TALONAVICULAR ARTHRITIS
Midfoot Degenerative Joint Disease | Triple Joint Complex | Surgical Challenge
ARTHRITIS SEVERITY
Critical Must-Knows
- TN joint is critical for hindfoot-forefoot motion and inversion/eversion
- Arthritis commonly involves adjacent joints - check subtalar and calcaneocuboid
- Isolated TN arthrodesis maintains 70-80% of hindfoot motion
- Triple arthrodesis indicated when multiple hindfoot joints involved
- Adult-acquired flatfoot (PTTD Stage 3) commonly leads to TN arthritis
Examiner's Pearls
- "TN joint contributes 50% of hindfoot inversion/eversion
- "Beaking on dorsal navicular = chronic TN arthritis hallmark
- "Beware posterior tibial tendon dysfunction coexistence
- "Isolated TN fusion: consider ball-and-socket ankle contraindication
Quick Decision Guide: Talonavicular Arthritis Management
| Clinical Scenario | Imaging Findings | Treatment | Key Pearl |
|---|---|---|---|
| Mild pain, active patient | Joint space narrowing only | NSAIDs, orthoses, activity modification | 6 months conservative trial mandatory |
| Moderate pain, failed conservative | TN arthritis isolated, subtalar preserved | Isolated TN arthrodesis | Preserves 70-80% hindfoot motion |
| Severe pain, PTTD Stage 3 | TN + subtalar + CC arthritis | Triple arthrodesis | Corrects deformity and pain simultaneously |
| Young, high demand, isolated TN | Moderate arthritis, preserved bone stock | Consider TN arthroplasty (emerging) | Limited long-term data available |
ARCHTalonavicular Joint Function
Memory Hook:The TN joint is the ARCH apex - lose it and the arch collapses!
TRAUMASTalonavicular Arthritis Causes
Memory Hook:Think of foot TRAUMAS that damage the TN joint over time!
FUSETalonavicular Arthritis Management
Memory Hook:Conservative measures first, then FUSE the joint when they fail!
Overview and Epidemiology
Clinical Significance
Talonavicular arthritis represents degeneration of the critical articulation between the talar head and navicular. As the apex of the medial longitudinal arch, TN joint pathology profoundly affects foot biomechanics, leading to arch collapse, forefoot abduction, and altered gait patterns. Understanding TN arthritis is essential as it rarely exists in isolation and commonly coexists with posterior tibial tendon dysfunction and adjacent joint pathology.
Pathophysiology
- Articular cartilage loss: Progressive degeneration
- Subchondral sclerosis: Abnormal loading patterns
- Osteophyte formation: Dorsal beaking characteristic
- Arch collapse: Loss of keystone support
- Forefoot abduction: Compensatory malalignment
Associated Conditions
- PTTD Stage 3: Most common association
- Subtalar arthritis: 60-70% coexistence
- Calcaneocuboid arthritis: 30-40% involvement
- Ankle valgus: Secondary deformity
- Hallux valgus: Forefoot compensation
Pathophysiology and Mechanisms
Critical Biomechanical Role
The TN joint is the apex of the medial longitudinal arch and contributes 50% of total hindfoot inversion and eversion. Loss of TN function shifts motion demands to adjacent joints (subtalar, ankle, calcaneocuboid), potentially accelerating degenerative changes. The posterior tibial tendon inserts on the navicular tuberosity and is intimately related to TN joint stability.
| Structure | Anatomical Details | Clinical Significance |
|---|---|---|
| Talonavicular articulation | Ball (talar head) and socket (navicular concavity) | Primary site of midfoot motion - 50% inversion/eversion |
| Spring ligament complex | Plantar support from calcaneus to navicular | Loss leads to talar head plantar subluxation |
| Posterior tibial tendon | Inserts on navicular tuberosity | Dysfunction causes medial column collapse and TN stress |
| Triple joint complex | TN, subtalar, calcaneocuboid | Function as integrated unit - isolated pathology rare |
Motion Contribution
The TN joint is part of the oblique axis of the hindfoot, allowing combined:
- Inversion: 50% contribution to total hindfoot inversion (20-30 degrees)
- Eversion: 50% contribution to total hindfoot eversion (10-15 degrees)
- Forefoot locking: Critical for rigid lever during push-off
- Shock absorption: Allows hindfoot adaptability on uneven ground
Classification and Grading
Radiographic Classification
| Grade | Radiographic Findings | Clinical Correlation | Management |
|---|---|---|---|
| Grade 1 (Mild) | Joint space narrowing under 50%, minimal osteophytes | Mild pain with activity, preserved function | Conservative management preferred |
| Grade 2 (Moderate) | 50-75% joint space loss, moderate osteophytes, subchondral sclerosis | Moderate pain limiting activity | Surgical candidates after failed conservative |
| Grade 3 (Severe) | Bone-on-bone, large osteophytes, deformity, dorsal beaking | Severe pain at rest, functional limitation | Arthrodesis or arthroplasty indicated |
Clinical Assessment
History
- Pain location: Dorsomedial midfoot, navicular region
- Pain character: Aching at rest, sharp with activity
- Aggravating factors: Walking, stairs, uneven ground
- Associated symptoms: Arch collapse, forefoot abduction
- Functional impact: Distance limitation, altered gait
- Previous injuries: Midfoot trauma, ankle sprains
Examination
- Inspection: Medial arch height, forefoot abduction
- Palpation: TN joint tenderness, dorsal osteophytes
- Range of motion: Hindfoot inversion/eversion reduced
- Posterior tibial function: Single heel rise test
- Gait analysis: Antalgic, loss of push-off power
- Adjacent joints: Subtalar, ankle, first ray mobility
Do Not Miss Posterior Tibial Tendon Dysfunction
Up to 70% of TN arthritis cases have coexisting PTTD. Failure to address PTT dysfunction leads to recurrent deformity after TN fusion. Always perform single heel rise test and assess for too-many-toes sign. Stage the PTTD appropriately as it may alter surgical planning.
Physical Examination Maneuvers
Systematic Examination Sequence
Arch height: Evaluate medial longitudinal arch - collapsed versus normal. Hindfoot alignment: Valgus suggests PTTD, varus suggests other pathology. Too-many-toes sign: Visible lateral toes when viewing from behind = flatfoot.
Technique: Patient stands on affected leg and rises onto toes. Positive finding: Inability to rise or maintain position = PTT dysfunction. Heel inversion: Normal heel inverts during heel rise; absent in PTTD.
TN joint motion: Stabilize talus, move navicular - crepitus and pain. Subtalar motion: Inversion/eversion - compare to contralateral. Flexibility: Rigid versus flexible deformity affects surgical options.
TN stress test: Direct pressure over TN joint reproduces pain. Forefoot abduction stress: Worsens pain if TN unstable. Tiptoe test: Unable to achieve or maintain due to pain.
Investigations
Imaging Protocol
Views: AP, lateral, oblique foot radiographs standing. TN joint assessment: Joint space, osteophytes, dorsal beaking. Alignment: Talar head coverage by navicular, forefoot abduction. Adjacent joints: Evaluate subtalar and calcaneocuboid.
Indications: Surgical planning, assess deformity severity. Information: Bone stock quality, subchondral cyst size, fusion preparation. 3D reconstruction: Helpful for complex deformity understanding.
Indications: Assess PTT integrity, spring ligament, articular cartilage. Findings: Cartilage loss, bone marrow edema, tendon pathology. Role: Pre-operative planning when soft tissue pathology suspected.
Radiographic Findings
| Finding | Description | Clinical Implication |
|---|---|---|
| Joint space narrowing | Reduction in TN joint space under 2mm | Primary sign of arthritis - correlates with symptoms |
| Dorsal beaking | Osteophyte formation on dorsal navicular | Pathognomonic for chronic TN arthritis |
| Subchondral sclerosis | Increased density at articular surfaces | Chronic abnormal loading pattern |
| Talar head uncovering | Lateral subluxation, under 60% coverage | Indicates flatfoot deformity and PTTD |
Management Algorithm
Non-Operative Treatment
Indications:
- Mild to moderate symptoms
- Early-stage arthritis (Grade 1-2)
- Patient preference or medical comorbidities
- Minimum 6-month trial before considering surgery
Conservative Protocol
Reduce high-impact activities: Running, jumping, prolonged standing. Footwear: Supportive shoes with rocker-bottom sole, stiff midsole. Goal: Decrease stress on TN joint during daily activities.
Custom orthoses: Medial arch support, forefoot posting. Off-the-shelf: Arizona brace, UCBL orthosis for rigid support. Goal: Support arch, reduce TN motion, offload joint.
NSAIDs: First-line for pain and inflammation control. Corticosteroid injection: TN joint injection under image guidance. Duration: Maximum 2-3 injections per year.
Strengthening: Posterior tibial tendon, intrinsic foot muscles. Stretching: Gastrocnemius-soleus complex to reduce forefoot load. Gait training: Optimize mechanics to reduce TN stress.
Success Rate of Conservative Management
Approximately 40-50% of patients with mild to moderate TN arthritis achieve satisfactory symptom control with comprehensive conservative management. Predictors of success include flexible deformity, mild radiographic changes, and absence of significant PTTD.
Surgical Technique: Isolated TN Arthrodesis
Dorsomedial Approach to Talonavicular Joint
Surgical Steps
Position: Supine with bump under ipsilateral hip. Tourniquet: Thigh tourniquet recommended. C-arm: Position for AP, lateral, and oblique foot views.
Location: Dorsomedial foot, centered over TN joint. Landmarks: Start 2cm proximal to navicular tuberosity, extend distally 6-8cm. Orientation: Curvilinear following course of TN joint.
Identify: Extensor hallucis longus (EHL) tendon medially. Protect: Superficial peroneal nerve branches laterally. Develop: Interval lateral to EHL tendon.
Capsulotomy: Incise TN joint capsule dorsally. Exposure: Reflect capsule to expose articular surfaces completely. Identify: Talar head and navicular articular cartilage.
Neurovascular Structures at Risk
Superficial peroneal nerve: Dorsolateral to incision - identify and protect. Dorsalis pedis artery: Deep to extensor tendons - avoid excessive lateral retraction. Deep peroneal nerve: Adjacent to dorsalis pedis - preserve vascular supply.
Complications
| Complication | Incidence | Risk Factors | Management |
|---|---|---|---|
| Nonunion | 10-15% isolated TN, 15-20% double/triple | Smoking, diabetes, osteoporosis, poor bone contact | Revision fusion with bone graft and improved fixation |
| Adjacent joint arthritis | 20-30% at 10 years post-fusion | Increased motion demand, malalignment | Activity modification, orthoses, possible future fusion |
| Wound complications | 5-10% superficial infection, under 2% deep | Diabetes, smoking, poor soft tissue handling | Antibiotics for superficial, debridement for deep |
| Nerve injury | 2-5% temporary, under 1% permanent | Superficial peroneal nerve at risk | Usually resolves; neurolysis if persistent |
| Malunion | 5-10% malalignment | Poor intraoperative alignment, inadequate fixation | May require corrective osteotomy or revision |
Preventing Nonunion
Nonunion is the most common major complication. Prevention strategies: (1) Complete cartilage removal to bleeding bone, (2) Maximize bone contact surface area, (3) Rigid fixation with crossed screws or plate, (4) Bone graft for defects, (5) Post-op non-weight-bearing for 6-8 weeks, (6) Smoking cessation mandatory, (7) Optimize diabetes control.
Postoperative Care and Rehabilitation
Rehabilitation Timeline - Isolated TN Fusion
Immobilization: Below-knee cast or CAM boot. Weight-bearing: Non-weight-bearing with crutches. Elevation: Strict elevation to minimize swelling. Monitoring: Wound check at 2 weeks, suture removal.
Immobilization: Continue cast or boot. Weight-bearing: Non-weight-bearing continued. Radiographs: 6-week X-rays to assess fusion progress. DVT prophylaxis: Consider if risk factors present.
Weight-bearing: Transition to partial then full weight-bearing in boot. Criteria: Radiographic evidence of fusion (bridging trabeculae). Physical therapy: ROM exercises for adjacent joints. Monitoring: 12-week X-rays to confirm fusion.
Transition: Wean from boot to supportive shoe with orthosis. Activities: Gradual return to normal activities. Goals: Full weight-bearing, pain-free ambulation. Final assessment: 6-month clinical and radiographic evaluation.
Outcomes and Prognosis
| Outcome Measure | Isolated TN Fusion | Triple Arthrodesis | Notes |
|---|---|---|---|
| Fusion rate | 85-90% | 90-95% | Higher with plate fixation |
| Patient satisfaction | 80-85% | 75-85% | Pain relief primary driver |
| Return to activity | 70-80% return to pre-injury level | 60-70% | Younger, healthier patients do better |
| Adjacent joint arthritis | 20-30% at 10 years | 30-40% at 10 years | Increased with malalignment |
Predictors of Good Outcome
Positive Factors
- Successful fusion without complications
- Correct alignment restoration
- Isolated TN arthritis (no adjacent disease)
- Non-smoker, well-controlled diabetes
- Moderate activity expectations
Negative Factors
- Nonunion requiring revision
- Malalignment or malunion
- Pre-existing adjacent joint arthritis
- Smoking, uncontrolled diabetes
- High-impact activity demands
Evidence Base and Key Trials
Outcomes of Isolated Talonavicular Arthrodesis
- Retrospective series of 42 patients with isolated TN fusion
- 85% fusion rate at mean 18-month follow-up
- AOFAS scores improved from 42 to 78 post-operatively
- 15% developed adjacent joint symptoms within 5 years
Comparison of Single Versus Double Hindfoot Arthrodesis
- 44 isolated TN fusions versus 38 double arthrodesis (TN + STJ)
- Fusion rates similar (88% isolated vs 84% double)
- Hindfoot motion better preserved in isolated group (70% vs 40%)
- Adjacent joint arthritis rates similar at 5 years
Triple Arthrodesis Outcomes for Hindfoot Arthritis
- Long-term follow-up (average 25 years) of 132 triple arthrodeses
- 91% patient satisfaction at final follow-up
- Progressive ankle arthritis in 42% of patients
- Adjacent joint degeneration main limitation
Nonunion Rates in Talonavicular Arthrodesis
- Review of 95 TN arthrodesis procedures
- Overall union rate 89% at 6 months
- Risk factors for nonunion: smoking, rheumatoid arthritis, revision surgery
- Screw fixation alone associated with higher nonunion than combined techniques
Exam Viva Scenarios
Practice these scenarios to excel in your viva examination
Scenario 1: Diagnosis and Initial Management
"A 55-year-old woman presents with progressive medial midfoot pain over 2 years. She has difficulty walking more than 500 meters and notes that her arch has collapsed. On examination, she has tenderness over the TN joint, a flatfoot deformity, and can perform a single heel rise with difficulty. Weight-bearing radiographs show moderate TN joint space narrowing with dorsal beaking but preserved subtalar joint. How would you manage this patient?"
Scenario 2: Surgical Technique
"You have decided to proceed with isolated talonavicular arthrodesis in a 60-year-old diabetic patient with failed conservative management. Walk me through your surgical technique and key technical considerations."
Scenario 3: Complication Management
"At 6-month follow-up, your patient who underwent TN arthrodesis continues to have pain at the fusion site. Radiographs show a lucent gap at the TN joint with no bridging trabeculae. How do you manage this nonunion?"
MCQ Practice Points
Anatomy Question
Q: What percentage of total hindfoot inversion and eversion motion occurs at the talonavicular joint? A: 50% - The TN joint contributes approximately 50% of hindfoot inversion/eversion through its role in the oblique axis. Loss of TN motion shifts demands to subtalar and ankle joints.
Pathophysiology Question
Q: What is the most common cause of talonavicular arthritis? A: Post-traumatic arthritis - Midfoot fractures and dislocations are the leading cause. Adult-acquired flatfoot (PTTD Stage 3) is the second most common etiology.
Clinical Assessment Question
Q: What clinical sign is pathognomonic for chronic talonavicular arthritis on radiographs? A: Dorsal beaking of the navicular - Dorsal osteophyte formation on the navicular is characteristic of chronic TN arthritis and indicates longstanding degenerative changes.
Treatment Question
Q: What is the fusion rate for isolated talonavicular arthrodesis? A: 85-90% - Isolated TN fusion has high success rates. Nonunion occurs in 10-15% and is more common in smokers, diabetics, and cases with inadequate fixation.
Surgical Technique Question
Q: What is the standard fixation for isolated TN arthrodesis? A: Two crossed 3.5mm or 4.0mm cannulated screws - One screw from dorsal navicular to plantar talus, second from plantar navicular to dorsal talus. Crossed configuration provides rotational stability.
Complications Question
Q: What is the incidence of adjacent joint arthritis following isolated TN fusion at 10-year follow-up? A: 20-30% - Adjacent joint degeneration (subtalar, calcaneocuboid) occurs due to increased motion demands. Risk increased with malalignment and high activity levels.
Australian Context and Medicolegal Considerations
Public Hospital Pathways
- Category 2 for symptomatic arthritis affecting function
- Non-urgent elective for mild symptoms
- Allied health involvement: Podiatry and orthotics pre-operatively
- Multidisciplinary care: Diabetes, vascular, wound teams for diabetic patients
Informed Consent Essentials
- Nonunion risk: 10-15%, higher in smokers and diabetics
- Adjacent joint arthritis: 20-30% at 10 years
- Nerve injury: 2-5% superficial peroneal nerve
- Infection: 5-10% superficial, under 2% deep
- Prolonged recovery: 3-6 months to fusion, 6-12 months full recovery
Medicolegal Considerations
Key documentation requirements:
- Document comprehensive conservative trial (minimum 6 months) before surgery
- Assessment of adjacent joint status and reasoning for procedure selection
- Discussion of smoking cessation and diabetes optimization
- Detailed informed consent including nonunion and adjacent joint degeneration risks
- Post-operative non-compliance with weight-bearing restrictions can lead to failure - document instructions clearly