal stress fracture - highest non-union risk
- •True Jones = Zone 2, NOT Zone 1
Blood Supply
- •Nutrient artery enters distally - retrograde flow
- •Zone 2 is watershed zone
- •Poor blood supply = high non-union rate
- •Metaphyseal vessels supply tuberosity (Zone 1)
Torg Classification
- •Type I (acute): Sharp margins, no sclerosis
- •Type II (delayed): Widened line, some sclerosis
- •Type III (non-union): Wide gap, complete sclerosis
- •Sclerosis indicates need for surgery
Treatment by Zone
- •Zone 1: Conservative - NWB cast 4-6 weeks
- •Zone 2/3 athletes: Surgery - IM screw fixation
- •Zone 2/3 non-athletes: Conservative option with monitoring
- •Non-union: Surgery + bone graft
Surgical Technique
- •Entry point: most proximal/lateral tuberosity
- •Largest diameter screw (5mm or greater preferred)
- •Headless compression screw
- •Pitfall: entry too medial = varus angulation
Outcomes
- •Zone 1 conservative: 95% union, 8-10 weeks RTS
- •Zone 2/3 surgical: 90-95% union, 6-8 weeks RTS
- •Zone 2/3 conservative: 70-75% union, 12-20 weeks RTS
- •Surgery offers faster, more reliable healing