Revision Total Knee Arthroplasty

Radiographs: Radiolucent lines greater than 2mm, progressive, component subsidence. Rule out infection: Aspirate (WBC, PMN%, culture), ESR/CRP normal or mildly elevated. CT scan: If severe bone loss suspected - quantify AORI grade preoperatively.

AORI classification: Type 1 (intact), Type 2A/B (damaged), Type 3 (deficient). Constraint needs: Assess collateral ligament integrity from examination and prior radiographs. Implant availability: Ensure CCK, augments, stems, sleeves/cones available.

Remove loose components and cement - assess final bone loss intraoperatively. Type 1: Standard components, cement fill, short stems (50-75mm). Type 2: Metal augments, modular stems (75-100mm), CCK constraint. Type 3: Metaphyseal sleeve/cone, long cemented stems (100-150mm), hinge constraint.

Weight-bearing: WBAT for most cases (protected if TTO performed). ROM: Start immediately, goal 0-110° by 6 weeks. Surveillance: Annual radiographs and clinical exam for loosening.

Varus-valgus laxity: MCL or LCL insufficiency - requires CCK or hinge. Flexion-extension gap imbalance: Mismatch between extension and 90° gaps - may need thicker poly or increase constraint. Global instability: Both varus-valgus and AP instability - requires hinge.

Stress testing: Apply varus-valgus stress in extension and 90° flexion. MCL intact, LCL deficient: CCK with varus-valgus constraint (5-10°). Both collaterals deficient: Rotating hinge (0° laxity).

Mild instability (less than 5mm): Increase poly thickness, consider CCK. Moderate instability (5-10mm): CCK with stems and augments as needed. Severe instability (greater than 10mm or global): Rotating hinge with long stems (14-16cm).

Flexion-extension gap balancing: Adjust component sizing, augments, or poly thickness. Collateral ligament reconstruction: Rarely successful - better to increase constraint.

Aspiration: Synovial WBC greater than 3000, PMN greater than 80%, positive culture. Serum markers: ESR and CRP elevated. Alpha-defensin: Confirmatory if aspiration equivocal.

Remove all components, cement, infected tissue - aggressive debridement. Cultures: 5-6 samples from different areas (aerobic, anaerobic, fungal). Antibiotic spacer: Static or articulating, vancomycin + tobramycin in cement.

Organism-specific therapy: ID consult guided. Duration: 6 weeks IV antibiotics. Monitor: ESR/CRP should trend downward.

Stop antibiotics for 2 weeks. Aspirate before Stage 2: WBC less than 3000, PMN less than 80%, negative culture.

Remove spacer, debride again, assess bone loss (final AORI). Revise with CCK or hinge based on bone loss and instability. Postoperative antibiotics: 6 weeks oral (organism-directed).

Use prior incision if feasible - most lateral if multiple scars. Extend proximally and distally as needed for exposure (often 20-25cm). Skin flaps: Medial and lateral, full-thickness to preserve blood supply.

Medial parapatellar arthrotomy (standard approach). Extend proximally into vastus medialis obliquus if tight. Release adhesions carefully - dense scar tissue common.

Attempt gentle eversion - do NOT force if tight. If unable to evert: Consider quadriceps snip (45° oblique extension of VMO) or tibial tubercle osteotomy (TTO). TTO indications: Severe stiffness, patella baja, need for extensile exposure.

Release scar tissue from suprapatellar pouch, medial and lateral gutters. Protect popliteal artery - posterior capsule may be attenuated. Assess collateral ligaments - note MCL/LCL integrity for constraint decision.

Remove polyethylene insert first for visualization. Use insert removal tool if available, or carefully lever out.

Start with peripheral osteotomes to disrupt cement-bone interface. Work circumferentially around component borders. Use extraction device - slap hammer or impactor. Preserve bone: Work slowly, avoid aggressive levering.

Similar technique: Peripheral osteotomes, circumferential disruption. Protect MCL: Tibial component removal can avulse MCL insertion. Check for stem: If stemmed, may need flexible osteotomes down stem-cement interface.

Meticulous debridement of all cement - critical for final AORI assessment. Use curettes, osteotomes, power burrs carefully. Pulse lavage: High-volume irrigation to remove debris. Final assessment: True bone loss only visible after complete cement removal.

Trial components with stems and augments in situ. Assess stability: Varus-valgus, AP drawer, flexion-extension gaps. ROM check: Ensure no impingement, adequate flexion (greater than 110°). Patellar tracking: Assess with trial components, consider lateral release if needed.

Based on:

• Bone loss (AORI grade)
• Collateral ligament integrity (MCL/LCL competence)
• Flexion-extension gap balance
• Extensor mechanism function

Select: PS (rare), CCK (most common), or rotating hinge (Type 3 or global instability).

Third-generation cementing:

• Pulse lavage and dry bone surfaces
• Cement restrictors in femur and tibia if stems used
• Pressurize cement for bone interdigitation
• Insert stems first (cemented in diaphysis), then components
• Remove excess cement before polymerization

Polyethylene insert: Select thickness for stability (usually thicker than primary, 12-15mm). Final stability check: Varus-valgus, AP drawer in extension and 90° flexion. ROM: Ensure full extension and at least 110° flexion without impingement. Patellar resurfacing: Usually yes - revise or resurface if not previously done.

Meticulous hemostasis: Bipolar cautery, avoid excessive cautery near skin edges. Tranexamic acid: Topical or IV (reduces blood loss by 30-40%).

Drain use: Controversial - many surgeons use closed suction drain for 24-48 hours. Removal criteria: Output less than 30mL per 8 hours.

Capsule/extensor mechanism: Repair with #1 or #2 absorbable suture (Vicryl). If TTO performed: Fix tubercle with two screws or heavy suture through drill holes. Fascia: Close in layers to reduce dead space. Subcutaneous: 2-0 absorbable suture. Skin: Staples or subcuticular (staples faster, subcuticular cosmetic).

Dressing: Bulky compressive dressing. Splint: Optional knee immobilizer if extensor mechanism weak or TTO performed. Duration: 24-48 hours, then begin ROM.

DVT prophylaxis: Chemical (enoxaparin or rivaroxaban) and mechanical (SCDs). Pain control: Multimodal analgesia (acetaminophen, NSAIDs, opioids as needed). Mobilization: Out of bed to chair on Day 1, ambulate with walker Day 2. Weight-bearing: WBAT (weight-bearing as tolerated) for most revisions. ROM: CPM or bedside PT - goal 0-90° by discharge. Drain removal: 24-48 hours when output less than 30mL per 8 hours.

Weight-bearing: Progress to full weight-bearing with assistive device. ROM exercises: Active-assisted and passive, goal 0-110° by 6 weeks. Quadriceps strengthening: Straight leg raises, quad sets, terminal knee extension. Gait training: Progress from walker to cane to independent. Wound care: Staples removed at 2 weeks, monitor for infection. Radiographs: 6-week films to assess alignment, component position, no early loosening.

Discontinue assistive device when safe gait without limp. Resistance exercises: Progress resistance training for quads, hamstrings, hip abductors. Functional activities: Stairs, sit-to-stand, balance exercises. ROM maintenance: Continue ROM exercises, goal 0-120° flexion. Return to activities: Light ADLs, avoid high-impact (running, jumping).

Functional milestones: Independent ADLs, driving (8-12 weeks), return to work (12-16 weeks). Activity modification: Avoid high-impact sports - low-impact only (cycling, swimming, golf). Annual follow-up: Radiographs and clinical exam to monitor for loosening, wear, osteolysis. Expectations: 70-80% function of primary TKA, pain improvement in 80-85% of patients.

TDWB: Touch-down weight-bearing only (10-20 lbs). Brace: Knee immobilizer locked in extension for ambulation. ROM: Passive ROM only (CPM, therapist-assisted) - NO active extension. Quad sets: Isometric only, no SLR (to protect tubercle fixation).

Radiographs: Confirm tubercle union before advancing. Weight-bearing: Progress to WBAT, then full weight-bearing if union confirmed. Active ROM: Begin gentle active ROM if union solid. Strengthening: Progress quad strengthening cautiously.

Functional activities: Resume normal activities if tubercle healed. Radiographs: 6-month films to confirm maintained union.