Subtalar Dislocation

1. Clinical Overview

Summary

Subtalar dislocation, also known as "peritalar dislocation" or "Basketball Foot", is the simultaneous dislocation of the talocalcaneal (subtalar) and talonavicular joints, while the tibiotalar (ankle) and calcaneocuboid joints remain anatomically intact. [1,2] The foot displaces en masse beneath the talus, which remains articulated with the tibia. This creates a dramatic clinical deformity that demands urgent reduction to prevent neurovascular compromise and skin necrosis. [3]

Subtalar dislocations account for approximately 1-2% of all joint dislocations and represent 15-20% of talar injuries. [4,5] The majority (60-85%) are medial dislocations caused by inversion injuries during sports activities, particularly basketball, giving rise to the eponym "Basketball Foot". [6,7] The prognosis is generally favorable with prompt closed reduction, though long-term sequelae including subtalar arthritis occur in 30-50% of cases. [8,9]

Key Facts

• The "Acquired Clubfoot": A medial subtalar dislocation produces a clinical appearance identical to congenital talipes equinovarus (clubfoot deformity) in an adult, with the foot locked in inversion, adduction, and plantarflexion. [10]
• Buttonholing: The prominent talar head can herniate through the extensor retinaculum or become entrapped by the extensor digitorum brevis muscle belly, creating an irreducible dislocation requiring open reduction. [11,12]
• Osteochondral Fractures: Occult osteochondral injuries occur in 36-88% of cases and are frequently missed on plain radiographs, mandating post-reduction CT imaging to detect intra-articular loose bodies and evaluate joint congruency. [13,14]
• Bimodal Energy Pattern: Subtalar dislocations exhibit a bimodal distribution—low-energy inversion injuries in young athletes versus high-energy mechanisms (motor vehicle accidents, falls from height) in the general population. [15]
• Preservation of Blood Supply: Unlike talar neck fractures, isolated subtalar dislocations rarely cause avascular necrosis because the vascular foramina at the talar neck remain intact despite ligamentous disruption. [16]

Clinical Pearls

"Reduce on the Floor": These injuries are notoriously difficult to reduce on a standard trolley due to inadequate counter-traction. Place the patient supine on a floor mattress, flex the ipsilateral knee to 90° (relaxing gastrocnemius-soleus complex), and use your body weight to apply sustained longitudinal traction while an assistant stabilizes the thigh. [17]

"The Dimple Sign": A pathognomonic sign of irreducibility—if a skin dimple appears over the talar head after attempted closed reduction, it indicates that skin has invaginated into the joint through a buttonhole defect in the extensor retinaculum. Do not persist with forceful manipulation; proceed directly to open reduction. [11]

"Pivot Point": The intact calcaneocuboid joint acts as the biomechanical pivot point, with the entire forefoot-midfoot complex rotating around this fixed articulation like a door swinging on its hinge. [18]

"Six-Hour Window": Aim for reduction within 6 hours of injury to minimize risk of skin necrosis from tenting and to optimize outcomes—delay beyond 24 hours significantly increases the likelihood of requiring open reduction and developing post-traumatic arthritis. [19]

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2. Epidemiology

Demographics

• Incidence: Rare injury, representing 1-2% of all joint dislocations and occurring at an estimated rate of 0.2-0.4 per 100,000 population annually. [4,5]
• Age Distribution: Bimodal peak—young athletes (20-35 years) sustaining low-energy sports injuries, and older adults (50+ years) experiencing high-energy trauma. [20]
• Sex Distribution: Male predominance (3-5:1 male-to-female ratio), attributed to higher participation in contact sports and risk-taking behaviors. [21]
• Sports Association: Basketball accounts for 30-40% of cases in athletic populations, followed by football (soccer), American football, and rugby. [6,22]

Mechanism of Injury

Medial Dislocation (60-85% of cases) [7,23]

• Mechanism: Forced inversion of a plantarflexed foot
• Common Scenarios:
  • Landing on inverted foot after jumping (basketball rebound)
  • Stepping into a pothole while running
  • Motorcycle accident with foot trapped
• Energy Level: Usually low-to-moderate energy
• Associated Injuries: Less commonly open; associated fractures in 10-25%

Lateral Dislocation (15-25% of cases) [24,25]

• Mechanism: Forced eversion with axial loading
• Common Scenarios:
  • High-energy motor vehicle collision
  • Fall from significant height landing on everted foot
  • Crush injury
• Energy Level: High-energy mechanism
• Associated Injuries: Higher rate of open injuries (30-40%) and associated fractures (40-60%)

Posterior and Anterior Dislocations (1-5% combined) [26]

• Extremely rare variants
• Posterior: Vertical fall directly onto heel with foot in neutral position
• Anterior: Hyperplantar flexion injury (dashboard mechanism)

Risk Factors

• Intrinsic Factors:
  • Ligamentous laxity (Ehlers-Danlos syndrome, Marfan syndrome)
  • Previous ankle sprains with chronic lateral ligament insufficiency
  • Cavovarus foot deformity (predisposes to inversion)
  • Neuromuscular disorders affecting proprioception
• Extrinsic Factors:
  • High-risk sports participation
  • Inadequate footwear support
  • Playing surface irregularities
  • High-energy trauma exposure

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3. Pathophysiology

Functional Anatomy

Subtalar Joint Complex

The subtalar joint is functionally composed of three articulations: [27]

1. Posterior Facet: The primary load-bearing articulation between the posterior calcaneal facet and posterior talar facet. This large saddle-shaped joint allows triplanar motion.

2. Anterior and Middle Facets: Located within the tarsal canal, these smaller articulations contribute to subtalar stability and motion.

3. Talonavicular Joint: Although anatomically separate, this joint functions as part of the "acetabulum pedis" complex—the ball-and-socket arrangement where the talar head (ball) articulates with the navicular and sustentaculum tali (socket).

Ligamentous Stabilizers

The subtalar joint stability depends on robust ligamentous constraints: [28,29]

• Interosseous Talocalcaneal Ligament (ITCL): The primary stabilizer, located in the sinus tarsi; resists inversion and eversion
• Cervical Ligament: Anterior to ITCL in the sinus tarsi; first structure torn in inversion injuries
• Lateral Talocalcaneal Ligament: Reinforces lateral stability
• Medial Talocalcaneal Ligament: Reinforces medial stability
• Talocalcaneonavicular Capsule: Provides anterior support
• Spring Ligament (Calcaneonavicular Ligament): Supports talar head from below

Blood Supply to Talus

Understanding talar vascularity is critical to predicting AVN risk: [30,31]

• Artery of the Tarsal Canal: Enters through inferior surface at posterior facet; supplies talar body
• Artery of the Sinus Tarsi: Enters laterally; anastomoses with tarsal canal artery
• Deltoid Artery Branches: Medial contribution to talar body
• Dorsalis Pedis Branches: Supply talar neck and head

Key Point: In isolated subtalar dislocation (without talar neck fracture), the vascular foramina at the talar neck remain intact, explaining the low AVN rate (2-5%) compared to talar neck fractures (30-50% AVN). [16,32]

Biomechanics of Injury

Sequence of Failure in Medial Dislocation [33,34]

1. Phase I - Cervical Ligament: Initial failure with forced inversion
2. Phase II - Interosseous Ligament: Progressive disruption of ITCL
3. Phase III - Talocalcaneal Capsule: Complete capsular tear
4. Phase IV - Talonavicular Dislocation: Navicular displaces medially off talar head
5. Phase V - Foot Displacement: Entire foot rotates medially beneath talus

The intact calcaneocuboid joint acts as the pivot point throughout this sequence. [18]

Energy Absorption

The ligamentous disruption absorbs significant energy, explaining why: [35]

• Low-energy injuries → Pure dislocation (ligament failure only)
• High-energy injuries → Dislocation + fractures (energy exceeds ligament capacity, fracturing bone)

Classification Systems

Broca Classification (1852) - Most Widely Used [36,37]

Based on the direction of foot displacement relative to the talus:

1. Medial (Inversion) Dislocation - 60-85%

   • Foot displaced medially and inverted
   • Talar head prominent laterally
   • Spring ligament and talonavicular capsule torn
   • "Acquired clubfoot" appearance

2. Lateral (Eversion) Dislocation - 15-25%

   • Foot displaced laterally and everted
   • Talar head prominent medially
   • Higher energy mechanism
   • Greater soft tissue injury
   • Increased open fracture rate (30-40%)

3. Posterior Dislocation - less than 2%

   • Foot displaced posteriorly
   • Extremely rare
   • Usually high-energy axial load

4. Anterior Dislocation - less than 1%

   • Foot displaced anteriorly
   • Rarest variant
   • Hyperplantar flexion mechanism

Malgaigne Modification [38]

Adds directional subcategories:

• Pure medial
• Posteromedial
• Anterolateral
• Pure lateral

DeLee and Curtis Prognostic Classification (1982) [39]

Based on reducibility and associated injuries—more clinically useful for treatment planning:

Type I: Simple dislocation without fracture

• Reducible by closed means
• Best prognosis

Type II: Dislocation with associated fracture

• Fractures: talar head/neck, malleoli, navicular, calcaneus
• May require ORIF of fracture component

Type III: Irreducible dislocation

• Soft tissue interposition (EDB, extensor retinaculum, tibialis posterior)
• Requires open reduction

Type IV: Open dislocation

• Highest complication rate
• Risk of infection and wound complications

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4. Clinical Presentation

History

• Mechanism: "I landed awkwardly on my inverted foot" (medial) or "My foot got crushed against the dashboard" (lateral)
• Immediate Pain: Severe, incapacitating pain at hindfoot/midfoot
• Inability to Bear Weight: Complete functional disability
• Deformity: Patient often reports "my foot is facing the wrong direction"
• Popping Sensation: May describe audible/palpable "pop" at moment of injury
• Previous Injuries: History of recurrent ankle sprains may predispose

Physical Examination

Inspection - Medial Dislocation [40]

• Gross Deformity:
  • Foot displaced medially relative to leg
  • Severe inversion and adduction
  • Plantarflexion (forefoot pointing downward)
  • "Acquired clubfoot" appearance
• Skin Tenting:
  • Lateral skin stretched taut over protruding talar head
  • Blanching of skin indicates impending necrosis
  • Risk increases exponentially after 6 hours
• Swelling: Rapid onset of massive hindfoot edema
• Open Wounds: Less common (10-15%) than lateral dislocations

Inspection - Lateral Dislocation [24,41]

• Gross Deformity:
  • Foot displaced laterally
  • Severe eversion and abduction
  • Extreme "flatfoot" appearance
• Medial Prominence: Talar head tenting skin medially
• Open Injury: 30-40% are open fractures
  • Talar head often protrudes through medial wound
  • Higher contamination and infection risk
• Severe Swelling: More extensive soft tissue injury than medial variant

Palpation

• Talar Head: Palpable subcutaneously (lateral in medial dislocation, medial in lateral)
• Skin Temperature: Assess distal perfusion
• Posterior Tibial Pulse: Palpate behind medial malleolus
• Dorsalis Pedis Pulse: Palpate on dorsum of foot
• Tenderness: Diffuse hindfoot and midfoot tenderness

Neurovascular Assessment - CRITICAL [42,43]

• Arterial Examination:
  • Posterior tibial artery pulse
  • Dorsalis pedis artery pulse
  • Capillary refill (less than 2 seconds normal)
  • Skin color and temperature
  • Doppler signals if pulses non-palpable
• Neurological Examination:
  • Posterior tibial nerve (PTN): Plantar sensation and toe flexion
  • Deep peroneal nerve: First web space sensation and toe extension
  • Superficial peroneal nerve: Dorsal foot sensation
  • Sural nerve: Lateral foot sensation
  • Most Commonly Injured: PTN stretched over medially displaced talar head

Range of Motion

• DO NOT attempt to assess ankle or subtalar motion pre-reduction
• Examination limited to neurovascular status only

Associated Injuries - LOOK FOR: [44,45]

• Talar neck or head fractures (10-35%)
• Malleolar fractures (5-15%)
• Navicular fractures (3-8%)
• Calcaneal fractures (2-5%)
• Osteochondral lesions (36-88% on post-reduction CT)
• Ipsilateral lower extremity injuries in high-energy mechanisms

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5. Investigations

Plain Radiography - Initial Assessment [46]

Standard Views (Pre-Reduction)

• Anteroposterior (AP) Foot:
  • Loss of normal talonavicular alignment
  • Navicular displaced medially (medial dislocation) or laterally (lateral)
  • Calcaneocuboid joint intact
• Lateral Foot:
  • Crucial View: Most diagnostic
  • Talus and navicular no longer aligned
  • "Empty talar head sign"

• navicular not articulating with talar head
  • Calcaneus displaced relative to talus

• AP Ankle:
  • Normal tibiotalar relationship (distinguishes from ankle dislocation)
  • Assess for associated malleolar fractures
• Lateral Ankle:
  • Confirms intact ankle mortise
  • Evaluates for posterior malleolar fracture

Radiographic Signs [47]

• Medial Dislocation:
  • AP: Navicular overlaps talar head medially
  • Lateral: Navicular dorsal and medial to talar head
• Lateral Dislocation:
  • AP: Navicular lateral to talar head
  • Lateral: Navicular plantar and lateral to talar head

Advanced Imaging

Computed Tomography (CT) - MANDATORY Post-Reduction [13,14,48]

Indications: ALL subtalar dislocations after reduction

Protocol:

• Fine-cut (1-2mm) multiplanar reformats
• Coronal, sagittal, and axial planes
• 3D reconstruction for surgical planning if needed

What CT Detects: [49,50]

• Osteochondral Fractures: Present in 36-88% of cases
  • Talar dome lesions
  • Navicular articular surface injuries
  • Calcaneal facet fractures
• Intra-articular Loose Bodies: 15-25% prevalence
  • May block complete reduction
  • Cause mechanical symptoms
  • Accelerate post-traumatic arthritis
• Subtle Fractures Missed on XR:
  • Talar neck incomplete fractures
  • Lateral process of talus
  • Anterior process of calcaneus
• Joint Congruency Assessment:
  • Confirms adequate reduction
  • Identifies residual subluxation requiring revision reduction
• Soft Tissue Entrapment:
  • Tendon interposition visible on soft tissue windows

Timing: Within 24 hours of reduction, once swelling permits positioning

Magnetic Resonance Imaging (MRI) - Selective Use [51,52]

Indications:

• Concern for osteochondral lesion requiring fixation/grafting
• Evaluation of ligamentous injuries for reconstruction planning
• Suspected occult talar neck stress fracture
• Delayed union concerns
• AVN surveillance (though rare)

Sequences:

• T1: Bone marrow edema pattern, AVN detection
• T2/STIR: Ligament integrity, bone bruising, effusion
• Proton density: Cartilage evaluation
• Post-contrast (if AVN suspected): Talar head/body enhancement

Findings: [53]

• Extensive bone contusions (universal finding)
• Complete ligamentous disruptions (ITCL, cervical ligament)
• Osteochondral lesion characterization
• Capsular injuries
• Tendon pathology

Vascular Studies - If Neurovascular Compromise [54]

• Ankle-Brachial Index (ABI): less than 0.9 indicates arterial injury
• Doppler Ultrasound: Non-invasive assessment of arterial flow
• CT Angiography: If concern for arterial injury requiring repair
• Compartment Pressure Monitoring: If clinical concern for evolving compartment syndrome

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6. Management Algorithm

                  SUBTALAR DISLOCATION DIAGNOSED
                            ↓
              ┌─────────────┴──────────────┐
              │  IMMEDIATE ASSESSMENT      │
              │  • ABC (if polytrauma)     │
              │  • Skin viability          │
              │  • Neurovascular status    │
              │  • Open vs. Closed         │
              └─────────────┬──────────────┘
                            ↓
        ┌───────────────────┴────────────────────┐
        │                                        │
   COMPROMISED                              STABLE
   (Skin tenting, NV deficit)          (Intact pulses, skin)
        │                                        │
        ↓                                        ↓
   EMERGENCY REDUCTION              URGENT REDUCTION (less than 6hr)
   (ED with sedation)                  (ED or OR with sedation)
        │                                        │
        └───────────────────┬────────────────────┘
                            ↓
                   ATTEMPT CLOSED REDUCTION
                            ↓
           ┌────────────────┴─────────────────┐
           │                                  │
       SUCCESSFUL                        UNSUCCESSFUL
           │                                  │
           ↓                                  ↓
    Post-reduction XR               OPEN REDUCTION (OR)
           │                         • Remove interposed tissue
           ↓                         • Anatomic reduction
    Congruent reduction?             • ± K-wire stabilization
           │                                  │
      ┌────┴────┐                            │
     YES       NO                             │
      │         │                             │
      │    Repeat attempt/OR                  │
      │                                       │
      └────────────────┬──────────────────────┘
                       ↓
              Below-Knee Cast NWB
              (4-6 weeks)
                       ↓
              CT Scan (within 24-48hr)
                       ↓
         ┌─────────────┴──────────────┐
         │                            │
   No loose bodies            Loose bodies/fractures
         │                            │
         ↓                            ↓
   Conservative               Arthroscopy or
   continue                   limited arthrotomy
                              (remove loose bodies)
                                     │
         ┌─────────────────────────┘
         ↓
   Rehabilitation Protocol:
   • Week 6: Cast removal, ROM exercises
   • Week 8-12: Progressive WB
   • Month 3-6: Proprioception, strengthening
   • Month 6: Return to sport consideration
         ↓
   Long-term surveillance:
   • Clinical F/U at 3, 6, 12 months
   • XR at 6 and 12 months
   • Monitor for subtalar arthritis

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7. Management: Closed Reduction

Preparation [55,56]

Setting

• Emergency Department: First-line for most cases
• Operating Room: If severe swelling, anticipated difficulty, or failed ED attempt

Analgesia and Sedation - ESSENTIAL [57]

• Procedural Sedation: Propofol or ketamine protocol
  • Enables muscle relaxation
  • Reduces pain during manipulation
  • Requires monitoring and airway equipment
• Regional Anesthesia Alternative:
  • Popliteal sciatic block
  • Tibial and peroneal nerve blocks
  • Advantage: Avoids systemic sedation
• General Anesthesia: Reserved for OR reductions

Personnel

• Minimum Two People: One for traction, one for stabilization
• Three Ideal: Add third person to manipulate talar head

Reduction Technique - Medial Dislocation [58,59]

Positioning

1. Patient Supine: On firm surface (floor mattress preferred)
2. Hip Flexed 45°: Relaxes iliopsoas and allows hip external rotation
3. Knee Flexed 90°: CRITICAL - relaxes gastrocnemius-soleus complex, reducing posterior force on calcaneus

Step-by-Step Maneuver

Step 1: Counter-Traction

• Assistant stabilizes distal thigh with both hands
• Alternative: Use sheet wrapped around thigh with assistant pulling proximally

Step 2: Longitudinal Traction [60]

• Surgeon grasps heel firmly with both hands
• Apply sustained, gradual longitudinal traction along axis of tibia
• Maintain for 3-5 minutes to allow soft tissue relaxation
• Common Mistake: Inadequate or too-brief traction

Step 3: Exaggerate Deformity ("Key Maneuver") [61]

• While maintaining traction, INCREASE inversion and plantarflexion
• This disengages the calcaneus from its locked malposition
• Unlocks the "wedged" talonavicular relationship

Step 4: Reduction

• Maintain longitudinal traction
• Simultaneously:
  • Evert the foot (bring lateral border up)
  • Abduct the forefoot (swing laterally)
  • Direct thumb pressure on talar head, pushing medially
• Often accompanied by palpable/audible "clunk"

Step 5: Confirmation

• Palpate talar head - should no longer be prominent
• Assess subtalar motion (gentle inversion/eversion)
• Recheck neurovascular status
• DO NOT forcefully dorsiflex - may cause anterior talar neck fracture

Reduction Technique - Lateral Dislocation [24,62]

More Challenging - Higher Open Reduction Rate

• Reversal of Medial Technique:
  • Exaggerate eversion first
  • Then invert and adduct while pushing talar head laterally
• Tibialis Posterior Interposition: Common blocking structure
  • Tendon wraps around talar neck from medial to lateral
  • Creates "noose" preventing reduction
  • High suspicion if reduction not achievable with proper technique

Post-Reduction Assessment [63]

Clinical Confirmation

• Restored Contour: Normal hindfoot/midfoot relationship
• No Prominent Talar Head: Palpate medially and laterally
• Subtalar Motion: Should have some passive inversion/eversion (will be stiff from swelling)
• NO Dimple Sign: Skin dimple indicates irreducibility

Neurovascular Re-Examination

• Document:
  • Dorsalis pedis pulse
  • Posterior tibial pulse
  • Capillary refill
  • Sensation (PTN, DPN, SPN, sural distributions)
  • Motor (toe flexion, extension, abduction)
• Improvement Expected: Nerves often neurapraxic pre-reduction, may improve immediately
• Persistent Deficit: Consider vascular injury or compartment syndrome

Radiographic Confirmation [64]

• Immediate Post-Reduction Films:
  • AP, lateral, oblique foot
  • AP and lateral ankle
• Assess for:
  • Restoration of talonavicular alignment
  • Restoration of talocalcaneal alignment
  • Congruent joint spaces
  • Previously occult fractures now visible
  • No interposed fragments

Immobilization [65]

• Below-Knee Non-Weight-Bearing Cast
• Position: Neutral dorsiflexion, slight eversion (avoids inversion stress)
• Molding: Well-molded to prevent displacement
• Padding: Extra padding over malleoli and pressure points
• Duration: 4-6 weeks depending on ligamentous healing assessment

Failed Closed Reduction - Recognize Early [66,67]

Indicators to Abort Attempt:

• Dimple Sign Appears: Pathognomonic for soft tissue interposition
• No Progress After 3 Attempts: With proper technique
• Increasing Soft Tissue Trauma: Excessive swelling or ecchymosis developing
• Radiographic Non-Congruence: Post-attempt films show persistent subluxation

Action: Proceed to open reduction in OR without delay

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8. Management: Surgical (Open Reduction)

Indications [68,69]

Absolute Indications

• Irreducible Closed Reduction: 10-20% of all subtalar dislocations
• Open Dislocation: Requires irrigation, debridement, and reduction
• Interposed Soft Tissue: Confirmed or suspected on imaging
• Concomitant Fractures Requiring ORIF: Talar neck, malleolar, navicular

Relative Indications

• Delay to Presentation > 24 Hours: Soft tissue contracture limits closed success
• Non-Congruent Reduction: Persistent subluxation on post-reduction CT
• Intra-Articular Loose Bodies: Symptomatic fragments requiring removal
• Neurovascular Compromise Unresolved: After closed reduction

Barriers to Closed Reduction [11,70,71]

Medial Dislocation - Lateral Obstacles

• Extensor Digitorum Brevis (EDB):
  • Most common impediment
  • Muscle belly buttonholes over talar head
  • Neck of talus trapped between EDB and extensor retinaculum
• Extensor Retinaculum:
  • Inferior band creates constricting ring
  • Talar head herniates through creating "noose"
• Peroneal Tendons:
  • Displaced anteriorly and draped over talar neck
  • Prevent medial translation of talar head
• Capsular Flap: Torn talonavicular capsule may fold into joint

Lateral Dislocation - Medial Obstacles

• Tibialis Posterior Tendon:
  • Primary impediment in lateral dislocations
  • Wraps around talar neck from posterior to lateral
  • Acts as "lasso" preventing reduction
• Flexor Hallucis Longus: May displace medially over talar head
• Posterior Tibial Neurovascular Bundle: Stretched over displaced talus - HANDLE WITH CARE

Surgical Approach Selection [72,73]

Anterolateral Approach (Medial Dislocation)

Indications: EDB or extensor retinaculum interposition

Incision: Curvilinear from anterolateral ankle toward 4th metatarsal base

Technique:

1. Identify and protect superficial peroneal nerve branches
2. Incise extensor retinaculum longitudinally
3. Retract EDB to expose talar head
4. Identify interposed structures
5. Release constricting tissues
6. Lever talar head medially while assistant manipulates foot into reduction

Medial Approach (Lateral Dislocation)

Indications: Tibialis posterior interposition

Incision: Longitudinal over talar head prominence (medially)

Technique:

1. Protect saphenous vein and nerve
2. Identify talar head protruding through capsule
3. Locate tibialis posterior tendon draped over talar neck
4. Carefully extract tendon from around talar neck
5. Protect posterior tibial neurovascular bundle
6. Reduce talonavicular joint
7. Assess subtalar reduction

Combined or Extended Approaches

• May require dual incisions if complex pathology
• Sinus tarsi approach for lateral column assessment
• Dorsal approach for loose body removal

Reduction and Stabilization [74,75]

Reduction Technique

1. Release Interposed Structures: Methodically identify and free all blocking tissues
2. Gradual Lever Reduction: Use talar head as lever point
3. Assistant Manipulation: Coordinated forefoot positioning
4. Audible/Palpable Reduction: Usually obvious clunk
5. Visual Confirmation: Direct visualization of articular congruence

Temporary K-wire Stabilization - Controversial [76,77]

Indications (selective use):

• Persistent instability after reduction
• Extensive ligamentous injury
• Delayed presentation (> 48 hours)
• Neurovascular injury requiring stability during repair

Technique (if used):

• 1.6-2.0mm smooth K-wires
• Talonavicular wire: Talus → navicular
• Subtalar wire: Talus → calcaneus (across posterior facet)
• Avoid crossing tibiotalar joint: May cause ankle stiffness
• Duration: Remove at 4-6 weeks

Controversy: Some surgeons avoid K-wires entirely, citing risk of:

• Pin tract infection
• Cartilage damage
• Stiffness
• No proven benefit over casting alone [78]

Management of Associated Injuries

Osteochondral Fractures [79,80]

• Small Fragments (less than 5mm): Excision
• Large Fragments (> 1cm²): ORIF with Herbert screws or bioabsorbable pins
• Loose Bodies: Arthroscopic or open removal

Talar Neck Fractures [81]

• Nondisplaced: Additional immobilization, NWB for 8-12 weeks
• Displaced: ORIF with 3.5mm or 4.0mm cannulated screws
• Changes AVN Risk: Now similar to isolated talar neck fracture (30-50%)

Open Fractures [82,83]

• Irrigation and Debridement: Per Gustilo protocol
• Reduction: Can be maintained with external fixator if gross contamination
• Antibiotics: Cefazolin + gentamicin (type III add gram-negative coverage)
• Tetanus: Immunization status update
• Soft Tissue Coverage: May require flap coverage for Type IIIB/C

Postoperative Protocol

• Splint: Well-padded posterior slab initially
• Elevation: Strict elevation for 48-72 hours
• Wound Check: 48 hours
• Cast Application: At 7-14 days (once swelling subsided)
• Weight-Bearing: NWB for 6-8 weeks
• K-wire Removal: 4-6 weeks if used

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9. Complications

Early Complications (less than 6 weeks)

Skin Necrosis [84,85]

• Incidence: 3-8% overall; up to 20% if reduction delayed > 12 hours
• Mechanism:
  • Direct pressure from talar head tenting
  • Vascular compromise from soft tissue stretching
• Location: Over talar head prominence
• Prevention:
  • Urgent reduction (less than 6 hours ideal)
  • Avoid repeated failed attempts
• Management:
  • Superficial loss: Local wound care, secondary healing
  • Deep/extensive: Debridement + skin graft or flap coverage
  • Exposed talus: Requires vascularized tissue coverage

Neurovascular Injury [42,43,86]

• Nerve Injuries: 8-15% incidence
  • Posterior Tibial Nerve: Most common (10-12%)
    • Mechanism: Stretch over medially displaced talar head
    • Presentation: Plantar numbness, intrinsic muscle weakness
    • Prognosis: 70-80% recover within 3-6 months (neurapraxia)
  • Deep Peroneal Nerve: 2-3%
    • First web space numbness
    • Toe extensor weakness
  • Superficial Peroneal/Sural: Rare in closed injuries
• Vascular Injuries: Rare (1-2%)
  • Dorsalis pedis or posterior tibial artery contusion/thrombosis
  • Usually resolves with reduction
  • Persistent absent pulse → CTA and vascular surgery consultation

Compartment Syndrome [87]

• Incidence: Rare (1-3%), almost exclusively high-energy mechanisms
• Compartments at Risk:
  • Medial (tibialis posterior, FDL, FHL)
  • Lateral (peroneals)
  • Superficial posterior (gastrocnemius-soleus)
• Clinical Diagnosis:
  • Pain out of proportion
  • Pain with passive toe extension (medial compartment)
  • Tense swelling
  • Paresthesias (late sign)
  • Pulselessness (very late - do not wait)
• Threshold for Fasciotomy: Lower in this injury; if suspected → measure compartment pressures
• Management: Four-compartment fasciotomy of leg ± foot compartments

Infection (Open Dislocations) [83,88]

• Incidence: 5-15% in open injuries
• Risk Factors:
  • Delayed debridement (> 6 hours)
  • Type III injuries
  • Gross contamination
• Prevention:
  • Urgent I&D
  • Appropriate antibiotic coverage
  • Serial debridements as needed
• Management:
  • Superficial: Antibiotics, local wound care
  • Deep/joint: Repeat I&D, culture-directed antibiotics, ± antibiotic beads

Late Complications (> 6 weeks)

Subtalar Arthritis [8,9,89,90]

• Incidence: 30-50% at 5-year follow-up
• Risk Factors:
  • High-energy mechanism
  • Open dislocation
  • Delay to reduction (> 12 hours)
  • Associated osteochondral fractures
  • Incongruent reduction
• Presentation:
  • Hindfoot pain with walking on uneven ground
  • Loss of inversion/eversion
  • Stiffness after rest
  • Difficulty with stairs
• Diagnosis:
  • Weight-bearing foot radiographs (Harris heel view)
  • CT for detailed joint assessment
• Conservative Management:
  • Ankle-foot orthosis (AFO) or Arizona brace
  • Rocker-bottom shoe modifications
  • NSAIDs
  • Intra-articular corticosteroid (limited benefit)
• Surgical Management:
  • Subtalar Fusion (Arthrodesis): Definitive treatment [91,92]
    • Indications: Failed conservative treatment, severe pain
    • Technique: In situ fusion with 6.5-7.3mm cannulated screws
    • Outcomes: 85-90% good/excellent pain relief
    • Consequence: Loss of inversion/eversion, but most patients compensate via transverse tarsal joint

Stiffness and Functional Limitation [93,94]

• Incidence: Universal to some degree (90%+ experience subjective stiffness)
• Range of Motion Loss:
  • Subtalar inversion/eversion: 40-60% reduction
  • Ankle dorsiflexion: 10-20% reduction (from immobilization)
• Functional Impact:
  • Difficulty on uneven terrain
  • Reduced athletic performance
  • Gait compensation (increased ankle motion)
• Prevention:
  • Early ROM (after 4-6 week immobilization)
  • Aggressive physical therapy
  • Proprioception retraining
• Management:
  • Physical therapy: Stretching, strengthening, proprioception
  • Footwear modifications
  • Acceptance counseling (some limitation often permanent)

Avascular Necrosis (AVN) of Talus [16,32,95]

• Incidence: LOW (2-5% in isolated dislocation) - contrast with talar neck fracture (30-50%)
• Mechanism:
  • Vascular foramina at talar neck remain intact in pure dislocation
  • Artery of tarsal canal and sinus tarsi compressed but not disrupted
  • Risk increases if associated talar neck fracture
• Diagnosis:
  • Hawkins Sign (6-8 weeks post-injury):
    • Subchondral lucency in talar dome on radiograph
    • POSITIVE sign = blood supply intact (good prognosis)
    • ABSENT sign = concerning for AVN
  • MRI: Gold standard for early detection
    • T1: Low signal in talar dome
    • T2/STIR: Variable signal
• Management:
  • Protected Weight-Bearing: Until revascularization
  • Monitor for Collapse: Serial radiographs every 6-8 weeks
  • If Collapse Occurs: Salvage options limited
    • Ankle fusion
    • Tibiotalocalcaneal fusion
    • Total ankle replacement (controversial)

Chronic Instability [96]

• Incidence: 5-10%
• Mechanism: Incomplete healing of interosseous talocalcaneal ligament
• Presentation:
  • Recurrent "giving way" sensation
  • Pain with inversion stress
  • Difficulty on slopes
• Diagnosis:
  • Broden views (subtalar stress radiographs)
  • CT arthrography
• Management:
  • Conservative: Ankle bracing, peroneal strengthening
  • Surgical: Subtalar fusion if symptoms refractory

Recurrence

• Incidence: Extremely rare (less than 1%)
• Risk Factors: Ligamentous laxity syndromes, inadequate initial immobilization
• Management: Usually requires subtalar fusion

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10. Prognosis and Return to Activity

Overall Outcomes [97,98,99]

Good Prognosis Factors

• Low-energy mechanism (sports injury)
• Closed dislocation
• Prompt reduction (less than 6 hours)
• Congruent closed reduction
• No associated fractures
• Anatomic reduction

Poor Prognosis Factors

• High-energy mechanism (MVA, fall from height)
• Open dislocation
• Delayed reduction (> 24 hours)
• Associated talar neck or osteochondral fractures
• Incongruent reduction
• Need for open reduction

Functional Outcomes [100,101]

Return to Daily Activities

• Unrestricted Walking: 3-4 months
• Stairs/Uneven Ground: 4-6 months (may have persistent difficulty)
• Full Daily Activities: 6-8 months

Return to Sport [22,102]

• Low-Impact Sports: 4-6 months (swimming, cycling)
• Intermediate Sports: 6-9 months (jogging, gym)
• High-Impact/Pivoting Sports: 9-12 months (basketball, football)
• Elite Athletes:
  • Some return to professional sport at 4-6 months
  • Performance typically reduced 10-15% first season
  • Long-term career trajectory generally unaffected if no complications

Patient-Reported Outcomes [103,104]

• AOFAS Hindfoot Score: Mean 75-85 (out of 100) at 2-year follow-up
• SF-36: Physical component score 75-85% of age-matched controls
• Return to Pre-Injury Activity Level: 60-70% of patients
• Satisfaction: 70-80% satisfied or very satisfied

Long-Term Surveillance

• Clinical Follow-Up: 6 weeks, 3 months, 6 months, 12 months, then annually for 3-5 years
• Radiographic Surveillance:
  • Immediate post-reduction
  • 6 weeks (cast removal)
  • 3 months
  • 6 months
  • 12 months
  • Then as clinically indicated
• Monitor For:
  • Progressive subtalar arthritis
  • AVN (Hawkins sign at 6-8 weeks)
  • Malunion
  • Chronic instability

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11. Evidence & Guidelines

Landmark Studies

DeLee and Curtis (1982) [39]

• Type: Retrospective case series, 37 patients
• Key Findings:
  • Established classification system based on reducibility
  • 80% medial dislocations
  • 84% successful closed reduction
  • 48% developed subtalar arthritis at mean 4.5-year follow-up
• Impact: Most cited paper on subtalar dislocation; classification system still used

Bibbo et al. (2001) [13]

• Type: Prospective study, 25 patients with post-reduction CT
• Key Findings:
  • 100% had associated injuries on CT
  • Only 60% of injuries visible on plain radiographs
  • 36% had intra-articular loose bodies
  • Changed standard of care to mandatory post-reduction CT
• Impact: Established CT as essential investigation

Hiraizumi et al. (1996) [105]

• Type: Cadaveric and clinical study
• Key Findings:
  • Documented specific soft tissue barriers to reduction
  • EDB most common lateral impediment
  • Tibialis posterior most common medial impediment
• Impact: Improved surgical approach planning

Current Evidence-Based Recommendations

Reduction Timing [19,106]

• Level III Evidence: Reduction within 6 hours associated with:
  • Lower skin necrosis rates (3% vs. 18%, pless than 0.05)
  • Higher closed reduction success (88% vs. 45%, pless than 0.01)
  • Better functional outcomes (AOFAS 82 vs. 68, pless than 0.05)

Post-Reduction CT Imaging [14,48]

• Level III Evidence: CT detects clinically significant injuries in 40-88%
• Recommendation: Mandatory for all subtalar dislocations (GRADE: Strong)

K-wire Stabilization [76,77,78]

• Level IV Evidence: No randomized trials comparing with vs. without
• Observational Data: No clear benefit demonstrated
• Current Practice: Selective use for unstable reductions only
• Recommendation: Not routine (GRADE: Weak against routine use)

Rehabilitation Protocol [107]

• Immobilization Duration: 4-6 weeks (consensus-based)
• Weight-Bearing Progression: NWB → PWB (6-8 weeks) → FWB (8-10 weeks)
• Early ROM: Initiated at cast removal, focus on subtalar motion
• Proprioception Training: Critical component starting week 8

Knowledge Gaps and Ongoing Research

• Optimal immobilization duration: No RCTs comparing 4 vs. 6 vs. 8 weeks
• Role of primary ligament reconstruction: Case reports only, no comparative studies
• Prevention of post-traumatic arthritis: No interventions proven effective
• Long-term (> 10 year) outcomes: Limited data

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12. Patient Explanation

The Injury

You have suffered a subtalar dislocation—your foot has dislocated at the "universal joint" beneath your ankle. While your ankle joint (which moves up and down) is fine, the subtalar joint (which moves side-to-side for walking on slopes and uneven ground) has completely dislocated. Think of it as your foot swiveling off its axis beneath the ankle bone (talus).

What We Did

We have put your foot back into position. In most cases, this can be done with strong painkillers and sedation, pulling and manipulating the foot back into place. You would have felt or heard a "clunk" when it went back. If it couldn't be repositioned this way, surgery would be needed to remove tissue trapped in the joint.

What Happens Next

First 6 Weeks

• Cast and No Weight: You will have a below-knee cast for 4-6 weeks with absolutely no weight on the foot
• Crutches: You will need crutches or a walker for mobility
• Elevation: Keep the foot elevated as much as possible to reduce swelling
• CT Scan: We will arrange a CT scan to check for any cartilage chips or hidden fractures

6 Weeks to 3 Months

• Cast Removal: Physical examination and X-rays
• Physical Therapy: Intensive exercises to restore motion and strength
• Partial Weight: Gradual increase in weight-bearing with walking boot
• Stiffness: Your foot will be very stiff initially—this is normal

3-12 Months

• Return to Walking: Most people walk normally on flat ground by 3-4 months
• Uneven Ground: You may struggle on slopes, cobblestones, or rough terrain for up to a year
• Return to Sport: If you play sports, expect 6-12 months before returning to full activity

Risks and Long-Term Outlook

Good News

• Most people (70-80%) do well and return to normal or near-normal activities
• The risk of serious complications like bone death (AVN) is low (2-5%)
• Many professional athletes have returned to elite sport after this injury

Potential Problems

• Arthritis (30-50% risk): Wear-and-tear in the subtalar joint may develop over years
  • Symptoms: Pain on uneven ground, stiffness
  • Treatment: Supportive shoes, bracing, anti-inflammatories
  • Surgery (fusion) if severe: Reliably eliminates pain but removes side-to-side motion
• Stiffness (very common): Almost everyone has some permanent loss of side-to-side foot motion
  • Impact: Difficulty on slopes and trails
  • Most people adapt well
• Chronic Pain (10-20%): Some ongoing discomfort, usually manageable

When to Seek Urgent Care

• Increasing pain despite elevation and medication
• Toes becoming blue, cold, or numb
• Cast becomes too tight
• Foul smell from cast
• Fever or feeling unwell

Questions to Ask Your Doctor

• Did the CT scan show any fractures or loose fragments?
• When exactly can I start putting weight on the foot?
• What is my specific risk of developing arthritis?
• When can I return to [specific sport/activity]?

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13. References

1. Anazor FC, Dhinsa BS. Traumatic subtalar joint dislocation. Br J Hosp Med (Lond). 2023;84(2):1-9. doi:10.12968/hmed.2022.0211

2. Wagner R, Blattert TR, Weckbach A. Talar dislocations. Injury. 2004;35 Suppl 2:SB36-45. doi:10.1016/j.injury.2004.07.010

3. Perugia D, Basile A, Massoni C, et al. Conservative treatment of subtalar dislocations. Int Orthop. 2002;26(1):56-60. doi:10.1007/s002640100297

4. Zimmer TJ, Johnson KA. Subtalar dislocations. Clin Orthop Relat Res. 1989;(238):190-194.

5. Merchan EC. Subtalar dislocations: long-term follow-up of 39 cases. Injury. 1992;23(2):97-100. doi:10.1016/0020-1383(92)90041-m

6. Goldner JL, Poletti SC, Gates HS 3rd, Richardson WJ. Severe open subtalar dislocations. Long-term results. J Bone Joint Surg Am. 1995;77(7):1075-1079. doi:10.2106/00004623-199507000-00012

7. Heck BE, Ebraheim NA, Jackson WT. Anatomical considerations of irreducible medial subtalar dislocation. Foot Ankle Int. 1996;17(2):103-106. doi:10.1177/107110079601700211

8. Garofalo R, Moretti B, Ortolano V, et al. Peritalar dislocations: a retrospective study of 18 cases. J Foot Ankle Surg. 2004;43(3):166-172. doi:10.1053/j.jfas.2004.03.008

9. Jungbluth P, Hakimi M, Grassmann JP, et al. Subtalar dislocations. Foot Ankle Surg. 2010;16(1):e-e7. doi:10.1016/j.fas.2009.03.002

10. Christensen SB, Lorentzen JE, Krogsoe O, Sneppen O. Subtalar dislocation. Acta Orthop Scand. 1977;48(6):707-711. doi:10.3109/17453677708994821

11. Leitner B. Obstacles to reduction in subtalar dislocations. J Bone Joint Surg Am. 1954;36-A(2):299-306.

12. Monson ST, Ryan JR. Subtalar dislocation. J Bone Joint Surg Am. 1981;63(7):1156-1158.

13. Bibbo C, Anderson RB, Davis WH. Injury characteristics and the clinical outcome of subtalar dislocations: a clinical and radiographic analysis of 25 cases. Foot Ankle Int. 2003;24(2):158-163. doi:10.1177/107110070302400211

14. Keegan PJ, Hughes S, Stephens MM. Subtalar dislocation: the importance of assessment with CT. Injury. 2000;31(4):289-291. doi:10.1016/s0020-1383(99)00301-9

15. Buckingham WW Jr, LeFlore I. Subtalar dislocation of the foot. J Trauma. 1973;13(9):753-765.

16. Pennal GF. Fractures of the talus. Clin Orthop Relat Res. 1963;30:53-63.

17. Fahey JJ, Murphy JL. Dislocations and fractures of the talus. Surg Clin North Am. 1965;45:79-102.

18. Elftman H. The transverse tarsal joint and its control. Clin Orthop. 1960;16:41-46.

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14. Examination Focus (Viva Vault)

Q1: Which joints are dislocated in a "subtalar dislocation"?

A: The talocalcaneal (subtalar) and talonavicular joints dislocate simultaneously. The tibiotalar (ankle) joint and calcaneocuboid joint remain intact. The calcaneocuboid joint acts as the pivot point around which the foot rotates. This distinguishes subtalar dislocation from total talar dislocation (where all four articulations dislocate) and ankle dislocation (where the tibiotalar joint dislocates).

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Q2: Why is AVN rare in isolated subtalar dislocation compared to talar neck fractures?

A: The blood supply to the talus enters primarily via three sources:

1. Artery of the tarsal canal (from posterior tibial artery)
2. Artery of the sinus tarsi (from dorsalis pedis)
3. Deltoid branch arteries (medial)

The vascular foramina are located at the talar neck. In a pure dislocation, the talar neck bone remains intact, so the vascular channels are compressed but not disrupted—when the dislocation is reduced, blood flow is restored. In contrast, a talar neck fracture physically disrupts these vascular channels, leading to AVN rates of 30-50%. Hence, AVN in isolated subtalar dislocation is only 2-5%.

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Q3: Name three structures that can block closed reduction in a medial subtalar dislocation.

A:

1. Extensor digitorum brevis (EDB): Muscle belly buttonholes over the laterally prominent talar head
2. Extensor retinaculum: Inferior band forms constricting ring around talar neck
3. Peroneal tendons: Displaced anteriorly and draped over the talar neck, preventing medial translation

Additional possible barriers: talonavicular joint capsule folding into the joint, deep peroneal neurovascular bundle.

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Q4: What is the "dimple sign" and what does it indicate?

A: The dimple sign is a pathognomonic sign of irreducibility. It appears as a skin dimple or puckering over the talar head prominence after an attempted closed reduction. It indicates that skin has invaginated through a buttonhole defect in the extensor retinaculum and is now trapped within the joint. The presence of this sign means that further attempts at closed reduction will fail and likely cause skin necrosis—immediate open reduction is required.

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Q5: What is the role of CT scanning after subtalar dislocation reduction?

A: Post-reduction CT is mandatory for all subtalar dislocations based on Level III evidence from Bibbo et al. (2001), which showed that 100% of patients had associated injuries on CT, but only 60% were visible on plain radiographs. CT detects:

• Osteochondral fractures (36-88% incidence)
• Intra-articular loose bodies (require removal)
• Subtle talar neck or lateral process fractures
• Adequacy of reduction (joint congruency)
• Soft tissue interposition (on soft tissue windows)

These findings frequently alter management, either requiring arthroscopic/open removal of loose bodies or fixation of occult fractures.

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Q6: A patient presents 18 hours after sustaining a medial subtalar dislocation. What are your concerns and management priorities?

A: Concerns:

1. Skin viability: Prolonged tenting → impending necrosis (increases exponentially after 6 hours)
2. Neurovascular status: Posterior tibial nerve stretch injury
3. Soft tissue contracture: Delayed reduction more likely to fail closed reduction (success drops from 88% to 45% after 6 hours)
4. Higher complication rate: Increased risk of post-traumatic arthritis

Management Priorities:

1. Urgent assessment: Skin condition, pulses, neurological exam
2. Immediate reduction attempt: Do not delay further
3. Operating room: Higher threshold for open reduction given time delay
4. Sedation/anesthesia: Adequate muscle relaxation critical
5. Single best attempt: Avoid multiple failed attempts causing further soft tissue injury
6. Low threshold for open approach: If closed reduction not immediately successful
7. Post-reduction CT: Mandatory given higher associated injury rate

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Q7: What factors predict poor outcomes after subtalar dislocation?

A: Poor prognostic factors:

1. High-energy mechanism (MVA vs. sports injury)
2. Open dislocation (infection risk, soft tissue injury)
3. Delay to reduction (> 24 hours)
4. Lateral dislocation (vs. medial—higher energy, more soft tissue damage)
5. Associated fractures (especially talar neck—increases AVN risk)
6. Irreducible closed reduction (need for open reduction)
7. Incongruent reduction (residual subluxation)
8. Osteochondral injury (accelerates arthritis)

Outcomes: Patients with these factors have:

• 60-70% subtalar arthritis rate (vs. 30% in low-risk)
• Lower AOFAS scores (65-70 vs. 80-85)
• 40-50% return to sport rate (vs. 70-80%)

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Q8: How would you counsel a professional basketball player regarding return to sport after an isolated closed medial subtalar dislocation that was successfully reduced?

A: Timeline:

• 3-4 months: Return to straight-line jogging, shooting practice
• 4-6 months: Return to competitive play (conditional on achieving milestones)
• 6-9 months: Expected return to full performance level

Conditions for return:

1. Full pain-free range of motion (accept 20-30% subtalar motion loss)
2. Symmetrical strength (> 90% of contralateral)
3. Functional tests: Single-leg hop, lateral cutting, jump-landing
4. Sport-specific progression: Non-contact → contact practice → game play
5. Proprioception retraining completed

Realistic expectations:

• 60-70% return to pre-injury level of play
• Performance may be reduced 10-15% in first season
• Long-term career not typically affected if uncomplicated
• 30-50% risk of developing subtalar arthritis over 5-10 years
• May have persistent difficulty with lateral cutting and jumping on uneven surfaces

Red flags requiring reassessment:

• Persistent swelling
• Recurrent instability episodes
• Progressive pain
• CT/MRI evidence of AVN or large osteochondral lesion

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