Total Knee Arthroplasty - Cemented

Patient Assessment and Selection

Indications

• End-stage osteoarthritis with radiographic Kellgren-Lawrence grade 3-4, failed conservative management for 3-6 months minimum (NSAIDs, physiotherapy, activity modification, weight loss if BMI over 30, intra-articular injections with corticosteroid or hyaluronic acid)
• Inflammatory arthritis (rheumatoid arthritis, psoriatic arthritis, ankylosing spondylitis) with severe joint destruction despite medical management with DMARDs (methotrexate, sulfasalazine) and biologics (TNF inhibitors, IL-6 inhibitors)
• Post-traumatic arthritis following tibial plateau fracture, distal femoral fracture, or chronic ligamentous instability (ACL/PCL deficiency) with secondary degenerative changes
• Osteonecrosis with collapse and secondary degenerative changes
• Significant functional limitation: inability to walk more than 1-2 blocks, unable to climb stairs, night pain affecting sleep, impact on activities of daily living and quality of life
• Patient age typically over 65 years (longer survival rates in older patients), but younger patients considered if severe symptoms and realistic expectations regarding activity level and revision risk

Contraindications

• Absolute: Active infection (septic arthritis, osteomyelitis, cellulitis), inadequate soft tissue envelope with open wounds or active ulceration, extensor mechanism dysfunction (quadriceps rupture, patellar tendon rupture) not reconstructable, severe vascular insufficiency precluding healing
• Relative: Age less than 50-55 years (higher revision rates, consider alternatives like HTO or UKA), severe obesity (BMI over 40, increased complications infection, thromboembolism, mechanical failure), active substance abuse or psychiatric illness limiting compliance with rehabilitation, medical comorbidities with prohibitive anaesthetic risk, neuropathic arthropathy (Charcot joint) with severe bone loss and instability

Medical Optimization

• Glycemic control: HbA1c less than 7% (ideally less than 6.5%), defer surgery if over 8% until optimized with endocrinology input
• Smoking cessation: minimum 4-6 weeks preoperatively, reduces wound complications and infection risk
• Weight loss: target BMI less than 35-40, consider bariatric surgery referral if morbid obesity
• Malnutrition screening: albumin over 35g/L, total lymphocyte count over 1500, consider nutritional supplementation if deficient
• Dental clearance: treat active dental caries, periodontal disease (potential source bacteremia and hematogenous seeding)
• Dermatologic assessment: treat active skin conditions (psoriasis, eczema, ulceration) before surgery
• Cease anticoagulation and antiplatelet agents per anaesthetic guidelines (warfarin 5 days, clopidogrel 7 days, continue aspirin)

Radiographic Planning

• Weight-bearing films essential: AP pelvis-to-ankle (mechanical axis), standing AP knee, lateral knee, skyline patella (Merchant or sunrise view)
• Deformity analysis: Measure mechanical axis deviation (normal passes through center of knee), quantify varus/valgus deformity, assess if fixed or correctable (stress radiographs if uncertain)
• Component sizing: Template femoral and tibial component sizes, assess canal dimensions if considering stemmed components, identify potential bone loss requiring augments
• Specific assessments: Patellar morphology (Wiberg classification, depth of trochlear groove), patella alta or baja (Insall-Salvati ratio normal 0.8-1.2), tibial slope (normal 3-7 degrees posterior), presence of spurs or osteophytes
• Advanced imaging: CT scan for complex deformity (assess bone stock, version), rotational alignment if prior deformity or fracture, patient-specific instrumentation if available, MRI rarely indicated unless soft tissue assessment needed

Positioning and Exposure

Patient Setup

• Supine position on standard operating table with radiolucent extension or foot holder
• Leg holder preferred (independent positioning, stable throughout case) or foot-of-bed flexion capability to allow knee flexion to 90+ degrees
• Tourniquet on proximal thigh, padding adequate to prevent skin injury
• Test knee can flex to 90 degrees and extend fully before preparation
• Ensure ability to assess mechanical axis with sterile alignment rod intraoperatively
• Lateral thigh post if using leg holder (prevents external rotation of limb)
• Prepare entire limb from tourniquet to toes, include foot for alignment assessment

Skin Incision

• Standard: Midline or medial parapatellar, 12-15cm length from 5-7cm proximal to superior pole patella to tibial tuberosity
• Previous scars: Use most lateral incision if multiple (best blood supply from lateral genicular artery), avoid skin bridges less than 5cm width (necrosis risk)
• Incision pearls: Straight longitudinal orientation, centered over patella or 1cm medial, identify landmarks (tibial tuberosity, patella, quadriceps tendon) before incising, develop full-thickness skin flaps without excessive undermining
• Handling: Gentle retraction with skin hooks (not forceps which crush dermis), maintain hemostasis, avoid tension on skin edges

Arthrotomy

• Medial parapatellar (standard): Incise medial retinaculum 5-8mm medial to patellar border from superior pole to inferior pole, extend proximally into quadriceps tendon in line with VMO fibers (medial to rectus), extend distally along medial border patellar tendon to tibial tuberosity
• Depth: Through capsule into joint, confirm entry by visualizing synovium and articular cartilage
• Preservation: Stay medial to patella to preserve peri-patellar vascular ring, preserve VMO insertion on distal medial patella
• Mark edges: Place stay sutures in capsular edges to aid later repair and prevent retraction
• Alternative approaches: Midvastus (split VMO in line with fibers, less disruption to extensor mechanism), subvastus (elevate VMO from intermuscular septum, preserves quad tendon), lateral parapatellar (for severe valgus with contracted lateral structures)

Bony Preparation and Resection

Exposure and Preparation

• Evert patella laterally with gentle pressure and knee flexion (60-90 degrees optimal)
• If difficult eversion: Extend quadriceps incision proximally first, release adhesions, consider gentle lateral retinacular release if absolutely necessary (high risk devascularization)
• Excise infrapatellar fat pad flush with anterior tibia (improves visualization), preserve some fat for soft tissue coverage
• Remove anterior cruciate ligament remnant from tibial and femoral insertions using curved osteotome
• Excise medial and lateral menisci completely with meniscal knives
• Remove peripheral osteophytes (femoral and tibial) - falsely tighten gaps
• Identify posterior cruciate ligament (preserve for CR design, may release for PS design)
• Assess coronal and sagittal deformity with knee extended

Tibial Preparation

• Alignment guide: Extramedullary alignment rod along anterior tibial crest, aimed at center of ankle mortise (between malleoli) or second metatarsal
• Varus/valgus: Set to perpendicular to mechanical axis (0 degrees), adjust for deformity
• Posterior slope: 3-7 degrees (match native tibial slope or component design requirement - CR often 3-5 degrees, PS may accept 5-7 degrees)
• Resection depth: 8-10mm from less affected plateau (lateral in varus knee typically less worn, medial in valgus knee), minimum resection 2mm to ensure good bleeding bone for cement fixation
• Execute cut: Oscillating saw staying on guide, complete cut medial to lateral, protect MCL and popliteal vessels with retractors, ensure complete cut to allow removal without fracture
• Verification: Place tibial trial component, check alignment with EM rod, confirm perpendicular to mechanical axis, assess posterior slope, check coverage (overhang causes soft tissue irritation, underhang risks subsidence)

Femoral Preparation

• Intramedullary guide: Open femoral canal at center of trochlear notch with drill or box cutter, insert IM rod
• Valgus angle: Set 5-7 degrees (angle between femoral mechanical axis and anatomical axis), individualize based on preoperative templating
• Distal resection: 8-10mm from least worn condyle (lateral in valgus knee, medial in varus knee), use distal cutting guide
• Femoral rotation (CRITICAL):
  • Posterior condylar axis (PCA) plus 3 degrees external rotation - measure from posterior condyles
  • Transepicondylar axis (TEA) - MOST RELIABLE - lateral epicondylar prominence to medial epicondylar sulcus
  • Whiteside's line (AP axis) - perpendicular to line from trochlear groove to intercondylar notch
  • If conflict between references, prioritize epicondylar axis
  • Internal rotation causes: patellar maltracking, lateral subluxation, flexion gap asymmetry (tight medially), flexion instability
• Anterior/posterior cuts: Size femoral component to fill AP dimension without anterior notching (stress riser for supracondylar fracture) or posterior overhang (impingement), make cuts with 4-in-1 guide or sequential cutting blocks
• Chamfer cuts: Complete anterior and posterior chamfers
• Box cut (if PS design): Use box chisel sized to femoral component, create box centered on femoral axis, avoid perforation of posterior cortex

Gap Balancing and Assessment

Extension Gap

• Place spacer blocks between tibial and femoral resected surfaces in full extension (0 degrees)
• Target: 8-10mm thickness (match planned component thickness including polyethylene)
• Assess: Knee should extend fully to 0 degrees, medial and lateral compartments balanced (equal tension), no lift-off of spacer
• If tight medially (varus knee): Release deep MCL incrementally with pie-crusting technique (multiple punctures with scalpel through capsular MCL), remove remaining osteophytes, avoid releasing superficial MCL (primary stabilizer)
• If tight laterally (valgus knee): Release ITB from Gerdy's tubercle, posterolateral capsule, popliteus tendon, lateral collateral ligament incrementally, protect common peroneal nerve
• If globally tight: Resect more distal femur (increases both extension and flexion gaps equally)

Flexion Gap

• Place spacer blocks at 90 degrees knee flexion
• Target: Equal to extension gap (8-10mm), rectangular shape (equal medial and lateral tension), femoral component should be parallel to tibial cut
• If tight in flexion: Downsize femoral component (increases flexion gap), increase distal femoral resection (increases flexion gap more than extension gap), release posterior capsule or PCL if CR design
• If loose in flexion: Upsize femoral component, use thicker polyethylene insert
• If asymmetric (medial or lateral tightness): Usually due to femoral rotation error (internal rotation creates medial tightness in flexion), reassess femoral component rotation, adjust if needed

Trial Components

• Insert tibial trial component: align with tibial tuberosity anteriorly, center mediolaterally (or 1-2mm medial to geometric center)
• Insert polyethylene trial: thickness determined by gap balancing assessment
• Insert femoral trial: rotation as determined using bony landmarks
• Reduce patella and knee
• Systematic assessment:
  • Alignment: EM rod through knee center, mechanical axis restored
  • Stability: varus/valgus stress in extension and flexion - stable with soft endpoint, no excessive laxity
  • ROM: full extension (0 degrees), flexion minimum 110 degrees (goal 120+ degrees)
  • Patellar tracking: 'no thumb test' - patella should centralize by 30-40 degrees flexion without manual pressure, track centrally through full ROM

Cement Technique Principles

Bone Preparation

• Remove all trial components
• Pulsatile lavage with minimum 3L saline (preferably 6L), ensure all debris removed from posterior capsule, gutters, suprapatellar pouch
• Curette sclerotic bone gently to create bleeding cancellous surface (improves cement interdigitation)
• Dry bone surfaces thoroughly: suction, sponges, pulsatile compressed air
• CRITICAL: Wet bone prevents cement interdigitation and leads to early loosening
• Insert intramedullary canal plugs if using stemmed components

Cement Mixing and Application

• Mix cement (antibiotic-loaded per institutional protocol - typically gentamicin 1g per 40g cement, or tobramycin)
• Timing: apply at dough phase (no longer sticky, does not adhere to glove)
• Application technique: Apply thin layer to bone surfaces (not component), use finger or brush to spread evenly, pressurize into cancellous bone with cement pressurizer or finger pressure
• Creates macro-interlock between cement and bone for long-term fixation
• Volume: Thin layer 2-3mm thickness, avoid excessive cement (increases heat generation, necrosis risk)

Component Insertion Sequence

Tibial Component

• Apply pressurized cement to tibial cut surface, ensure complete coverage including periphery
• Insert tibial baseplate in predetermined position (align with tibial tuberosity, centered ML or 1-2mm medial)
• Impact gently with mallet until fully seated, check seating on AP and lateral planes
• Hold with impactor or presser to maintain pressure
• Cement removal: Remove excess cement from periphery with curette while still viscous (before fully hardened), pay special attention to posterior cement extrusion (near popliteal vessels - remove carefully under direct vision)
• Maintain constant pressure until cement fully hardened (polymerization complete, no longer warm)
• Positioning pearls: Anteroposterior rotation - align with center of tibial tuberosity (avoid internal rotation causes patellar maltracking), mediolateral - centered or 1-2mm medial, avoid overhang (soft tissue irritation) or underhang (subsidence risk)

Femoral Component

• Apply pressurized cement to all femoral surfaces: distal condyles, anterior, posterior, chamfers, box (if PS design)
• Insert femoral component in predetermined rotation (verify visually with landmarks)
• Impact until fully seated, verify rotation has not changed
• Hold component with impactor or use cementation rod through IM canal
• Cement removal: Remove excess cement meticulously especially from posterior condyles (can limit flexion), intercondylar area (impingement), and trochlear groove (patellar maltracking)
• Maintain pressure until cement hardened
• Rotation verification: Re-check rotation using epicondylar axis, Whiteside's line, posterior condylar axis before cement sets, most common error is inadvertent internal rotation during impaction

Patellar Component

• Apply cement to prepared patellar bone bed (ensure bleeding surface, adequate fixation holes drilled)
• Insert patellar component (3-peg or dome design per system)
• Positioning: Center component on patella (avoid medialization which increases lateral subluxation risk, avoid lateralization which causes medial impingement)
• Orient dome component (if applicable) to match anatomic orientation
• Impact gently until seated
• Remove excess cement from articular rim (cement extrusion causes impingement and maltracking)
• Hold until cement hardened
• Thickness check: Total patellar thickness (bone remnant plus component) should equal or be slightly less (1-2mm) than native patella thickness to avoid overstuffing and reduced ROM

Final Assembly and Assessment

Polyethylene Insertion

• Select polyethylene insert based on gap balancing (typically 8-12mm thickness)
• Insert into tibial baseplate ensuring locking mechanism fully engaged
• Verify locking: Different designs have different mechanisms - visual confirmation, tactile click, tug test to confirm locked
• Unlocked polyethylene can dislocate postoperatively (catastrophic complication)

Final Lavage

• Pulsatile lavage entire joint with 3-6L saline minimum
• Remove ALL cement debris and bone fragments (third-body wear significantly reduces longevity)
• Inspect systematically: posterior capsule, medial and lateral gutters, suprapatellar pouch, intercondylar notch, undersurface of patella

Final Assessment

• Reduce knee with final components
• Alignment: EM alignment rod through mechanical axis (should pass through center of knee)
• ROM: Full extension 0 degrees (flexion contracture not acceptable), flexion goal 110+ degrees (120+ ideal)
• Stability: Varus/valgus stress in extension and 90 degrees flexion - stable with soft endpoint, minimal laxity (less than 5 degrees opening), avoid excessive constraint
• Patellar tracking: Through full ROM without thumb pressure, should centralize by 30-40 degrees flexion, track centrally without subluxation through full flexion
• Lateral release (only if needed): If patellar maltracking persists after verifying component rotation and position correct, sequential lateral release: (1) Lateral retinaculum only, (2) If still maltracking, release ITB insertion, avoid extensive release (devascularization, fracture risk)

Wound Closure

Deep Layer

• Close medial parapatellar arthrotomy with interrupted or continuous absorbable sutures (1-0 or 0 Vicryl)
• Achieve watertight closure (prevents fluid extravasation, hematoma formation)
• Repair quadriceps tendon extension if extended proximally, ensure robust repair
• Verify patellar tendon insertion intact at tibial tuberosity (disruption is devastating complication)
• Closure pearls: Interrupted sutures more secure if tissues under tension or friable, continuous faster but risk of dehiscence if one suture breaks, consider non-absorbable sutures (Ethibond) for reinforcement if poor tissue quality

Subcutaneous and Skin

• Close subcutaneous layer in two layers if thick, single layer if thin, use absorbable sutures (2-0 or 3-0 Vicryl)
• Skin closure: staples (fast, equivalent outcomes), subcuticular absorbable (cosmetic, patient preference), or skin sutures (easy removal)
• Apply sterile dressing: absorptive inner layer, compression outer layer
• Drain use: Controversial - consider if significant oozing, anticoagulation planned early, or high-risk patient for hematoma. If used, remove at 24-48 hours (prolonged use increases infection risk)

Postoperative Management

Immediate Postoperative (0-24 hours)

• Recovery room: neurovascular examination (pulses, capillary refill, sensation, motor function), assess pain control
• Analgesia: multimodal approach - regional block (adductor canal or femoral nerve block), oral analgesia (paracetamol, NSAIDs if not contraindicated, opioids as needed), local infiltration analgesia (LIA) during surgery
• Thromboprophylaxis: Risk stratify per ANZCOR guidelines - standard risk (aspirin 100mg OD), high risk (LMWH enoxaparin 40mg SC daily or rivaroxaban 10mg OD or apixaban 2.5mg BD), duration minimum 10-14 days, extend to 35 days if high risk
• Mechanical prophylaxis: early mobilization (day 0 or 1), TED stockings or intermittent pneumatic compression devices
• Antibiotics: Continue perioperative prophylaxis for 24 hours (cefazolin 2g IV 8-hourly or vancomycin 15-20mg/kg 12-hourly if MRSA risk per eTG guidelines)
• Wound care: Keep dressing dry and intact for 48-72 hours, elevate limb to reduce swelling
• Continuous passive motion (CPM): Controversial - some evidence for improved early ROM, not mandatory

Early Postoperative (1-7 days)

• Physiotherapy: Commence day 1 - mobilization with walking frame or crutches, quadriceps exercises, ROM exercises, stairs practice
• ROM goals: Full extension immediately, progressive flexion (90 degrees by day 3-5, 110 degrees by 2 weeks)
• Wound assessment: Check at 48-72 hours when dressing changed, assess healing, drainage, signs infection (erythema, warmth, purulent discharge)
• Remove drain if present at 24-48 hours
• Radiographic assessment: Standing AP and lateral knee (component position, alignment, cement mantle), identify any immediate complications (fracture, malposition)
• Discharge planning: Most patients 3-5 days, criteria (mobilizing safely, pain controlled on oral analgesia, wound healing appropriately, no complications), arrange physiotherapy outpatient or home visits, provide discharge instructions

Subacute Phase (2-6 weeks)

• Wound review at 10-14 days: Remove sutures/staples, assess healing, educate regarding wound care
• Physiotherapy: Progressive strengthening, ROM exercises, gait training, return to ADLs
• ROM goals: 0 degrees extension, 110+ degrees flexion by 6 weeks
• Return to driving: Typically 4-6 weeks (right TKA, able to perform emergency stop, off opioids)
• Thromboprophylaxis: Continue for 10-14 days minimum (35 days if high risk - prior VTE, thrombophilia, cancer)

Long-term Follow-up

• Radiographic surveillance: 6 weeks, 6 months, 1 year, then annually or biannually
• Assess for: lucent lines (progressive over 2mm concerning for loosening), component migration or subsidence, polyethylene wear, osteolysis, periprosthetic fracture
• Clinical assessment: ROM (expect 0-120 degrees), pain (should be minimal to none), function (walking distance, stairs, return to activities)
• Complications screening: Infection (persistent pain, swelling, erythema, drainage), instability (giving way, sense of looseness), stiffness (ROM less than 90 degrees flexion)
• Dental prophylaxis: Antibiotic prophylaxis before dental procedures for 2 years post-TKA per ANZSA guidelines (amoxicillin 2g PO 1 hour before or cefazolin 2g IV if unable to take oral)
• Patient education: Activity modification (avoid high impact - running, jumping, contact sports, prefer low impact - walking, swimming, cycling), weight management, report concerning symptoms early (pain, swelling, fevers)

Additional Complications

Venous Thromboembolism (VTE) - DVT and PE

• Incidence: Without prophylaxis DVT 40-60%, PE 1-3%, fatal PE 0.1-0.5%. With appropriate prophylaxis significantly reduced to DVT 1-5%, PE less than 1%, fatal PE less than 0.1%
• Prevention: All patients require thromboprophylaxis per ANZCOR guidelines. Risk stratify: standard risk (aspirin 100mg OD for 35 days), high risk (LMWH enoxaparin 40mg SC daily or rivaroxaban 10mg OD or apixaban 2.5mg BD for 35 days). High risk defined as: age over 75, BMI over 35, prior VTE, thrombophilia, cancer, immobility. Mechanical prophylaxis: early mobilization day 0 or 1, calf pumps intraoperatively, TED stockings or intermittent pneumatic compression devices. Regional anaesthesia beneficial (reduces VTE risk compared to general anaesthesia)
• Recognition: Clinical suspicion (leg swelling, pain, erythema, Homan's sign for DVT; chest pain, dyspnoea, hypoxia, tachycardia, hemoptysis for PE). Diagnosis: compression ultrasound for DVT (sensitivity 95% for proximal DVT, less for calf), D-dimer if negative excludes DVT (high sensitivity, low specificity), CTPA for PE (gold standard)
• Management: Anticoagulation (LMWH therapeutic dose or DOAC - rivaroxaban 15mg BD for 3 weeks then 20mg OD or apixaban 10mg BD for 7 days then 5mg BD), duration minimum 3 months, consider 6-12 months if unprovoked or recurrent VTE. Massive PE with hemodynamic instability: thrombolysis (alteplase) or surgical/catheter embolectomy. IVC filter if anticoagulation absolutely contraindicated (active bleeding, recent hemorrhagic stroke) - rare indication, high complication rate

Neurovascular Injury

• Incidence: Popliteal artery injury less than 0.1% (devastating if occurs), common peroneal nerve injury 0.5-2% (higher in valgus deformity correction up to 5%)
• Prevention: Protect popliteal vessels during posterior tibial cut (retractors in place, careful saw technique, do not plunge posteriorly, visualize blade exit), remove posterior cement extrusion gently under direct vision, avoid hyperextension during closure (stretches popliteal artery), monitor pulses intraoperatively before and after tourniquet release. Peroneal nerve: incremental soft tissue releases in valgus knee (avoid aggressive ITB/LCL release in single step), padding during surgery, avoid compression from hematoma or tight dressings postoperatively, limit valgus correction to 15-20 degrees in single stage (consider staged correction if severe deformity over 20 degrees)
• Recognition: Vascular injury - loss of pulses, pale cool foot, pain out of proportion. Peroneal nerve - foot drop (loss of dorsiflexion and eversion), sensory loss over dorsum of foot, high-stepping gait
• Management: Vascular injury - EMERGENCY, remove tourniquet immediately, assess knee position (hyperextension - reduce to flexion), assess for hematoma (decompress if present), vascular surgery consult emergently, arterial exploration and repair or bypass required, delay over 6 hours dramatically increases limb loss risk (ischemic time critical), postoperative monitoring in ICU, may require fasciotomies if compartment syndrome. Peroneal nerve palsy - most are neurapraxia from traction during correction (especially in valgus knee), will recover over 6-12 months in majority, provide ankle-foot orthosis (AFO), physiotherapy, patient education and reassurance, serial EMG studies at 3, 6, 12 months to document recovery, if complete transection suspected from sharp injury (rare): early exploration within 72 hours and primary repair or grafting

Wound Complications

• Incidence: 2-5%, increased with obesity, diabetes, vascular insufficiency, multiple previous incisions, poor soft tissue envelope, steroid use, immunosuppression
• Prevention: Preoperative optimization (smoking cessation, diabetes control, nutritional supplementation if malnourished albumin less than 35g/L). Surgical technique: use most lateral previous incision if multiple (best blood supply from lateral genicular artery), avoid skin bridges less than 5cm between incisions (necrosis risk), minimize skin flap undermining, gentle handling with skin hooks not forceps, meticulous hemostasis (avoid hematoma), pressure dressing postoperatively (not excessively tight), avoid tight closure if tissues under tension
• Recognition: Superficial dehiscence (skin edges separated, fat visible, no deep involvement), deep dehiscence (extends to capsule or joint, significant concern), skin necrosis (black eschar, non-viable edges), persistent drainage over 5-7 days (concerning for deep infection)
• Management: Superficial dehiscence - local wound care, dressing changes, allow secondary intention healing if small (less than 2cm), consider delayed primary closure or skin graft if larger once healthy granulation tissue. Deep dehiscence or significant skin necrosis - debridement of non-viable tissue, cultures for infection (common association), plastic surgery consult for flap coverage if large defect (medial gastrocnemius flap common choice for proximal defects, free flap if extensive), IV antibiotics if infection present. Persistent drainage over 5-7 days - concern for deep infection, aspirate joint and culture, consider washout if infection confirmed, do NOT allow wound to drain externally for prolonged period (over 1-2 weeks - colonization then infection inevitable)

Periprosthetic Fracture

• Incidence: 0.5-2% overall, increasing with osteoporosis, revision surgery, and time from index arthroplasty. Femur commonest (supracondylar), then tibia, then patella
• Prevention: Avoid anterior femoral notching (stress riser for supracondylar fracture - size femoral component correctly to fill AP dimension without notch). Adequate patellar remnant (12-15mm - thinner increases fracture risk). Gentle component impaction (avoid aggressive hammering). Protect bone during cement removal in revision surgery (minimize bone loss). Identify and treat osteoporosis preoperatively (DEXA scan if indicated, bisphosphonates, vitamin D 1000-2000IU daily, calcium 1200-1500mg daily). Patient education regarding fall prevention (home hazards, gait aids if unsteady)
• Recognition: Acute pain, inability to weight-bear, deformity if displaced, loss of active extension if extensor mechanism disrupted (patellar fracture). Radiographs: AP, lateral, obliques to visualize fracture, full-length femur or tibia films to assess alignment and plan fixation
• Classification: Fracture site (femur/tibia/patella), timing (intraoperative vs postoperative), component stability (stable vs loose - critical distinction). Femur: Lewis and Rorabeck (I - non-displaced stable component, II - displaced stable component, III - loose component). Tibia: Felix et al (I-IV based on location and stability). Patella: Ortiguera and Berry (I - stable component intact mechanism, II - component disruption, III - inferior pole avulsion, IV - comminuted)
• Management: Femur - if component stable (type I/II): ORIF with locking plate and cables/screws, avoid screws through cement mantle (poor purchase), bridge plating technique, bone graft if comminution; if component loose (type III): revision TKA with long-stemmed femoral component bypassing fracture by 2 cortical diameters (100-150mm), distal femoral replacement (DFR) if bone loss severe, plate fixation adjunct if needed. Tibia - if component stable: ORIF with locking plate, if component loose: revision with stemmed tibial component. Patella - if non-displaced with intact extensor mechanism: non-operative (cylinder cast or locked knee brace in extension for 6 weeks, protected weight-bearing); if displaced: ORIF (tension band wiring, partial patellectomy if inferior pole, cerclage if transverse); if extensor mechanism disrupted: surgical repair (primary repair if possible, allograft reconstruction if tissue inadequate, tibial tubercle advancement if distal avulsion, partial or complete patellectomy last resort - very poor outcomes)