ANKLE ARTHRITIS
Post-traumatic Predominance | Arthrodesis vs TAR | Functional Outcomes | Adjacent Joint Disease
TREATMENT OPTIONS
Critical Must-Knows
- Post-traumatic is the commonest cause (70%) - unlike hip/knee (primary OA)
- Ankle arthrodesis remains gold standard with 90% union and satisfaction
- TAR for lower demand, good alignment, adequate bone stock, intact deltoid
- Adjacent joint arthritis affects 24% at 22 years post-fusion
- Neutral alignment critical for both fusion and replacement
Examiner's Pearls
- "Most ankle OA is post-traumatic (fractures, instability, osteochondral lesions)
- "Ankle tolerates less cartilage loss than hip/knee before symptoms
- "TAR contraindicated with significant varus/valgus deformity, neuropathy, AVN
- "Fusion position: neutral DF, 5 degrees valgus, 5-10 degrees ER, slight posterior translation
Clinical Imaging
Imaging Gallery
Critical Ankle Arthritis Exam Points
Post-traumatic Predominance
70% of ankle OA is post-traumatic - this differs from hip and knee where primary OA predominates. Causes include malunited fractures, recurrent instability, and osteochondral lesions. Always take a detailed trauma history.
Fusion vs Replacement
Arthrodesis is the gold standard with reliable outcomes. TAR for lower-demand patients with good alignment, adequate bone stock, and intact deltoid. Contraindications to TAR: severe deformity, AVN, neuropathy, young high-demand patients.
Fusion Position
Optimal fusion position: neutral dorsiflexion, 5 degrees hindfoot valgus, 5-10 degrees external rotation, slight posterior translation of talus. Malposition causes significant functional impairment.
Adjacent Joint Disease
24% develop adjacent joint arthritis at 22 years post-fusion. Subtalar and talonavicular joints most commonly affected. This drives interest in motion-preserving TAR but patient selection is critical.
Ankle Arthritis Management At a Glance
| Treatment | Indications | Advantages | Disadvantages |
|---|---|---|---|
| Conservative | Early disease, low demand, comorbidities | Non-invasive, reversible | Limited long-term efficacy |
| Arthrodesis | Gold standard, most patients | Reliable pain relief, 90% union | Loss of motion, adjacent joint disease |
| TAR | Lower demand, good alignment, adequate bone | Motion preservation, gait improvement | Higher revision rate, strict selection |
| Supramalleolar osteotomy | Malalignment with early arthritis | Joint preservation, corrects deformity | Limited to appropriate deformity patterns |
| Distraction arthroplasty | Young patients, limited disease | Joint preservation | Limited evidence, prolonged treatment |
ANKLE - Causes of Ankle Arthritis
Memory Hook:ANKLE arthritis is mostly post-traumatic unlike hip/knee
FUSION - Optimal Position
Memory Hook:FUSION position must be perfect for good outcomes - neutral DF, slight valgus, ER
TAR - Contraindications
Memory Hook:TAR has strict contraindications - AVN, severe deformity, neuropathy are absolute
INFECTION After Ankle Surgery
Memory Hook:INFECTION management is systematic - identify organism and treat appropriately
Overview and Epidemiology
Ankle arthritis is less common than hip or knee arthritis but causes significant disability. Importantly, the etiology differs fundamentally from other large joints.
Etiology distribution:
- Post-traumatic: 70% (fractures, instability, osteochondral lesions)
- Primary osteoarthritis: 7-12%
- Inflammatory arthritis: 12% (RA, seronegative)
- Other: Hemophilia, osteonecrosis, Charcot, post-infectious
Key epidemiological features:
- Overall prevalence approximately 1% of population
- Post-traumatic OA develops 10-20 years after initial injury
- Tibial plafond fractures have highest rate of post-traumatic arthritis
- Ankle OA is more disabling than hip or knee OA in quality of life studies
Why Post-traumatic Predominates
The ankle joint has the thinnest articular cartilage of major weight-bearing joints (1-1.5mm vs 3-4mm in knee). This makes it vulnerable to damage from fracture incongruity but also means it normally distributes load efficiently. Post-traumatic changes from malunion or instability rapidly lead to OA.
Natural history without treatment:
- Progressive joint space narrowing
- Osteophyte formation limiting motion
- Increasing pain and functional limitation
- Deformity development (usually varus)
- Gait abnormalities and proximal compensation
Anatomy and Biomechanics
The ankle (tibiotalar) joint is a highly constrained mortise joint with minimal inherent stability from soft tissues alone.
Bony anatomy:
- Tibial plafond: Concave articular surface
- Medial malleolus: Medial buttress
- Fibula/lateral malleolus: Lateral buttress, 1cm more distal than medial
- Talus: Wider anteriorly (trapezoidal), provides stability in dorsiflexion
Ligamentous stability:
- Deltoid (medial): Primary restraint to valgus; deep and superficial components
- Lateral complex: ATFL, CFL, PTFL - resist varus
- Syndesmosis: AITFL, PITFL, interosseous ligament - maintain mortise width
Deltoid Integrity for TAR
An intact deltoid ligament is essential for TAR success. Preoperative valgus deformity with deltoid insufficiency is a relative contraindication to TAR as the implant will fail to balance properly.
Biomechanics:
- Range of motion: Primarily dorsiflexion (20 degrees) and plantarflexion (50 degrees)
- Force transmission: 5x body weight during running
- Contact area: Small (approximately 350mm²) but high congruency
- Axis of rotation: Oblique through tips of malleoli
Adjacent joint relationship:
- Subtalar joint: 25-30 degrees of motion, compensates for ankle fusion
- Talonavicular joint: Allows additional accommodation
- Hindfoot complex function interdependent
Why ankle tolerates fusion:
- Subtalar joint provides significant compensatory motion
- Talonavicular accommodates rotation
- Gait adaptations possible with proper fusion position
Classification Systems
Radiographic Grading
| Grade | Radiographic Features | Clinical Correlation |
|---|---|---|
| Grade 0 | No features of OA | Asymptomatic |
| Grade 1 | Doubtful narrowing, possible osteophytes | Minimal symptoms |
| Grade 2 | Definite osteophytes, possible narrowing | Moderate symptoms |
| Grade 3 | Moderate osteophytes, definite narrowing, some sclerosis | Significant symptoms |
| Grade 4 | Large osteophytes, marked narrowing, severe sclerosis, deformity | End-stage disease |
Originally designed for knee OA but commonly applied to ankle.
Clinical Assessment
History:
- Pain location (anterior, medial, lateral)
- Relationship to activity and weight bearing
- Morning stiffness duration
- Previous trauma (fractures, sprains, instability)
- Previous surgery
- Functional limitations (walking distance, stairs, uneven ground)
- Night pain (suggests more advanced disease)
- Response to conservative treatment
Examination:
Clinical Examination Findings
| Finding | Significance | Implications |
|---|---|---|
| Range of motion | Reduced DF/PF, crepitus | Severity indicator |
| Alignment | Varus/valgus tilt | Affects surgical planning |
| Instability | Anterior drawer, talar tilt | May need ligament reconstruction |
| Tenderness | Location guides differential | Anterior = impingement, medial/lateral = gutter OA |
| Gait | Antalgic, compensatory patterns | Functional assessment |
| Adjacent joints | Subtalar, talonavicular motion | Fusion compensates, TAR requires |
Adjacent Joint Assessment
Adequate subtalar and talonavicular motion is essential for good outcomes after ankle fusion. If these joints are already arthritic or fused, ankle fusion will cause significant stiffness. This may favor TAR if other factors permit.
Provocative tests:
- Anterior impingement test (pain with forced dorsiflexion)
- Compression/rotation test (pain with axial load and rotation)
- Silfverskiold test (gastrocnemius contracture assessment)
Vascular assessment:
- Dorsalis pedis and posterior tibial pulses
- Capillary refill
- Consider ABI if concerns (diabetics, smokers)
Investigations
Weight-bearing views essential
Standard views:
- Weight-bearing AP ankle
- Weight-bearing lateral ankle
- Mortise view
- Hindfoot alignment view if deformity
Key features to assess:
- Joint space narrowing pattern
- Osteophyte location and size
- Subchondral sclerosis and cysts
- Deformity (varus/valgus tilt)
- Adjacent joint involvement
Stress views:
- Anterior drawer (ATFL integrity)
- Talar tilt (CFL integrity)
- Consider if instability suspected
Weight-bearing views are critical as they reveal functional joint space and alignment.
Management Algorithm
First-line management
Activity modification:
- Low-impact activities
- Weight loss if overweight
- Avoid aggravating activities
Medications:
- NSAIDs (oral or topical)
- Acetaminophen
- Consider PPI protection long-term
Bracing:
- Ankle-foot orthosis (AFO)
- Rocker-bottom shoes
- Custom orthotics
Injections:
- Corticosteroid (2-3 per year maximum)
- Hyaluronic acid (limited evidence)
- PRP (experimental)
Physical therapy:
- Strengthening periarticular muscles
- Range of motion maintenance
- Gait training
Conservative measures may delay surgery but rarely prevent eventual progression in symptomatic patients.
Surgical Technique
Anterior or lateral approach
Positioning:
- Supine with bump under ipsilateral hip
- Tourniquet at thigh
Ankle Fusion Steps
Anterior approach between tibialis anterior and EHL, or lateral transfibular approach. Protect superficial peroneal nerve.
Remove all articular cartilage from tibial plafond and talar dome. Use curettes, osteotomes, or burr. Fenestrate subchondral bone. Preserve overall contour for stability.
Position foot: neutral DF, 5 degrees valgus, 5-10 degrees ER, slight posterior translation. Compare to opposite side. Check alignment with fluoroscopy.
Multiple options: crossed screws (2-3 large fragment), anterior plate, IM nail. Compress fusion site. Confirm alignment on final fluoroscopy.
Layered closure. Posterior splint in neutral position. Non-weight bearing initially.
Crossed screws technique: 6.5-7.3mm cannulated screws, typically 2 from anterior tibia into talus and 1 from medial malleolus into talus.
Complications
Ankle arthrodesis
Early:
- Wound complications (5-10%)
- Infection (2-5%)
- DVT/PE
- Nerve injury (superficial peroneal)
Delayed:
- Nonunion (5-10%)
- Malunion (position errors)
- Hardware prominence/irritation
Late:
- Adjacent joint arthritis (24% at 22 years)
- Persistent pain (10%)
- Stress fractures
Risk factors for nonunion:
- Smoking (most significant)
- Diabetes
- AVN of talus
- Previous infection
- Technical errors
Smoking cessation is mandatory before fusion surgery.
Postoperative Care
Rehabilitation Phases
Non-weight bearing, posterior splint. Elevation. Wound check at 2 weeks.
Non-weight bearing, short leg cast. Continue elevation. Serial X-rays.
Protective weight bearing in CAM boot if union progressing. PT for adjacent joint ROM.
Wean boot. Rocker-bottom shoes. Gait training.
Union assessment with CT if radiographic healing uncertain. May require bone stimulation if delayed.
Outcomes and Prognosis
Treatment Outcomes Comparison
| Treatment | Pain Relief | Function | Survivorship/Union |
|---|---|---|---|
| Ankle Arthrodesis | 85-90% good/excellent | Stiff but functional | 90% union rate |
| Total Ankle Replacement | 80-85% good/excellent | Better ROM and gait | 80-90% at 10 years |
| Supramalleolar Osteotomy | Variable | Joint preservation | May delay arthroplasty/fusion |
Arthrodesis outcomes:
- 85-90% patient satisfaction
- Reliable pain relief
- Return to work and recreational activities
- Some difficulty on uneven ground
- Shoe wear modifications may be needed
TAR outcomes:
- 80-85% satisfaction
- Better gait kinematics than fusion
- Preserved ankle ROM (10-15 degrees)
- Higher revision rate than fusion
- Careful patient selection critical
Comparison studies:
- Similar pain relief and function scores
- TAR has improved gait parameters
- TAR has higher complication/revision rate
- Fusion more appropriate for young, active patients
- TAR preferred for older, lower-demand patients
The choice between fusion and TAR depends on patient factors and surgeon experience.
Evidence Base
Fusion vs TAR Outcomes
- Similar patient satisfaction rates
- TAR: improved gait kinematics
- Fusion: lower revision rate
- TAR: higher complication rate
Adjacent Joint Arthritis After Fusion
- 24% symptomatic adjacent OA at 22 years
- Subtalar most commonly affected
- Talonavicular second most common
- Risk increases with time
TAR Survivorship
- 80-90% 10-year survivorship
- Improvement with modern designs
- Patient selection affects outcomes
- Revision to fusion remains salvage option
Post-traumatic OA Predominance
- 70% post-traumatic etiology
- Primary OA only 7-12%
- Malunited fractures major cause
- Instability contributes significantly
Optimal Fusion Position
- Neutral DF essential
- Slight valgus preferred to varus
- External rotation matches gait
- Malposition causes dysfunction
Exam Viva Scenarios
Practice these scenarios to excel in your viva examination
Scenario 1: Treatment Choice
"A 58-year-old woman presents with end-stage ankle arthritis following an ankle fracture 20 years ago. She has 15 degrees of varus deformity. She works as a receptionist and wants to return to walking for exercise. What are her surgical options?"
Scenario 2: TAR Candidate
"A 65-year-old retired man presents with ankle arthritis and neutral alignment. His subtalar joint has good motion. He is a non-smoker with well-controlled diabetes. He wants to maintain ankle motion for recreational golf. Would you consider TAR?"
Scenario 3: Fusion Nonunion
"A patient returns 4 months after ankle fusion with persistent pain. X-rays show incomplete union at the fusion site. He is a smoker. How would you manage this?"
MCQ Practice Points
Key facts for MCQs:
- Post-traumatic etiology: 70% (most common)
- Primary OA: only 7-12%
- Fusion union rate: 90%
- TAR 10-year survivorship: 80-90%
- Adjacent joint arthritis after fusion: 24% at 22 years
- Fusion position: neutral DF, 5 degrees valgus, 5-10 degrees ER
Common MCQ topics:
- Etiology of ankle OA (post-traumatic predominance)
- Fusion vs TAR indications
- Optimal fusion position
- TAR contraindications
- Complications (nonunion risk factors)
- Adjacent joint arthritis incidence
- Post-traumatic OA pathophysiology
Differential diagnosis points:
- Subtalar arthritis (hindfoot pain, different motion loss)
- Ankle instability (positive drawer, talar tilt)
- Osteochondral lesion (may be early cause)
- Inflammatory arthritis (symmetrical, systemic features)
Ankle OA Etiology
Q: What is the most common etiology of ankle osteoarthritis? A: Post-traumatic (70%) - unlike the hip and knee where primary OA predominates. Only 7-12% of ankle OA is primary/idiopathic.
Fusion Position
Q: What is the optimal fusion position for ankle arthrodesis? A: Neutral dorsiflexion, 5 degrees valgus, 5-10 degrees external rotation, and slight posterior translation of the talus.
TAR Survivorship
Q: What is the 10-year implant survivorship for modern total ankle replacement? A: 80-90% with modern 3rd generation designs.
TAR Contraindications
Q: What deformity threshold is a relative contraindication for TAR? A: Greater than 15-20 degrees varus or valgus deformity, as it affects implant longevity and function.
Adjacent Joint Arthritis
Q: What is the incidence of symptomatic adjacent joint arthritis after ankle fusion? A: 24% at 22 years. The subtalar joint is most commonly affected.
Australian Context
Ankle arthritis management in Australia follows international evidence-based guidelines with high-quality outcomes for both fusion and TAR. The Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR) tracks TAR outcomes, providing valuable data on implant performance in the Australian population.
Both ankle fusion and TAR are performed in public hospital systems and private practice settings. Wait times for elective surgery vary by state and region. Specialist foot and ankle surgeons typically perform these procedures in metropolitan teaching hospitals.
Smoking cessation support is available through general practice and Quitline services, and should be strongly encouraged given the significant impact on fusion outcomes. Multidisciplinary care including physiotherapy and orthotics is accessible through public and private systems.
Exam Cheat Sheet
Ankle Arthritis
High-Yield Exam Summary
Key Numbers
- •Post-traumatic: 70% of cases
- •Fusion union rate: 90%
- •TAR 10-year survival: 80-90%
- •Adjacent joint OA: 24% at 22 years
Fusion Position (Critical)
- •Neutral dorsiflexion
- •5 degrees hindfoot valgus
- •5-10 degrees external rotation
- •Slight posterior translation
TAR Contraindications
- •Severe deformity greater than 15-20 degrees
- •Talar AVN
- •Peripheral neuropathy
- •Young, high-demand patients
TAR Ideal Candidate
- •Age greater than 55 years
- •Lower demand activity
- •Neutral alignment
- •Intact deltoid ligament
Exam Traps
- •Recommending TAR for severe varus
- •Wrong fusion position
- •Not knowing post-traumatic predominance
- •Operating on active smoker
References
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