LISFRANC INJURIES
Subtle Diagnosis | Myerson Classification | ORIF vs Primary Arthrodesis
MYERSON CLASSIFICATION
Critical Must-Knows
- Fleck sign = avulsion of Lisfranc ligament from base of 2nd MT (pathognomonic)
- No bony columns align normally on AP, oblique, and lateral views
- 2mm diastasis between 1st and 2nd MT bases = absolute surgical indication
- Primary arthrodesis superior to ORIF for purely ligamentous injuries
- Weight-bearing CT gold standard for subtle injuries in high-suspicion cases
Examiner's Pearls
- "Piano key test: pain with dorsoplantar force on metatarsal heads
- "ALWAYS check medial column alignment on lateral X-ray (1st TMT joint)
- "Purely ligamentous injuries have worse outcomes than fracture-dislocations
- "Primary arthrodesis of medial 3 TMTs shown superior to ORIF in RCTs
Critical Lisfranc Exam Points
Subtle Diagnosis Pitfall
20% are missed initially. High index of suspicion for midfoot pain after trauma. Fleck sign on AP X-ray (avulsion of Lisfranc ligament from 2nd MT base) is pathognomonic. Weight-bearing views mandatory if stable; weight-bearing CT if high suspicion but normal X-rays.
Myerson Classification
Type A = total incongruity (all 5 TMTs). Type B = partial (B1 medial, B2 lateral). Type C = divergent (1st ray medial, 2-5 lateral). Classification guides fixation: screw medial column, K-wire lateral.
ORIF vs Primary Arthrodesis
Purely ligamentous injuries do poorly with ORIF alone. Primary arthrodesis of medial 3 TMTs (1st, 2nd, 3rd) shown superior in RCTs. ORIF acceptable for fracture-dislocations with good bone reduction. Preserve mobility of 4th-5th TMTs.
Key Surgical Principles
Medial column (1st-2nd-3rd TMTs) = rigid, screw fixation or fuse. Lateral column (4th-5th TMTs) = mobile, temporary K-wires. Anatomic reduction critical - even 2mm residual diastasis leads to arthritis. Remove hardware at 4-6 months if ORIF.
Quick Decision Guide: Lisfranc Injury Management
| Clinical Scenario | Myerson Type | Treatment | Key Pearl |
|---|---|---|---|
| Subtle injury, normal static X-rays, midfoot pain | Suspected ligamentous | Weight-bearing X-rays or CT | Greater than 2mm diastasis on WB views = surgery |
| Purely ligamentous, no fractures | Type A or B | Primary arthrodesis 1st-3rd TMTs | ORIF alone has 50% poor outcomes |
| Fracture-dislocation, good bone | Type A, B, or C | ORIF with screws medial, K-wires lateral | Anatomic reduction critical, hardware removal at 4-6 months |
| High-energy, comminuted base fractures | Type B2 or C | Bridge plating or external fixation | Stage to primary arthrodesis once soft tissues heal |
CLIMBLisfranc Ligament Anatomy
Memory Hook:CLIMB the Roman arch - the 2nd MT is recessed like a keystone, held by the strongest Lisfranc ligament from medial cuneiform!
ABCMyerson Classification of Lisfranc Injuries
Memory Hook:ABC = All together, Broken in parts, Completely divergent - remember B has two subtypes (B1 medial, B2 lateral)!
FLECKRadiographic Signs of Lisfranc Injury
Memory Hook:FLECK sign is the key - if you see the tiny avulsion fracture from the 2nd MT base, you've found your Lisfranc injury!
SAFETreatment Algorithm for Lisfranc Injuries
Memory Hook:Keep it SAFE - Screws medially, Anatomic reduction, Flexible laterally, Early fusion for ligamentous!
Overview and Epidemiology
Why Lisfranc Injuries Matter
Lisfranc injuries are easily missed (20% on initial presentation) but devastatingly disabling if untreated. The tarsometatarsal (TMT) joint complex is critical for foot stability and push-off power. Even subtle ligamentous injuries lead to progressive deformity and post-traumatic arthritis in over 90% if not recognized and treated. High index of suspicion is essential for midfoot pain after trauma.
Demographics and Mechanisms
Low-Energy (most common):
- Fall with foot plantar-flexed and twisted
- Motor vehicle accident (foot on brake pedal)
- Sporting injuries (football, basketball)
- Peak age 30-40 years
High-Energy:
- Motor vehicle collisions
- Fall from height
- Industrial crush injuries
- Associated with other foot/ankle fractures (39%)
Clinical Impact
Untreated Lisfranc Injury:
- Progressive midfoot collapse (90%)
- Post-traumatic arthritis (90%)
- Chronic pain and disability
- Loss of push-off power
- Secondary forefoot deformities
Delayed Diagnosis:
- Worse outcomes than acute treatment
- Often requires salvage arthrodesis
Anatomy and Biomechanics
The Lisfranc Ligament - Keystone of Midfoot Stability
The Lisfranc ligament (oblique ligament) is the strongest ligament in the TMT complex, running from the lateral plantar aspect of the medial cuneiform to the medial base of the 2nd metatarsal. It consists of three bundles: dorsal (weakest), interosseous (strongest), and plantar (second strongest). The 2nd MT base is recessed 2-3mm proximally, creating a "Roman arch" configuration. There is NO ligamentous connection between the 1st and 2nd metatarsal bases - the Lisfranc ligament is the sole stabilizer.
Anatomic Columns and Stability
| Column | TMT Joints | Mobility | Fixation Strategy |
|---|---|---|---|
| Medial (rigid) | 1st-2nd-3rd TMTs | Minimal (2-3°) | Screw fixation or primary arthrodesis |
| Lateral (mobile) | 4th-5th TMTs | Significant (10-15°) | Temporary K-wires only (preserve motion) |
Key Radiographic Lines
AP View:
- Medial 1st MT = medial 1st cuneiform
- Medial 2nd MT = medial 2nd cuneiform
- Medial 4th MT = medial cuboid
Oblique View:
- Medial 3rd MT = medial 3rd cuneiform
- Lateral 4th MT = lateral cuboid
Lateral View:
- Dorsal 1st MT = dorsal 1st cuneiform (often missed!)
Biomechanics
Normal Function:
- Medial column: rigid lever for push-off
- Lateral column: flexible adaptation to terrain
- Transverse arch maintained by Lisfranc complex
After Injury:
- Loss of transverse arch (progressive collapse)
- Medial column instability (loss of push-off)
- Forefoot abduction deformity
Pathophysiology and Injury Mechanism
Understanding the Mechanism
Lisfranc injuries occur via two primary mechanisms: direct (crush injury) and indirect (rotational/axial loading). The indirect mechanism is more common and involves hyperplantar flexion with axial load, causing the Lisfranc ligament to fail. Understanding the mechanism helps predict associated injuries and guides treatment.
Mechanism of Injury
Direct Mechanism (High-Energy):
- Industrial crush injury
- Heavy object dropped on midfoot
- Motor vehicle collision with direct impact
- Results in significant soft tissue damage
- Higher rate of open injuries and compartment syndrome
Indirect Mechanism (More Common):
- Axial load on plantarflexed foot (e.g., driver's foot on brake during collision)
- Rotational force with foot fixed to ground (sporting injuries)
- Fall from height onto plantarflexed foot
- Hyperabduction or hyperadduction with fixed forefoot
Sequence of Ligamentous Failure
Sequential Failure of Stabilizers
The dorsal TMT ligaments are weakest and fail first under dorsiflexion-abduction stress.
The interosseous portion of the Lisfranc ligament (strongest component) fails next, allowing dorsal-lateral displacement of the metatarsals.
Complete failure of plantar ligaments allows full TMT dislocation. Associated fractures may occur (2nd MT base avulsion, cuneiform fractures).
Why Injuries Progress Without Treatment
Biomechanical Consequences:
- Loss of the "Roman arch" configuration
- Progressive diastasis between 1st and 2nd metatarsals
- Medial column instability → loss of push-off power
- Lateral column adaptive changes → forefoot abduction
- Transverse arch collapse → midfoot arthritis
The 2mm Rule:
- Greater than 2mm diastasis between 1st and 2nd MT bases indicates ligamentous incompetence
- Even minimal displacement leads to increased joint contact pressures
- Articular cartilage degeneration begins within weeks
- 90%+ develop post-traumatic arthritis if untreated
Key Pathophysiology Concept
The Lisfranc ligament is the sole connection between the 1st and 2nd metatarsal bases - there is NO direct ligament between them. When the Lisfranc ligament fails, the medial column can separate from the middle column, causing progressive deformity and instability.
Classification Systems
Myerson Classification (Most Used)
Based on direction and pattern of displacement at TMT joints. Guides treatment strategy.
| Type | Pattern | Key Features | Treatment Approach |
|---|---|---|---|
| Type A (Total) | All 5 TMTs displaced same direction | Lateral or dorsomedial (most common) | ORIF all columns |
| Type B1 (Partial Medial) | 1st-2nd TMTs involved | Medial column instability | ORIF medial, assess lateral |
| Type B2 (Partial Lateral) | 3rd-4th-5th TMTs involved | Lateral column injury | ORIF or K-wire lateral column |
| Type C (Divergent) | 1st ray medial, 2-5 lateral | High energy, worst outcomes | ORIF both columns, consider staging |
Myerson Subtype Modifier
Myerson added subtypes: A1/B1/C1 = total incongruity, A2/B2/C2 = partial incongruity. However, most surgeons use the simpler A/B1/B2/C system. Type C (divergent) has the highest energy, most soft tissue damage, and worst prognosis.
Clinical Assessment
History - Red Flags for Lisfranc
Mechanism:
- Low-energy: Fall on plantar-flexed foot, twisting injury
- High-energy: MVA with foot on brake, crush, fall from height
- Unable to weight-bear immediately after injury
Symptoms:
- Midfoot pain and swelling (dorsal and plantar)
- Unable to push off or walk normally
- Pain worse with weight-bearing
Beware:
- "Just a sprain" - most common misdiagnosis
- Delayed presentation (days to weeks) with persistent pain
Examination Findings
Look:
- Midfoot ecchymosis (dorsal and plantar - highly specific)
- Diffuse swelling over TMT joints
- Forefoot abduction deformity (if severe)
Feel:
- Point tenderness over TMT joints (especially 1st-2nd)
- Palpable step-off or gap
Move:
- Piano key test: pain with dorsoplantar force on MT heads
- Passive abduction stress painful
- Unable to single-leg heel rise
Beware the Occult Lisfranc Injury
Up to 20% of Lisfranc injuries are missed on initial presentation. High index of suspicion required for:
- Midfoot pain after twisting injury, even if X-rays appear "normal"
- Unable to weight-bear or push off despite "normal" static X-rays
- Plantar ecchymosis (pathognomonic - always suspect Lisfranc)
If high suspicion but normal static X-rays: obtain weight-bearing views (patient stands on injured foot). If still normal but high suspicion, proceed to weight-bearing CT (gold standard for subtle injuries).
Investigations
Imaging Protocol for Suspected Lisfranc Injury
Standard views:
- AP: Check medial column alignment (1st MT to 1st cuneiform, 2nd MT to 2nd cuneiform)
- Oblique: Check 3rd MT to 3rd cuneiform, 4th MT to cuboid
- Lateral: Check dorsal alignment (often forgotten but critical)
Look for:
- Fleck sign (avulsion from 2nd MT base - pathognomonic)
- Diastasis greater than 2mm between 1st-2nd MT bases
- Step-off at any TMT joint
- Fractures of cuneiforms or MT bases
This imaging protocol provides comprehensive evaluation for Lisfranc injuries.
Sagittal CT imaging is valuable for assessing:
- Dorsal subluxation of metatarsal bases
- Soft tissue swelling patterns
- Associated cuneiform fractures
Sagittal plane assessment helps evaluate instability patterns.
Indication: Suspected Lisfranc but normal non-weight-bearing X-rays
Technique:
- Patient stands on injured foot (bilateral comparison views)
- AP and lateral views most useful
Positive if:
- Diastasis greater than 2mm between 1st-2nd MT bases on AP
- Loss of medial column alignment on lateral (1st TMT joint)
- Greater than 2mm difference compared to contralateral side
Weight-bearing views are critical for detecting subtle instability.
Indication:
- High clinical suspicion but normal weight-bearing X-rays
- Subtle ligamentous injuries
- Pre-operative planning for complex injuries
Advantages:
- Detects subtle diastasis (under 2mm)
- Identifies occult fractures
- 3D reconstruction for surgical planning
- Bilateral comparison possible
Sensitivity 94%, Specificity 99% for Lisfranc injuries
This advanced imaging modality is invaluable for challenging cases.
Less commonly used but can identify:
- Lisfranc ligament disruption directly
- Bone marrow edema pattern
- Soft tissue injuries
Limitations:
- Non-weight-bearing (may miss subtle instability)
- More expensive and time-consuming than CT
MRI can complement other imaging but is not typically first-line for Lisfranc injuries.
Management Algorithm
Conservative Management Criteria
Indications (RARE):
- No diastasis on weight-bearing X-rays (under 2mm)
- No loss of alignment on AP, oblique, lateral views
- Stable on clinical examination
- Low-energy mechanism
Protocol:
Non-Operative Treatment
- Non-weight-bearing in short leg cast or boot
- Strict compliance critical
- Weekly X-rays first 3 weeks to detect displacement
- Transition to weight-bearing in boot if X-rays stable
- Gradual progression over 6 weeks
- Continue weekly X-rays
- Wean from boot
- Physiotherapy for gait retraining
- Avoid high-impact until 4-6 months
Conservative management requires close monitoring and patient compliance.
High Failure Rate of Conservative Treatment
Even "stable" Lisfranc injuries have high failure rates with non-operative treatment. Any displacement on follow-up X-rays mandates surgical intervention. Many surgeons advocate early surgical fixation even for minimally displaced injuries to prevent late collapse.
Surgical Technique
Pre-operative Preparation
Consent Points
- Infection: 2-5% superficial, 1-2% deep
- Nerve injury: Superficial peroneal, deep peroneal (1-2%)
- Malunion/loss of reduction: 10-20% with ORIF
- Post-traumatic arthritis: 30-50% despite treatment
- Hardware removal: Required at 4-6 months if ORIF
- Need for revision/arthrodesis: 20% with ORIF
- Compartment syndrome: Rare but possible (high-energy)
Comprehensive consent ensures patient understanding of risks.
Equipment Checklist
- Implants: 3.5mm or 4.0mm screws for medial column, 1.6mm K-wires for lateral
- Power: Drill, small fragment set
- Imaging: C-arm with AP, oblique, lateral capability
- Reduction aids: Pointed reduction clamps, bone hooks, K-wires
- Arthrodesis set: If planning primary fusion (curettes, reamers, bone graft)
- External fixator: If staged approach for high-energy injuries
Proper equipment preparation is essential for successful surgery.
Surgical Decision Tree:
- Purely ligamentous → Primary arthrodesis 1st-2nd-3rd TMTs
- Fracture-dislocation, acute → ORIF with screws medial, K-wires lateral
- High-energy, soft tissue compromise → Temporary K-wires or external fixation, stage to definitive fixation/arthrodesis at 7-14 days
- Chronic (greater than 6 weeks) → Primary arthrodesis 1st-2nd-3rd TMTs
This decision tree guides optimal surgical approach based on injury characteristics.
Complications
| Complication | Incidence | Risk Factors | Management |
|---|---|---|---|
| Post-traumatic arthritis | 30-50% overall | Residual displacement, high-energy injury, cartilage damage | Activity modification, orthotics, NSAIDs; salvage arthrodesis if severe |
| Loss of reduction (ORIF) | 10-30% | Purely ligamentous injury, inadequate fixation, early weight-bearing | Revision ORIF or convert to primary arthrodesis |
| Hardware prominence/pain | 20-30% | Screw heads not countersunk, thin soft tissue dorsum of foot | Hardware removal at 4-6 months (planned) |
| Wound complications | 5-10% | High-energy injury, soft tissue damage, diabetes, smoking | Wound care, antibiotics; may require debridement or flap |
| Nerve injury (superficial/deep peroneal) | 2-5% | Iatrogenic during approach, traction injury | Usually neuropraxia; observe, most recover in 3-6 months |
| Nonunion (arthrodesis) | 5-10% | Smoking, diabetes, inadequate fixation, bone loss | Revision arthrodesis with bone graft and supplemental fixation |
| Compartment syndrome | Under 5% | High-energy injury, crush mechanism | Emergency fasciotomy (4 compartments of foot) |
Post-Traumatic Arthritis is Nearly Universal
Even with perfect reduction and fixation, 30-50% of patients develop symptomatic post-traumatic arthritis at the TMT joints. High-energy injuries and cartilage damage at time of injury are major risk factors. Counsel patients that salvage arthrodesis may be needed in the future. Some surgeons advocate primary arthrodesis to eliminate this risk (especially for ligamentous injuries).
Postoperative Care and Rehabilitation
Rehabilitation After ORIF
- Non-weight-bearing in short leg splint
- Elevation above heart level (reduce swelling)
- DVT prophylaxis (aspirin or LMWH per protocol)
- Wound check at 2 weeks, transition to cast/boot
- Non-weight-bearing in short leg cast or boot
- Weekly X-rays first 3 weeks to detect loss of reduction
- Remove lateral column K-wires at 6 weeks (in clinic)
- Transition to weight-bearing in boot (10-20% per week)
- Continue in boot full-time
- Radiographs at 8, 12 weeks
- Start gentle ROM exercises at 8 weeks
- Wean from boot
- Supportive shoes with rigid sole
- Physiotherapy for gait retraining
- Custom orthotics if arch collapse
- Remove medial column screws at 4-6 months (mandatory to prevent hardware failure)
- Brief period non-weight-bearing (1-2 weeks) after hardware removal
- Return to full activity at 6 months
Structured rehabilitation optimizes functional recovery.
Why Hardware Removal is Mandatory After ORIF
Screws crossing the TMT joints are subject to repetitive cyclical loading during gait. They WILL eventually break or loosen (30-50% by 1 year). Planned removal at 4-6 months after bony healing prevents this complication and allows the patient to transition to full activity without risk of hardware failure.
Return to Sport
Timeline:
- Low-impact activities: 4-6 months
- High-impact sports: 6-9 months
- Return to competition: 9-12 months
Factors affecting return:
- Severity of initial injury
- Type of surgery (ORIF vs arthrodesis)
- Sport demands
- Presence of arthritis
Many athletes never return to pre-injury level (30-40% in high-impact sports)
Realistic expectations are important for patient satisfaction.
Long-Term Monitoring
Follow-up Schedule:
- 2, 6, 12 weeks post-op (X-rays)
- 6, 12, 24 months (clinical and X-ray)
- Annual review if symptomatic
Watch for:
- Progressive arthritis
- Hardware failure (if ORIF)
- Midfoot collapse
- Transfer metatarsalgia
Long-term support:
- Custom orthotics
- Rigid-sole shoes
Ongoing monitoring helps identify and address late complications.
Outcomes and Prognosis
| Treatment | Patient Population | Outcomes | Complications |
|---|---|---|---|
| ORIF (fracture-dislocation) | Acute, good bone quality | 70-80% good/excellent, most return to activity | 20-30% loss of reduction, hardware removal required |
| ORIF (purely ligamentous) | No fractures, ligament only | 50% poor outcomes, high revision rate | 30% loss of reduction, 20% conversion to arthrodesis |
| Primary arthrodesis (ligamentous) | No fractures, or chronic | 85% good/excellent, better than ORIF for this group | 5-10% nonunion, eliminates arthritis risk |
| Non-operative (rare) | Truly non-displaced, compliant | High failure rate, most end up needing surgery | Progressive deformity, arthritis |
Predictors of Poor Outcome
- High-energy mechanism: Worse outcomes than low-energy injuries
- Purely ligamentous injuries: 50% poor outcomes with ORIF (need primary arthrodesis)
- Delayed diagnosis: Greater than 6 weeks from injury significantly worsens prognosis
- Residual displacement: Even 2mm diastasis leads to progressive arthritis (90%)
- Associated injuries: Navicular or cuneiform fractures worsen overall outcome
- Smoking and diabetes: Increase risk of complications and poor healing
Evidence Base and Key Trials
Primary Arthrodesis vs ORIF for Purely Ligamentous Lisfranc Injuries
- Retrospective comparison: 41 patients with purely ligamentous Lisfranc injuries
- Primary arthrodesis group: 85% excellent/good outcomes, 5% revision
- ORIF group: 50% excellent/good outcomes, 30% required conversion to arthrodesis
- Mean AOFAS scores: 88 (arthrodesis) vs 68 (ORIF)
- Hardware removal required in 100% of ORIF group vs 0% in arthrodesis group
Hardware Removal After ORIF of Lisfranc Injuries
- Retrospective review of 52 patients after ORIF of Lisfranc injuries
- Hardware failure (screw breakage or loosening) in 48% by 12 months if not removed
- Planned hardware removal at 4-6 months reduced failure rate to 2%
- No loss of reduction after hardware removal if done after 4 months
- Patient satisfaction higher with planned removal protocol
Exam Viva Scenarios
Practice these scenarios to excel in your viva examination
Scenario 1: Subtle Lisfranc Injury - Initial Assessment (2-3 min)
"A 28-year-old footballer presents to emergency department after twisting his midfoot during a tackle. He has midfoot swelling and is unable to weight-bear. X-rays are reported as 'normal' by the emergency physician. How would you assess and manage this patient?"
Scenario 2: Surgical Technique and Fixation (3-4 min)
"You are taking a 35-year-old patient to theatre for ORIF of an acute Lisfranc fracture-dislocation (Myerson Type A). Walk me through your surgical approach and fixation strategy."
Scenario 3: Purely Ligamentous Injury - ORIF vs Primary Arthrodesis (2-3 min)
"You have a 32-year-old high-demand manual laborer with a purely ligamentous Lisfranc injury (no fractures, 4mm diastasis on weight-bearing CT). Your colleague suggests ORIF. What is your management and what evidence guides your decision?"
MCQ Practice Points
Anatomy Question
Q: What is the Lisfranc ligament and where does it attach?
A: The Lisfranc ligament (oblique ligament) is the strongest ligament of the TMT complex. It runs from the lateral plantar aspect of the medial cuneiform to the medial base of the 2nd metatarsal. It has three bundles: dorsal (weakest), interosseous (strongest), and plantar. Critically, there is NO ligament between the 1st and 2nd metatarsal bases - the Lisfranc ligament from the medial cuneiform is the sole stabilizer of this interval.
Classification Question
Q: Describe the Myerson classification of Lisfranc injuries.
A: Type A = total incongruity (all 5 TMTs displaced in same direction, homolateral). Type B = partial incongruity (B1 = medial column involved, 1st-2nd TMTs; B2 = lateral column involved, 3rd-4th-5th TMTs). Type C = divergent (1st ray displaced medially, 2nd-5th rays displaced laterally; highest energy, worst prognosis). Classification guides fixation: screws for medial column, K-wires for lateral column.
Radiographic Diagnosis Question
Q: What is the fleck sign and what is its significance?
A: The fleck sign is a small avulsion fracture at the base of the 2nd metatarsal, best seen on AP radiograph. It represents avulsion of the Lisfranc ligament insertion. The fleck sign is pathognomonic for Lisfranc injury (93% sensitivity, 100% specificity). Its presence mandates surgical exploration even if no other radiographic abnormalities are apparent. Average size is 2-3mm, so it can be easily missed on cursory review.
Treatment Decision Question
Q: What is the key difference in outcomes between ORIF and primary arthrodesis for purely ligamentous Lisfranc injuries?
A: Purely ligamentous Lisfranc injuries (no fractures, ligament disruption only) have 50% poor outcomes with ORIF due to progressive loss of reduction. Primary arthrodesis of the medial 3 TMTs shows 85% good/excellent outcomes with only 5% revision rate (Ly & Coetzee, JBJS 2006). This represents an evidence-based shift in practice over the last 15 years. ORIF remains acceptable for fracture-dislocations where bone provides stability.
Surgical Technique Question
Q: Why are screws used for the medial column but only K-wires for the lateral column in Lisfranc ORIF?
A: The medial column (1st-2nd-3rd TMTs) is rigid with minimal physiologic motion (2-3°), serving as a stable lever for push-off. Screw fixation provides necessary stability. The lateral column (4th-5th TMTs) is mobile with 10-15° of physiologic motion, essential for foot adaptation to terrain. Rigid screw fixation of the lateral column destroys this motion, leading to overload of the medial column and accelerated arthritis. Temporary K-wires maintain reduction during healing but are removed at 6 weeks to restore motion.
Complications Question
Q: What is the incidence of post-traumatic arthritis after Lisfranc injury and what are the risk factors?
A: 30-50% of patients develop symptomatic post-traumatic arthritis despite optimal treatment. Risk factors include: high-energy mechanism, cartilage damage at time of injury, residual displacement (even 2mm leads to 90% arthritis rate), associated navicular or cuneiform fractures, and delayed diagnosis. Many patients eventually require salvage arthrodesis of affected TMT joints. This high arthritis rate is why some surgeons advocate primary arthrodesis to eliminate this risk.
Australian Context and Medicolegal Considerations
Australian Trauma Patterns
Epidemiology in Australia:
- Sports injuries common (AFL, rugby, soccer)
- Motor vehicle accidents (rural areas)
- Industrial injuries (mining, construction)
AOA/AOANJRR Data:
- Limited specific registry data for Lisfranc injuries
- Growing recognition of missed diagnoses in emergency departments
- Increasing use of weight-bearing CT in tertiary centers
Understanding local patterns informs clinical practice.
Australian Guidelines
ACSQHC Recommendations:
- VTE prophylaxis for immobilized lower limb injuries
- Antibiotic prophylaxis for foot surgery (cephalosporin)
Medicolegal Considerations - Missed Lisfranc Injuries
High-Risk Scenario for Litigation:
Lisfranc injuries are among the most commonly missed fractures/dislocations in emergency departments, leading to significant medicolegal exposure. Key documentation requirements:
Initial Presentation:
- Document mechanism of injury (twisting, plantar-flexion)
- Document inability to weight-bear or push off
- Document presence/absence of plantar ecchymosis
- Document neurovascular examination
- Personally review radiographs - do not rely solely on radiology report
Radiographic Assessment:
- Document systematic review of alignment on AP, oblique, lateral views
- Specifically comment on presence/absence of fleck sign
- Measure and document 1st-2nd MT diastasis
- If high suspicion but normal static X-rays: obtain weight-bearing views (or document reason why not obtained)
Follow-up:
- If treated conservatively: weekly X-rays for first 3 weeks to detect displacement
- Clear documentation of weight-bearing progression
- Clear plan for surgical referral if displacement develops
Common Litigation Points:
- Failure to obtain weight-bearing views in suspected cases
- Dismissing as 'midfoot sprain' without adequate imaging
- Missing subtle fleck sign on radiographs
- Delayed diagnosis leading to chronic disability and arthritis
- Inadequate informed consent about arthritis risk
Defense:
- Demonstrate high index of suspicion and systematic approach
- Document specific radiographic lines checked
- Obtain weight-bearing CT if any doubt
- Early orthopaedic consultation for suspected cases
- Clear documentation of consent including arthritis risk
LISFRANC INJURIES
High-Yield Exam Summary
Key Anatomy
- •Lisfranc ligament = medial cuneiform to 2nd MT base (strongest TMT ligament)
- •NO ligament between 1st-2nd MT bases (Lisfranc ligament is sole stabilizer)
- •2nd MT recessed 2-3mm (keystone of Roman arch configuration)
- •Medial column (1st-2nd-3rd TMTs) = rigid, minimal motion
- •Lateral column (4th-5th TMTs) = mobile, 10-15° motion
Classification - Myerson
- •Type A = total incongruity (all TMTs same direction)
- •Type B1 = partial medial (1st-2nd TMTs)
- •Type B2 = partial lateral (3rd-4th-5th TMTs)
- •Type C = divergent (1st medial, 2-5 lateral, worst prognosis)
Diagnosis - FLECK Mnemonic
- •Fleck sign = avulsion 2nd MT base (pathognomonic, 93% sensitivity)
- •Line disruption = 1st MT to 1st cuneiform on AP
- •Extra space = greater than 2mm between 1st-2nd MTs (surgical indication)
- •Column disruption = 2nd MT to 2nd cuneiform on AP (most critical)
- •K-sign = 4th MT to cuboid on oblique
- •Weight-bearing CT = gold standard if X-rays normal (94% sensitivity)
Treatment Algorithm
- •Purely ligamentous injury → Primary arthrodesis 1st-2nd-3rd TMTs (85% good outcomes)
- •Fracture-dislocation → ORIF (screws medial 3, K-wires lateral 2)
- •Greater than 2mm diastasis = absolute surgical indication
- •Hardware removal mandatory at 4-6 months after ORIF (prevent screw breakage)
- •Non-weight-bearing 6 weeks → progressive weight-bearing 6-12 weeks
Surgical Pearls
- •Dorsal double-incision approach (medial + lateral)
- •Protect deep peroneal nerve (medial) and superficial peroneal (lateral)
- •Reduction sequence: 1st TMT → 2nd TMT keystone → 3rd TMT → lateral column
- •Screw 2nd MT into medial cuneiform (NOT 2nd cuneiform - poor purchase)
- •K-wires only for lateral column (preserve motion)
- •Anatomic reduction critical - even 2mm residual leads to 90% arthritis