TRIPLE ARTHRODESIS
Hindfoot Fusion | Deformity Correction | Salvage Procedure
INDICATION CATEGORIES
Critical Must-Knows
- Triple arthrodesis fuses talonavicular, subtalar, and calcaneocuboid joints - eliminates all hindfoot motion
- Primary indication: rigid hindfoot deformity with arthritis not amenable to isolated fusion
- Positioning critical: 5-7° hindfoot valgus prevents excessive lateral column loading
- Adjacent joint disease: 15-20% develop tibiotalar or midfoot arthritis within 10 years
- Contraindications: active infection, severe vascular insufficiency, tobacco use (relative)
Examiner's Pearls
- "Examiners ask about optimal hindfoot position - 5-7° valgus prevents lateral overload
- "Know PTTD reconstruction vs triple arthrodesis decision-making algorithm
- "Understand why isolated subtalar fusion may be preferred in selective cases
- "Be able to discuss adjacent joint disease prevention strategies and counseling
Clinical Imaging
Imaging Gallery
Critical Triple Arthrodesis Exam Points
Joint Positioning
5-7° hindfoot valgus is critical. Varus positioning causes lateral column overload and pain. Neutral positioning may still overload lateral structures. Verify with intraoperative fluoroscopy in multiple planes.
Adjacent Joint Disease
15-20% develop tibiotalar or midfoot arthritis within 10 years. Counsel patients preoperatively. Younger, more active patients at higher risk. Consider isolated fusion when possible.
Fusion Sequence
Talonavicular joint fused first - establishes hindfoot alignment. Subtalar follows to lock position. Calcaneocuboid last to accommodate length. Order matters for deformity correction.
Nonunion Risk
10-15% overall nonunion rate with highest risk at calcaneocuboid (20-25%). Smoking cessation mandatory. Bone graft for cystic changes. Rigid fixation essential.
Quick Decision Guide: Triple Arthrodesis vs Alternatives
| Clinical Scenario | Deformity Type | Treatment Choice | Key Pearl |
|---|---|---|---|
| Stage II PTTD, flexible flatfoot | Flexible, passively correctable | Medializing calcaneal osteotomy + FDL transfer | Preserve motion - avoid fusion if possible |
| Stage III PTTD, rigid flatfoot, isolated subtalar arthritis | Rigid, subtalar arthritis only | Isolated subtalar fusion | Preserves TN and CC motion - better function |
| Post-traumatic arthritis all 3 joints, rigid valgus | Rigid, pan-hindfoot arthritis | Triple arthrodesis | Gold standard for pan-hindfoot disease |
| Severe cavovarus, CMT disease, rigid | Rigid cavovarus, neuromuscular | Triple arthrodesis + soft tissue balancing | May need Achilles lengthening, peroneus longus-to-brevis |
TRIPLJoints Involved in Triple Arthrodesis
Memory Hook:TRIPL reminds you this is a TRIPLE fusion - remember TN first, position in valgus, watch the lateral column!
SALVAIndications for Triple Arthrodesis
Memory Hook:SALVA = 'salvage' procedure - when other options have failed or pan-hindfoot disease exists!
NAILSComplications of Triple Arthrodesis
Memory Hook:NAILS = what holds the fusion together, but also the problems - nonunion tops the list!
Overview and Epidemiology
Triple arthrodesis is a hindfoot fusion procedure that involves simultaneous fusion of the talonavicular (TN), subtalar (ST), and calcaneocuboid (CC) joints. First described by Ryerson in 1923 for poliomyelitis deformities, it remains a powerful salvage procedure for rigid hindfoot deformity with pan-hindfoot arthritis.
Historical Evolution
Originally developed for poliomyelitis and neuromuscular deformities, triple arthrodesis is now most commonly performed for post-traumatic arthritis, failed PTTD reconstruction, and rigid flatfoot/cavovarus deformity. Modern techniques emphasize preservation of hindfoot height and optimal alignment to reduce adjacent joint stress.
Common Indications
- Post-traumatic arthritis: Calcaneal fracture sequelae
- End-stage PTTD: Stage III/IV rigid flatfoot
- Neuromuscular deformity: CMT, polio, stroke
- Inflammatory arthritis: RA, seronegative
- Failed coalition resection: Salvage procedure
- Charcot arthropathy: Neuropathic hindfoot
Patient Demographics
- Age: Typically 40-70 years
- Gender: Slight female predominance (PTTD-related)
- Risk factors: Diabetes, smoking, obesity
- Expectations: Pain relief over motion restoration
- Activity level: Generally lower demand patients
- Alternatives: Isolated fusions when possible
Pathophysiology and Mechanisms
Understanding the biomechanics of hindfoot motion is critical to appreciating the functional impact of triple arthrodesis and the development of adjacent joint disease.
Hindfoot Motion Loss
Triple arthrodesis eliminates essentially all hindfoot inversion/eversion (50-60° normally). This forces compensatory motion through the tibiotalar joint and midfoot, increasing stress by 200-300%. Patients lose adaptability to uneven terrain and have altered gait mechanics.
Joint Contributions to Hindfoot Motion
| Joint | Normal Motion | Function | Impact of Fusion |
|---|---|---|---|
| Subtalar | 40-50° inversion/eversion | Primary hindfoot motion, shock absorption | Largest motion loss - transfers stress to ankle |
| Talonavicular | 10-15° rotation, pronation/supination | Couples with subtalar, medial column stability | Loss affects midfoot motion, arch mechanics |
| Calcaneocuboid | 5-10° gliding, rotation | Lateral column length accommodation | Least motion lost but highest nonunion risk |
Neurovascular Structures
- Dorsalis pedis: Crosses talonavicular joint dorsomedially
- Deep peroneal nerve: Runs with dorsalis pedis - protect during exposure
- Sural nerve: Lateral approach - 5-10% injury rate
- Posterior tibial artery: Medial, usually safe from surgical approach
- Peroneal tendons: Lateral retinaculum must be preserved
Biomechanical Consequences
- 200-300% increased tibiotalar stress: Leads to ankle arthritis
- Midfoot compensatory motion: Increased Chopart and Lisfranc stress
- Altered gait: Reduced pushoff, decreased stride length
- Uneven terrain difficulty: Loss of hindfoot adaptability
- Leg length: May shorten 5-10mm with deformity correction
Classification and Patient Selection
Primary Indications
| Category | Etiology | Key Features | Surgical Considerations |
|---|---|---|---|
| Post-traumatic arthritis | Calcaneal fracture sequelae, talar fracture, Lisfranc injury | Rigid deformity, bone loss, malunion | May require bone graft, deformity correction |
| End-stage PTTD | Stage III/IV posterior tibial tendon dysfunction | Fixed flatfoot, TN/ST arthritis, talar head uncovering | Restore arch height, consider tibiotalar arthritis risk |
| Neuromuscular deformity | CMT, polio, stroke, cerebral palsy | Progressive cavovarus or valgus, muscle imbalance | Requires soft tissue balancing (Achilles, peroneal transfer) |
| Inflammatory arthritis | Rheumatoid, seronegative spondyloarthropathy | Multi-joint involvement, forefoot also affected | Consider pan-foot reconstruction, optimize medical therapy |
Isolated Fusion vs Triple Arthrodesis
Consider isolated subtalar or talonavicular fusion when disease is limited to one joint and deformity is correctable. Triple arthrodesis should be reserved for pan-hindfoot disease or when isolated fusion is insufficient to correct rigid deformity. This preserves more motion and reduces adjacent joint stress.
Clinical Assessment
History
- Pain location: Medial arch, lateral column, sinus tarsi
- Onset: Acute trauma vs chronic progressive
- Prior treatments: Orthotics, bracing, injections, previous surgery
- Functional loss: Distance walking, uneven terrain, stairs
- Neuromuscular symptoms: Weakness, imbalance, progression
- Medical comorbidities: Diabetes, vascular disease, smoking
- Expectations: Pain relief vs activity level restoration
Physical Examination
- Alignment: Varus, valgus, or neutral hindfoot position
- Flexibility: Passive correction with hindfoot inversion/eversion
- Tibialis posterior: Strength, single-limb heel rise ability
- Peroneal strength: Varus deformity may have weak evertors
- Ankle range: Dorsiflexion, plantarflexion - may compensate
- Neurovascular: Pulses, sensation, ABI if concerns
- Special tests: Hindfoot flexibility (Jack test), Coleman block
Assess Deformity Flexibility
Determine if deformity is flexible or fixed - this guides surgical planning. Use Coleman block test for cavovarus: if hindfoot corrects to neutral with forefoot blocked, consider forefoot-driven deformity requiring first ray osteotomy in addition to triple arthrodesis.
Clinical Patterns and Surgical Implications
| Deformity Pattern | Clinical Findings | Surgical Plan |
|---|---|---|
| Rigid flatfoot (PTTD Stage III) | Fixed valgus, arch collapse, forefoot abduction, TN pain | Triple arthrodesis to restore arch, neutral hindfoot alignment |
| Rigid cavovarus (CMT) | Fixed inversion, high arch, claw toes, lateral foot pain | Triple arthrodesis + soft tissue (Achilles, peroneus longus-to-brevis) |
| Post-traumatic arthritis | Stiffness, bone block, malunion, variable alignment | Triple arthrodesis, may need bone graft or osteotomy |
Investigations
Imaging Protocol
Views: AP, lateral, mortise foot; AP, lateral ankle
Key measurements:
- Lateral talo-first metatarsal angle (normal 0-10°)
- Calcaneal pitch (normal 20-30°)
- Talonavicular coverage angle
- Tibiotalar joint space and arthritis
Assess: Alignment, arthritis severity, bone quality, prior hardware
Indications: Complex deformity, malunion, bone defects, surgical planning
Utility:
- Precise joint arthritis assessment
- Bone loss quantification
- Hardware placement planning
- Subtalar coalition or coalition resection failure evaluation
Indications: Soft tissue pathology (PTTD, spring ligament), osteonecrosis assessment
Not routine: Bony detail better on CT; clinical exam usually sufficient for soft tissue
ABI (Ankle-Brachial Index): Mandatory if diabetes, smoking, age over 60, or pulse abnormalities
Threshold: ABI less than 0.7 requires vascular consultation; less than 0.5 is absolute contraindication
Radiographic Arthritis Grading
- Grade 0: Normal joint space
- Grade 1: Joint space narrowing only
- Grade 2: Narrowing + subchondral sclerosis
- Grade 3: Grade 2 + osteophytes
- Grade 4: Severe narrowing, cysts, bone-on-bone
Surgical indication: Grade 3-4 with rigid deformity
Laboratory Studies
- CBC, ESR, CRP: Baseline, infection screening
- HbA1c: Diabetes control (target under 7.5%)
- Vitamin D: Optimize fusion (target over 30 ng/mL)
- Nutritional panel: Albumin, prealbumin if malnourished
- Smoking status: Cotinine if patient reports cessation
Nonoperative Management
Triple arthrodesis is a salvage procedure reserved for failed conservative management and progressive rigid deformity with disabling pain.
Nonoperative Treatment Algorithm
Stepwise Conservative Management
- Reduce impact activities: Avoid running, jumping, prolonged standing
- Assistive devices: Walking aids for distance ambulation
- Workplace modifications: Seated work, reduced walking requirements
- Realistic expectations: Accept activity limitations vs surgical fusion
- Custom AFO (ankle-foot orthosis): Arizona brace, UCBL (rigid flatfoot)
- CROW boot: Charcot restraint orthotic walker for neuropathic feet
- Custom insoles: Arch support, lateral posting, cushioning
- Rocker-bottom shoes: Reduce forefoot pressures, aid propulsion
- NSAIDs: Short courses for flare-ups
- Corticosteroid injections: Temporary relief (3-6 months), diagnostic
- Physical therapy: Stretching, strengthening, gait training
- Weight loss: Reduce hindfoot loading in obese patients
When Conservative Fails
Indications for surgery: Failure of 3-6 months of appropriate conservative management (orthoses, activity modification, injections) with persistent disabling pain and functional limitation. Patient must accept loss of hindfoot motion and adjacent joint disease risk.
Management Algorithm
Treatment Algorithm for Hindfoot Deformity with Arthritis
Systematic Decision-Making
Passive correction test: Attempt to manually correct deformity
- Flexible deformity: Corrects to neutral passively → consider joint-preserving procedures (osteotomy, tendon transfer)
- Rigid deformity: Does not correct → fusion required
Tests: Coleman block test (cavovarus), hindfoot inversion/eversion stress (flatfoot)
Weight-bearing radiographs + CT if needed
- Isolated joint arthritis: Single joint (TN or ST) → consider isolated fusion
- Two-joint arthritis: TN + ST → consider double arthrodesis
- Pan-hindfoot arthritis: All three joints (TN, ST, CC) → triple arthrodesis indicated
Key: Minimize number of joints fused to reduce adjacent joint stress
All patients require failed conservative management before fusion
- Custom AFO or UCBL orthosis (rigid hindfoot support)
- Activity modification (avoid impact, prolonged standing)
- NSAIDs, corticosteroid injections (diagnostic + therapeutic)
- Physical therapy (stretching, strengthening, gait training)
Proceed to surgery: If persistent disabling pain after adequate conservative trial
Mandatory optimization:
- Smoking cessation: 6 weeks minimum (verify with cotinine)
- Diabetes control: HbA1c under 7.5%
- Vascular assessment: ABI over 0.7 (consult vascular if under 0.7)
- Nutrition: Albumin over 3.5, vitamin D over 30 ng/mL
- Weight loss: BMI reduction if obese (reduces wound complications)
Choose appropriate fusion:
- Isolated subtalar: ST arthritis only, correctable deformity
- Talonavicular: TN arthritis, flexible ST joint
- Double arthrodesis: TN + ST disease, sparing CC
- Triple arthrodesis: Pan-hindfoot arthritis, rigid deformity requiring all three joints fused
Counsel: Loss of hindfoot motion, 6 weeks non-weightbearing, 10-15% nonunion, 15-20% adjacent joint disease
Conservative Trial Documentation
Document adequate conservative trial before proceeding with triple arthrodesis. This includes 3-6 months of appropriate orthotic management (AFO or UCBL), activity modification, and medical management. Fusion without conservative trial may not meet insurance requirements and medicolegal standards.
Surgical Technique
Patient Positioning and Preparation
Operating Room Setup
Supine on radiolucent table (or lateral for isolated lateral approach).
- Ipsilateral hip: Bump under hip to internally rotate leg slightly
- Contralateral leg: Padded, leg holder or frog-leg position
- Thigh tourniquet: High thigh, padded, typically 250-300 mmHg
- Bony prominences: Sacrum, contralateral heel, elbows
- Nerve protection: Ulnar nerves padded, peroneal nerve at fibular head (contralateral)
- Tourniquet time: Plan for less than 90 minutes, deflate for closure
- Foot free-draped: Allow manipulation and positioning
- Proximal to mid-calf: Adequate exposure for hardware, bone graft harvest
- C-arm access: Confirm AP, lateral, and oblique foot views possible
- Sterile tourniquet: If planning prolonged case
Consent Points
- Nonunion: 10-15% overall, up to 25% calcaneocuboid
- Adjacent joint arthritis: 15-20% within 10 years
- Infection: 2-5% superficial, 1-2% deep
- Nerve injury: 5-10% sural nerve numbness (lateral approach)
- Malposition: Requiring revision surgery (2-5%)
- DVT/PE: Standard orthopedic risk
Equipment Checklist
- Implants: Multiple 6.5mm or 7.0mm cannulated screws, consider plates for CC
- Power tools: Oscillating saw, burr, drill
- Reduction aids: Laminar spreaders, bone clamps, K-wires
- Bone graft: Local (resected bone) + consider iliac crest or allograft
- Fluoroscopy: C-arm with radiolucent table
Complications
| Complication | Incidence | Risk Factors | Prevention/Management |
|---|---|---|---|
| Nonunion | 10-15% overall, 20-25% calcaneocuboid | Smoking, diabetes, malnutrition, poor fixation | Smoking cessation, bone graft, rigid fixation. Revision with bone graft + new fixation. |
| Adjacent joint arthritis | 15-20% tibiotalar or midfoot within 10 years | Young, active patients; increased joint stress | Counsel preoperatively; consider isolated fusion if possible. May require ankle fusion. |
| Infection (superficial) | 2-5% | Diabetes, smoking, obesity, poor wound care | Optimize comorbidities, wound care. Oral antibiotics, local wound care usually sufficient. |
| Deep infection | 1-2% | Diabetes, vascular disease, hardware | IV antibiotics, surgical debridement ± hardware removal after fusion healed. |
| Sural nerve injury | 5-10% numbness, 1-2% painful neuroma | Lateral approach, excessive retraction | Careful dissection, gentle retraction. Neuroma excision + nerve burial if painful. |
| Malposition (varus/valgus) | 2-5% requiring revision | Inadequate intraoperative assessment | Verify alignment fluoroscopically before final fixation. Revision osteotomy if symptomatic. |
| Lateral column overload | 10-15% if hindfoot in neutral or varus | Neutral or varus positioning | Position hindfoot in 5-7° valgus. Lateral column pain may require salvage procedures. |
Nonunion Management
Nonunion (10-15%) is the most common major complication. Diagnosed by persistent pain, lack of bridging bone on CT at 4-6 months. Management: If asymptomatic, observe. If symptomatic, revision fusion with bone graft (iliac crest or BMP) and new fixation - consider plate augmentation for calcaneocuboid nonunion.
Early Complications (0-6 weeks)
- Wound dehiscence: 3-5%, higher with diabetes, smoking
- Hematoma: 2-3%, usually self-limiting
- DVT/PE: Standard orthopedic risk (0.5-1%)
- Compartment syndrome: Rare (less than 1%), high index of suspicion
- Hardware prominence: 5-10%, may require removal after fusion
Late Complications (over 6 months)
- Nonunion: 10-15%, highest at CC joint
- Adjacent joint arthritis: 15-20% tibiotalar or midfoot
- Persistent pain: 20-30%, often lateral column overload
- Stress fracture: 5th metatarsal, navicular (compensatory stress)
- Hardware failure: Screw breakage (2-3%), usually after fusion solid
Postoperative Care and Rehabilitation
Immediate Postoperative Period
- Strict elevation: Foot above heart level, minimize dependency
- Ice therapy: 20 minutes on/off while awake
- Non-weightbearing: Crutches or walker, no foot contact with floor
- DVT prophylaxis: Aspirin 325mg daily or LMWH per protocol
- Pain management: Multimodal analgesia, opioid weaning
- Wound check: Remove sutures/staples at 10-14 days if wounds healed
- Cast change: Replace splint with well-molded short leg cast, non-weightbearing
- X-rays: AP and lateral foot to assess alignment and hardware position
- Continue: Strict non-weightbearing for 6 weeks total
- Clinical assessment: Pain, swelling, wound healing
- X-rays: AP, lateral, mortise to assess early fusion
- Weightbearing: If early fusion signs, transition to weightbearing as tolerated in CAM boot
- If no fusion: Continue non-weightbearing cast for additional 2-4 weeks
Strict Non-Weightbearing for 6 Weeks
Non-weightbearing for the first 6 weeks is critical to prevent nonunion and hardware failure. Patients must use crutches or walker with zero foot contact. Early weightbearing increases nonunion risk from 10-15% to 20-30%.
Outcomes and Prognosis
Functional Outcomes by Indication
| Indication | Pain Relief | Satisfaction | Functional Outcome | Notes |
|---|---|---|---|---|
| Post-traumatic arthritis | Good (80-85%) | Moderate (70%) | Moderate - limited by adjacent joint stress | Younger patients, higher adjacent joint disease risk |
| End-stage PTTD | Excellent (85-90%) | Good (75%) | Good for pain relief, limited mobility | Older, lower-demand patients generally satisfied |
| Neuromuscular deformity | Good (75-80%) | Variable (60-70%) | Limited by underlying disease progression | May require revision for recurrent deformity |
| Inflammatory arthritis | Good (80%) | Good (70-75%) | Limited by systemic disease | Often pan-foot disease requiring additional procedures |
Predictors of Poor Outcome
Risk factors for poor functional outcome and dissatisfaction:
- Young age (under 40): Higher activity demands, longer time for adjacent joint disease
- Varus or neutral positioning: Lateral column overload pain
- Tobacco use: Higher nonunion, revision, and persistent pain rates
- Workers' compensation: Lower satisfaction in some studies (confounded by litigation)
- Pre-existing adjacent joint arthritis: Progression to pantalar fusion (20-30%)
Long-term Outcomes (over 5 years)
- Fusion maintenance: 85-90% remain fused long-term
- Pain relief: 75-80% report significant pain improvement
- Walking distance: Improved in 70%, limited by adjacent joint pain in 20%
- Satisfaction: 70-75% would undergo surgery again
- Revision rate: 10-15% for nonunion, malposition, or adjacent joint disease
Adjacent Joint Surveillance
- Tibiotalar arthritis: 10-15% within 10 years, higher in young/active
- Midfoot arthritis: 5-10% within 10 years (Lisfranc, naviculocuneiform)
- Monitoring: Annual X-rays for first 3 years, then as clinically indicated
- Symptoms: New onset ankle or midfoot pain, stiffness, swelling
- Treatment: Conservative first (orthotics, activity modification); ankle fusion if severe
Evidence Base and Key Trials
Biomechanical Effects of Hindfoot Fusions on Ankle and Midfoot Joints
- Triple arthrodesis increases tibiotalar joint stress by 200-300% during gait
- Midfoot compensatory motion increases by 150-200%, especially at Lisfranc joint
- Hindfoot valgus positioning (5-7 degrees) reduces lateral column stress vs neutral
- Isolated subtalar fusion increases adjacent joint stress less than triple arthrodesis
Long-term Results of Triple Arthrodesis: Average 30-Year Follow-up
- 52 patients followed average 30 years post-triple arthrodesis
- Tibiotalar arthritis developed in 48% by 20 years, 65% by 30 years
- Patient satisfaction remained 70% despite adjacent joint disease
- Nonunion rate 15% (highest at calcaneocuboid joint - 20%)
- Revision surgery rate 12% for nonunion or malalignment
Comparison of Isolated Subtalar vs Triple Arthrodesis for Hindfoot Arthritis
- Isolated subtalar fusion preserves TN and CC motion - better functional scores
- Triple arthrodesis better for severe deformity correction or pan-hindfoot arthritis
- Adjacent joint disease rate: 10% isolated ST fusion vs 30% triple arthrodesis at 10 years
- Nonunion: 8% isolated ST vs 15% triple arthrodesis
Smoking and Outcomes After Triple Arthrodesis
- Nonunion rate: 26% in smokers vs 11% in non-smokers (p less than 0.05)
- Revision surgery: 18% smokers vs 7% non-smokers
- Smoking cessation 6 weeks preoperatively reduced but did not eliminate increased risk
- Delayed union common in smokers even if eventual fusion achieved
Optimal Hindfoot Alignment After Triple Arthrodesis
- Hindfoot valgus 5-7 degrees optimal - minimizes lateral column overload
- Neutral or varus alignment associated with 60% lateral foot pain vs 15% with valgus
- Peroneal tendonitis and 5th metatarsal stress fractures common with varus positioning
- Fluoroscopic verification essential - clinical assessment alone misses 20% malpositions
Exam Viva Scenarios
Practice these scenarios to excel in your viva examination
Scenario 1: Indication and Decision-Making (2-3 minutes)
"A 58-year-old woman with longstanding posterior tibial tendon dysfunction presents with worsening medial foot pain and inability to walk more than 100 meters. She has tried custom orthotics and bracing for 12 months without relief. Examination shows fixed flatfoot deformity with hindfoot valgus that does not correct passively. Weight-bearing radiographs demonstrate talonavicular subluxation with joint space loss, subtalar arthritis, and some calcaneocuboid narrowing. She asks about surgical options. What is your assessment and management?"
Scenario 2: Surgical Technique Deep Dive (3-4 minutes)
"You have decided to proceed with triple arthrodesis for a patient with post-traumatic pan-hindfoot arthritis. Walk me through your surgical technique, including approach, joint preparation sequence, and fixation strategy."
Scenario 3: Nonunion Complication Management (2-3 minutes)
"A 52-year-old diabetic man underwent triple arthrodesis 8 months ago. He has persistent lateral foot pain despite following non-weightbearing protocol and progressive weightbearing as instructed. Clinical exam shows tenderness over the calcaneocuboid joint with some motion. CT scan shows solid fusion of talonavicular and subtalar joints but nonunion of calcaneocuboid with sclerotic bone ends and a 3mm gap. How do you manage this patient?"
MCQ Practice Points
Anatomy Question
Q: Which joint in a triple arthrodesis has the highest risk of nonunion and why?
A: The calcaneocuboid joint has the highest nonunion risk (20-25% vs 10-15% overall) due to its smaller surface area, poor vascularity, and high compression forces across the lateral column during weightbearing. Additional risk factors include smoking, diabetes, and inadequate fixation. Strategies to reduce CC nonunion include structural bone graft and plate fixation (vs screws alone) in high-risk patients.
Positioning Question
Q: What is the optimal hindfoot position during triple arthrodesis and what happens if positioned incorrectly?
A: 5-7 degrees hindfoot valgus is optimal. Positioning in neutral or varus causes lateral column overload pain in 60% of patients (vs 15% with valgus), leading to peroneal tendonitis, sural nerve irritation, and 5th metatarsal stress fractures. Valgus positioning distributes load more evenly across hindfoot and reduces compensatory lateral column stress. Verify intraoperatively with fluoroscopy (mortise view) and clinical assessment (heel bisects Achilles).
Complication Question
Q: What is the incidence and natural history of adjacent joint arthritis after triple arthrodesis?
A: 15-20% of patients develop tibiotalar or midfoot arthritis within 10 years after triple arthrodesis, increasing to 50-65% by 20-30 years. This occurs because eliminating hindfoot motion increases tibiotalar joint stress by 200-300% and midfoot stress by 150-200% during gait. Risk factors include younger age, higher activity level, and neutral/varus hindfoot positioning. Counsel patients preoperatively about this long-term risk and need for surveillance.
Indication Question
Q: How do you distinguish between a patient who needs isolated subtalar fusion vs triple arthrodesis?
A: Isolated subtalar fusion is indicated for arthritis limited to the subtalar joint with preserved talonavicular and calcaneocuboid joints, and correctable deformity. Triple arthrodesis is indicated for pan-hindfoot arthritis involving all three joints (TN, ST, CC) or when severe rigid deformity cannot be corrected by isolated fusion. Advantages of isolated ST fusion: preserves TN and CC motion (better function), reduces adjacent joint stress (10% vs 30% adjacent arthritis at 10 years), and lower nonunion risk (8% vs 15%). Always consider least extensive fusion that achieves goals.
Surgical Technique Question
Q: In what order should the three joints be fused during triple arthrodesis and why does sequence matter?
A: Talonavicular first, subtalar second, calcaneocuboid third. TN fusion establishes overall hindfoot alignment in sagittal and transverse planes (arch height, forefoot abduction/adduction). Subtalar fusion locks this position and sets hindfoot varus/valgus. Calcaneocuboid adjusts lateral column length to accommodate medial column position. Incorrect sequence makes deformity correction difficult or impossible - if you fuse ST first in wrong position, cannot correct via TN later.
Evidence Question
Q: What is the effect of smoking on triple arthrodesis outcomes?
A: Smoking doubles the nonunion rate from 11% to 26% (Perlman & Thordarson, 1999) and increases revision surgery from 7% to 18%. Smoking causes microvascular compromise and impaired bone healing. Management: Mandatory 6-week smoking cessation preoperatively (verify with cotinine testing); consider bone graft augmentation and extended non-weightbearing in smokers. Even with cessation, residual increased risk - counsel patients accordingly.
Australian Context and Medicolegal Considerations
Australian Practice Patterns
- AOANJRR: Limited hindfoot fusion registry data (focus on ankle arthroplasty)
- Common indications: Post-traumatic arthritis (workplace/motor vehicle), end-stage PTTD
- Public vs private: Long waitlists for elective hindfoot fusion in public system
- TAC/WorkCover: Common for post-traumatic cases - document work capacity
- Diabetes prevalence: High rates in Indigenous populations - preoperative optimization critical
Australian Guidelines
- ACSQHC: Surgical site infection prevention bundle (hair removal, antibiotic prophylaxis)
- Thromboprophylaxis: Aspirin 100mg daily for 35 days (low-risk) or LMWH (high-risk per ACCP)
- Smoking cessation: Medicare-funded Quitline counseling and NRT subsidized (PBS)
- Diabetes management: HbA1c target under 7.5% per RACGP guidelines before elective surgery
- Indigenous health: Close collaboration with Aboriginal Medical Services for diabetes/vascular management
Medicolegal Considerations
Key documentation requirements:
- Informed consent: Document discussion of nonunion (10-15%), adjacent joint disease (15-20%), loss of hindfoot motion, infection, nerve injury, and alternative treatments (isolated fusion, conservative management)
- Smoking status: Document smoking history, counseling for cessation, and patient agreement (or refusal) - higher nonunion risk if continues
- Diabetes control: HbA1c, optimization plan, and patient compliance documented
- Vascular assessment: ABI documented for all high-risk patients (diabetes, age over 60, smoking, vascular disease history)
- Complications: Nonunion managed appropriately (observation vs revision) - early detection and discussion
Common litigation issues:
- Nonunion not diagnosed early: Persistent pain should prompt CT at 3-4 months if X-ray equivocal
- Malposition causing lateral overload: Intraoperative fluoroscopy documentation of alignment critical
- Inadequate consent: Patients not counseled about permanent loss of hindfoot motion and adjacent joint disease risk
- Wound complications in diabetics/smokers: Document preoperative optimization and postoperative wound care protocol
Funding Information
- Triple arthrodesis procedures covered under public system
- Private patients should confirm coverage with their health fund
- Out-of-pocket costs vary depending on surgeon fees and hospital charges
- Bone graft harvest additional if structural graft needed
Hospital and System Considerations
- Public waitlist: 6-12 months typical for elective triple arthrodesis
- Private: 2-4 weeks typical wait, out-of-pocket costs $5,000-10,000
- Implant costs: Screws $200-400 each, plates $1,000-2,000 - hospital funded
- Allied health: Physiotherapy, orthotics, wound care - variable coverage
- Follow-up: Long-term surveillance for adjacent joint disease (annual X-rays years 1-3)
TRIPLE ARTHRODESIS
High-Yield Exam Summary
Key Anatomy and Biomechanics
- •Three joints fused: talonavicular, subtalar, calcaneocuboid - eliminates all hindfoot motion
- •Subtalar joint provides 40-50° inversion/eversion - largest motion loss
- •Triple arthrodesis increases tibiotalar stress 200-300% - causes adjacent joint disease
- •Sural nerve at risk with lateral approach - 5-10% numbness, protect during dissection
- •Calcaneocuboid has poorest vascularity - highest nonunion risk (20-25%)
Indications and Classification
- •Primary indication: rigid hindfoot deformity with pan-hindfoot arthritis
- •Post-traumatic arthritis most common (calcaneal fracture sequelae)
- •End-stage PTTD (Stage III/IV) with fixed flatfoot and arthritis
- •Neuromuscular: CMT, polio, stroke - progressive cavovarus or valgus
- •Contraindications: active infection, severe vascular disease (ABI under 0.5), active smoking (relative)
Surgical Algorithm
- •Two-incision approach: medial for TN, lateral (sinus tarsi) for ST and CC
- •Joint sequence: TN first (establishes alignment), ST second (locks position), CC third (length)
- •Position hindfoot in 5-7° valgus - prevent lateral overload (verify fluoroscopically)
- •Fixation: 2 screws TN (rotational control), 1-2 screws ST, 1-2 screws or plate CC
- •Postoperative: strict non-weightbearing 6 weeks, progressive WB in boot weeks 6-12
Surgical Pearls
- •TN fusion first - establishes sagittal/transverse alignment; wrong sequence prevents correction
- •5-7° valgus critical - neutral/varus causes 60% lateral pain vs 15% with valgus
- •Protect sural nerve on lateral approach - runs posteroinferior with short saphenous vein
- •CC needs rigid fixation ± bone graft - highest nonunion risk especially smokers/diabetics
- •Verify alignment before final fixation - mortise fluoroscopy and clinical heel bisection
Complications and Management
- •Nonunion 10-15% overall, 20-25% calcaneocuboid - diagnose with CT, revise if symptomatic
- •Adjacent joint arthritis 15-20% within 10 years - counsel preoperatively, surveillance X-rays
- •Lateral overload from varus/neutral positioning - requires salvage osteotomy or fusion
- •Smoking doubles nonunion (26% vs 11%) - mandatory 6-week cessation, consider bone graft
- •Infection 2-5% superficial, 1-2% deep - optimize diabetes/vascular status preoperatively
Key Evidence and Outcomes
- •Fusion rate 85-90% at 1 year with modern rigid fixation
- •Patient satisfaction 70-75% - good pain relief but limited function
- •Saltzman 30-year follow-up: 65% develop tibiotalar arthritis by 30 years
- •Isolated subtalar fusion reduces adjacent joint disease (10% vs 30% triple) - consider when feasible
- •Perlman: smoking doubles nonunion and revision - cessation critical for success