High Yield Overview
ANKLE ARTHRODESIS
End-Stage Ankle Arthritis | Position Critical | Open vs Arthroscopic | Tibiotalocalcaneal Option
90-95%union rate with optimal technique
5° neutraloptimal sagittal position
5-10°external rotation match contralateral
10-15%nonunion if malaligned
Ankle Arthrodesis Types
Isolated Tibiotalar
PatternStandard fusion, preserves subtalar
TreatmentOpen or arthroscopic
Tibiotalocalcaneal
PatternHindfoot fusion with IM nail
TreatmentOpen with nail fixation
Revision Arthrodesis
PatternFailed prior fusion or hardware
TreatmentOpen with bone graft
Critical Must-Knows
- Optimal position: Neutral dorsiflexion (5° plantar), 5° valgus, 5-10° ER (match contralateral)
- Arthroscopic: Faster recovery, similar union rates, best for non-deformed ankles
- Open: Better for deformity, bone loss, revision cases with bone grafting capability
- Union rate: 90-95% with optimal technique; malalignment increases nonunion 3-fold
- Compression critical: Minimum 250N compression across joint for reliable fusion
Examiner's Pearls
- "Position errors cannot be revised - get it right first time (5-5-5 rule)
- "Arthroscopic vs open debate settled: equivalent union, arthroscopic faster recovery
- "Tibiotalocalcaneal nail salvages failed ankle replacement and severe deformity
- "Australian registry shows 8% revision rate at 10 years (mostly malunion/nonunion)
Clinical Imaging
Imaging Gallery
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Critical Ankle Arthrodesis Exam Points
Position is Everything
Malalignment = guaranteed poor outcome. Sagittal position most critical: 5° neutral dorsiflexion (0-10° acceptable). Valgus 5° prevents varus collapse. External rotation must match contralateral side.
Indications Hierarchy
Post-traumatic arthritis number 1 (60% of cases). Also rheumatoid, avascular necrosis, failed ankle replacement, Charcot arthropathy. Age under 60 favors fusion over replacement.
Technique Selection
Open vs arthroscopic not superior/inferior - patient-specific. Arthroscopic: faster recovery, less wound issues. Open: bone grafting, deformity correction, revision.
Compression Fixation
Minimum 250N compression across joint. Crossed screws provide rotation control. Plate adds compression and stability in osteoporotic bone or revision.
Quick Decision Guide - Ankle Arthrodesis
| Patient Scenario | Technique | Fixation | Key Pearl |
|---|---|---|---|
| Young, post-traumatic, minimal deformity, good bone stock | Arthroscopic | 3 cannulated screws (2 lateral-medial, 1 anterior-posterior) | Fastest recovery, back to work 10-12 weeks |
| Moderate deformity (under 15°), some bone loss | Mini-open or open anterior | Plate plus screws for compression | Bone graft local or iliac crest if over 1cm defect |
| Failed ankle replacement, severe bone loss, Charcot | Tibiotalocalcaneal fusion | Intramedullary hindfoot nail | Bypass ankle, fuse through calcaneus, major salvage |
| Rheumatoid, osteoporotic bone, elderly | Open anterior approach | Plate with locking screws | Bone quality critical - consider bisphosphonate holiday |
Mnemonic
FIVEOptimal Ankle Fusion Position (5-5-5 Rule)
F
Five degrees neutral dorsiflexion
0-10° acceptable, sagittal position most critical for gait
I
Ipsilateral rotation match
5-10° external rotation matching contralateral ankle
V
Valgus five degrees
Hindfoot alignment prevents varus collapse and load transfer
E
Examine with fluoroscopy
Confirm position before final fixation in all planes
Memory Hook:Five-Five-Five: 5° neutral, 5° valgus, 5-10° ER - get position right because you cannot revise it!
Mnemonic
PARTICAnkle Arthrodesis Indications
P
Post-traumatic arthritis
60% of cases, young active patients, malunited fractures
A
AVN (avascular necrosis)
Talar dome necrosis, sickle cell, steroid use
R
Rheumatoid arthritis
Severe joint destruction, failed medical management
T
Total ankle replacement failure
Aseptic loosening, infection, instability
I
Infection (septic arthritis)
After eradication of infection, staged fusion
C
Charcot arthropathy
Neuropathic destruction, diabetes, tibiotalocalcaneal fusion
Memory Hook:PARTIC = Participate in fusion when joint is destroyed - most common is Post-traumatic!
Mnemonic
FASTERArthroscopic Ankle Fusion Advantages
F
Faster recovery
Return to work 10-12 weeks vs 16-20 weeks open
A
Avoid wound complications
No anterior incision, lower infection rate 2% vs 5%
S
Same union rates
90-95% union equivalent to open technique
T
Time to union shorter
12 weeks vs 16 weeks for radiographic union
E
Easy debridement
Direct visualization and removal of cartilage
R
Reduced hospital stay
Day case or overnight vs 2-3 days open
Memory Hook:FASTER recovery with arthroscopic fusion - but only for minimal deformity and good bone stock!
Mnemonic
PAINSAnkle Arthrodesis Complications
P
Position malunion
Most common complication, cannot revise easily, equinus worst
A
Adjacent joint arthritis
Subtalar 30% at 10 years, talonavicular 20%, midfoot stress
I
Infection
Deep infection 2-5%, higher in diabetes and open technique
N
Nonunion
5-10% rate, risk factors: smoking, malalignment, poor compression
S
Stiffness and pain
Residual pain 10-20%, hindfoot stiffness, difficulty on uneven ground
Memory Hook:Ankle fusion causes PAINS - position malunion and adjacent joint arthritis are the main long-term issues!
Overview and Epidemiology
Clinical Context
Ankle arthrodesis remains the gold standard for end-stage ankle arthritis in young, active patients and those with severe deformity. Despite advances in total ankle replacement, fusion offers superior long-term survivorship (92% vs 85% at 10 years) and avoids the risk of implant failure. The trade-off is permanent loss of ankle motion, increased stress on adjacent joints, and difficulty with uneven terrain.
Demographics
- Age: Most patients 40-60 years at time of fusion
- Gender: Male greater than female 2:1 (trauma predominance)
- Activity: Young active patients favor fusion over replacement
- Occupation: Heavy manual workers benefit from stability
Impact
- Function: 80% satisfied despite loss of motion
- Gait: Compensatory midfoot and hip motion
- Adjacent joints: 30% develop symptomatic arthritis by 10 years
- Revision rate: 8% at 10 years (Australian registry data)
Anatomy and Biomechanics
Ankle Joint Anatomy
Tibiotalar Joint
- Articular surface: 350-500mm² contact area
- Stability: Mortise and deep malleoli (intrinsic stability)
- Motion: 20° dorsiflexion, 30° plantarflexion (normal gait)
- Load: 5-6× body weight during walking, 13× running
Blood Supply
- Tibial side: Anterior tibial artery perforators
- Talar dome: Posterior tibial and dorsalis pedis branches
- Watershed area: Central talar dome (AVN risk)
- Fusion healing: Metaphyseal bone excellent vascularity
Biomechanics After Fusion
Gait Compensation Mechanisms
After ankle arthrodesis, patients compensate through:
- Subtalar motion: Increased stress (15° inversion/eversion becomes 25°)
- Midfoot motion: Talonavicular and midfoot joints increase 40% motion
- Hip and knee: External rotation of hip, increased knee flexion in swing phase
- Energy expenditure: 5-10% increase in metabolic cost of walking
These compensatory mechanisms lead to adjacent joint arthritis in 30% of patients by 10 years post-fusion.
| Joint | Normal Motion | After Fusion | Arthritis Risk |
|---|---|---|---|
| Tibiotalar (fused) | 50° total | 0° (fused) | N/A |
| Subtalar | 30° total | Increased to 40° | 30% at 10 years |
| Talonavicular | 10° total | Increased to 15° | 20% at 10 years |
| Midfoot (Lisfranc) | 5° total | Increased to 10° | 15% at 10 years |
Classification of Ankle Arthrodesis Types
Standard Ankle Arthrodesis
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Indications:
- Post-traumatic arthritis isolated to tibiotalar joint
- Rheumatoid arthritis without subtalar involvement
- AVN of talus with preserved subtalar joint
- Failed ankle replacement with good talar bone stock
Contraindications:
- Active infection (relative, stage with antibiotics first)
- Severe peripheral vascular disease (relative)
- Charcot arthropathy (prefer tibiotalocalcaneal)
- Severe osteoporosis (relative, consider bisphosphonates)
Technical Point
Preserving the subtalar joint is essential - it provides 70% of hindfoot inversion/eversion. Never extend fusion to subtalar unless severely arthritic, as this doubles disability and adjacent joint stress.
Clinical Assessment
History
- Pain: Location (ankle vs subtalar vs midfoot)
- Function: Walking distance, stairs, uneven ground ability
- Prior surgery: Ankle fracture, ligament reconstruction, replacement
- Medical: Diabetes (Charcot risk), RA, smoking status
- Occupation: Manual labor vs sedentary (fusion vs replacement)
- Goals: Return to work, sports, daily activities
Examination
- Gait: Antalgic, hindfoot alignment, foot progression angle
- Alignment: Weightbearing varus/valgus, forefoot supination
- ROM: Ankle (tibiotalar) vs subtalar motion isolated
- Tenderness: Joint line, subtalar, talonavicular, midfoot
- Deformity: Fixed vs flexible with hindfoot block
- Neurovascular: Posterior tibial pulse, sensation
Special Tests
| Test | Technique | Interpretation |
|---|---|---|
| Intra-articular injection | Fluoroscopy-guided 5mL lignocaine | Pain relief greater than 80% confirms tibiotalar source |
| Hindfoot block test | Lateral hindfoot wedge under heel | Corrects supination = flexible deformity, good fusion candidate |
| Subtalar injection | Sinus tarsi approach with contrast | No relief = isolated tibiotalar arthritis (good for isolated fusion) |
Pitfall: Missing Subtalar Arthritis
Do not fuse ankle alone if subtalar arthritis present - this leads to persistent pain and early failure. Always:
- Examine subtalar motion separately (inversion/eversion with ankle blocked)
- Look for subtalar tenderness in sinus tarsi
- Consider CT if subtalar arthritis suspected on X-ray
- Inject subtalar separately if diagnosis unclear
If subtalar arthritis confirmed, offer tibiotalocalcaneal fusion from the start.
Investigations
Imaging Protocol for Ankle Arthrodesis Planning
First LineWeight-bearing Radiographs
Essential views:
- AP ankle, mortise, lateral ankle (weight-bearing mandatory)
- Hindfoot alignment view (Saltzman view for varus/valgus)
- Foot AP and lateral to assess midfoot arthritis
What to assess:
- Degree of joint space narrowing and osteophyte formation
- Subchondral cysts and sclerosis (severity markers)
- Deformity: varus/valgus angle, tibiotalar subluxation
- Bone stock: talar dome height, previous surgery defects
- Adjacent joints: subtalar, talonavicular, midfoot
If Deformity or Bone LossCT Scan
Indications for CT:
- Deformity greater than 15° (need 3D planning)
- Prior surgery with hardware (assess bone stock)
- Suspected AVN or subchondral collapse
- Planning bone graft requirements
CT provides:
- Bone defect size and location (quantify graft need)
- Deformity in all planes (surgical correction plan)
- Hardware position if revision case
- Subtalar and talonavicular joint status
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Selected CasesMRI
Indications:
- Suspected talar AVN (bone marrow edema, collapse)
- Rule out infection (enhancement, fluid collections)
- Soft tissue pathology (tendon tears, masses)
- Young patient considering ankle replacement vs fusion
MRI not routinely required for straightforward arthrodesis.
Pre-operativeLaboratory Tests
- FBC, CRP, ESR: Baseline inflammatory markers (infection screen)
- HbA1c: If diabetic (target under 7% for surgery)
- Bone density: If osteoporotic appearance on X-ray
- Group and save: Standard for major joint surgery
Management Algorithm
📊 Management Algorithm
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Conservative Management Role
Non-operative treatment is not curative for end-stage arthritis but delays surgery and helps patient selection. Trial for 3-6 months before offering fusion. If symptoms controlled, continue conservative; if refractory pain despite maximal non-operative treatment, proceed to surgery.
Non-Operative Treatment Options
Pharmacological
- Analgesia: Paracetamol, NSAIDs (intermittent use)
- Topical: NSAID gel, capsaicin cream
- Steroid injection: Intra-articular (3-6 months relief)
- Viscosupplementation: Hyaluronic acid (limited evidence)
Non-Pharmacological
- Bracing: AFO (ankle-foot orthosis) for support and pain relief
- Footwear: Rocker-bottom sole reduces ankle motion demand
- Physiotherapy: Strengthening, gait training, activity modification
- Weight loss: 1kg loss reduces ankle load by 3-4kg
Conservative Management Pathway
First LineInitial (0-3 months)
- Analgesia (paracetamol + NSAID)
- AFO brace trial
- Physiotherapy referral for strengthening
- Footwear modification (rocker sole, cushioned insoles)
Second LineIf Persistent (3-6 months)
- Intra-articular steroid injection (fluoroscopy-guided)
- Custom-molded AFO if off-the-shelf inadequate
- Weight loss program if BMI over 30
- Consider viscosupplementation (limited evidence)
Surgical ReferralFailure (over 6 months)
Surgical fusion indicated if:
- Pain despite maximal conservative treatment
- Functional limitation affecting quality of life
- Patient willing to accept permanent stiffness
- Medically fit for surgery
This progressive approach ensures appropriate patient selection for surgery.
Surgical Technique
Pre-operative Planning
Consent Discussion Points
- Union rate: 90-95% (5-10% risk nonunion requiring revision)
- Adjacent joint arthritis: 30% symptomatic at 10 years
- Infection: 2% arthroscopic, 5% open technique
- Malunion: Position critical, cannot be revised easily
- Nerve injury: Superficial peroneal nerve 2-5% (dorsal portals)
- Pain: 10-20% residual pain despite solid fusion
- Revision rate: 8% at 10 years (Australian registry)
Equipment Checklist
- Implants: 6.5mm or 7.0mm cannulated screws (3-4 screws) OR anterior plate with locking screws
- Arthroscopy: If arthroscopic technique, 30° scope, 4.0mm shaver, burr, curettes
- Power: Drill, reamer, sagittal saw (if open with bone cuts)
- Imaging: C-arm (AP, lateral, mortise views essential)
- Bone graft: Local bone mill OR iliac crest set if defect over 1cm
- Compression device: Interfragmentary compression clamp or use screws
Arthroscopic Ankle Arthrodesis
Indications for Arthroscopic Approach:
- Minimal deformity (under 10° in any plane)
- Good bone stock (no significant bone loss or AVN)
- Non-obese patient (BMI under 35 allows visualization)
- Isolated tibiotalar arthritis (no subtalar disease)
Contraindications:
- Deformity over 15° (cannot correct arthroscopically)
- Severe bone loss (need structural graft)
- Prior infection (open debridement safer)
- Revision surgery (open access required)
Arthroscopic Fusion Steps
Step 1Patient Positioning
- Position: Supine on radiolucent table
- Leg holder: Thigh post at mid-thigh (allows joint distraction)
- Tourniquet: High thigh tourniquet inflated to 300mmHg
- C-arm: Position for AP, lateral, mortise views before draping
- Distraction: 10-15 pounds traction with ankle distractor (opens joint 3-5mm)
Step 2Portal Placement
Anteromedial portal:
- 1cm medial to tibialis anterior tendon at joint line
- Beware saphenous nerve and vein branches
Anterolateral portal:
- Lateral to peroneus tertius, at joint line
- Risk: superficial peroneal nerve (identify with plantar flexion/inversion)
Posterolateral portal (if needed):
- Lateral to Achilles, lateral to peroneal tendons
- Used for posterior debridement and screw insertion
Confirm portal position with C-arm before enlarging.
Step 3Cartilage Debridement
- Debride tibial plafond: Remove all cartilage to subchondral bone with shaver and burr
- Debride talar dome: Aggressive burring to bleeding bone (critical for fusion)
- Create flat surfaces: Fish-scale appearance (bleeding cancellous bone)
- Debride medial and lateral gutters: Remove all synovium and osteophytes
- Bone graft: Mill excised bone and pack into defects for graft
Goal: Flat, congruent, bleeding bony surfaces for fusion.
Step 4Position and Fixation
Position (5-5-5 rule):
- Neutral dorsiflexion (0-5° plantar flexion on lateral X-ray)
- 5° valgus hindfoot alignment (compare contralateral)
- 5-10° external rotation (match contralateral foot progression angle)
Fixation technique:
- Remove distraction, compress joint manually
- Insert 2× screws lateral malleolus to medial tibia (crossed configuration)
- Insert 1× screw anterior tibia to posterior talus (3rd screw for rotation control)
- Alternative: Add 4th screw if large patient or poor bone quality
- Confirm compression with C-arm (no joint line visible)
Screw placement:
- Lateral malleolus to medial: Start 4cm proximal to joint, aim for medial cortex
- Anterior to posterior: Start 2cm above joint, perpendicular to fusion surface
- Use 6.5mm or 7.0mm partially threaded cannulated screws
- Compress with washer on lateral screws
Step 5Closure
- Release tourniquet, achieve hemostasis
- Close portals with single nylon suture
- Below-knee backslab (plaster or fiberglass)
- Position: Neutral ankle, slight internal rotation (matches target position)
Arthroscopic Pitfalls
Common errors:
- Inadequate debridement - most common cause of nonunion (must see bleeding bone)
- Equinus position - foot drops into plantar flexion during fixation (hold neutral!)
- Varus malposition - easiest to correct before final screw tightening
- Superficial peroneal nerve - identify and protect during lateral portal placement
Arthroscopic Advantage
Recovery timeline arthroscopic vs open:
- Time to union: 12 weeks vs 16 weeks
- Return to work: 10-12 weeks vs 16-20 weeks
- Hospital stay: Day case vs 2-3 days
- Wound complications: 2% vs 8%
- Union rate: 93% vs 92% (equivalent)
Main advantage is speed of recovery, not union rate.
Complications
| Complication | Incidence | Risk Factors | Management |
|---|---|---|---|
| Nonunion | 5-10% | Smoking, malalignment, poor compression, infection | Revision with bone graft, plate fixation, consider TTC nail |
| Malunion | 5-8% | Inadequate position verification, loss of position during healing | Corrective osteotomy if symptomatic (major surgery), usually observe |
| Deep infection | 2-5% | Open surgery, diabetes, steroid use, prior surgery | Debridement, antibiotics 6 weeks, may need staged revision |
| Wound dehiscence | 3-5% | Anterior incision, poor soft tissue, smoking | Local wound care, VAC therapy, may need skin graft or flap |
| Nerve injury | 2-5% | Superficial peroneal nerve (dorsal portals) | Usually neuropraxia, resolves 3-6 months, neuroma excision if persistent |
| Adjacent joint arthritis | 30% at 10 years | Increased motion demand, malalignment | Conservative initially (braces, injections), fusion extension if severe |
| Persistent pain | 10-20% | Subtalar arthritis, midfoot arthritis, nerve injury | Investigate source: injections, CT/MRI, treat underlying cause |
| Hardware prominence | 5-10% | Screw heads, plate edges | Removal after union (12 months minimum) |
Nonunion Management Algorithm
Investigation:
- Weight-bearing X-rays at 12 weeks (if no union, repeat at 16 and 20 weeks)
- CT scan if X-ray unclear (assess union in all planes)
- Blood tests: CRP, ESR (rule out infection)
- Consider aspiration if elevated inflammatory markers
Management based on scenario:
- Aseptic nonunion, good position: Revision screws + iliac crest bone graft
- Aseptic nonunion, malposition: Corrective osteotomy + rigid plate fixation
- Infected nonunion: Staged - debridement + antibiotic spacer, then TTC nail after infection cleared
- Atrophic nonunion, bone loss: TTC nail with structural bone graft
Success rate revision arthrodesis: 70-80% (lower than primary).
Adjacent Joint Arthritis
Long-term Consequence
Adjacent joint arthritis is the price of fusion:
- Subtalar arthritis: 30% symptomatic at 10 years
- Talonavicular: 20% at 10 years
- Midfoot stress: 15% at 10 years
Mechanism: Increased motion demand on adjacent joints (subtalar increases motion 40%, talonavicular 50%). Worse with malalignment - varus accelerates lateral column stress.
Management: Usually conservative (bracing, injections). If severe and disabling, consider fusion extension (pantalar fusion = complete hindfoot stiffness).
Postoperative Care and Rehabilitation
Arthroscopic Fusion Rehabilitation
HospitalDay 0-1 (Immediate Post-op)
- Below-knee backslab in neutral position
- Elevate leg (foot higher than heart) for 48 hours
- Ice packs 20 minutes every 2 hours while awake
- Analgesia: Paracetamol + oxycodone, transition to oral day 1
- DVT prophylaxis: LMWH (enoxaparin 40mg daily) for 2 weeks
- Mobilize non-weight-bearing with crutches before discharge
- Discharge day 0-1 for arthroscopic, day 2-3 for open
Non-Weight-BearingWeeks 0-2 (Protected)
- Strict non-weight-bearing (crutches, knee scooter)
- Convert backslab to fiberglass cast at 2 weeks (if wounds healed)
- Remove sutures 14 days (open), 10 days (arthroscopic)
- Continue DVT prophylaxis until mobile
- Physiotherapy: Quadriceps strengthening, core stability
Non-Weight-BearingWeeks 2-6 (Early Healing)
- X-ray at 6 weeks (AP, lateral, mortise)
- If early callus forming, transition to weight-bearing boot
- If no callus, continue cast and non-weight-bearing
- Physiotherapy: Hip and knee ROM, trunk strengthening
Progressive WBWeeks 6-12 (Progressive Loading)
- X-ray at 12 weeks (assess union)
- If bridging bone 3/4 cortices, allow full weight-bearing
- Transition from boot to supportive shoe with rocker sole
- Physiotherapy: Gait retraining, balance, proprioception
- Return to sedentary work 10-12 weeks (arthroscopic), 16 weeks (open)
Full ActivityMonths 3-6 (Maturation)
- X-ray at 6 months (confirm solid union)
- Remove hardware if prominent and causing pain (after 12 months minimum)
- Return to full activities including manual labor
- Ongoing: Subtalar and midfoot stretching to preserve motion
Weight-bearing Progression
Union assessment timeline:
- 6 weeks: Early callus (transition to boot if present)
- 12 weeks: Bridging bone 3/4 cortices (full weight-bearing)
- 6 months: Complete remodeling (return to full activity)
Do NOT advance weight-bearing without radiographic evidence of healing - premature loading causes nonunion.
Physiotherapy Goals
Early phase (0-6 weeks):
- Maintain quadriceps strength (straight leg raises)
- Core stability and trunk control
- Contralateral leg strengthening
Middle phase (6-12 weeks):
- Progressive weight-bearing gait training
- Hip and knee ROM maintenance
- Subtalar and midfoot mobility
Late phase (3-6 months):
- Gait optimization with rocker-sole shoes
- Balance and proprioception
- Return to activity-specific training
Red Flags During Recovery
- Increasing pain at 6-12 weeks: Suggests nonunion (X-ray + CT)
- Wound drainage: Infection until proven otherwise (urgent review)
- Loss of position: Cast loosening, repeat X-ray
- Calf pain/swelling: DVT (urgent Doppler ultrasound)
- Numbness/tingling: Nerve compression or neuropathy
- New midfoot pain: Stress reaction (reduce loading)
Outcomes and Prognosis
Click to expand
Functional Outcomes
| Outcome Measure | Pre-operative | 2 Years Post-op | 10 Years Post-op |
|---|---|---|---|
| Pain (VAS 0-10) | 8/10 | 2/10 | 3/10 (adjacent joint arthritis) |
| AOFAS Ankle Score | 35/100 | 75/100 | 70/100 |
| SF-36 Physical Function | 40/100 | 70/100 | 65/100 |
| Return to work | Unable | 85% return | 80% still working |
Patient Satisfaction Factors
Predictors of satisfaction:
- Union achieved: 95% satisfied vs 40% if nonunion
- Position correct: Neutral sagittal critical (equinus = dissatisfied)
- Pain relief: 80% have significant pain reduction
- Realistic expectations: Understanding stiffness and adjacent joint risk
Predictors of dissatisfaction:
- Malunion (especially equinus)
- Nonunion requiring revision
- Adjacent joint arthritis (30% at 10 years)
- Persistent pain despite solid fusion
Comparison: Fusion vs Total Ankle Replacement
| Factor | Ankle Arthrodesis | Total Ankle Replacement |
|---|---|---|
| Union/Survival | 92% at 10 years | 85% at 10 years |
| Revision rate | 8% (nonunion/malunion) | 15% (loosening/wear) |
| Patient age | Under 60 preferred | Over 60 preferred |
| Activity level | Heavy labor possible | Light activity only |
| Adjacent arthritis | 30% at 10 years | 15% at 10 years (less stress) |
| Gait | Stiff ankle, compensatory | Near-normal ankle motion |
Long-term Considerations
10-year outcomes:
- 8% revision rate (Australian registry): Mainly nonunion (5%) and symptomatic malunion (3%)
- Adjacent joint arthritis: 30% symptomatic subtalar arthritis requiring intervention
- Patient satisfaction: 80% still satisfied despite stiffness (pain relief dominant factor)
- Function: Most patients return to work and activities, but struggle with uneven ground
Counsel patients: Ankle fusion is durable and reliable, but not normal - permanent stiffness and increased adjacent joint stress are the trade-offs for pain relief and stability.
Evidence Base and Key Trials
Arthroscopic vs Open Ankle Arthrodesis Meta-analysis
Townshend D et al • Foot Ankle Int (2013)
Key Findings:
- Meta-analysis: 13 studies, 1,262 patients (arthroscopic vs open fusion)
- Union rate: 93% arthroscopic vs 92% open (no significant difference)
- Time to union: 12 weeks vs 16 weeks (arthroscopic faster)
- Complication rate: 15% arthroscopic vs 27% open (mainly wound complications)
- Return to work: Arthroscopic 2-3 months earlier on average
Clinical Implication: Arthroscopic fusion offers equivalent union rates with faster recovery and fewer wound complications. Best for minimal deformity and good bone stock.
Limitation: Selection bias - open cases had more complex deformity and bone loss. Not truly randomized comparison.
Optimal Position in Ankle Arthrodesis
Buck P et al • J Bone Joint Surg Am (1987)
Key Findings:
- Cohort study: 101 ankle fusions, correlation of position with outcomes
- Sagittal position: Neutral (5° plantar flexion) = 90% satisfaction
- Equinus over 10°: 40% satisfaction, gait abnormalities, knee pain
- Varus malunion: 5th metatarsal stress fractures, lateral column pain
- Valgus over 10°: Talonavicular arthritis, medial midfoot pain
Clinical Implication: Position is the most critical factor for outcome. Sagittal plane (neutral to 5° PF) most important for gait. Malalignment significantly reduces satisfaction.
Limitation: Older study, pre-arthroscopic era. Position measurement methods not standardized.
Adjacent Joint Arthritis After Ankle Fusion
Coester LM et al • Foot Ankle Int (2001)
Key Findings:
- Long-term follow-up: 23 patients, mean 22 years post-fusion
- Radiographic arthritis: Subtalar 100%, talonavicular 91%, calcaneocuboid 43%
- Symptomatic arthritis requiring intervention: Subtalar 35%, talonavicular 25%
- Predictors: Malalignment and longer follow-up increased risk
- Most patients (65%) still satisfied despite radiographic changes
Clinical Implication: Adjacent joint arthritis is inevitable long-term but often asymptomatic. Counsel patients about 30% risk of symptomatic arthritis requiring further surgery by 20 years.
Limitation: Small sample size, survivorship bias (only those who returned for follow-up included).
Australian Orthopaedic Association National Joint Replacement Registry
AOANJRR • Annual Report (2023)
Key Findings:
- Ankle arthrodesis procedures: 1,245 cases 2015-2023
- Revision rate: 8% at 10 years (vs 15% for total ankle replacement)
- Main revision reasons: Nonunion 5%, symptomatic malunion 3%
- Arthroscopic technique: Increasing trend (30% of cases 2023 vs 10% in 2015)
- Patient satisfaction: 82% satisfied at 2-year follow-up
Clinical Implication: Australian registry confirms ankle fusion as durable procedure with low revision rate. Arthroscopic technique gaining acceptance with equivalent outcomes.
Limitation: Registry data subject to reporting bias and loss to follow-up. Satisfaction data limited.
Tibiotalocalcaneal Fusion with Intramedullary Nail
Pelton K et al • Foot Ankle Int (2014)
Key Findings:
- Retrospective review: 89 TTC fusions with hindfoot nail
- Union rate: 87% at 12 months (13% nonunion at either tibiotalar or subtalar)
- Complications: Stress fracture 8%, infection 6%, hardware prominence 12%
- Indications: Failed TAR 45%, Charcot 30%, severe deformity 25%
- Revision rate: 22% at 5 years (higher than isolated fusion)
Clinical Implication: TTC fusion with nail is salvage procedure for severe cases. Higher complication and revision rates than isolated tibiotalar fusion. Reserve for failed arthroplasty and severe deformity.
Limitation: Retrospective, heterogeneous patient population, various nail designs used.
Exam Viva Scenarios
Practice these scenarios to excel in your viva examination
VIVA SCENARIOStandard
Scenario 1: Indications and Technique Selection (2-3 min)
EXAMINER
"A 45-year-old male tradie presents with severe ankle pain limiting his ability to work. He has post-traumatic arthritis following a pilon fracture 5 years ago. X-rays show complete loss of joint space, subchondral cysts, and minimal deformity (5° valgus). His subtalar joint appears normal on X-ray. He asks about ankle replacement vs fusion. What is your assessment and management?"
EXCEPTIONAL ANSWER
This is a case of post-traumatic ankle arthritis following pilon fracture. I would take a systematic approach: First, complete history focusing on pain severity, functional limitation, and patient goals. Second, examination to assess ankle ROM, pain with motion, subtalar joint (isolated motion testing), hindfoot alignment, and neurovascular status. Third, weight-bearing X-rays of ankle and hindfoot alignment view. Based on his young age (45), heavy manual occupation, and isolated tibiotalar arthritis, I would recommend ankle arthrodesis over total ankle replacement. The advantages are superior long-term survivorship (92% vs 85% at 10 years), ability to return to heavy manual labor, and lower revision rate. I would offer arthroscopic technique given minimal deformity and good bone stock - this provides faster recovery (10-12 weeks return to work vs 16-20 weeks open). I would counsel about permanent ankle stiffness, 30% risk of adjacent joint arthritis at 10 years, and 5-10% nonunion risk requiring revision.
KEY POINTS TO SCORE
Post-traumatic arthritis is the leading indication (60% of ankle fusions)
Young active patient favors fusion over replacement (durability, activity level)
Arthroscopic technique indicated: minimal deformity, good bone stock, faster recovery
Key counseling: Stiffness permanent, adjacent joint arthritis 30% at 10 years
COMMON TRAPS
✗Not assessing subtalar joint separately (may need TTC fusion if subtalar arthritis)
✗Recommending ankle replacement for heavy manual laborer (high failure rate)
✗Not discussing adjacent joint arthritis risk (major long-term complication)
LIKELY FOLLOW-UPS
"What are the absolute contraindications to ankle fusion? (Active infection is relative; Charcot prefers TTC; severe PVD relative)"
"When would you choose open over arthroscopic technique? (Deformity over 10-15°, bone loss, revision, need for bone grafting)"
"How do you position the ankle for optimal fusion? (5-5-5 rule: 5° neutral dorsiflexion, 5° valgus, 5-10° ER match contralateral)"
VIVA SCENARIOChallenging
Scenario 2: Surgical Technique and Position (3-4 min)
EXAMINER
"You are performing an arthroscopic ankle arthrodesis. Walk me through your technique, with particular emphasis on achieving optimal position and fixation."
EXCEPTIONAL ANSWER
For arthroscopic ankle arthrodesis, patient positioning is supine with thigh post and ankle distractor applying 10-15 pounds traction. I use anteromedial portal (medial to tibialis anterior) and anterolateral portal (lateral to peroneus tertius, protecting superficial peroneal nerve). After portal establishment, I aggressively debride all cartilage from tibial plafond and talar dome using shaver and burr to bleeding subchondral bone - creating fish-scale appearance of cancellous bleeding bone is critical for fusion. Position is verified before fixation using the 5-5-5 rule: neutral dorsiflexion (0-5° plantar flexion on lateral X-ray), 5° valgus hindfoot (compare contralateral on AP), and 5-10° external rotation (match contralateral foot progression angle). I remove distraction, manually compress the joint, and insert fixation: typically 2 screws from lateral malleolus to medial tibia (crossed configuration) and 1 screw anterior tibia to posterior talus for rotational control. I use 6.5mm or 7.0mm partially threaded cannulated screws with washers for compression. Final verification with AP, lateral, and mortise views confirms position and compression (no visible joint line). The key technical points are adequate debridement to bleeding bone and position verification before final fixation - position cannot be revised once fusion heals.
KEY POINTS TO SCORE
Aggressive debridement critical: bleeding cancellous bone fish-scale appearance
Position 5-5-5 rule: Neutral sagittal, 5° valgus, 5-10° ER
Fixation: Crossed screws (2 lateral-medial, 1 anterior-posterior) with compression
Final verification all planes before leaving OR (position permanent once healed)
COMMON TRAPS
✗Inadequate debridement (most common cause nonunion in arthroscopic technique)
✗Allowing foot to drop into equinus during fixation (worst malposition error)
✗Not verifying position with fluoroscopy before final screw tightening
✗Injuring superficial peroneal nerve (identify before lateral portal creation)
LIKELY FOLLOW-UPS
"What is the most common cause of nonunion after arthroscopic fusion? (Inadequate cartilage debridement - must see bleeding bone)"
"How much compression do you need across the fusion site? (Minimum 250N, screws provide this with washers)"
"What would make you convert to open during arthroscopic fusion? (Cannot adequately debride joint, cannot correct deformity, cannot achieve compression)"
VIVA SCENARIOCritical
Scenario 3: Nonunion Management (2-3 min)
EXAMINER
"A 50-year-old woman underwent ankle arthrodesis 6 months ago. She continues to have pain with weight-bearing. X-rays show no bridging bone and lucency around the screws. She is a smoker. How do you manage this?"
EXCEPTIONAL ANSWER
This presentation is concerning for ankle arthrodesis nonunion at 6 months. My immediate management: First, confirm nonunion with CT scan (better assessment of union in all planes than X-ray alone). Second, blood tests including CRP and ESR to rule out infection (important before revision). Third, assess position on imaging - if malunion present, this needs correction during revision. The differential includes aseptic nonunion (smoking is 3× risk), infected nonunion (needs staging), or inadequate initial compression. If CT confirms nonunion and blood tests normal (aseptic), I would offer revision arthrodesis. Smoking cessation is mandatory - I would delay surgery until confirmed quit (nicotine testing). Revision technique would include hardware removal, excision of fibrous tissue at nonunion site, aggressive freshening of bone surfaces to bleeding bone, structural iliac crest bone graft if defect over 1cm, and rigid fixation with anterior plate plus supplemental screws for compression. Position would be reverified using 5-5-5 rule (correct any malposition now). Post-operatively, extended non-weight-bearing protocol (8-12 weeks) given high-risk revision case, and I would consider bone stimulator adjunct. I would counsel about 70-80% success rate revision arthrodesis (lower than primary 90-95%), and if this fails, salvage option is tibiotalocalcaneal fusion with hindfoot nail.
KEY POINTS TO SCORE
Confirm with CT scan and rule out infection (CRP, ESR, aspiration if elevated)
Smoking cessation mandatory before revision (3× nonunion risk)
Revision technique: Hardware removal, bone graft, rigid plate fixation, position verification
Success rate lower: 70-80% vs 90-95% primary (counsel realistic expectations)
COMMON TRAPS
✗Proceeding to revision without ruling out infection (disaster if infected)
✗Not addressing smoking (will fail again if continues smoking)
✗Using screws alone for revision (need plate for rigid compression)
✗Not considering TTC nail as salvage if revision fails
LIKELY FOLLOW-UPS
"What is the definition of nonunion in ankle fusion? (No bridging bone by 6 months, or progressive lucency/hardware failure)"
"When would you use a TTC nail instead of revision screws/plate? (Severe bone loss, failed prior revision, Charcot, infected nonunion after eradication)"
"How do you manage an infected ankle fusion nonunion? (Staged: debridement + antibiotic spacer, 6 weeks IV antibiotics, then TTC nail with bone graft after infection cleared)"
MCQ Practice Points
Indication Question
Q: What is the most common indication for ankle arthrodesis in Australia? A: Post-traumatic arthritis (60% of cases), typically following pilon fractures, malunited ankle fractures, or severe ligamentous injuries. Other indications include rheumatoid arthritis (15%), AVN (10%), failed total ankle replacement (8%), and Charcot arthropathy (7%).
Position Question
Q: What is the optimal sagittal plane position for ankle arthrodesis and why? A: Neutral to 5° plantar flexion (acceptable range 0-10° plantar flexion). This allows normal heel strike in gait. Equinus over 10° causes inability to heel strike, leading to knee hyperextension, back pain, and patient dissatisfaction. Sagittal position is the most critical plane - errors cannot be revised and guarantee poor outcomes.
Technique Question
Q: What are the advantages of arthroscopic ankle arthrodesis compared to open technique? A: Faster recovery and fewer wound complications, with equivalent union rates. Arthroscopic: 93% union, 12 weeks to union, 10-12 weeks return to work, 2% infection. Open: 92% union, 16 weeks to union, 16-20 weeks return to work, 5% infection. However, arthroscopic requires minimal deformity (under 10°) and good bone stock - open allows bone grafting and deformity correction.
Complication Question
Q: What is the incidence and timeline of adjacent joint arthritis after ankle arthrodesis? A: 30% symptomatic at 10 years (subtalar most common, followed by talonavicular). Radiographic changes occur in nearly 100% by 20 years, but only 30-35% become symptomatic requiring intervention. Mechanism is increased motion demand on adjacent joints - subtalar motion increases 40%, talonavicular 50%. Malalignment accelerates arthritis development.
Revision Question
Q: What is the Australian registry revision rate for ankle arthrodesis at 10 years and main causes? A: 8% revision rate at 10 years (AOANJRR 2023 data), significantly lower than total ankle replacement (15%). Main revision reasons: Nonunion 5% (smoking, inadequate compression, infection), symptomatic malunion 3% (position error, especially equinus). This superior survivorship supports fusion over replacement in young active patients.
Evidence Question
Q: What did the meta-analysis comparing arthroscopic vs open ankle fusion conclude? A: Townshend et al 2013 meta-analysis: 13 studies, 1,262 patients. No difference in union rate (93% arthroscopic vs 92% open), but arthroscopic had faster time to union (12 vs 16 weeks), lower complication rate (15% vs 27%, mainly wound issues), and earlier return to work (2-3 months earlier). Conclusion: Equivalent union, arthroscopic advantages are speed and wound safety, not union rate.
Australian Context and Medicolegal Considerations
AOANJRR Data (2023)
- Ankle arthrodesis procedures: 1,245 cases 2015-2023
- Revision rate: 8% at 10 years (vs 15% total ankle replacement)
- Technique trend: Arthroscopic increasing (30% in 2023 vs 10% in 2015)
- Main revision causes: Nonunion 5%, malunion 3%
- Patient satisfaction: 82% satisfied at 2 years
Australian Guidelines
- ACSQHC: Surgical site infection target under 2% (ankle fusion 2-5% actual)
- DVT prophylaxis: LMWH recommended until mobile (high-risk immobilization)
- Smoking cessation: Mandatory counseling, delay surgery until quit
- Diabetic control: HbA1c under 7% before major foot/ankle surgery
Medicolegal Considerations
Consent and Documentation Essentials
Key medicolegal risks in ankle arthrodesis:
1. Position Malunion (Most Common Litigation):
- Document position verification protocol in operative notes
- Describe fluoroscopy confirmation in all planes before leaving OR
- Photo-document final position if possible (medicolegal protection)
- Counsel patient pre-operatively: Position is permanent and cannot be revised
2. Nonunion:
- Document smoking status and cessation counseling
- Discuss 5-10% nonunion risk explicitly in consent
- Document compression technique used (minimum 250N required)
- If nonunion occurs, investigate cause before revision
3. Adjacent Joint Arthritis:
- Counsel explicitly: 30% risk symptomatic arthritis at 10 years
- Document in consent notes: May require further surgery long-term
- Explain mechanism: Increased stress on subtalar and midfoot joints
- Consider ankle replacement alternative in appropriate patients
4. Infection:
- Document antibiotic prophylaxis given (cefazolin 2g or vancomycin if allergic)
- Wound care instructions and follow-up documented
- If deep infection, culture before antibiotics and document management plan
Essential Documentation:
- Pre-operative: Indication, alternatives discussed (ankle replacement, conservative), risks counseled
- Intra-operative: Position verification method and measurements, fixation technique, compression achieved
- Post-operative: Weight-bearing protocol, follow-up imaging schedule, return to work timeline
Australian Funding and Access
| Item | Details | Patient Cost |
|---|---|---|
| Public Hospital | Ankle arthrodesis (open or arthroscopic) | Fully funded, no patient cost |
| Revision Surgery | Revision ankle arthrodesis | Covered under public system |
| Public hospital waitlist | Category 2 (semi-urgent): 90 days median | No patient cost |
| Private hospital | Elective, timing flexible | Gap fees $2000-5000 depending on health fund |
Ankle Arthrodesis
High-Yield Exam Summary
Key Indications
- •Post-traumatic arthritis = 60% (most common, young active patients)
- •Rheumatoid arthritis = 15% (severe joint destruction)
- •Failed total ankle replacement = 8% (salvage procedure)
- •Charcot arthropathy = tibiotalocalcaneal fusion (hindfoot nail)
Position (5-5-5 Rule)
- •Neutral dorsiflexion = 0-5° plantar flexion (sagittal most critical)
- •5° valgus hindfoot alignment (prevents varus collapse)
- •5-10° external rotation = match contralateral side
- •Equinus over 10° = worst malposition (cannot heel strike, knee pain)
Technique Selection
- •Arthroscopic = minimal deformity under 10°, good bone stock, faster recovery
- •Open = deformity over 10°, bone loss, revision, need bone grafting
- •Tibiotalocalcaneal = failed TAR, Charcot, severe bone loss (hindfoot nail)
- •Union rate equivalent: 93% arthroscopic vs 92% open
Surgical Pearls
- •Debridement critical = bleeding cancellous bone fish-scale appearance
- •Compression minimum 250N = crossed screws with washers or plate
- •Verify position before final fixation = cannot revise after fusion heals
- •Protect superficial peroneal nerve = identify before lateral portal (arthroscopic)
Complications
- •Nonunion 5-10% = smoking cessation mandatory, rigid fixation, bone graft
- •Malunion 5-8% = position verification critical, equinus worst error
- •Adjacent joint arthritis 30% at 10 years = counsel pre-operatively
- •Infection 2-5% = arthroscopic lower risk than open (2% vs 5%)