import { ComparisonTable, ContentSection, EvidenceCard, ExamCheatSheet, ExamPearl, ExamWarning, InfoCard, InfoCardGrid, MedicalImage, MnemonicCard, OnePagerSummary, SafetyAlert, Tab, Tabs, Timeline, TimelineItem, VivaScenario, VivaScenarioSection } from '@/components/mdx' {/* SECTION 1: ONE-PAGER SUMMARY */} {/* SECTION 2: EXAM WARNING */} **FDL runs deep to PTT** in tarsal tunnel. Harvest distal to master knot of Henry. Transfer through drill hole in navicular with interference screw or suture anchor fixation. **10-20° heel valgus** requires correction. MDCO shifts calcaneus medially 10-12mm, restoring lever arm. Lateral column may need lengthening if abduction deformity present. **Stage I**: Conservative ± debridement. **Stage II flexible**: FDL + MDCO ± LCL lengthening. **Stage III rigid**: Triple arthrodesis. **Stage IV**: Deltoid reconstruction or ankle fusion. **Operate when conservative fails** (6 months orthosis/PT) OR **rapid progression**. Delay leads to rigidity (Stage III) requiring arthrodesis. Early Stage II has best outcomes. {/* SECTION 2.5: AT A GLANCE QUICK DECISION TABLE */} {/* SECTION 3: MNEMONICS */} {/* SECTION 4: OVERVIEW AND EPIDEMIOLOGY */} PTTD is the most common cause of acquired adult flatfoot deformity. Without intervention, Stage II flexible deformity progresses to Stage III rigid deformity requiring arthrodesis. Early surgical reconstruction with FDL transfer and MDCO in Stage II preserves hindfoot motion while correcting alignment, achieving 85-90% good outcomes in appropriately selected patients. - **Age**: 40-60 years (active adults) - **Gender**: Female predominance 9:1 - **Risk factors**: Obesity (BMI over 30), diabetes, hypertension, steroid use - **Bilateral**: 10-20% have contralateral involvement - **Stage I to II**: 50% progress within 2-5 years - **Stage II to III**: 30-40% develop rigidity without treatment - **Stage III**: Arthrodesis required (loss of hindfoot motion) - **Stage IV**: Ankle valgus tilt = poor outcomes even with fusion {/* SECTION 5: DETAILED ANATOMY AND BIOMECHANICS */} The FDL runs **deep to the PTT** throughout the tarsal tunnel, sharing a common synovial sheath proximally. At the level of the sustentaculum tali, the tendons diverge - PTT courses superficially and medially to insert on the navicular tuberosity, while FDL continues distally passing under the master knot of Henry (where it crosses superficial to FHL) before inserting on the distal phalanges of the lateral four toes. This anatomical proximity makes FDL the ideal transfer for PTT reconstruction. **Normal function:** - PTT inverts heel during stance phase - Locks transverse tarsal joint (Chopart) for rigid lever - Maintains medial longitudinal arch **After PTT failure:** - Heel drifts into valgus (ground reaction force lateral to ankle) - Transverse tarsal joint unlocks (midfoot collapse) - Arch collapses (flatfoot deformity) - Forefoot abducts relative to hindfoot (too many toes sign) **How MDCO works:** - Medial shift of calcaneus 10-12mm - Ground reaction force shifts medial to ankle joint - Achilles now creates inversion moment (vs eversion before) - Reduced load on reconstructed PTT - Corrects heel valgus 10-20° **Why combination surgery works:** - FDL provides active support - MDCO provides passive correction - Synergistic effect = 85-90% success {/* SECTION 6: CLASSIFICATION SYSTEMS */} ### Johnson & Strom Classification (1989, Modified 1997) The critical distinction is **Stage II flexible** (correctable deformity) versus **Stage III rigid** (fixed deformity). This determines whether joint-sparing soft tissue reconstruction is possible or whether arthrodesis is required. Test with passive correction - if heel valgus and arch collapse can be fully corrected passively, patient is Stage II and a candidate for FDL transfer + MDCO. If deformity is fixed, patient is Stage III and requires triple arthrodesis. ### Myerson Substaging of Stage II (Useful for Surgical Planning) The **too many toes sign** indicates forefoot abduction. Standing behind the patient, you see more than 1-2 toes lateral to the heel. This indicates Stage IIb or IIc and requires lateral column lengthening in addition to standard FDL + MDCO to address the transverse plane deformity. Understanding these substages helps in surgical planning and patient outcomes. {/* SECTION 7: CLINICAL ASSESSMENT */} - **Symptoms**: Progressive medial ankle pain and swelling - **Functional loss**: Difficulty with prolonged walking, stairs, uneven ground - **Deformity awareness**: Noticed progressive flatfoot, shoe wear changes - **Single heel raise**: Unable to perform (Stage II or higher) - **Conservative treatment**: Duration and response to orthoses, PT, NSAIDs - **Inspection**: Flatfoot deformity, heel valgus, too many toes sign from behind - **Palpation**: PTT tenderness medial ankle to navicular insertion - **Single heel raise test**: Inability = PTT dysfunction Stage II or higher - **Passive correction**: Can deformity be corrected? (Flexible vs rigid) - **Ankle examination**: Check for deltoid tenderness, valgus instability (Stage IV) Always examine the ankle in PTTD patients. Stage IV involves deltoid ligament incompetence with ankle valgus tilt. Check for medial ankle tenderness over deltoid, perform valgus stress test, and obtain mortise ankle X-ray to measure medial clear space (normal under 4mm) and talar tilt. Missing Stage IV leads to undertreatment - triple arthrodesis alone will fail without addressing ankle instability. {/* SECTION 8: INVESTIGATIONS */} **Views required:** - AP foot (talus-first metatarsal angle - normal under 4°, PTTD often over 30°) - Lateral foot (medial arch collapse, talus-first metatarsal angle, calcaneal pitch) - Hindfoot alignment view (heel valgus measurement) **Key measurements:** - Lateral talus-first MT angle (normal 0-4°, Stage II often 15-30°) - Calcaneal pitch angle (normal 20-30°, Stage II often under 15°) - Talonavicular coverage angle (uncoverage indicates deformity) **Stage IV addition:** - Ankle mortise view (medial clear space, talar tilt) **Indications:** - Confirm PTT pathology (tear vs degeneration vs tenosynovitis) - Assess spring ligament integrity (may require reconstruction) - Rule out alternative diagnosis **Not required for surgical decision** if clinical diagnosis clear and deformity pattern evident on weight-bearing X-rays. **Hindfoot alignment stress views:** - Determine if deformity is flexible (correctable) or rigid (fixed) - Critical for Stage II vs Stage III distinction - If deformity corrects with stress = Stage II = soft tissue reconstruction - If deformity fixed = Stage III = arthrodesis required Non-weight-bearing radiographs **underestimate deformity** in PTTD. Always obtain weight-bearing AP, lateral, and hindfoot alignment views. The deformity may appear minimal or absent on non-weight-bearing films but become evident under physiological load. This can lead to underestimation of surgical requirements and inappropriate procedure selection. {/* SECTION 9: MANAGEMENT ALGORITHM */} ### Stage II Surgical Algorithm (Flexible Deformity) **Goal**: Restore PTT function, correct alignment, preserve hindfoot motion. **Hindfoot valgus only (Stage IIa):** - FDL transfer + MDCO **Hindfoot valgus + forefoot abduction (Stage IIb):** - FDL + MDCO + lateral column lengthening (Evans or CC distraction) **Hindfoot valgus + forefoot abduction + forefoot varus (Stage IIc):** - FDL + MDCO + LCL lengthening + Cotton osteotomy (medial cuneiform opening wedge) **Test**: Manually correct heel valgus and arch collapse with patient sitting. **If fully correctable** = Stage II = proceed with soft tissue reconstruction **If rigid** = Stage III = arthrodesis required (soft tissue reconstruction will fail) Assess spring ligament complex during FDL transfer. If complete tear or severe attenuation, perform spring ligament reconstruction with suture anchor repair or augmentation. - Weeks 0-6: Non-weight-bearing in short leg cast - Weeks 6-10: Partial weight-bearing in boot - Weeks 10-12: Full weight-bearing in boot - Week 12+: Transition to supportive shoe with custom orthosis - Return to activity: 4-6 months FDL transfer alone has 60-70% success rate. MDCO alone does not address PTT loss. **FDL transfer + MDCO** achieves 85-90% good outcomes because: 1. FDL provides **active dynamic support** (tendon muscle unit) 2. MDCO provides **passive static correction** (bony realignment) 3. MDCO **offloads the reconstructed tendon** by shifting ground reaction force medially 4. Combination addresses both soft tissue and bony components of deformity This combination approach is the gold standard for Stage II PTTD. ### Stage III Surgical Algorithm (Rigid Deformity) **Goal**: Restore alignment, relieve pain, accept loss of hindfoot motion. **Triple arthrodesis** = fusion of three joints: 1. Talonavicular (most important for deformity correction) 2. Subtalar (talocalcaneal) 3. Calcaneocuboid Fusing all three joints is necessary because they are interdependent - isolated fusion leads to adjacent joint arthritis. - **Heel valgus**: Correct to neutral or slight varus (5° varus) - **Forefoot abduction**: Correct to neutral alignment - **Medial arch**: Restore appropriate height - **Avoid overcorrection**: Rigid cavovarus worse than mild residual valgus - **Talonavicular**: Staples or crossed screws (most critical fusion) - **Subtalar**: 1-2 screws from calcaneus into talus - **Calcaneocuboid**: Staple or screw Ensure compression at all fusion sites. Bone graft if significant deformity correction or bone loss. - Weeks 0-6: Non-weight-bearing in short leg cast - Weeks 6-12: Partial weight-bearing in boot (check X-rays for healing) - Weeks 12-16: Progress to full weight-bearing - Fusion typically complete by 12-16 weeks - Return to activity: 6-9 months Triple arthrodesis for Stage III PTTD achieves **80-85% good outcomes** in pain relief and patient satisfaction. However, **loss of hindfoot motion** (inversion/eversion) affects ability to walk on uneven ground. Adjacent joint arthritis (ankle, midfoot) occurs in 20-30% at 10 years. This is why early surgical intervention in Stage II is preferred - preserve hindfoot motion with FDL + MDCO. Understanding the trade-offs helps in patient counseling. ### Stage IV Surgical Algorithm (Ankle Valgus Tilt) **Goal**: Restore hindfoot AND ankle alignment, prevent progressive ankle arthritis. **Mortise ankle view:** - Medial clear space over 4mm (normal under 4mm) - Talar tilt (lateral tilt of talus in mortise) **Indicates deltoid insufficiency** - triple arthrodesis alone will fail because ankle instability persists. **Indications**: Stage IV with ankle instability but no significant ankle arthritis. **Technique**: - Perform triple arthrodesis to correct hindfoot - Reconstruct deltoid with allograft or autograft (semitendinosus) - Protect with ankle brace postoperatively **Outcomes**: Variable, 60-70% success, risk of recurrent instability. **Indications**: Stage IV with established ankle valgus arthritis. **Technique**: - Fuse ankle (tibiotalar) AND hindfoot (subtalar, talonavicular) in one construct - Intramedullary nail from calcaneus through talus into tibia - Correct valgus alignment to neutral **Outcomes**: 75-80% fusion rate, significant functional limitation (loss of ankle AND hindfoot motion), salvage procedure. Stage IV has **poorest outcomes** of all PTTD stages. Emphasize to patients: - Significant functional limitation expected - Loss of ankle and hindfoot motion - Adjacent joint arthritis risk (knee, midfoot) - Salvage procedure to prevent further deterioration Performing triple arthrodesis alone in a Stage IV patient (ankle valgus present) leads to **failure**. The ankle instability persists, causing recurrent deformity or progressive ankle arthritis. Always obtain ankle mortise view in PTTD patients to assess for medial clear space widening and talar tilt. If present, must address ankle instability with deltoid reconstruction or TTC fusion. Stage IV requires comprehensive ankle and hindfoot treatment. {/* SECTION 10: SURGICAL TECHNIQUE */} ### Patient Positioning and Setup **Supine position** on standard operating table. - **Affected limb**: Bump under ipsilateral hip to internally rotate leg (improves access to medial ankle and hindfoot) - **Knee**: Flexed 30-40° with padded support - **Contralateral limb**: Padded and positioned comfortably - **Sacrum and coccyx**: Gel padding to prevent pressure ulcers - **Contralateral heel**: Padded support - **Arms**: Tucked or on arm boards, avoid excessive abduction (brachial plexus) - **Bony prominences**: All contact points padded - **Thigh tourniquet**: Padded, inflated to 300mmHg (or limb occlusion pressure + 100mmHg) - **Exsanguination**: Elevate limb 2 minutes OR Esmarch bandage - **Typical tourniquet time**: 90-120 minutes for FDL + MDCO combination - **Landmarks exposed**: Medial ankle, medial hindfoot, lateral calcaneus visible - **Foot and ankle**: Free draped to allow manipulation and assessment of correction - **Imaging**: C-arm positioned for AP, lateral, and oblique foot views Placing a bump under the **ipsilateral hip** internally rotates the leg, bringing the medial ankle and hindfoot into better surgical view. This improves access to the PTT, FDL harvest site, and navicular insertion. Without this positioning, the surgeon must work around the leg externally rotated, making exposure more difficult. Proper positioning optimizes surgical exposure and efficiency. ### FDL Harvest and Transfer to Navicular **Curvilinear medial incision:** - Start 8cm proximal to medial malleolus - Curve posterior to medial malleolus - Extend distally to navicular tuberosity - Length: Approximately 10-12cm **Protects**: Saphenous vein and nerve (anterior to incision), posterior tibial neurovascular bundle (posterior) - Open flexor retinaculum (tarsal tunnel release) - Identify PTT (most superficial tendon in tunnel) - Identify FDL **deep to PTT** - shares common sheath proximally - At level of sustentaculum tali, PTT and FDL separate - FDL continues distally, coursing deep and plantar - Follow FDL distally to **master knot of Henry** (where FDL crosses superficial to FHL) - Make small plantar incision to access FDL at this level - **Transect FDL distal to knot of Henry** with scalpel - Pull FDL proximally into main incision (will strip from toe insertions) - Typical harvest length: 12-15cm - Expose navicular tuberosity (medial prominence of navicular bone) - Identify PTT insertion (may be degenerated or torn) - Create drill hole: **Plantar-to-dorsal direction**, starting just plantar to PTT insertion, exiting dorsal navicular - Drill size: 6-8mm to accommodate tendon graft - Thread FDL through navicular tunnel from plantar to dorsal - Ensure tendon passes smoothly without kinking - Pull FDL tight with foot held in **maximum plantarflexion and inversion** - This position restores arch and tensions tendon appropriately **Fixation options:** - **Interference screw** (preferred): Insert screw alongside tendon in tunnel, compresses tendon against bone - **Suture anchor**: Place anchor on dorsal navicular, suture tendon to bone - **Bone tunnel with suture**: Pass sutures through second tunnel, tie over dorsal bridge **Check tension:** Foot should maintain arch with tendon under appropriate tension. If substantial PTT tissue remains (Stage I-IIa), can perform **side-to-side anastomosis** of FDL to PTT remnant for augmentation. If PTT is severely degenerated (Stage IIb-IIc), FDL acts as **primary reconstruction** without PTT repair. If you transect FDL **proximal** to the master knot of Henry, you lose length and may disrupt the FHL (which crosses deep to FDL at this point). Always harvest **distal** to the knot of Henry. The tendon will strip from its toe insertions as you pull it proximally - this is expected and causes minimal donor morbidity (flexion of lateral toes is not functionally significant). FDL transfer provides active dynamic arch support and PTT function. ### Medial Displacement Calcaneal Osteotomy **Lateral oblique incision:** - 4-5cm incision centered over lateral calcaneus - Start 2cm distal to lateral malleolus - Extend distally toward calcaneal-cuboid joint **Protects**: Sural nerve (posterior to incision) - Incise periosteum longitudinally - Elevate periosteum superiorly and inferiorly to expose lateral calcaneal wall - Identify **proposed osteotomy level**: 1.5-2cm distal to posterior calcaneal tuberosity - Must be posterior to calcaneocuboid joint (check with fluoroscopy) - **Osteotomy orientation**: **Perpendicular to long axis of calcaneus** (in sagittal plane) - **Slight dorsal-plantar obliquity**: Dorsal to plantar direction (prevents plantar fragment displacement) - Use **oscillating saw** to create osteotomy - **Complete cut** through medial cortex (check with fluoroscopy) - Use **bone clamp or laminar spreader** to displace posterior fragment medially - **Translation distance**: 10-12mm (approximately 1cm) - **Goal**: Correct heel valgus to neutral or slight varus (5° varus ideal) - **Assess correction**: - Clinically: Heel alignment from posterior view - Fluoroscopy: Lateral view shows medial shift, calcaneal pitch improved **Screw fixation:** - Insert **2 screws** from lateral to medial across osteotomy site - Screw size: 6.5mm or 7.0mm partially threaded cancellous screws - Direction: Angled slightly dorsal-to-plantar - Compression: Tighten screws to compress osteotomy (promotes healing) **Check fluoroscopy**: Confirm screw position, adequate compression, maintained correction. With FDL transfer and MDCO complete: - **Heel alignment**: Should be neutral or slight varus - **Arch**: Restored with FDL tensioned appropriately - **Forefoot abduction**: If significant residual abduction, may need lateral column lengthening (see next tab) The medial displacement of the calcaneus shifts the **ground reaction force medial** to the ankle joint axis. This changes the Achilles tendon moment arm from an **eversion moment** (before MDCO) to an **inversion moment** (after MDCO). This passive correction offloads the reconstructed FDL, allowing it to function in a biomechanically favorable environment. Without MDCO, FDL transfer alone has only 60-70% success because the heel valgus persists and overpowers the tendon. MDCO is the essential bony complement to FDL soft tissue reconstruction. ### Lateral Column Lengthening (Evans or CC Distraction) **Indication**: Stage IIb with forefoot abduction (too many toes sign) that persists after FDL + MDCO. **Evans osteotomy** lengthens the lateral column (anterior calcaneus) by inserting a bone graft wedge into the anterior calcaneal body. This corrects forefoot abduction by: - Lengthening lateral column relative to medial column - Rotating forefoot from abduction to neutral - Locking transverse tarsal joint (Chopart) - **Site**: 1-1.5cm proximal to calcaneocuboid joint - **Avoid joint**: Must be in calcaneal body, not in CC joint (causes arthritis) - **Orientation**: Perpendicular to long axis of calcaneus - Insert **laminar spreader** into osteotomy - Gradually distract to correct forefoot abduction - **Target distraction**: 8-12mm (measure with calibrated spreader or implant trial) - **Fluoroscopy check**: Talus-first MT angle improves (should correct to under 10-15°) **Graft options:** - **Autograft**: Tricortical iliac crest (gold standard, but donor site morbidity) - **Allograft**: Femoral head wedge or tricortical iliac crest allograft (preferred to avoid donor site) - **Synthetic**: Porous metal or calcium phosphate wedge (weaker fixation) Insert graft wedge to maintain distraction. - **Plate fixation**: Small fragment plate across osteotomy (more stable) - **Screw fixation**: 1-2 screws across graft (less stable, graft can collapse) Ensure graft is compressed and stable. **Overcorrection** of Evans osteotomy (distraction over 12mm) can create **excessive forefoot adduction** and **lateral column overload**. This leads to painful calcaneocuboid arthritis. Conservative distraction (8-10mm) is safer. If more correction needed, consider calcaneal-cuboid distraction arthrodesis (see below). Lateral column lengthening corrects forefoot abduction in advanced PTTD. ### Cotton Osteotomy (Medial Cuneiform Opening Wedge) **Indication**: Residual **forefoot varus** after hindfoot correction with FDL + MDCO ± LCL. After correcting hindfoot valgus with MDCO, the forefoot may be in **relative varus** (medial column plantarflexed, lateral column dorsiflexed). This creates an unstable foot and may overload lateral column. **Cotton osteotomy** elevates the medial column by opening wedge osteotomy of the medial cuneiform, restoring forefoot-hindfoot relationship. **Dorsomedial incision** over medial cuneiform: - 3-4cm incision centered over medial cuneiform - Between EHL tendon (lateral) and tibialis anterior tendon (medial) - **Location**: Medial cuneiform body (avoid first tarsometatarsal joint) - **Orientation**: Dorsal-to-plantar, parallel to first TMT joint - **Open wedge**: Distract dorsally to elevate medial column - **Wedge size**: 4-8mm (based on degree of forefoot varus) - Insert **bone graft wedge** (autograft from calcaneus or allograft) - Fix with **plate or screws** across osteotomy - **Check forefoot alignment**: Forefoot should be plantigrade (neutral pronation/supination) Cotton osteotomy is **not always needed**. Perform intraoperatively after completing FDL + MDCO ± LCL. Assess forefoot alignment with foot held in corrected hindfoot position. If medial column is plantarflexed relative to lateral (forefoot varus), add Cotton. If forefoot is plantigrade, Cotton is not needed. Unnecessary Cotton can create **medial column overload**. Cotton osteotomy is an adjunct for specific forefoot varus situations. ### Closure Technique and Immediate Postoperative Care - Release tourniquet after completing all osteotomies and fixation - Achieve **meticulous hemostasis** (foot and ankle surgeries prone to hematoma) - Identify and cauterize any bleeding vessels **Drain considerations:** - **FDL transfer alone**: Drain usually not needed - **FDL + MDCO**: Consider drain if significant oozing - **FDL + MDCO + LCL + Cotton**: Drain recommended (multiple osteotomies) If used: Small hemovac or Jackson-Pratt drain, remove at 24-48 hours or when output under 30mL/day. - **Periosteum**: Close over bone (promotes healing) - **Deep fascia**: Close with 2-0 absorbable suture - **Subcutaneous**: Close with 3-0 absorbable suture - Ensure no tension on skin closure - **Technique**: 3-0 or 4-0 nylon interrupted vertical mattress sutures - **Alternative**: Running subcuticular 4-0 monocryl (better cosmesis) - **Dressing**: Non-adherent dressing, fluffs, soft roll - Apply **well-padded short leg splint** - **Position**: Neutral ankle dorsiflexion, hindfoot neutral to slight varus - **Mold**: Mold splint to maintain arch - Avoid excessive plantar flexion (Achilles contracture risk) - **Elevation**: Foot elevated above heart for 48-72 hours - **Ice**: Apply to reduce swelling - **Pain control**: Multimodal analgesia (nerve block, oral opioids, NSAIDs) - **DVT prophylaxis**: Aspirin 325mg daily or enoxaparin if high risk - **Neurovascular checks**: Monitor for compartment syndrome (rare but catastrophic) Foot and ankle surgery with tourniquet use, prolonged procedure time, and multiple osteotomies increases compartment syndrome risk. Monitor for **severe pain out of proportion** to injury, **pain with passive stretch** of toes, and **tense swollen foot**. If suspected, **emergently release splint** and assess. If clinical suspicion high, measure compartment pressures. Compartment syndrome of the foot requires **urgent fasciotomy** of all nine compartments. Meticulous closure and postoperative care prevent early complications. {/* SECTION 11: COMPLICATIONS */} The most common cause of **recurrent deformity** after FDL + MDCO is **inadequate correction** at index surgery. To prevent: 1. **Assess deformity in all planes**: Valgus, abduction, arch collapse 2. **Add lateral column lengthening** if too many toes sign present (Stage IIb) 3. **MDCO translation**: Ensure 10-12mm medial shift (measure intraoperatively) 4. **FDL tension**: Set with foot in plantarflexion and inversion (restores arch) 5. **Postop compliance**: Strict non-weight-bearing for 6 weeks, orthosis use long-term {/* SECTION 12: POSTOPERATIVE CARE AND REHABILITATION */} - **Splint**: Well-padded short leg splint in neutral position - **Elevation**: Foot above heart continuously for 48-72 hours - **Weight-bearing**: Strict non-weight-bearing (NWB) with crutches or walker - **DVT prophylaxis**: Aspirin 325mg daily or enoxaparin if high risk - **Pain**: Multimodal analgesia, consider nerve block - **Immobilization**: Keep splint dry and intact - **Elevation**: As much as possible - **NWB**: Continue strict NWB - **Follow-up**: Week 2 - remove splint, assess wound, transition to cast - **Transition to cast**: Apply well-molded short leg cast - **Position**: Maintain arch, neutral hindfoot - **NWB**: Continue strict NWB for full 6 weeks - **Rationale**: Protect FDL fixation (highest failure risk first 6 weeks), allow MDCO healing - **Imaging**: X-rays to confirm MDCO healing - **Transition to boot**: Removable CAM boot - **Weight-bearing**: Start partial weight-bearing (25-50% body weight) in boot - **PT**: Begin gentle range of motion exercises (ankle dorsi/plantarflexion) - **Progress to full weight-bearing** in boot - **PT**: Strengthening exercises (calf raises, resistance bands) - **Orthosis fitting**: Custom UCBL or AFO orthosis fabricated for long-term support - **Imaging**: Confirm complete MDCO healing - **Wean from boot**: Transition to supportive shoe + custom orthosis - **PT**: Progress strengthening, proprioception, gait training - **Activity**: Gradually increase activity level over 3-4 months - **Return to full activity**: 4-6 months postop The **6-week NWB period** protects the FDL transfer fixation. FDL is fixed to navicular with interference screw or anchor, and early weight-bearing can cause **pullout** before tendon-bone healing occurs (which takes 6-8 weeks). Additionally, MDCO requires 6-8 weeks to achieve radiographic union. Patients who bear weight early have significantly higher rates of FDL failure and MDCO nonunion. Strict adherence to protocol optimizes outcomes. - **Immobilization**: Short leg cast - **NWB**: Strict non-weight-bearing - **Elevation**: First 2 weeks especially - **DVT prophylaxis**: Continue throughout NWB period - **Imaging**: AP, lateral, oblique foot X-rays - **Assess fusion**: Look for bridging trabeculae - **Decision**: If early healing, progress to PWB. If no healing, continue NWB 2-4 more weeks - **Transition to boot**: If healing progressing - **PWB**: Start 25-50%, progress to full over 4-6 weeks - **PT**: Gentle ankle ROM (hindfoot fused, but ankle and forefoot move) - **Imaging**: Confirm fusion (expect 80-90% union by 12 weeks) - **FWB**: Progress to supportive shoe - **PT**: Strengthening, gait training - **Full fusion**: Typically complete by 4-6 months - **Return to activity**: Gradual progression - **Expectations**: Hindfoot motion lost, but stability restored Triple arthrodesis has **10-15% nonunion rate**, most commonly at the **talonavicular joint**. Risk factors: smoking, diabetes, NSAID use, inadequate fixation. If nonunion occurs, patients have persistent pain and instability. Treatment: Revision fusion with bone graft (autograft iliac crest preferred), BMP augmentation, rigid fixation with screws. Some patients require prolonged immobilization (4-6 months total). Longer immobilization required for arthrodesis vs soft tissue reconstruction. {/* SECTION 13: OUTCOMES AND PROGNOSIS */} **Risk factors for failure:** - **Obesity** (BMI over 35): Increased load overcomes reconstruction - **Diabetes**: Impaired healing, tendon quality - **Smoking**: Impaired bone healing (MDCO nonunion risk) - **Advanced deformity**: Stage IIc with severe triplanar deformity - **Non-compliance**: Early weight-bearing, inadequate orthosis use - **Underlying inflammatory arthritis**: RA, psoriatic arthritis (disease progression despite surgery) Patients with multiple risk factors may be better served with **primary triple arthrodesis** rather than attempting soft tissue reconstruction. **FDL + MDCO:** - 80-85% maintain correction at 5 years - 10-15% develop recurrent deformity - 5-10% require revision surgery - Adjacent joint arthritis risk: Low (under 10%) **Triple arthrodesis:** - 90-95% maintain correction at 10 years - Adjacent joint arthritis: 20-30% (ankle, midfoot) - Revision fusion needed in 5-10% **FDL + MDCO:** - Return to recreational sports: 70-80% - Improved walking distance and endurance - Hindfoot motion preserved (critical for uneven ground) **Triple arthrodesis:** - Limited athletic participation (hindfoot rigid) - Walking on flat ground: Good - Walking on uneven ground: Impaired - Permanent orthosis often needed {/* SECTION 14: EVIDENCE BASE */} {/* SECTION 15: VIVA SCENARIOS */} {/* SECTION 16: MCQ PRACTICE POINTS */} **Q: The flexor digitorum longus tendon is harvested for posterior tibial tendon reconstruction. At what anatomical landmark should the FDL be transected to maximize harvest length while minimizing donor morbidity?** A: **Distal to the master knot of Henry**. The master knot of Henry is the crossing point where FDL passes superficial to FHL in the midfoot. Transecting FDL distal to this point allows the tendon to be pulled proximally, stripping it from its insertions on the lateral four toes with minimal donor morbidity (toe flexion loss is not functionally significant). Transecting proximal to the knot risks losing harvest length and disrupting FHL. **Q: A patient with PTTD has medial arch collapse and heel valgus that can be fully corrected with passive manipulation. What Johnson & Strom stage is this, and what is the surgical treatment?** A: **Stage II - Flexible flatfoot deformity**. The key feature is **passive correctability** - the deformity can be fully corrected when manipulated, indicating the joints are not arthritic or fixed. Treatment is **FDL transfer + MDCO** (± lateral column lengthening if forefoot abduction present). If the deformity were rigid (not correctable), it would be Stage III requiring triple arthrodesis. **Q: What is the biomechanical effect of medial displacement calcaneal osteotomy in PTTD reconstruction?** A: MDCO **shifts the ground reaction force medial to the ankle joint axis**, changing the Achilles tendon moment arm from an **eversion moment** (contributing to heel valgus) to an **inversion moment** (correcting heel valgus). This passive correction **offloads the reconstructed FDL** by reducing the load on the tendon. Without MDCO, FDL transfer alone has only 60-70% success because the biomechanics remain unfavorable. Combination FDL + MDCO achieves 85-90% success. **Q: The too many toes sign in PTTD indicates what deformity component, and how does it affect surgical planning?** A: The too many toes sign (viewing more than 1-2 toes from behind when standing behind the patient) indicates **forefoot abduction**, which is a transverse plane deformity. This classifies the patient as **Stage IIb** (if flexible). Surgical planning must include **lateral column lengthening** (Evans osteotomy or calcaneocuboid distraction arthrodesis) in addition to standard FDL transfer + MDCO. Without addressing the forefoot abduction, the deformity will recur. **Q: What distinguishes Stage IV PTTD from Stage III, and how does this change surgical management?** A: Stage IV involves **deltoid ligament insufficiency** with **ankle valgus tilt**, in addition to the rigid flatfoot deformity of Stage III. On mortise ankle view, the **medial clear space is over 4mm** (normal under 4mm) and there is talar tilt. Surgical management requires addressing **both hindfoot and ankle** - triple arthrodesis alone will fail. Options are triple + deltoid reconstruction (if no ankle arthritis) or tibiotalocalcaneal fusion (if ankle arthritis present). Stage IV has the worst prognosis of all PTTD stages. **Q: What is the most common cause of recurrent deformity after FDL transfer + MDCO for Stage II PTTD?** A: **Inadequate correction at index surgery**. Specifically: (1) Inadequate MDCO medial translation (under 10mm), (2) Missing lateral column lengthening in a patient with too many toes sign (Stage IIb), (3) Inadequate FDL tensioning. Other causes include patient non-compliance (early weight-bearing), obesity (excessive load on reconstruction), and progression of underlying disease. Prevention requires meticulous surgical technique with adequate correction in all three planes (valgus, abduction, arch collapse) and strict postoperative non-weight-bearing protocol. {/* SECTION 17: AUSTRALIAN CONTEXT */} - **Public hospital access**: PTTD reconstruction typically performed in public system after conservative management failure - **Private practice**: Increasing volume of FDL transfer + MDCO procedures - **Waiting times**: 6-12 months in public system (allows adequate conservative trial) - **DVA patients**: Common presentation in older veterans, comprehensive rehabilitation access - **ACSQHC**: VTE prophylaxis mandatory for major foot/ankle surgery (aspirin 325mg daily or LMWH) - **Perioperative antibiotic**: Cephazolin 2g IV within 60 minutes of incision - **Diabetic patients**: Multidisciplinary care with endocrinology, optimized HbA1c prior to elective surgery - **AOANJRR**: No specific registry for PTTD reconstruction (arthroplasty registry only) **Key documentation requirements:** 1. **Conservative management failure**: Document at least 6 months of conservative treatment (UCBL orthosis, physiotherapy, NSAIDs) before recommending surgery. Medicolegal risk if surgery performed without adequate conservative trial. 2. **Staging and surgical planning**: Document passive correction test result (flexible vs rigid), too many toes sign presence, and radiographic measurements (heel valgus, talus-1st MT angle). This justifies procedure selection (FDL + MDCO vs triple arthrodesis vs combination with LCL). 3. **Informed consent**: Must counsel about: - Success rates (85-90% for FDL + MDCO, but lower if risk factors present) - 6 weeks non-weight-bearing (patient must have support at home or arrange care) - Recurrent deformity risk 10-15% - Sural nerve injury risk (document nerve protection intraoperatively) - Alternative treatments (triple arthrodesis, continued conservative management) 4. **Risk factor counseling**: Document discussion of obesity (BMI over 35), diabetes, smoking as risk factors for failure/complications. Consider deferring surgery until risk factors optimized (weight loss, smoking cessation). 5. **Postoperative complications**: Early recognition and documentation of compartment syndrome symptoms, wound complications, and CRPS. Delayed recognition of compartment syndrome is a significant medicolegal risk. **Common litigation issues in PTTD surgery:** - Sural nerve injury (most common nerve injured in MDCO) - Recurrent deformity due to inadequate correction or wrong procedure selection (FDL + MDCO in Stage III rigid deformity) - Compartment syndrome (rare but catastrophic if missed) - Infection requiring hardware removal or amputation (diabetic patients at highest risk) {/* SECTION 18: EXAM CHEAT SHEET */}

Posterior Tibial Tendon Dysfunction - Surgical Reconstruction

Posterior Tibial Tendon Dysfunction - Surgical Reconstruction