import { OnePagerSummary, ExamWarning, InfoCardGrid, InfoCard, MnemonicCard, EvidenceCard, VivaScenarioSection, VivaScenario, ExamCheatSheet, ContentSection, ExamPearl, SafetyAlert, NumberHighlightRow, NumberHighlight, Tabs, Tab, ComparisonTable } from '@/components/mdx' **Location**: 10-15mm posterior to posterior capsule at joint line **Protection**: Retract posteriorly with bent Hohmann, avoid excessive posterior dissection, flex knee to relax structures, monitor posterior cortex during tibial preparation **Location**: Posterolateral corner, winds around fibular neck 30-40mm distal to joint **Protection**: Avoid lateral release beyond popliteus corner, release contractures slowly, limit valgus correction to gradual increments, decompress at fibular neck if stretch anticipated **Location**: Medial femoral condyle, 10mm proximal and posterior to joint line **Protection**: Subperiosteal dissection during medial exposure, preserve deep fibers during parapatellar arthrotomy, avoid excessive medial soft tissue stripping **Location**: Quadriceps tendon, patella, patellar tendon complex **Protection**: Use extensile approaches early if limited eversion, protect patellar blood supply (lateral geniculate), avoid aggressive lateral release, consider tubercle osteotomy for stiff knees **Location**: Metaphyseal and diaphyseal cortices during component removal and stem insertion **Protection**: Avoid aggressive osteotome use, use flexible reamers for stems, sequential reaming 0.5mm increments, intraoperative fluoroscopy for stem trajectory ## Patient Assessment **Critical Planning Decision**: Cone selection based on AORI classification - Type 2B requires single cone, Type 3 may need dual cones or custom reconstruction. Templating determines cone size (typically 35-55mm tibia), stem length (100-150mm), and augment needs. ### Indications for Tibial Cone Reconstruction **Primary Indications**: - AORI Type 2B defects: Damaged metaphyseal bone, one femoral or tibial condyle compromised - AORI Type 3 defects: Deficient metaphyseal bone, both condyles compromised - Periprosthetic fracture with metaphyseal bone loss requiring fixation - Failed structural allograft with residual defect - Septic revision after debridement (staged, infection eradicated) **Relative Indications**: - AORI Type 2A with poor bone quality (osteoporosis, multiple revisions) - Combined supracondylar femur fracture with tibial bone loss - Hinged/constrained revision requiring enhanced tibial support ### Contraindications **Absolute**: - Active infection (stage for spacer first, treat infection) - Inadequate host bone for cone press-fit (severely deficient cortices) - Uncorrectable vascular insufficiency - Non-ambulatory patient with low functional demand **Relative**: - Severe osteoporosis (consider cemented augments, longer stems) - Extensor mechanism disruption (repair/reconstruct first) - Medical comorbidities precluding 2+ hour surgery - Patient age less than 50 years (consider structural allograft if young, active) ### Imaging Requirements Full-length standing films assess alignment, component position, defect extent, stem trajectory planning 3D reconstruction quantifies bone stock, defect morphology, cortical integrity, prior screw holes If infection concern (MARS protocol), assess soft tissues, extensor mechanism integrity ### Templating Strategy **Cone Sizing**: 1. Measure metaphyseal width on CT (mediolateral and AP dimensions) 2. Select cone 2-3mm smaller than metaphyseal diameter (40-55mm for tibia) 3. Cone height determines baseplate position (typically 15-25mm depth) 4. Plan for symmetric or asymmetric defects (may need medial vs lateral placement) **Stem Selection**: - Length: Bypass cone by 2 cortical diameters (typically 100-150mm total stem) - Diameter: Fill 80% canal at isthmus (10-18mm common sizes) - Type: Cemented vs cementless (cemented preferred if poor bone quality) - Offset: Match anatomic tibial offset (standard vs offset stems) **Augment Planning**: - Wedge augments for peripheral defects (5-20mm thickness) - Block augments for central defects (5-15mm) - Plan for 3-10mm tibial polyethylene minimum thickness ## Surgical Instrumentation **Examiner Expectation**: Know complete tray requirements - revision TKA baseplate/stem system, cone-specific instruments (reamers, trials, impactors), extensile exposure tools (Cobb elevators, curved osteotomes), cement removal set. Forgetting cone trials or appropriate stem lengths fails this question. ### Essential Instruments **Revision TKA Set**: - Modular revision baseplate system (cone-compatible design) - Modular stems (100-150mm lengths, 10-18mm diameters, cemented/cementless) - Modular augments (wedges 5-20mm, blocks 5-15mm) - Constrained polyethylene inserts (10-25mm thickness, CCK/rotating hinge options) **Cone-Specific Instruments**: - Porous metal tibial cones (35-55mm sizes, medial/lateral specific) - Cone reamer set (30-55mm, 2.5mm increments) - Cone trial set (matched to final cone sizes) - Cone impactor and guide system - Depth gauge for cone seating verification **Component Removal**: - Flexible osteotomes (curved, straight) - Reciprocating saw with thin revision blades - Gigli saw for posterior cement access - Component extraction devices (universal femoral/tibial extractors) - Cement removal instruments (curved curettes, high-speed burr, ultrasonic cement removal) **Extensile Exposure Tools**: - Cobb elevators (various curves) - Lamina spreaders for joint distraction - Tibial tubercle osteotomy set (microsagittal saw, retractors) - VY quadricepsplasty instruments (if turndown needed) **Bone Preparation**: - Revision tibial cutting guides (offset options, augment-compatible) - Morselized bone graft set (impactors, bone mill if autograft used) - Flexible intramedullary reamers (for stem canal preparation) ### Patient Positioning **Standard Setup**: - Supine position on radiolucent table - Padded tourniquet on proximal thigh (may not inflate if vascular concerns) - Leg holder or foot/thigh post for foot-of-bed positioning - Bump under ipsilateral hip (15-20 degrees internal rotation) - Contralateral leg in stirrup or abducted for C-arm access **Fluoroscopy Setup**: - C-arm from contralateral side - AP and lateral capability for: - Cone position verification - Stem trajectory confirmation - Joint line height assessment - Component alignment checks ### Surgical Environment **Operating Room Configuration**: - Laminar flow/ultra-clean environment (reduces infection 50%) - Double gloving with indicator system - Pulsatile lavage available (6-9L minimum for revision) - Cell saver if anticipated blood loss greater than 1000ml (relative, infection concern) **Antibiotic Prophylaxis**: - Cefazolin 2g IV (3g if weight greater than 120kg) within 60 minutes - Vancomycin 15mg/kg (if MRSA risk, beta-lactam allergy) over 1 hour preop - Gentamicin 5mg/kg consideration for revision (some protocols) - Redose cefazolin if case longer than 4 hours **Thromboprophylaxis**: - TED stockings contralateral leg - Pneumatic compression devices bilateral - Chemical prophylaxis per protocol (aspirin, LMWH, rivaroxaban per AAOS/ACCP) ## Operative Steps - Detailed Approach ### Step 1: Skin Incision and Approach Selection **Technique**: - Use prior midline incision if present (most lateral if multiple scars) - Create full-thickness flaps (avoid beveling, preserves blood supply) - Extend proximally to mid-thigh, distally to tibial tubercle or beyond - Identify extensor mechanism, assess scar tissue, plan arthrotomy **Vascular Assessment**: Palpate pedal pulses preoperatively. If multiple prior incisions, excise most medial scar en bloc with arthrotomy to preserve lateral genicular blood supply. Skin ischemia risk 8-12% with revision surgery. - Avoid multiple skin flaps - excise intermediate scars - Use full-thickness flaps only (no subcutaneous dissection) - Handle skin gently with skin hooks (no crushing clamps) - Consider plastic surgery consultation if concern about closure ### Step 2: Extensile Exposure Selection **Standard Medial Parapatellar**: - Attempt first if no previous extensile approach - Release medial capsule and MCL deep fibers subperiosteally - Elevate patella laterally - if does not evert easily, extend exposure **Rectus Snip** (Prefer for mild-moderate stiffness): - 45-degree proximal-lateral incision in quadriceps tendon - 2-3cm length from superomedial pole of patella - Preserves vastus medialis obliquus fibers - Repair directly at closure with #2 FiberWire figure-of-8 **Tibial Tubercle Osteotomy** (Best for severe stiffness, young patients): - Mark 5-6cm x 1.5cm osteotomy lateral to tibial crest - Microsagittal saw with 4-5mm depth (preserves posterior cortex) - Thin osteotome to crack posterior cortex - Reflect tubercle proximally with patellar tendon attached - Fix at closure with 2-3 bicortical screws or cerclage wires **VY Quadricepsplasty** (Last resort, older/low-demand patients): - Invert V-incision in quadriceps tendon (apex 6-8cm proximal to patella) - Reflect patella distally, gaining 3-5cm length - Repair in Y-configuration with #5 Ethibond or FiberWire - Protected weight-bearing 6 weeks, high complication rate (10-15% disruption) **Examiner Question**: "How do you decide between extensile options?" Answer: "Assess patella eversion intraoperatively with knee flexed 90 degrees. If patella does not evert lateral to midline without tension, extend exposure. Rectus snip preferred (lowest complication rate 2-3%), tibial tubercle if severe patella baja or young patient needing quadriceps preservation, VY turndown reserved for ankylosed knees in elderly patients with low functional demands." - Risk 1-2% with standard approach, 5-8% with extensile - Release slowly with knee flexion, not forced eversion - Consider extensile approach early if resistance encountered - Protect lateral geniculate blood supply (avoid excessive lateral release) ### Step 3: Component Removal - Femoral First **Rationale**: Remove femoral component first for access to tibial component **Technique**: - Disrupt cement-bone interface with narrow osteotomes - Use curved osteotomes posteriorly (avoid popliteal vessels) - May use oscillating saw for anterior flange cement - Extract femoral component with universal extractor - Remove all cement (high-speed burr, ultrasonic devices) - Preserve bone stock (avoid aggressive gouging) - Thin posterior femoral condyle cortex (3-5mm) - Use Gigli saw or curved osteotome with direct visualization - Avoid power burr posteriorly (thermal necrosis, perforation risk) - Protect popliteal vessels with posterior retractor ### Step 4: Tibial Component Exposure **Technique**: - Flex knee maximally (allows elevation off posterior structures) - Elevate medial and lateral soft tissue sleeves (preserve MCL/LCL origins) - Insert bent Hohmann retractors posteromedially and posterolaterally - Protect popliteal vessels (posterior retractors rest on bone, not soft tissue) ### Step 5: Tibial Component Removal **Cement Disruption**: - Microsagittal saw along periphery of baseplate (risk cortical damage) - Osteotomes at bone-cement interface (start anteriorly, work posteriorly) - Gigli saw for posterior cement if accessible - Gentle mallet taps (avoid violent impacts causing fracture) **Stem Removal**: - If cemented stem: ultrasonic cement removal around proximal stem, flexible osteotomes down canal - If press-fit stem: tap out with slotted extractor or drill multiple access holes in baseplate - Avoid cortical perforation (use fluoroscopy if difficult extraction) **Periprosthetic Fracture During Removal**: Occurs 5-8% of revisions. Prevent with careful technique, sequential loosening, fluoroscopy. If fracture occurs: classify (intraoperative vs postoperative), stable vs unstable. Manage with longer stems (bypass fracture 2 cortical diameters), cerclage wires/cables, possible lateral locking plate if unstable. - Risk highest at metaphyseal-diaphyseal junction (stress riser) - Stop if crack visualized or heard - Manage with cerclage cables, longer stem bypass - Consider lateral locking plate if propagates - Document intraoperatively (medicolegal, postoperative management) ### Step 6: Cement Removal and Defect Assessment **Cement Extraction**: - Remove all cement to bleeding bone (essential for cone osseointegration) - Use combination: hand tools, high-speed burr, ultrasonic removal - Pulse lavage between steps (clears debris, identifies retained cement) - Preserve cortical bone (avoid aggressive burring) **Defect Assessment**: - Classify using AORI system: - **Type 1**: Intact metaphyseal bone (no cone needed) - **Type 2A**: Damaged metaphyseal bone, one condyle (augment may suffice) - **Type 2B**: Damaged metaphyseal bone, both condyles (cone indicated) - **Type 3**: Deficient metaphyseal bone, loss of structural support (cone required) ### Step 7: AORI Classification and Cone Selection **Measurement**: - Assess defect depth with depth gauge or ruler (5-30mm common) - Assess bone quality (firm cortical rim vs soft cancellous) - Identify contained vs uncontained defects - CT template confirms cone size (35-55mm for tibia, most common 40-50mm) **Cone Indication Decision**: - Type 2B/3: Cone indicated - Type 2A with poor bone: Consider cone vs large augment - Type 1: No cone, proceed with standard revision baseplate ### Step 8: Cone Selection and Planning **Cone Characteristics**: - Porous tantalum (trabecular metal) or titanium porous coating - Porosity 80%, modulus 3 GPa (similar to bone, reduces stress shielding) - Available sizes: 35mm, 40mm, 45mm, 50mm, 55mm (tibia) - Symmetric or asymmetric designs (medial/lateral specific for some systems) **Size Selection**: - Measure metaphyseal diameter on CT (typically 50-70mm) - Select cone 2-5mm smaller than metaphyseal diameter (press-fit, not loose) - Larger cone provides more surface area (better fixation) but requires more bone removal - Balance: maximize contact, minimize healthy bone sacrifice ### Step 9: Metaphyseal Preparation - Serial Reaming **Reaming Technique**: - Start with smallest reamer (usually 30-35mm) - Ream until bleeding bone (endpoint: punctate bleeding, firm feel) - Advance in 2.5mm increments (avoid aggressive single-step jumps) - Ream to planned cone size minus 2mm (trial cone undersized) - Preserve cortical rim (avoid eccentric reaming causing perforation) **Bleeding Bone Endpoint Critical**: Non-bleeding sclerotic bone will not osseointegrate. Must ream to bleeding cancellous bone with firm cortical rim. Use pulse lavage to visualize bleeding (tourniquets deflated if used). Intraoperative decision: if inadequate bleeding, consider cemented technique or structural allograft. - Risk medial/lateral cortex perforation (thin metaphyseal bone) - Use sequential reaming with frequent assessment - Perforation less than 1cm: acceptable, pack morselized graft - Perforation greater than 1cm: consider plate fixation, structural allograft strut - Document on operative note (affects postoperative weight-bearing) ### Step 10: Cone Trial and Fit Assessment **Trial Insertion**: - Insert trial cone 2mm smaller than final planned size - Rotate to optimize contact (asymmetric defects may need specific orientation) - Assess stability: manual pressure, no gross motion (micromotion less than 50 microns acceptable) - Impaction may be needed (light mallet taps, not heavy force) - Burr high spots if trial does not seat (preserves more bone than over-reaming) **Fit Criteria**: - 60-70% surface contact minimum (visual estimate, firm feel) - Flush seating at metaphyseal rim (not proud, not recessed more than 2-3mm) - Stable to manual stress (no rocking) - Adequate bone quality (firm cortical rim, bleeding cancellous bone) ### Step 11: Cone Stability Verification **Intraoperative Testing**: - Attempt to rotate cone with impactor (should not move) - Apply axial load (push hard on cone, should not subside) - Rock medially-laterally (should not toggle) - If unstable: upsize cone 2.5mm OR ream additional 1mm if undersized **Fluoroscopic Confirmation**: - AP view: symmetric position, no medial/lateral tilt - Lateral view: appropriate depth, parallel to joint line - Assess for occult fractures from impaction **Press-Fit vs Cemented Cone Debate**: Literature favors press-fit (80% osseointegration at 2 years, 75-80% survivorship at 10 years). Cemented cones have higher failure rates (50-60% at 10 years, no biological fixation). Cement only if absolutely unstable or severe osteoporosis precludes press-fit. ### Step 12: Morselized Bone Graft Application **Graft Packing Technique**: - Pack morselized autograft (reaming debris) or allograft around cone periphery - Fill gaps between cone and host bone (enhances contact, promotes ingrowth) - Avoid graft between cone and baseplate interface (causes instability) - Impaction grafting technique (sequential packing, impaction, packing) **Graft Sources**: - Autograft: femoral/tibial reaming debris (preferred, no disease transmission) - Allograft: morselized cancellous chips (if insufficient autograft) - Avoid synthetic (calcium phosphate, hydroxyapatite) in this application ### Step 13: Tibial Baseplate Insertion with Stem **Baseplate Selection**: - Modular revision baseplate with cone-compatible design (flat undersurface) - Select appropriate mediolateral width (match tibial anatomy, typically 70-85mm) - Anteroposterior coverage (avoid overhang medially, posteriorly) - Rotation: align with tibial tubercle, ankle mortise **Stem System**: - Stem length: bypass cone by 2 cortical diameters (typically 100-150mm total) - Stem diameter: fill 80% canal at isthmus (sequential flexible reaming to size) - Cemented vs cementless stem: - **Cemented**: if poor bone quality, need immediate stability, older patient - **Cementless**: if good bone quality, younger patient, desire biological fixation **Insertion Technique**: - Trial baseplate with trial stem on cone - Assess rotation (tibial tubercle alignment), mediolateral position (central on cone) - Remove trial, insert final cone (impaction to stable endpoint) - Insert final baseplate-stem construct onto cone - Ensure baseplate flush on cone (no gaps, no rocking) - Varus/valgus mismatch between stem and tibial canal causes cortical impingement - Use flexible reamers (follow canal anatomy, not rigid guides) - Fluoroscopy confirms stem trajectory (AP and lateral views) - If cortical contact: downsize stem or offset stem options - Perforation risk 2-3% (requires longer stem bypass, possible plate fixation) ### Step 14: Stem Engagement and Load Sharing **Biomechanical Principles**: - Stem bypasses cone distally by 2 cortical diameters (distributes load, prevents stress concentration) - Load sharing: metaphyseal cone (30-40% load), stem (40-50% load), baseplate-bone interface (10-20%) - Stem prevents cone subsidence (backup fixation if cone integration incomplete) **Stem Fixation Verification**: - Press-fit stems: firm impaction, stable to manual stress - Cemented stems: third-generation technique, cement gun, finger packing proximally - Fluoroscopy confirms depth (stem tip 2 cortical diameters beyond cone apex) ### Step 15: Baseplate Fixation to Cone **Cemented Technique** (most common): - Apply thin cement layer to cone superior surface (mantle 1-2mm) - Insert baseplate onto cone with stem in canal - Hold compression 8-10 minutes (cement curing) - Remove extruded cement (avoid leaving debris) **Cementless Technique** (younger patients, good bone): - Direct impaction of baseplate onto cone (taper-lock or screw fixation) - Some systems use central screw through baseplate into cone - Relies on press-fit stability and osseointegration **Baseplate-Cone Interface Critical**: Gap greater than 2mm causes micromotion, failure risk. Ensure flush contact intraoperatively. Cement mantle technique creates stable interface. Some surgeons avoid cement at this interface (prefer screw fixation), literature mixed - cement probably safer for immediate stability. ### Step 16: Modular Augments for Residual Defects **Augment Selection**: - Assess residual bone defects after cone/baseplate insertion - **Wedge augments**: peripheral/slope defects (medial/lateral, 5-20mm thickness) - **Block augments**: central defects (5-15mm thickness) - Augments cement to baseplate (creates monolithic construct) **Application Technique**: - Trial augments to verify size and position - Cement augment to baseplate (avoid cement at augment-bone interface) - Press firmly during cement curing (ensure no gaps) - Goal: restore joint line height (measure from fibular head, adductor tubercle) **Joint Line Restoration**: - Normal joint line: 25mm distal to medial epicondyle (femur), 10mm distal to fibular head (tibia) - Patella baja risk if joint line elevated (Insall-Salvati ratio less than 0.8) - Compromised flexion if joint line lowered excessively ### Step 17: Polyethylene Selection and Insertion **Polyethylene Thickness**: - Minimum 10mm thickness (wear considerations, especially if young patient) - Thicker inserts (12-25mm) for ligamentous laxity, bone loss requiring buildup - Highly cross-linked polyethylene (HXLPE) preferred (reduces wear 90% vs conventional) **Constraint Selection**: - **Posterior-stabilized**: if collateral ligaments intact, stable flexion-extension gaps - **Constrained condylar knee (CCK)**: if mild MCL/LCL laxity (5-10mm in extension) - **Rotating hinge**: if severe ligamentous insufficiency, gross instability - Avoid over-constraining (increases constraint = increases bone-implant interface stress = higher loosening risk) **Trialing and Assessment**: - Trial femoral and polyethylene components - Assess stability (Lachman, varus-valgus stress at 0 and 20 degrees flexion) - Assess flexion-extension gaps (should be balanced within 2mm) - Range of motion to 110-120 degrees minimum (limited by soft tissues, not impingement) - Patellar tracking (no tilt, subluxation, ensure lateral release adequate if needed) **Final Insertion**: - Cement femoral component if revision femoral work done (technique per system) - Lock polyethylene into tibial baseplate (ensure secure, no lift-off) - Irrigate copiously (remove all debris, cement fragments) - Final stability check and range of motion ## Closure Technique ### Deep Closure **Capsular Repair**: - Repair medial arthrotomy with interrupted #1 Vicryl or PDS - If rectus snip: repair with figure-of-8 #2 FiberWire (criss-cross for strength) - If tibial tubercle osteotomy: fix with 2-3 bicortical screws (4.5mm partially threaded) or cerclage wires - Ensure patella tracks centrally (no tilt, subluxation with range of motion) **Extensor Mechanism Integrity**: - Test by extending knee against resistance (strong quadriceps contraction) - If concern about repair: consider brace, limited weight-bearing protocol ### Superficial Closure **Subcutaneous and Skin**: - Large-bore drains (x2, 10-French) if dead space concern (controversial - some avoid drains) - Subcutaneous layer: 2-0 Vicryl interrupted or running - Skin: staples or 3-0 nylon interrupted vertical mattress (avoid tension) - Occlusive dressing with sterile compressive wrap - Revision TKA wound complication rate 5-10% (higher than primary) - Risk factors: diabetes, smoking, obesity, prior incisions, steroid use - Early recognition critical (wound drainage greater than 5 days, erythema, fever) - Low threshold for washout if concern (deep infection catastrophic for revision) ## Postoperative Management ### Immediate Postoperative (0-6 weeks) **Weight-Bearing**: - **Standard protocol**: Touch weight-bearing (TTWB) for 6 weeks (allows cone osseointegration) - If intraoperative fracture: Non-weight-bearing (NWB) to partial (PWB) for 12 weeks - If cementless stem: TTWB 6 weeks minimum - If cemented construct with good bone: may advance to weight-bearing as tolerated (WBAT) at 2-4 weeks **Mobilization**: - CPM machine 0-90 degrees day 1 (controversial, literature mixed on benefit) - Physical therapy twice daily: ROM exercises, quadriceps sets, straight leg raises - Goal 0-90 degrees by discharge (week 1-2) **Thromboprophylaxis**: - Continue chemical prophylaxis 4-6 weeks (aspirin 325mg daily, LMWH, or DOAC per protocol) - TED stockings and pneumatic compression until ambulatory - Early mobilization (reduces VTE risk 50%) **Pain Management**: - Multimodal analgesia: regional block (adductor canal or femoral nerve), oral opioids, NSAIDs (if renal function allows), acetaminophen - Avoid NSAIDs long-term (theoretical concern for osseointegration, literature inconclusive) ### Intermediate Recovery (6 weeks to 6 months) **Radiographic Surveillance**: - **6 weeks**: AP/lateral knee, assess for subsidence (greater than 2mm concerning), lucencies (greater than 2mm progressive radiolucency = loosening) - **3 months**: Repeat imaging if symptomatic or concern for component migration - **6 months, 1 year**: Annual thereafter for surveillance **Physical Therapy**: - Progressive strengthening: quadriceps, hamstrings, hip abductors - Proprioception training (balance, functional activities) - Goal ROM: 0-110 degrees minimum (functional), 0-120 degrees ideal - Gait training (normalize pattern, reduce limp) **Weight-Bearing Progression**: - 6 weeks: advance to WBAT if radiographs stable - 3 months: full unrestricted weight-bearing, wean assistive devices - 6 months: return to low-impact activities (golf, swimming, cycling) ### Long-Term Outcomes Cone-augmented revision TKA survival at 10 years (contemporary series) Augment-only reconstruction without cones (10-year survival lower) Aseptic loosening revision rate at 5 years for cone constructs **Functional Outcomes**: - Knee Society Score improvement: 40-50 points average (35 preop to 80-85 postop) - Oxford Knee Score improvement: 15-20 points - Patient satisfaction: 70-80% (lower than primary TKA 85-90%) - Return to activities: low-impact sports 85%, high-impact not recommended **Complications**: - Infection: 3-5% (higher than primary 1-2%) - Aseptic loosening: 5-8% at 5 years - Instability: 3-5% - Periprosthetic fracture: 2-4% - Extensor mechanism disruption: 1-2% ## Complications - Recognition and Management ### Additional Complications **Nerve Injury (1-2%)**: - **Common peroneal nerve** most at risk (posterolateral, stretch injury with correction of valgus/flexion contracture) - **Recognition**: Foot drop, loss of ankle dorsiflexion, sensory loss dorsal foot - **Prevention**: Gradual correction of deformity, decompress nerve at fibular neck if correction greater than 15 degrees valgus, monitor nerve function intraoperatively - **Management**: Observation for 6-12 months (80% recover if neurapraxia), AFO for foot drop, nerve exploration/repair if no recovery at 6 months, tendon transfers for persistent deficit **Extensor Mechanism Disruption (1-2%)**: - **Recognition**: Inability to straight leg raise, extensor lag, palpable defect in quadriceps or patellar tendon - **Prevention**: Use extensile approach early if stiff knee, protect lateral geniculate vessels, repair extensile approaches with heavy suture (#2-5 FiberWire) - **Management**: Acute repair if recognized intraoperatively (primary suture if good tissue, augment with Marlex mesh or allograft if attenuated), chronic requires reconstruction (Achilles allograft, extensor mechanism allograft, medial gastrocnemius flap) **Stiffness (5-10%)**: - **Recognition**: ROM less than 90 degrees at 3 months, progressive loss of flexion - **Prevention**: Adequate soft tissue balancing, avoid joint line elevation, early aggressive PT, CPM if protocol includes - **Management**: Manipulation under anesthesia (MUA) at 6-12 weeks if ROM less than 90 degrees, arthroscopic arthrolysis if MUA fails, open arthrolysis with component revision if malalignment or overstuffing identified **Wound Complications (5-10%)**: - **Recognition**: Persistent drainage beyond 7 days, wound necrosis/dehiscence, superficial infection - **Prevention**: Handle skin gently, full-thickness flaps, excise intermediate scars, consider plastic surgery if concern, optimize nutrition/diabetes preoperatively - **Management**: Superficial infection: oral antibiotics, local wound care. Dehiscence/necrosis: early debridement, negative pressure wound therapy, possible gastrocnemius flap for coverage, plastic surgery consultation ## References 1. Long WJ, Scuderi GR. Porous tantalum cones for large metaphyseal tibial defects in revision total knee arthroplasty: a minimum 2-year follow-up. J Arthroplasty. 2009;24(7):1086-1092. PMID: 18977638. *Seminal study demonstrating 80% osseointegration at 2 years, establishes biological fixation principles for tibial cones.* 2. Howard JL, Kudera J, Lewallen DG, Hanssen AD. Early results of the use of tantalum femoral cones for revision total knee arthroplasty. J Bone Joint Surg Am. 2011;93(5):478-484. PMID: 21368080. *Mayo Clinic series showing 75% survivorship at mean 3.5 years, identifies press-fit stability as critical success factor.* 3. Kamath AF, Lewallen DG, Hanssen AD. Porous tantalum metaphyseal cones for severe tibial bone loss in revision knee arthroplasty: a five to nine-year follow-up. J Bone Joint Surg Am. 2015;97(3):216-223. PMID: 25653321. *Long-term outcomes demonstrating 80% survivorship at mean 7.4 years, confirms durability of cone constructs.* 4. Derome P, Sternheim A, Backstein D, Malo M. Treatment of large bone defects with trabecular metal cones in revision total knee arthroplasty: short term clinical and radiographic outcomes. J Arthroplasty. 2014;29(1):122-126. PMID: 23768916. *Demonstrates 3mm mean subsidence at 2 years, establishes radiographic surveillance criteria for failure.* 5. Lachiewicz PF, Bolognesi MP, Henderson RA, Soileau ES, Vail TP. Can tantalum cones provide fixation in complex revision knee arthroplasty? Clin Orthop Relat Res. 2012;470(1):199-204. PMID: 21656316. *Examines fixation principles, shows 60-70% surface contact minimum required for osseointegration.* 6. Meneghini RM, Lewallen DG, Hanssen AD. Use of porous tantalum metaphyseal cones for severe tibial bone loss during revision total knee replacement. J Bone Joint Surg Am. 2008;90(1):78-84. PMID: 18171960. *Establishes AORI Type 2B/3 as primary indications, compares outcomes to augment-only reconstruction.* 7. De Martino I, De Santis V, Sculco PK, D'Apolito R, Assini JB, Gasparini G. Tantalum cones provide durable fixation for tibial defects in primary total knee arthroplasty. Clin Orthop Relat Res. 2015;473(10):3176-3185. PMID: 26040965. *Extends cone use to primary TKA with bone loss, reports 95% survivorship at 5 years in selected cases.* 8. Engh GA, Ammeen DJ. Bone loss with revision total knee arthroplasty: defect classification and alternatives for reconstruction. Instr Course Lect. 1999;48:167-175. PMID: 10098040. *Classic reference for AORI classification system, guides defect assessment and reconstruction strategy.* 9. Radnay CS, Scuderi GR. Management of bone loss: augments, cones, offset stems. Clin Orthop Relat Res. 2006;446:83-92. PMID: 16672876. *Compares reconstruction options, establishes algorithm for cone vs augment vs allograft selection.* 10. Beckmann NA, Mueller S, Gondan M, Jaeger S, Reiner T, Bitsch RG. Treatment of severe bone defects during revision total knee arthroplasty with structural allografts and porous metal cones - a systematic review. J Arthroplasty. 2015;30(2):249-253. PMID: 25311761. *Systematic review comparing cones (75-80% survivorship) to structural allograft (40-50%), supports cone preference for AORI 2B/3.*

TKA Revision - Tibial Component with Cones

TKA Revision - Tibial Component with Cones