Fifth Metatarsal Stress Fractures

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.

Metaphyseal-Diaphyseal Junction (Jones Fracture):

• Junction between metaphysis and diaphysis
• Extends into 4th-5th intermetatarsal articulation
• Watershed zone between metaphyseal and diaphyseal blood supplies
• Nutrient artery enters distally - retrograde flow
• Cortical bone with limited cancellous component

High non-union risk due to compromised blood supply.

Proximal Diaphysis (Stress Fracture Zone):

• Proximal 1.5cm of diaphysis distal to Zone 2
• Pure cortical bone
• Highest mechanical stress concentration
• Chronic stress reaction may precede complete fracture
• Often shows medullary sclerosis on X-ray

Highest non-union risk - often requires bone grafting.

Lawrence and Botte Zone Classification (1993) - Standard for exam

This is the most clinically useful classification system.

Torg Classification (1984) - For Zone 2/3 fractures

Classifies based on radiographic appearance of chronicity:

| Type II (Delayed) | Widened fracture line, periosteal new bone, some sclerosis | Surgery recommended | | Type III (Non-union) | Wide fracture gap, complete sclerosis of medullary canal | Surgery with bone graft |

Stewart Classification - For Zone 1 fractures

Most Zone 1 fractures heal reliably with conservative management.

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.

Differential considerations:

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

Signs of chronicity (Torg criteria):

Identifying chronicity guides treatment selection and prognosis counseling.

Consider bone health workup for stress fractures:

• Vitamin D (25-OH)
• Calcium
• TSH
• Female athlete triad screening
• DEXA if recurrent stress fractures

Optimizing bone health is essential for fracture healing and prevention of recurrence.

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 management (recommended for athletes):

Indications:

• Competitive athletes with any Zone 2/3 fracture
• Torg Type II or III fractures
• Delayed union or non-union
• Need for expedited return to sport

Surgical technique:

• Intramedullary screw fixation
• Largest diameter screw that fits (4.5-6.5mm)
• Bone graft for Type III non-unions
• Headless compression screw preferred

Postoperative protocol:

• NWB 2-3 weeks
• Progressive WB weeks 3-6
• Return to sport 6-8 weeks

Surgical fixation offers faster and more reliable healing for athletes.

Conservative management (option for low-demand patients):

Protocol:

• Short leg non-weight bearing cast 6-8 weeks
• Serial X-rays every 2-3 weeks
• Transition to walking boot when healing evident
• Progressive weight bearing

Expected outcomes:

• Healing rate 70-75% for acute fractures
• Time to union 12-20 weeks
• Refracture risk 15-25%

When to convert to surgery:

• No healing progress at 6-8 weeks
• Development of medullary sclerosis
• Worsening symptoms

Conservative management requires strict compliance and close monitoring.

Treatment of established non-union:

Surgical approach:

• Debridement of sclerotic bone
• Medullary canal drilling/reaming
• Autologous bone graft (calcaneus or iliac crest)
• Intramedullary screw fixation

Augmentation options:

• Autograft (gold standard)
• Bone marrow aspirate concentrate
• Biologics (BMP-2 off-label)

Expected outcomes:

• Union rate 90-95% with bone graft
• Return to sport 10-16 weeks
• Refracture rate less than 10%

Established non-unions require aggressive debridement and bone grafting.

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.

Intramedullary screw fixation technique:

Technical pearls:

• Use largest diameter screw that fits
• Entry point is critical - too medial causes varus angulation
• Headless compression screw preferred
• Ensure screw crosses fracture site into distal metaphysis

Proper screw placement is essential for compression and stability.

Bone grafting for non-unions:

Indications:

• Torg Type III non-unions
• Significant medullary sclerosis
• Failed primary screw fixation

Graft options:

• Calcaneal autograft - lateral approach, cancellous bone (preferred)
• Iliac crest autograft - larger volume, more morbidity
• Intramedullary allograft - dowel graft technique

Technique:

• Debride sclerotic bone and fracture site
• Drill/ream medullary canal
• Pack cancellous graft into fracture site
• Fix with intramedullary screw

Bone grafting significantly improves union rates for non-unions.

Surgical pearls:

• High and lateral entry point prevents varus
• Largest possible screw diameter (aim for greater than 5mm)
• Confirm fracture compression with C-arm
• Protect sural nerve branches

Pitfalls to avoid:

• Entry point too medial - causes varus angulation
• Undersized screw - inadequate compression
• Failure to debride sclerotic bone in non-unions
• Missing concomitant soft tissue pathology

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.

Refracture:

Risk factors:

• Premature return to sport
• Previous non-union
• Undersized screw fixation
• Persistent biomechanical abnormalities

Prevention:

• Ensure radiographic union before return to sport
• Gradual activity progression
• Address underlying biomechanics (orthotics, flexibility)
• Consider screw removal with caution

Treatment:

• Revision fixation with larger screw
• Bone grafting
• Extended rehabilitation

Refracture rate is 15-25% with conservative treatment vs less than 5% with surgical treatment.

Screw-related complications:

• Screw prominence - may cause pain in shoes
• Screw breakage - rare with proper sizing
• Screw loosening - usually indicates non-union
• Sural nerve injury - from surgical approach

Management:

• Symptomatic screws can be removed after union
• Broken screws may need removal and revision fixation
• Loose screws indicate non-union - treat underlying problem

Hardware complications are uncommon with proper technique.

General complications:

• Wound infection (less than 1%)
• Sural nerve injury (numbness lateral foot)
• Peroneus brevis tendon injury
• Chronic pain
• Stiffness

Prevention:

• Meticulous soft tissue handling
• Protect sural nerve branches
• Avoid over-tightening closure
• Early ROM exercises

Most complications are minor and resolve with conservative measures.

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.

Progressive weight bearing:

Weeks 2-4:

• Transition to walking boot
• Progressive partial weight bearing
• Pool exercises if wound healed
• Stationary cycling (non-operative leg)

Weeks 4-6:

• Full weight bearing in boot
• X-ray to assess healing
• Begin closed-chain strengthening
• Gait training

Gradual progression prevents stress on healing bone.

Return to activity:

Weeks 6-8:

• Transition to regular footwear
• Progressive walking and light jogging
• Sport-specific conditioning
• Confirm radiographic healing

Weeks 8-12:

• Gradual return to sport
• Agility and cutting drills
• Full training with team
• Competition return when functional goals met

Athletes typically return to sport at 8-10 weeks post-surgery.

Return to sport criteria:

1. Radiographic union - bridging callus visible on X-ray
2. Pain-free weight bearing - no tenderness at fracture site
3. Full ROM - ankle and foot mobility restored
4. Strength restoration - single leg hop test equal to opposite
5. Sport-specific function - passes agility and performance tests

Protective measures:

• Consider orthotic for pes cavus
• Address flexibility deficits
• Gradual training progression
• Monitor for symptoms of recurrence

Meeting all RTS criteria minimizes refracture risk.