Most Common Type (70%)

Mechanism:

• Fall with knee flexed and foot inverted
• Direct blow to posteromedial fibular head
• Twisting injury during sports
• Parachuting injury classic

Characteristics:

• Fibular head prominent anterolaterally
• May be visible or palpable bump
• Usually reducible with closed technique
• Lower peroneal nerve risk

Treatment:

• Closed reduction (knee flexed 90 degrees)
• Direct posterior pressure on fibular head
• External rotation of foot aids reduction
• Immobilize 2-3 weeks

This is the most commonly encountered type in clinical practice.

Less Common (20%)

Mechanism:

• Direct blow to anterior fibular head
• Violent twisting or hyperflexion injury
• Dashboard injury

Characteristics:

• Fibular head displaced posteriorly and medially
• Higher peroneal nerve risk
• May be less visible clinically
• More difficult to reduce

Treatment:

• Closed reduction (knee flexed)
• Direct anterior pressure on fibular head
• CRITICAL: check nerve before and after
• May need open reduction if irreducible

This type carries the highest risk of peroneal nerve injury.

Associated with Ankle Injury (5%)

Mechanism:

• Part of Maisonneuve fracture pattern
• Ankle injury with proximal fibula migration
• Syndesmosis disruption

Characteristics:

• Fibula migrates proximally
• Always check ankle with PTFJ injury
• Usually reduces when ankle treated
• May need screw fixation

Treatment:

• Address ankle injury first
• Fixation of ankle often reduces PTFJ
• May need temporary screw across PTFJ
• Remove screw at 6-8 weeks

Always examine the entire fibula and ankle in PTFJ injuries.

Habitual Subluxation (5%)

Mechanism:

• Generalized joint hypermobility
• Habitual or voluntary subluxation
• No acute trauma
• Often painless

Characteristics:

• Often bilateral
• Patient may demonstrate subluxation
• No acute injury history
• Rarely symptomatic

Treatment:

• Reassurance and observation
• Activity modification if symptomatic
• Rarely needs surgery
• Fusion only if severely symptomatic

Most patients with Type IV do not require any surgical intervention.

Type I and II - Closed Reduction First

Assessment:

• Document peroneal nerve function (MANDATORY)
• Obtain AP and lateral knee radiographs
• Compare to contralateral side
• Rule out associated injuries

Closed Reduction:

1. Adequate analgesia/sedation in ED
2. Flex knee to 90 degrees (relaxes LCL and biceps)
3. Externally rotate foot
4. Apply direct pressure on fibular head
   • Type I: push posteriorly
   • Type II: push anteriorly
5. Feel/hear "clunk" with successful reduction
6. Confirm reduction with radiographs
7. Reassess peroneal nerve function

Success Rate: 85%+ for acute dislocations.

Closed reduction is the first-line treatment for most acute PTFJ dislocations.

Open Reduction Required

Indications:

• Failed closed reduction (2 attempts maximum)
• Soft tissue interposition suspected
• Associated fracture requiring fixation

Surgical Approach:

• Lateral approach over fibular head
• Identify and protect peroneal nerve
• Remove interposed tissue (biceps, capsule)
• Reduce joint under direct vision
• Repair anterior and posterior tibiofibular ligaments
• Consider temporary screw fixation
• Closure and immobilization

Post-Op: Immobilize 3-4 weeks, remove screw at 6-8 weeks

Failed Conservative Treatment

Conservative Trial First:

• Physiotherapy for 3-6 months
• Strengthening of surrounding muscles
• Activity modification
• Bracing during sport

Surgical Options if Failed:

Option 1: PTFJ Fusion (Preferred)

• Simple and reliable technique
• 90%+ good/excellent results
• Minimal functional deficit
• Low complication rate
• Return to sport 3-4 months

Option 2: Ligament Reconstruction

• Biceps femoris tendon strip
• Preserves joint motion
• More technically demanding
• Higher recurrence risk
• Return to sport 4-6 months

Fusion is generally preferred for its reliability and excellent outcomes.

Maisonneuve Pattern

Management:

• Address ankle injury first
• ORIF of ankle fracture
• Syndesmosis fixation
• PTFJ usually reduces with ankle treatment

If PTFJ Unstable:

• Temporary screw across PTFJ
• 3.5mm cortical screw
• Remove at 6-8 weeks
• Protected weight bearing until screw removed

Treatment of the ankle injury typically addresses the PTFJ dislocation.

Acute Irreducible Dislocation

Patient Position:

• Supine on operating table
• Bump under ipsilateral hip
• Knee flexed over bolster

Incision:

• Longitudinal lateral incision
• Centered over fibular head
• 6-8 cm length

Approach:

1. Incise skin and subcutaneous tissue
2. Identify and protect common peroneal nerve (CRITICAL)
3. Incise fascia anterior to nerve
4. Reflect biceps femoris posteriorly
5. Expose PTFJ capsule

Reduction:

1. Incise capsule longitudinally
2. Remove any interposed soft tissue (biceps, capsule)
3. Reduce fibular head under direct vision
4. Repair anterior and posterior tibiofibular ligaments
5. Consider temporary 3.5mm screw if unstable

Closure:

• Repair capsule with absorbable sutures
• Repair fascia
• Skin closure
• Apply long leg splint in slight flexion

Post-Op: Immobilize 3-4 weeks, remove screw at 6-8 weeks if used.

Chronic Instability (Preferred Method)

Patient Position:

• Supine with bump under hip
• Knee flexed over bolster

Incision:

• Lateral approach over fibular head
• Protect peroneal nerve throughout

Technique:

1. Expose PTFJ through lateral approach
2. Identify and protect peroneal nerve at all times
3. Remove articular cartilage with curette
4. Decorticate bone surfaces to bleeding bone
5. Appose tibia and fibula
6. Fix with 3.5mm cortical screw and washer
7. Add 1/3 tubular plate for extra stability if needed
8. Consider bone graft in joint space

Advantages:

• Simple and reliable technique
• 90-95% fusion rate
• Minimal functional deficit
• Excellent long-term outcomes

Closure:

• Standard layered closure
• Long leg cast initially

Post-Op: Cast 3 weeks, then brace with gradual weight-bearing.

Ligament Reconstruction (Motion-Preserving)

Biceps Femoris Strip Technique:

Steps:

1. Expose fibular head and identify biceps insertion
2. Harvest 5mm wide strip of biceps tendon
3. Leave distal attachment intact (blood supply)
4. Create drill holes in tibia and fibula
5. Weave strip through holes in figure-8 pattern
6. Tension with knee in 15 degrees flexion
7. Secure with sutures or interference screws

Advantages:

• Preserves joint motion
• Maintains proprioception
• More anatomic restoration

Disadvantages:

• Technically demanding
• Higher recurrence risk than fusion (10-15%)
• Longer rehabilitation

Post-Op: Locked brace 4 weeks, gradual ROM progression, return to sport 4-6 months.

Complications

Peroneal Nerve Injury

Incidence: 5-10% of all PTFJ dislocations

Types:

• Neurapraxia (most common, 80%)
• Axonotmesis (15%)
• Neurotmesis (rare, less than 5%)

Management:

• Observation for neurapraxia initially
• EMG/NCS at 3-4 weeks if no clinical recovery
• Exploration if no improvement by 3 months
• Ankle-foot orthosis for foot drop during recovery
• Nerve repair or grafting if needed at exploration

Prognosis:

• Most neurapraxia recover within 6-12 weeks
• Axonotmesis may take 3-6 months
• Complete recovery in 85% of nerve injuries
• Some permanent deficit possible in severe cases

Recurrent Instability

Incidence: 5-10% after initial reduction

Risk Factors:

• Oblique joint variant
• Inadequate immobilization (less than 2 weeks)
• Generalized ligamentous laxity
• Return to activity too early
• Inadequate rehabilitation

Management:

• Rehabilitation initially (3-6 months trial)
• Bracing during sport
• Surgery if persistent symptomatic instability

Chronic Pain

Incidence: 10-15% have ongoing pain

Causes:

• Articular cartilage damage at injury
• Residual microinstability
• Peroneal nerve irritation
• Post-traumatic arthritis

Management:

• Activity modification
• Physical therapy and strengthening
• Corticosteroid injection if localized synovitis
• Fusion for severe refractory cases

Failed Reduction

Incidence: 10-15% cannot reduce closed

Causes:

• Soft tissue interposition (biceps, capsule)
• Delayed presentation (more than 2 weeks)
• Associated fracture
• Fibular head button-holed through fascia

Management:

• Open reduction required
• Remove interposed tissue
• Repair ligaments
• Consider temporary screw fixation

Other Complications

Early:

• Vascular injury (rare)
• Compartment syndrome (rare)
• Wound complications after surgery

Late:

• Post-traumatic arthritis (uncommon)
• Hardware complications if screw used
• Non-union after fusion (less than 5%)

Postoperative Care

After Open Reduction

Immediate (0-2 weeks):

• Long leg splint with knee 15-20 degrees flexion
• Non-weight bearing
• Ice and elevation
• Pain management
• Monitor peroneal nerve function daily

2-4 weeks:

• Convert to hinged knee brace
• Start gentle ROM exercises
• Maintain NWB or touch weight bearing
• Physiotherapy begins

4-6 weeks:

• Progress to partial weight bearing
• Increase ROM exercises
• Strengthening begins

6-8 weeks:

• Remove temporary screw if placed
• Progress to full weight bearing
• Continue strengthening

3 months:

• Return to normal activities
• Sport-specific rehabilitation

After PTFJ Fusion

Immediate (0-3 weeks):

• Long leg cast with knee in slight flexion
• Non-weight bearing
• Wound care
• Monitor for complications

3-6 weeks:

• Remove cast
• Hinged brace
• Start ROM exercises (fusion site stable)
• Progressive weight bearing

6-12 weeks:

• Continue strengthening
• Gradual return to activities
• Monitor fusion on radiographs

3-4 months:

• Return to sport if fusion solid
• Resume full activities
• Minimal functional deficit expected

After Ligament Reconstruction

Immediate (0-4 weeks):

• Long leg cast or locked brace
• Non-weight bearing
• Protect reconstruction

4-8 weeks:

• Unlock brace
• Start gentle ROM
• Progress to partial weight bearing
• Avoid stress on reconstruction

8-12 weeks:

• Full ROM goal
• Strengthening program
• Progress to full weight bearing

4-6 months:

• Return to sport
• Functional testing before clearance

Red Flags Postoperatively

Immediate Concerns:

• New foot drop (peroneal nerve injury)
• Loss of reduction on radiograph
• Wound infection
• Compartment syndrome symptoms

Late Concerns:

• Recurrent instability
• Persistent pain
• Hardware failure
• Non-union (fusion cases)

Outcomes and Prognosis

After Closed Reduction

Acute Dislocations:

• 85-90% good to excellent outcomes
• Reduction success rate 85%+
• Most maintain reduction with 2-3 weeks immobilization
• Return to normal activities 6-8 weeks
• Return to sport 8-12 weeks

Recurrence Rate:

• 5-10% develop recurrent instability
• Higher in oblique joint variant
• Higher with inadequate immobilization
• Most occur within first 6 months

Functional Outcomes:

• Minimal long-term functional deficit
• Most return to pre-injury activity level
• Rare post-traumatic arthritis
• Occasional mild discomfort with extreme flexion

After Open Reduction

Success Rate:

• 85-90% maintain reduction
• Slightly higher recurrence than closed reduction (10-15%)
• Good functional outcomes in most cases

Recovery Timeline:

• Longer immobilization (3-4 weeks)
• Return to sport 3-4 months
• May have mild stiffness initially

After PTFJ Fusion

Stability:

• 90-95% achieve solid fusion
• Fusion rate greater than 95% at 3 months
• Excellent stability, no recurrence

Functional Outcomes:

• 90%+ good to excellent patient satisfaction
• Minimal functional deficit from fusion
• No significant gait abnormality
• Can return to high-level sport

Recovery:

• Return to activities 3-4 months
• Return to sport 4-6 months
• Permanent stability achieved

Complications:

• Non-union less than 5%
• Minimal restriction from fusion

After Ligament Reconstruction

Stability:

• 80-85% good stability (higher recurrence than fusion)
• Motion preserved
• 10-15% recurrent instability

Functional Outcomes:

• Good outcomes in 80-85%
• Preserves joint motion
• May feel more "normal" than fusion

Recovery:

• Longer rehabilitation (4-6 months)
• Return to sport 6-9 months
• Requires compliance with rehab

Peroneal Nerve Recovery

Complete Recovery:

• 85-90% of nerve injuries recover completely
• Neurapraxia: 6-12 weeks recovery
• Axonotmesis: 3-6 months recovery

Partial Recovery:

• 10% have mild residual weakness
• Usually does not limit function significantly
• May need ankle-foot orthosis initially

Poor Recovery:

• Less than 5% have permanent significant deficit
• May need tendon transfers or ankle fusion

Prognostic Factors

Good Prognosis:

• Acute injury (less than 2 weeks)
• Type I (anterolateral) dislocation
• Successful closed reduction
• Adequate immobilization
• No peroneal nerve injury
• Horizontal joint variant

Poor Prognosis:

• Delayed presentation (greater than 4 weeks)
• Type II (posteromedial) with nerve injury
• Irreducible dislocation
• Oblique joint variant
• Generalized ligamentous laxity
• Multiple recurrences

Long-Term Follow-Up Studies

10-Year Outcomes:

• 85% excellent outcomes after appropriate treatment
• 10% mild symptoms not limiting activities
• 5% significant ongoing problems

Return to Sport:

• 90% return to pre-injury sport level
• May take 6-12 months for high-level athletes
• Contact sports may require longer recovery

Patient Satisfaction:

• Greater than 90% satisfied with outcome
• Fusion patients report excellent stability
• Reconstruction patients value preserved motion

Viva Scenarios

Surgical Options for Chronic Instability:

• PTFJ fusion: simple, reliable, 90%+ success, minimal functional deficit
• Ligament reconstruction: motion-preserving, more technically demanding
• Temporary screw: allows ligament healing, remove at 6-8 weeks

Outcomes:

• Acute closed reduction: 85-90% excellent outcomes
• PTFJ fusion: greater than 90% patient satisfaction
• Ligament reconstruction: 80-85% good stability
• Peroneal nerve recovery: 85-90% complete recovery

Common Exam Scenarios

Scenario 1: "28-year-old parachutist with lateral knee pain after landing"

• Answer: Type I anterolateral PTFJ dislocation

Scenario 2: "Patient with PTFJ dislocation, irreducible after two attempts"

• Answer: Open reduction required, likely soft tissue interposition

Scenario 3: "Recurrent PTFJ instability despite 6 months conservative treatment"

• Answer: Surgical options are fusion (preferred) or reconstruction

Scenario 4: "Ankle fracture with tender proximal fibula"

• Answer: Type III superior PTFJ dislocation (Maisonneuve pattern)

Scenario 5: "New foot drop after PTFJ reduction"

• Answer: Peroneal nerve injury from reduction maneuver

Key Numbers to Remember

• 70% - Type I (anterolateral) proportion
• 85% - Closed reduction success rate
• 90 degrees - Knee flexion for reduction
• 2-3 weeks - Immobilization duration
• 5-10% - Peroneal nerve injury rate
• 5-10% - Recurrent instability rate
• 90%+ - PTFJ fusion success rate
• 85-90% - Nerve recovery rate
• 6-8 weeks - Screw removal timing

Examiner Favorites

"Why does knee flexion help with reduction?"

• Relaxes LCL and biceps femoris attachments to fibular head

"What structure is interposed in irreducible dislocations?"

• Biceps femoris tendon or joint capsule most common

"Why is PTFJ fusion well-tolerated?"

• Joint has minimal motion normally (less than 5 degrees)
• No significant functional deficit from fusion

"What predisposes to recurrent instability?"

• Oblique joint variant (more vertical articular surface)
• Inadequate immobilization duration
• Generalized ligamentous laxity