Midfoot Pain | Progressive Deformity | Surgical Reconstruction
ARTHRITIS SEVERITY
Critical Must-Knows
- TMT arthritis most commonly follows Lisfranc injury (missed or inadequate treatment)
- Second TMT joint is recessed - keystone preventing dorsal subluxation
- Fusion gold standard - motion at TMT 1-3 minimal (2-3 degrees), unlike TMT 4-5 (10-15 degrees)
- Selective fusion - fuse stiff medial column (TMT 1-3), preserve mobile lateral column (TMT 4-5)
- Non-union rate 5-15% with TMT arthrodesis - requires rigid fixation
Clinical Pearls
- "Distinguish primary vs post-traumatic (most common after Lisfranc injury)
- "Piano key sign on exam - dorsal subluxation of metatarsal bases
- "Weight-bearing radiographs essential - reveal instability not seen non-WB
- "Fusion extends medially if involves naviculocuneiform or intercuneiform joints
Critical TMT Arthritis Exam Points
Anatomy and Biomechanics
TMT 1-3 form rigid medial column. TMT 2 is keystone - recessed between cuneiforms preventing dorsal/plantar translation. Loss of this architecture causes collapse deformity.
Post-Traumatic Arthritis
80% of TMT arthritis is post-traumatic. Most follows inadequately treated Lisfranc injuries. Missed subtle injuries progress to arthritis within 2-5 years.
Surgical Decision
Selective fusion principle. Fuse medial column (TMT 1-3) for stability, preserve lateral column (TMT 4-5) for forefoot adaptation on uneven ground.
Operative Fixation
Rigid fixation mandatory. Non-union rate 5-15%. Use compression screws or dorsal plates. Avoid crossing unfused TMT 4-5 with hardware.
Quick Decision Guide
| Arthritis Severity | Clinical Features | Treatment | Key Pearl |
|---|---|---|---|
| Mild (Early) | Activity pain, minimal deformity, joint space preserved | Conservative: orthoses, activity modification | 80% respond to orthotics in first 2 years |
| Moderate | Daily pain, walking limitation, visible osteophytes | Trial conservative first, then arthrodesis | Steroid injections diagnostic - predicts fusion success |
| Severe | Constant pain, deformity, complete joint loss | Arthrodesis TMT 1-3 +/- NC/IC joints | Extend fusion if adjacent joint involvement on imaging |
KRISTMT Joint Stability Anatomy
| K | Keystone TMT 2 recessed between cuneiforms - prevents dorsal/plantar translation |
| R | Rigid medial column TMT 1-3 minimal motion (2-3 degrees) - forms stable arch base |
| I | Intermetatarsal ligaments Strong plantar and dorsal ligaments bind metatarsal bases |
| S | Sagittal plane motion TMT 4-5 allow 10-15 degrees - adapt forefoot to terrain |
| K | Keystone TMT 2 recessed between cuneiforms - prevents dorsal/plantar translation | I | Intermetatarsal ligaments Strong plantar and dorsal ligaments bind metatarsal bases |
| R | Rigid medial column TMT 1-3 minimal motion (2-3 degrees) - forms stable arch base | S | Sagittal plane motion TMT 4-5 allow 10-15 degrees - adapt forefoot to terrain |
Hook:KRIS keeps the midfoot stable - Keystone anatomy and Rigid medial column contrasts with mobile lateral column!
MIDASPost-Traumatic Arthritis Risk Factors
| M | Missed Lisfranc injury Subtle injuries missed on initial radiographs progress to arthritis |
| I | Inadequate reduction Residual subluxation greater than 2mm leads to degenerative changes |
| D | Delayed treatment Beyond 6 weeks - soft tissue contracture prevents anatomic reduction |
| A | Articular comminution Intra-articular fractures heal with step-off causing focal overload |
| S | Subluxation persistent Hardware failure or insufficient fixation allows recurrent instability |
| M | Missed Lisfranc injury Subtle injuries missed on initial radiographs progress to arthritis | A | Articular comminution Intra-articular fractures heal with step-off causing focal overload |
| I | Inadequate reduction Residual subluxation greater than 2mm leads to degenerative changes | S | Subluxation persistent Hardware failure or insufficient fixation allows recurrent instability |
| D | Delayed treatment Beyond 6 weeks - soft tissue contracture prevents anatomic reduction |
Hook:MIDAS touch turns Lisfranc injuries to gold - but missed injuries turn to arthritis!
FUSEArthrodesis Principles
| F | Fusion medial column TMT 1-3 arthrodesis - minimal functional loss due to low native motion |
| U | Unfuse lateral column Preserve TMT 4-5 motion for forefoot accommodation |
| S | Stable rigid fixation Compression screws or plates - prevent non-union (5-15% risk) |
| E | Extend fusion proximally Include NC/IC joints if arthritic - check pre-op weight-bearing CT |
| F | Fusion medial column TMT 1-3 arthrodesis - minimal functional loss due to low native motion | S | Stable rigid fixation Compression screws or plates - prevent non-union (5-15% risk) |
| U | Unfuse lateral column Preserve TMT 4-5 motion for forefoot accommodation | E | Extend fusion proximally Include NC/IC joints if arthritic - check pre-op weight-bearing CT |
Hook:FUSE the medial column, but don't fuse everything - selective fusion preserves function!
Overview and Epidemiology
Tarsometatarsal (TMT) arthritis affects the joints between the metatarsal bases and the three cuneiforms (medial, intermediate, lateral) and cuboid. This complex of five joints forms the anatomic and functional transition between the midfoot and forefoot.
Clinical Significance
TMT arthritis is predominantly post-traumatic, with 80% of cases following Lisfranc injuries. The majority result from inadequately treated or missed subtle injuries that progress to arthritis within 2-5 years. Primary osteoarthritis is less common and typically affects the first TMT joint in isolation.
Demographics
- Post-traumatic: Equal gender distribution, age 30-50 years
- Primary OA: Female predominance (2:1), age 50-70 years
- TMT 1 most commonly affected in primary OA
- TMT 1-3 involved in post-traumatic arthritis
Impact
- Chronic disability: 60% unable to return to previous activity level
- Work limitation: 40% change occupation or reduce hours
- Progressive deformity: Forefoot abduction, arch collapse if untreated
- Adjacent joint arthritis: 30% develop NC or IC joint involvement by 5 years
Anatomy and Biomechanics
Keystone Architecture Critical for Stability
The second TMT joint is recessed 2-3mm dorsally between the intermediate cuneiform and bases of metatarsals 1 and 3. This "keystone" configuration provides inherent stability, preventing dorsal or plantar translation. Loss of this architecture (in Lisfranc injuries or arthritis) causes progressive midfoot collapse.
| Joint | Native Motion | Role | Fusion Impact |
|---|---|---|---|
| TMT 1 | 2-3° sagittal | Push-off stability | Minimal - stiff joint |
| TMT 2 | 1-2° (least mobile) | Keystone stability | No functional loss |
| TMT 3 | 2-3° sagittal | Completes medial arch | Minimal functional loss |
| TMT 4 | 10-12° sagittal | Forefoot flexibility | Significant loss if fused |
| TMT 5 | 12-15° sagittal | Ground adaptation | Significant loss if fused |
Anatomic Subdivisions
Medial column (TMT 1-3):
- Rigid, minimal motion (2-3 degrees total)
- Forms longitudinal arch base
- Primary weight-bearing during stance and push-off
- Dense plantar ligamentous support (Lisfranc ligament from medial cuneiform to MT2 base)
Lateral column (TMT 4-5):
- Mobile, 10-15 degrees sagittal motion
- Allows forefoot accommodation on uneven terrain
- Less ligamentous constraint
- Fusion significantly impairs function
Ligamentous Anatomy
- Lisfranc ligament: Strongest ligament - medial cuneiform to MT2 base (plantar)
- Intermetatarsal ligaments: Strong dorsal and plantar connections between MT bases 2-5
- No intermetatarsal ligament between MT1-2: Explains common Lisfranc injury pattern
Clinical Relevance
- Keystone loss: TMT 2 dorsal subluxation causes forefoot abduction deformity
- Medial column collapse: Loss of longitudinal arch with planovalgus foot
- Lateral column overload: Fusion TMT 1-3 increases stress on TMT 4-5
Pathophysiology
Post-Traumatic Arthritis (80% of cases)
The most common pathway to TMT arthritis follows inadequately treated Lisfranc injuries:
Post-Traumatic Arthritis Progression
Lisfranc injury with ligamentous disruption or fracture-dislocation. Subtle injuries often missed on initial radiographs if not weight-bearing views obtained.
Inadequate reduction (greater than 2mm displacement) or hardware failure allows persistent malalignment. Abnormal joint loading begins.
Cartilage breakdown at areas of abnormal contact stress. Joint space narrowing visible on radiographs. Intermittent activity-related pain.
Progressive joint space loss, subchondral sclerosis, osteophyte formation. Daily pain, walking limitation. Deformity may be visible.
Complete joint space loss, subchondral cysts, collapse deformity. Adjacent naviculocuneiform and intercuneiform joints often involved. Constant pain.
Primary Osteoarthritis (20% of cases)
Primary TMT arthritis typically affects the first TMT joint in isolation, likely due to mechanical factors:
- Hypermobility: First ray instability from ligamentous laxity
- Hallux valgus association: Lateral thrust force from great toe deformity
- Inflammatory arthritis: Rheumatoid, psoriatic arthritis can involve TMT joints
Classification
Arthritis Severity (Descriptive)
No universally accepted classification system exists for TMT arthritis severity. Typically described by radiographic changes:
Mild Arthritis
Radiographic features:
- Joint space narrowing (under 50% loss)
- Minimal osteophytes
- No subchondral cysts
- Preserved alignment
Clinical correlation:
- Activity-related pain
- Minimal functional limitation
- Conservative management often successful
Treatment approach: Conservative with orthoses, activity modification, NSAIDs. Surgery only if conservative fails after 6 months.
Clinical Presentation
History
- Pain location: Dorsal midfoot, worse with weight-bearing
- Onset: Gradual worsening over months to years
- Trauma history: Previous Lisfranc injury or high-energy foot trauma
- Functional limitation: Difficulty walking on uneven ground, stairs
- Footwear issues: Shoes feel tight dorsally, pressure over prominences
Examination
- Inspection: Dorsal prominence, forefoot abduction, arch collapse
- Palpation: Tenderness over TMT joints, palpable osteophytes
- Piano key test: Dorsal-plantar translation of metatarsal bases (instability)
- Single limb stance: Unable to perform or significant pain
- Range of motion: Limited or painful dorsiflexion at TMT joints
Key Clinical Signs
Piano key sign: Grasp metatarsal shaft and attempt dorsal-plantar translation at TMT joint. Positive test shows increased motion and pain compared to contralateral foot. Indicates instability or advanced arthritis.
Midfoot break sign: Observe patient standing on tiptoes from behind. Normal foot shows smooth arch contour. Arthritic foot shows "break" or collapse at TMT level.
Distinguish from Adjacent Pathology
TMT arthritis pain must be differentiated from naviculocuneiform arthritis, posterior tibial tendon dysfunction, and plantar fasciitis. Specific tenderness localized to TMT joints with pain on metatarsal manipulation suggests TMT arthritis.
Differential Diagnosis
Midfoot Pain - Key Differentials
| Condition | Distinguishing Features | Best Discriminating Test |
|---|---|---|
| TMT (Lisfranc) arthritis | Dorsal midfoot pain over TMT joints, often post-traumatic, positive piano-key/instability | Weight-bearing radiographs; fluoroscopic intra-articular anaesthetic relieves pain |
| Naviculocuneiform arthritis | Pain more proximal/medial, sag at NC joint on lateral view | Lateral weight-bearing radiograph; selective NC injection |
| Posterior tibial tendon dysfunction | Medial pain, progressive flatfoot, weak single-heel-rise, too-many-toes sign | Single-heel-rise test; MRI/ultrasound of PTT |
| Stress fracture (metatarsal/navicular) | Focal bony tenderness, activity-related, athletes/military | MRI or CT; bone scan if early |
| Gout / inflammatory arthritis | Acute red hot swollen joint or polyarticular pattern, raised inflammatory markers | Joint aspirate (crystals), serology |
| Plantar fasciitis | Plantar heel pain worst on first steps, not dorsal midfoot | Clinical - tenderness at calcaneal origin |
Investigations
Imaging Protocol
Essential views: AP, lateral, and oblique of foot, weight-bearing mandatory. Assess joint space narrowing, osteophytes, subluxation, alignment. Compare to contralateral foot.
Gold standard for pre-operative planning. Evaluates extent of arthritis, involvement of adjacent NC/IC joints, assesses reducibility of deformity. 3D reconstruction helpful.
Useful if diagnosis uncertain or suspecting soft tissue pathology (tendon, ligament). Shows bone marrow edema indicating active arthritis. Less useful than CT for bony architecture.
Local anesthetic + steroid injection into TMT joints under fluoroscopy guidance. Complete pain relief confirms TMT arthritis as pain source. Predicts fusion success.
Radiographic Features
| Finding | Significance | Treatment Implication |
|---|---|---|
| Joint space narrowing | Early arthritis | Consider conservative trial first |
| Subchondral sclerosis | Established arthritis | Fusion likely needed if symptomatic |
| Osteophytes dorsal | Chronic arthritis | May require dorsal cheilectomy at fusion |
| Subluxation/dislocation | Post-traumatic | Fusion with deformity correction |
| NC/IC joint involvement | Advanced disease | Extend fusion proximally |
Management
Conservative Management
Conservative management is first-line for mild to moderate TMT arthritis without significant deformity.
Orthotic Management
- Rigid custom orthoses: Control midfoot motion, redistribute pressure
- Full-length carbon fiber inserts: Maximum rigidity for severe symptoms
- Rocker-bottom shoe modification: Reduces force through TMT joints
- Accommodative padding: Offload prominent osteophytes
Medical Management
- NSAIDs: Regular use for 2-3 months trial (if no contraindications)
- Activity modification: Avoid impact activities, prolonged walking
- Weight loss: Reduces midfoot loading (5-10kg loss significantly helps)
- Physical therapy: Strengthening intrinsic foot muscles, gait training
Injection Therapy
Corticosteroid injection:
- Useful for both diagnostic and therapeutic purposes
- Local anesthetic + steroid (triamcinolone 40mg or equivalent)
- Fluoroscopic guidance ensures accurate placement
- Complete pain relief confirms TMT arthritis as pain source
- Therapeutic effect typically 3-6 months
- Can be repeated up to 3 times
Interpretation: If complete pain relief achieved, arthrodesis likely to be successful. If no improvement, consider alternative diagnosis or adjacent joint pathology.
Surgical Management
Indications for Surgery
Absolute Indications
- Failed conservative management (6 months adequate trial)
- Significant functional limitation affecting daily life
- Progressive deformity
- Severe pain limiting walking
Relative Indications
- Failed multiple injection attempts
- High functional demand requiring return to activity
- Patient preference after informed consent
- Adjacent joint involvement developing
Surgical Options
TMT Arthrodesis (Gold Standard)
Principle: Fusion of affected TMT joints to eliminate painful motion while preserving adjacent joint function.
Selective fusion strategy:
- Fuse TMT 1-3 (medial column): Minimal functional loss due to low native motion
- Preserve TMT 4-5 (lateral column): Maintains forefoot flexibility for ground adaptation
- Extend proximally if needed: Include NC or IC joints if arthritic on pre-op imaging
Operative Steps
Dual dorsal longitudinal incisions over TMT 1-2 and TMT 2-3 intervals. Protect superficial peroneal nerve branches. Expose joints, perform joint debridement to bleeding bone.
Remove all cartilage with osteotomes and curettes. Fashion flat apposing surfaces. Avoid excessive bone resection (causes shortening, transfer metatarsalgia). Preserve metatarsal length.
Correct deformity. Restore longitudinal arch height. Ensure metatarsal alignment in coronal plane (no forefoot abduction). Check with intraoperative fluoroscopy in multiple planes.
Compression screws: 4.0mm cannulated screws across each TMT joint. Direct compression essential. Or dorsal plates: Low-profile 2.7-3.5mm plates if poor bone quality. Avoid crossing TMT 4-5.
Layered closure. Consider drain if significant oozing. Bulky compressive dressing. Below-knee non-weight-bearing cast applied.
Fixation options:
- Compression screws: Preferred for good bone quality, maximal compression
- Dorsal plates: Better for osteoporotic bone, deformity correction
- Combination: Plates + screws for severe deformity or revision
Outcomes:
- Fusion rate: 85-95%
- Good-excellent results: 80-90%
- Return to walking: 3-4 months
- Full recovery: 6-12 months
Selective fusion TMT 1-3 preserves lateral column motion and provides good functional outcomes.
Technical Pearls
Do's (Pearls)
- Adequate debridement: Remove all cartilage to bleeding subchondral bone
- Preserve length: Avoid excessive bone resection - causes transfer metatarsalgia
- Compression fixation: Use lag screws for maximal compression across fusion site
- Restore alignment: Check arch height and forefoot alignment with fluoroscopy
- Bone graft: Consider if gaps remain after reduction - promotes fusion
Don'ts (Pitfalls)
- Don't fuse TMT 4-5: Causes significant functional impairment - preserve lateral column
- Don't cross unfused joints: Hardware crossing TMT 4-5 causes pain, breakage
- Don't under-resect: Leaving cartilage islands causes non-union
- Don't rush weight-bearing: 6-8 weeks NWB mandatory for fusion success
- Don't ignore NC/IC arthritis: Check pre-op CT and extend fusion if involved
Complications
| Complication | Incidence | Risk Factors | Management |
|---|---|---|---|
| Non-union | 5-15% | Smoking, diabetes, inadequate fixation | Revision fusion with bone graft, rigid fixation |
| Malunion | 5-10% | Inadequate reduction, hardware failure | May require revision if symptomatic deformity |
| Transfer metatarsalgia | 10-15% | Excessive bone resection, malposition | Orthotic management, rarely revision surgery |
| Adjacent joint arthritis | 15-20% at 5y | Altered biomechanics | Extend fusion if symptomatic and severe |
| Infection | 2-5% | Diabetes, poor wound healing | Antibiotics, debridement, may need hardware removal |
| Hardware irritation | 10-20% | Prominent dorsal hardware | Remove after fusion (1 year post-op) |
Non-Union Prevention
Non-union is the most common major complication of TMT arthrodesis. Prevention strategies include: adequate cartilage debridement to bleeding bone, rigid fixation with compression, bone grafting for gaps, minimum 6-8 weeks non-weight-bearing, smoking cessation pre-operatively. If non-union occurs, revision with iliac crest bone graft and revised fixation typically successful.
Postoperative Care and Rehabilitation
Rehabilitation Timeline
Immobilization: Below-knee cast, strict non-weight-bearing. Elevate limb above heart level. DVT prophylaxis (aspirin or LMWH). Remove drain if placed (48 hours). First dressing change 2 weeks.
Continue NWB: New cast or CAM boot. Sutures removed 2-3 weeks. Repeat radiographs at 6 weeks. Check for early signs of healing (callus formation). Maintain NWB until radiographic healing seen.
Weight-bearing begins: If radiographs show healing callus, start progressive WB in CAM boot. Gradual increase from toe-touch to full WB over 4-6 weeks. Physical therapy for gait training, edema management. CT scan if healing uncertain at 12 weeks.
Transition to shoes: When full WB comfortable and radiographs confirm solid fusion (3-4 months). Custom orthoses for support. Gradual return to activities. Avoid high-impact until 6 months. May remove hardware if prominent after fusion solid (1 year).
Full recovery: 6-12 months for maximal improvement. Annual follow-up to monitor adjacent joints. Orthotic management indefinitely. Modify activities as needed. Monitor for transfer metatarsalgia.
The prolonged non-weight-bearing period is critical for fusion success.
Outcomes and Prognosis
TMT arthrodesis provides reliable pain relief and functional improvement for appropriately selected patients.
| Treatment | Key Outcomes | Notes |
|---|---|---|
| Conservative management | 60-80% initial success, 40% eventually require surgery | Best for mild arthritis, patient must accept activity limitations |
| TMT 1-3 arthrodesis | 85-95% fusion rate, 80-90% good-excellent results | Gold standard - selective fusion preserves lateral column |
| Extended fusion (NC/IC) | Similar outcomes but longer recovery | Indicated if adjacent joints involved - check pre-op CT |
Prognostic Factors
Predictors of Good Outcome
Favorable factors include: non-smoker, normal BMI, good bone quality, isolated TMT 1-3 arthritis (no adjacent joint involvement), compliant patient able to remain NWB for 6-8 weeks, adequate surgical technique with rigid fixation and compression.
Predictors of Poor Outcome
Unfavorable factors include: smoking (doubles non-union risk), diabetes, obesity, poor bone quality (osteoporosis), extensive adjacent joint arthritis, inadequate fixation or poor surgical technique, patient non-compliance with weight-bearing restrictions.
Controversies and Areas of Uncertainty
ORIF vs primary arthrodesis (bony injuries)
Level 1 evidence favours primary arthrodesis for purely ligamentous Lisfranc injuries. For bony fracture-dislocations the question is unresolved - no RCT shows clear superiority, and many surgeons still favour anatomic ORIF to preserve native joints.
Extent of fusion
How far medially/proximally to extend fusion (TMT 1-3 alone vs including NC/IC joints) is judgement-based. Over-fusion sacrifices motion; under-fusion risks residual painful arthritis. Komenda found extent of fusion did not significantly affect outcome.
Fixation construct
Transarticular lag screws vs dorsal locking plates (which spare articular cartilage) is debated. Plates may suit osteoporotic bone and deformity correction; screws give direct compression. No construct has proven superior union rates in high-quality trials.
Lateral column fusion
Whether the mobile lateral column (TMT 4-5) should ever be fused remains contentious because of functional loss. Interposition arthroplasty and resection are described alternatives, but evidence is limited to small series.
Examiner hot-topic
The classic viva trap is to over-generalise the Ly and Coetzee RCT to all Lisfranc injuries. State clearly that its conclusion (primary arthrodesis superior) is established only for isolated, primarily ligamentous injuries.
Evidence Base and Key Studies
Primary Arthrodesis vs ORIF for Ligamentous Lisfranc Injury (Landmark RCT)
- Prospective randomised trial of 41 isolated primarily ligamentous Lisfranc injuries
- Primary arthrodesis of the medial two-to-three rays vs open reduction and screw fixation
- At 2 years, mean AOFAS Midfoot score 88 (arthrodesis) vs 68.6 (ORIF), p less than 0.005
- 5 of 20 ORIF patients developed deformity or arthrosis and were salvaged with fusion
Primary Arthrodesis vs ORIF - Reoperation Burden (RCT)
- 40 acute tarsometatarsal fracture/fracture-dislocations randomised to ORIF or primary arthrodesis
- Secondary surgery (including routine hardware removal) 78.6% after ORIF vs 16.7% after arthrodesis
- No significant difference in SF-36 or SMFA functional scores between groups
- Satisfaction comparable at mean 53 months
Arthrodesis for Post-Traumatic Midfoot Arthritis
- Retrospective series of 32 patients fused for intractable midfoot pain after trauma (mean 35 months post-injury)
- Mean AOFAS Midfoot score improved from 44 to 78 of 100 (p = 0.02)
- Only one asymptomatic non-union; complications included neuritis (3), metatarsalgia (2), malunion (2)
- Extent of fusion and injury mechanism did not significantly affect functional outcome
Salvage Arthrodesis of the Lisfranc Joint
- 16 patients (49 joints) salvaged by arthrodesis after failed initial Lisfranc treatment
- Good-to-excellent result in 11 of 16 (69%); symptomatic non-union at 4 sites in 3 patients
- Accurate reduction and early treatment correlated with better outcome
- Work-related injury and long delay to treatment correlated with worse outcome
Midfoot Joint Motion - Biomechanical Basis for Selective Fusion
- In vitro study of 10 cadaveric below-knee specimens with reference-pin tracking
- Medial column near-rigid: middle cuneiform-MT2 0.6 degrees and medial cuneiform-MT1 3.5 degrees of sagittal motion
- Lateral column mobile: cuboid-MT4 9.6 degrees and cuboid-MT5 10.2 degrees of sagittal motion
- Confirms TMT2 as the least mobile (keystone) articulation
Lisfranc Injury - Diagnosis and Treatment Algorithm (Review)
- Narrative review proposing a classification-free, stability-based treatment algorithm
- Delay in diagnosis worsens outcome; weight-bearing radiographs best assess stability
- Stable injuries treated non-operatively; unstable ligamentous injuries favour primary arthrodesis
- For bony unstable injuries, ORIF vs primary arthrodesis remains unresolved - more RCTs needed
Exam Viva Scenarios
Use these scenarios to practise clinical reasoning and management decisions
Scenario 1: Post-Traumatic TMT Arthritis
"A 45-year-old manual laborer presents with 2 years of progressive midfoot pain following a crush injury. He has tried orthotics and NSAIDs without benefit. Examination shows dorsal tenderness over TMT joints and positive piano key test at TMT 2-3. Weight-bearing radiographs show joint space loss at TMT 1-3 with subchondral sclerosis. How would you manage this patient?"
Scenario 2: Surgical Technique Discussion
"You are performing TMT 1-3 arthrodesis for post-traumatic arthritis. Walk me through your surgical approach, joint preparation, and fixation technique. What are the key technical points to ensure fusion success?"
Scenario 3: Complication Management - Non-Union
"A 52-year-old patient had TMT 1-3 arthrodesis 9 months ago. She followed weight-bearing restrictions but now complains of persistent midfoot pain with walking. Radiographs show lucency at TMT 2 fusion site with no bridging bone. CT confirms non-union at TMT 2. How would you manage this complication?"
MCQ Practice Points
Anatomy Question
Q: Which TMT joint is the keystone of the midfoot, recessed dorsally between adjacent metatarsals to provide stability? A: TMT 2 (second tarsometatarsal joint). The second metatarsal base is recessed 2-3mm dorsally between the intermediate cuneiform and the bases of MT1 and MT3. This keystone architecture provides inherent stability preventing dorsal or plantar translation.
Biomechanics Question
Q: What is the rationale for selective fusion of TMT 1-3 while preserving TMT 4-5 in TMT arthrodesis? A: TMT 1-3 have minimal native motion (2-3 degrees each) forming the rigid medial column, so fusion causes minimal functional loss. TMT 4-5 have significantly more motion (10-15 degrees) forming the mobile lateral column which allows forefoot adaptation to uneven terrain. Fusing the lateral column causes significant functional impairment.
Etiology Question
Q: What percentage of TMT arthritis is post-traumatic, and what is the most common preceding injury? A: 80% of TMT arthritis is post-traumatic, most commonly following inadequately treated Lisfranc injuries. Missed subtle injuries or residual subluxation greater than 2mm progresses to arthritis within 2-5 years. Anatomic reduction of Lisfranc injuries is critical to prevent arthritis.
Treatment Question
Q: What is the fusion rate for TMT 1-3 arthrodesis and what is the most common major complication? A: Fusion rate is 85-95% with good-excellent results in 80-90% of patients. The most common major complication is non-union (5-15% incidence). Risk factors include smoking, diabetes, inadequate fixation, and insufficient post-operative non-weight-bearing period.
Surgical Technique Question
Q: What is the critical technical principle to prevent non-union in TMT arthrodesis? A: Complete cartilage removal to bleeding subchondral bone is the most critical factor. All cartilage must be debrided with osteotomes and curettes, leaving no cartilage islands. Other important factors include rigid compression fixation, bone grafting for gaps, and minimum 6-8 weeks non-weight-bearing post-operatively.
Complication Question
Q: What complication occurs in 10-15% of TMT arthrodesis patients due to excessive bone resection at the fusion site? A: Transfer metatarsalgia. Excessive bone resection during joint preparation causes metatarsal shortening, which alters weight distribution and causes overload of adjacent metatarsals. Prevention requires preserving metatarsal length by avoiding over-resection of bone.
Guidelines, Registries & Global Practice
Global Epidemiology
- Midfoot (Lisfranc) injuries account for roughly 0.2% of all fractures, with an incidence around 1 per 55,000 person-years; up to 20-40% of low-energy injuries are missed at first presentation.
- Post-traumatic arthritis is the dominant pathway to symptomatic TMT arthritis worldwide; the strongest modifiable predictor is the quality of initial reduction.
- Primary (atraumatic) TMT osteoarthritis is less common, has a female predominance, and most often isolates to the first TMT joint, frequently in association with hallux valgus or first-ray hypermobility.
Side-by-Side Society Guidance
| Body | Position on midfoot injury / TMT arthritis | Practical message |
|---|---|---|
| AO Foundation | Anatomic reduction and stable fixation of Lisfranc injuries; primary arthrodesis favoured for comminuted or purely ligamentous patterns | Restore the medial-column keystone to prevent later arthritis |
| AOFAS (US) | Weight-bearing and stress imaging to detect subtle instability; arthrodesis is the standard salvage for established arthritis | Do not rely on non-weight-bearing films |
| BOA / BOAST (UK) | Early senior review of suspected midfoot injuries, weight-bearing radiographs, prompt definitive management | Minimise diagnostic delay |
| EFORT / European consensus | Stability-based (not classification-based) treatment; primary arthrodesis for ligamentous instability | Stability drives the decision |
Where guidelines genuinely differ
The unresolved controversy across all societies is bony unstable Lisfranc injuries: ORIF vs primary arthrodesis. For purely ligamentous instability the evidence (Ly and Coetzee RCT) favours primary arthrodesis; for bony injuries there is no Level 1 consensus and practice varies by surgeon and region.
Registry and Outcome Notes
- TMT arthritis and Lisfranc injuries are not implant-registry tracked the way hip/knee arthroplasty is (no NJR/AJRR/AOANJRR equivalent), so the evidence base rests on RCTs and case series rather than national registries.
- Across published series, medial-column arthrodesis achieves union in roughly 85-95% with good-to-excellent results in 80-90%; non-union (5-15%) is driven mainly by smoking, diabetes, and inadequate fixation.
High- vs Limited-Resource Practice
- Well-resourced settings: weight-bearing CT for planning, low-profile locking plates and lag screws, fluoroscopy, and protected non-weight-bearing with formal physiotherapy.
- Limited-resource settings: weight-bearing plain radiographs and clinical examination guide treatment; transarticular screws or K-wires substitute for plates; emphasis on accurate primary reduction is even greater because salvage surgery and imaging are less available.
- Universal principle regardless of resources: anatomic reduction of the medial-column keystone and early definitive management are the single most important determinants of avoiding post-traumatic arthritis.
TMT ARTHRITIS
Clinical summary
Key Anatomy
- •TMT 2 = Keystone - recessed 2-3mm dorsally between cuneiforms prevents translation
- •Medial column (TMT 1-3) = Rigid, minimal motion (2-3° each) - safe to fuse
- •Lateral column (TMT 4-5) = Mobile (10-15° motion) - preserve function
- •Lisfranc ligament = Strongest ligament from medial cuneiform to MT2 base plantar
Classification
- •Mild = Joint space narrowing under 50%, minimal osteophytes → Conservative trial
- •Moderate = 50-75% joint space loss, sclerosis → Trial conservative, then fuse if fails
- •Severe = Complete joint space loss, cysts, deformity → Arthrodesis indicated
- •Post-traumatic = 80% of cases - follows inadequately treated Lisfranc injury (residual displacement greater than 2mm)
Treatment Algorithm
- •First-line: Custom rigid orthoses + NSAIDs + activity modification (6 months trial)
- •Diagnostic injection: Confirms diagnosis, predicts fusion success if complete relief
- •Surgery: TMT 1-3 arthrodesis with compression screws or dorsal plates
- •Extend fusion: Include NC/IC joints if arthritic on pre-op CT
Surgical Pearls
- •Dual dorsal incisions protecting superficial peroneal nerve branches
- •Complete cartilage removal to bleeding bone - leave no islands
- •Preserve metatarsal length - avoid over-resection (causes transfer metatarsalgia)
- •Rigid compression fixation - 4.0mm screws preferred, plates if poor bone
- •NEVER cross unfused TMT 4-5 with hardware - causes pain and breakage
Complications
- •Non-union 5-15% - smoking, diabetes, inadequate fixation - revise with bone graft
- •Transfer metatarsalgia 10-15% - from excessive bone resection/shortening
- •Adjacent joint arthritis 15-20% at 5y - altered biomechanics - extend fusion if severe
- •Hardware irritation 10-20% - remove after fusion solid (1 year post-op)