Primary Total Knee Replacement - Comprehensive Technique

Indications

Absolute Indications

• End-stage knee arthritis with bone-on-bone radiographic changes
• Failed conservative management (6 months minimum: physio, weight loss, NSAIDs, injections)
• Pain limiting activities of daily living (ADLs)
• Patient understanding of procedure, realistic expectations, willing to comply with rehab

Relative Indications

• Inflammatory arthritis (RA, psoriatic arthritis) with joint destruction
• Post-traumatic arthritis with malunion/nonunion
• Osteonecrosis with collapse and secondary arthritis
• Neuropathic arthropathy (Charcot knee) - consider higher constraint

Contraindications

Absolute:

• Active infection (knee, systemic bacteremia)
• Insufficient bone stock for fixation (consider stemmed components, bone grafting)
• Absent extensor mechanism (consider arthrodesis or megaprosthesis)
• Severe peripheral vascular disease (risk limb loss)

Relative:

• Poor skin condition (scarring, ulceration, stasis dermatitis)
• Neuropathic joint requiring higher constraint
• Morbid obesity (BMI >40) - higher complication rates
• Young age (<55 years) - higher revision rates
• Active smoking - wound complications 3x higher
• Poorly controlled diabetes (HbA1c >8%) - infection risk

Preoperative Planning

Clinical Assessment

• History: Pain pattern, functional limitation, previous treatments, injections
• Examination: Deformity (varus/valgus), fixed flexion contracture, ROM, ligament stability, extensor mechanism integrity, skin condition, vascular status (pulses), neurological status
• Templating: Determine component sizes, assess bone quality, plan for defects
• Medical optimization: Cardiology clearance if indicated, optimize diabetes (HbA1c <8%), smoking cessation, dental clearance, nutritional status (albumin, pre-albumin)

Radiographic Assessment

• Weight-bearing AP and lateral knee: Joint space narrowing, osteophytes, subchondral sclerosis/cysts, bone defects
• Long leg alignment (hip-knee-ankle): Mechanical axis deviation, constitutional varus/valgus
• Skyline patella: Patellofemoral arthritis, dysplasia, tilt/subluxation
• Assess: Deformity magnitude, bone defects requiring grafting, extra-articular deformity, ligament competency

Implant Selection

• Cruciate retention: CR (cruciate-retaining) if intact PCL, PS (posterior-stabilized) if deficient PCL or >15° fixed flexion contracture
• Constraint level: Standard for most primary TKR, semi-constrained if ligament incompetence, hinged for severe instability
• Fixation: Cemented for most primary TKR (Gold standard), cementless in young active patients (controversial), hybrid (cementless femur, cemented tibia) rarely used
• Patellar resurfacing: ALWAYS in inflammatory arthritis, significant wear, patellofemoral symptoms; SELECTIVE in others (surgeon preference varies)

Patient Counseling

• Realistic expectations: Pain relief 90-95%, improved function but NOT normal knee
• ROM expectations: Target 0-120°, may not achieve full flexion
• Activity modification: Avoid high-impact activities (running, jumping sports)
• Longevity: 90% survival at 15-20 years, may require revision in lifetime
• Complications: Infection 1-2%, VTE 2-4%, stiffness 5-10%, revision risk 5-10% at 10 years

Positioning and Setup

Patient Position

• Supine position on operating table
• Operative leg free to flex through full ROM (0-120°)
• Foot of table dropped OR leg holder device attached to table
• Lateral post at hip level (prevents leg falling off table during surgery)
• Small bump under ipsilateral hip (15-20°) for external rotation of leg
• Tourniquet applied high on thigh (proximal as possible to maximize working space)

Tourniquet Management

• Inflation pressure: 300mmHg or LOP (limb occlusion pressure) +100mmHg
• Exsanguination: Elevate leg 2 minutes OR Esmarch bandage from toes to thigh (avoid if DVT risk)
• Time limit: Maximum 2 hours (deflate if approaching limit for hemostasis, then re-inflate if needed)
• Deflation: Before closure to achieve hemostasis, or after closure (surgeon preference)

Draping

• Leg draped free including foot (allows full ROM and alignment assessment)
• Waterproof barrier beneath leg
• Clear drapes optional (allows visualization of overall leg alignment)

Equipment Check

• Instrumentation: Complete TKR set, cutting guides, trials, spacer blocks
• Components: Correct sizes available based on templating
• Cement: 3rd generation antibiotic cement (gentamicin typical), mixing system
• Saw: Oscillating saw with fresh blades
• Retractors: Hohmann retractors for exposure, laminar spreaders for gap assessment
• Pulsatile lavage for bone preparation

Surgical Approach - Medial Parapatellar

Landmarks and Skin Incision

Palpate and mark landmarks:

• Superior pole of patella
• Inferior pole of patella
• Tibial tubercle
• Joint line (approximately 1cm below inferior pole patella)
• Medial epicondyle of femur
• Fibular head laterally

Skin incision:

• Midline longitudinal incision (CRITICAL for future revision surgery)
• Length: 12-15cm (adjustable based on exposure needs, body habitus)
• Proximal extent: 5cm above superior pole of patella
• Distal extent: 2-3cm below tibial tubercle
• Deepens straight down to capsule with full-thickness flaps

Rationale for midline:

• Allows flexibility for future revision (can extend proximally/distally)
• Can access medial or lateral side through same incision
• Preserves blood supply better than parapatellar skin incision
• If previous incisions present: ALWAYS use most LATERAL incision (preserves medial blood supply)

Arthrotomy - Medial Parapatellar

Step-by-step technique:

1. Proximal extension into quadriceps (4-5cm):

   • Incise quadriceps tendon 2-3mm medial to patella
   • Cut in line with muscle fibers (parallel to vastus medialis fibers)
   • Avoid cutting into muscle belly (bleeding, weakness)

2. Along medial patellar border:

   • Continue incision along medial border of patella
   • Stay on bone (protects medial blood supply)
   • Continue to inferior pole

3. Patellar tendon and tibial tubercle (MOST CRITICAL):

   • At inferior pole, curve slightly medially
   • Continue 2-3mm medial to patellar tendon
   • At tibial tubercle: STAY DIRECTLY ON BONE (protects insertion)
   • Avulsion here is catastrophic complication

4. Extension around medial tibia:

   • Extend arthrotomy posteriorly along proximal medial tibia
   • Incise deep to MCL fibers
   • Allows patellar eversion

Alternative Approaches (Know for Exam)

Subvastus approach:

• Vastus medialis elevated off intermuscular septum, not incised
• Preserves quadriceps mechanism integrity
• Better for patellar blood supply
• Limited exposure in large patients or muscular individuals
• Faster recovery, less anterior knee pain

Midvastus approach:

• Split vastus medialis obliquus in line with fibers
• Compromise between medial parapatellar and subvastus
• Slightly better quadriceps function than medial parapatellar
• Still allows good exposure

Lateral parapatellar approach:

• Indicated for severe valgus deformity (>20°), previous lateral incisions
• Through vastus lateralis
• Allows better access to lateral structures for release
• Risk of patellar devascularization higher

Patellar Eversion and Exposure

Gentle Patellar Eversion

• Evert patella laterally with gentle traction (not forcefully)
• Flex knee to 90° (facilitates eversion)
• Release medial gutter to level of fat pad with electrocautery (creates pocket for everted patella)

If Difficult Eversion - DO NOT FORCE

Options:

1. Lateral retinacular release (CAREFUL - risk patellar devascularization)
2. Subluxation instead of eversion (displace laterally without full eversion)
3. Tibial tubercle osteotomy for severe stiffness or revision cases
4. Convert to subvastus approach if not too far into procedure

Initial Assessment

• Remove loose bodies and debris
• Assess PCL integrity (if considering CR design)
• Assess menisci and cartilage status
• Identify osteophytes for removal

Systematic Osteophyte Removal

REMOVE ALL OSTEOPHYTES BEFORE BONE CUTS (affects soft tissue balance)

Femoral Osteophytes

• Anterior osteophytes: Rongeur or saw
• Medial/lateral osteophytes: From condyles and epicondylar regions
• Posterior femoral osteophytes: Use curved osteotome, careful of popliteal vessels
• Intercondylar osteophytes: From notch region

Tibial Osteophytes

• Peripheral osteophytes: Circumferentially around tibial plateau
• Intercondylar eminence: If excessive, but preserve PCL insertion if CR design

Patellar Osteophytes

• Inferior pole: Common location
• Peripheral: Around articular margin

Meniscal and ACL Remnants

• Remove meniscal remnants completely
• Remove ACL remnant (or preserve if CR design and intact)
• PCL: Preserve if CR design, remove if PS design

Landmark Identification for Rotational Alignment

Critical for femoral component rotation:

Transepicondylar Axis (TEA) - GOLD STANDARD

• Medial epicondyle: Epicondylar sulcus (most prominent point on medial epicondyle, palpable depression)
• Lateral epicondyle: Lateral epicondylar prominence (most prominent point)
• Line connecting these is Transepicondylar axis
• Most accurate and reproducible reference
• Not affected by posterior condylar wear

Whiteside's Line (AP Axis)

• Proximal point: Deepest point of trochlear groove (patellar groove)
• Distal point: Center of intercondylar notch (between spines)
• Line connecting these is Anteroposterior axis of femur
• Femoral component should be perpendicular to this line
• Can be affected by trochlear dysplasia

Posterior Condylar Axis +3° External Rotation

• Line connecting most posterior points of medial and lateral condyles
• +3° external rotation from this line approximates TEA
• Can be UNRELIABLE in:
  • Asymmetric posterior condylar wear (common in valgus knees)
  • Hypoplastic lateral condyle
  • Dysplastic condyles

If references are discrepant: PRIORITIZE TEA

Proximal Tibial Resection

MOST CRITICAL CUT FOR ALIGNMENT

Extramedullary Guide Setup

Distal alignment (ankle):

• Align to center of ankle (aim at 2nd ray of foot)
• Typically just medial to tibialis anterior tendon
• Creates perpendicular cut to tibial mechanical axis

Anterior alignment:

• Align to tibial tubercle anteriorly
• OR medial 1/3 of tubercle in varus knees
• Ensures correct anterior-posterior position

Coronal plane:

• Guide should be perpendicular to mechanical axis (0° varus/valgus)
• Use level or electronic alignment if available
• Verify alignment before cutting

Posterior Slope

Amount of slope:

• 3-7° posterior slope (match implant design requirements)
• CR designs: Usually need MORE slope (5-7°) for rollback
• PS designs: Usually need LESS slope (3-5°) as femoral cam provides rollback
• Built into cutting guide - set dial appropriately

Verification:

• Check slope angle with guide in place
• Adjust if needed before pinning

Resection Amount

Determine from least worn side:

• Usually lateral plateau in varus knees (medial worn)
• Usually medial plateau in valgus knees (lateral worn)
• Measure from least worn side: resect 8-10mm
• This restores joint line appropriately
• Mark resection level before cutting

Cutting Technique

Pin extramedullary guide securely:

• 2-3 pins into tibial metaphysis
• Verify alignment and slope before cutting
• Recheck distal alignment to ankle after pinning

Oscillating saw technique:

• Begin cut anteriorly, progress posteriorly
• STAY ANTERIOR (popliteal vessels 10-15mm posterior to posterior cortex)
• Cut perpendicular in coronal plane
• Maintain posterior slope in sagittal plane
• Complete cut with thin saw blade if needed for posterior portion

Verify cut:

• Check perpendicular in coronal plane (0° varus/valgus)
• Check posterior slope in sagittal plane (3-7°)
• Ensure complete cut, no residual bone bridges

Distal Femoral Resection

Intramedullary Guide Setup

Entry point:

• 1cm anterior to PCL insertion (if PCL still present)
• Center of intercondylar notch medial-lateral
• In line with femoral canal (not too anterior or posterior)
• Use awl to create entry point through anterior cortex

Insert IM rod:

• Advance into femoral canal
• Feel for endosteal contact (ensures central position)
• In bowed femur: may need anterolateral entry point to avoid anterior cortex perforation

Valgus Cut Angle

Set guide to 5-7° valgus:

• Compensates for 6° anatomic valgus of distal femur
• Creates cut perpendicular to femoral mechanical axis
• Standard is 5-6° for most systems
• Verify angle before pinning

Resection Amount

Measure from distal condyles:

• Usually 9-10mm from prominent condyle (typically lateral in varus knee, medial in valgus knee)
• Goal: Equal resection from both condyles (verified after cut)
• Adjust if asymmetric wear present
• Mark resection level on both condyles

Cutting Technique

Pin distal femoral cutting guide:

• Verify valgus angle (5-7°)
• Verify resection amount both condyles
• Pin securely to distal femur (2-3 pins)

Oscillating saw:

• Smooth, controlled cuts
• Complete cut through both condyles
• Protect collateral ligament origins (1cm proximal to joint line)
• Remove cut carefully

Verify cut:

• Check both condyles resected equally
• Verify valgus angle appropriate
• Ensure cut is smooth and flat

Femoral AP Sizing and Rotation

AP Sizing

Femoral sizing guide on distal cut:

• Size anteroposterior dimension of femur
• Goal: Avoid anterior overhang OR notching
• Avoid oversizing: Causes patellofemoral overstuffing, stiffness
• Avoid undersizing: Causes flexion instability, posterior impingement

Anterior check:

• Should have 3-5mm bone anterior to anterior flange
• NO notching (increases fracture risk 10-fold)

Posterior check:

• Posterior femoral component should cover posterior condyles
• Small amount of overhang acceptable (<2mm)
• Avoid excessive overhang (impingement)

Rotational Alignment - CRITICAL

Use all THREE references:

1. Transepicondylar axis (TEA): Femoral component parallel to this line
2. Whiteside's line perpendicular: Femoral component perpendicular to AP axis
3. Posterior condylar axis +3° ER: External rotation from posterior condyle line

Set cutting block rotation:

• Align to TEA primarily (most accurate)
• Verify agreement with other two references
• If discrepant: PRIORITIZE TEA
• Typical: 3° external rotation from posterior condylar axis

Consequences of malrotation:

Internal rotation:

• Patellar maltracking (medial tracking)
• Anterior knee pain
• Medial-side flexion gap tightness
• Lateral-side flexion gap looseness

Excessive external rotation:

• Lateral patellar subluxation
• Lateral flexion gap tightness
• Medial flexion gap looseness

4-in-1 Cutting Block

Position block:

• Correct AP size determined above
• Correct rotation determined above
• Pin securely to distal femoral cut

Block determines:

• Anterior cut (anterior flange position)
• Posterior cuts (both condyles)
• Anterior chamfer cuts
• Posterior chamfer cuts

Remaining Femoral Cuts

Anterior Cut

Critical check for notching:

• Should have 3-5mm bone anterior to cut
• If risks notching: Downsize femoral component OR accept slight anterior overhang

Oscillating saw:

• Complete anterior cut
• Remove cut block after anterior cut to assess

Posterior Cuts

Determines flexion gap:

• Equal posterior condyle resection creates rectangular flexion gap
• Asymmetric resection creates trapezoidal gap
• Cut both posterior condyles
• Usually equal thickness both sides (8-10mm)

Chamfer Cuts

Anterior and posterior chamfers:

• Beveled edges for component seating
• Complete all chamfer cuts
• Remove cutting block

Verify femoral preparation:

• Trial femoral component on prepared femur
• Should sit flush without rocking
• No anterior notching
• Appropriate rotation (verify with alignment guides)

Soft Tissue Balancing - Extension Gap

Extension Gap Assessment

Insert spacer blocks:

• Select thickness based on planned poly (usually 9-10mm)
• Insert between distal femur and proximal tibia
• Extend knee fully (0°)
• Apply varus and valgus stress

Goal: Rectangular extension gap

• Equal medial and lateral space
• Tight enough to be stable (minimal opening with stress)
• Loose enough to extend fully

Varus Knee (80% of Primary TKR)

Pathology:

• Medial compartment worn, bone loss medially
• Medial structures contracted (MCL, pes, posteromedial capsule)
• Lateral structures stretched

Sequential MEDIAL release:

1. Deep MCL fibers from proximal tibia (most effective)
2. Superficial MCL - staged release (mid-substance fibers, then full length)
3. Pes anserinus tendons (sartorius, gracilis, semitendinosus)
4. Semimembranosus tendon
5. Posteromedial capsule (CAREFUL - popliteal vessels posterior)

Technique:

• Release from tibial insertion (safer than femoral origin)
• Use electrocautery or sharp dissection
• Release in stages - reassess gap after each release
• Use laminar spreaders to assess tension
• Avoid complete MCL release (causes severe instability)

Valgus Knee (20% of Primary TKR)

Pathology:

• Lateral compartment worn, bone loss laterally
• Lateral structures contracted (LCL, popliteus, lateral capsule, ITB)
• Medial structures stretched
• Often deficient ACL/PCL

Sequential LATERAL release:

1. Lateral capsule and synovium (release from tibia)
2. Popliteus tendon (at femoral or tibial insertion)
3. Iliotibial band - posterior fibers (PIE procedure - Proximal ITB, Ellipse lateral capsule)
4. LCL - VERY CAREFUL, consider leaving slightly tight vs complete release
5. Lateral head gastrocnemius - release origin if needed

Technique:

• Release from tibial side when possible
• VERY CAREFUL with LCL - complete release causes severe instability
• May need higher constraint (semi-constrained) if severe
• Consider staged correction if >20° valgus deformity
• Protect common peroneal nerve (2-3cm distal to fibular head)

Fixed Flexion Contracture

Additional releases if contracture persists after gap balancing:

Posterior capsule release:

• Release posterior capsule from femoral insertion
• Excise posterior osteophytes (often major contributor)
• Release posterior fibers of collaterals

PCL recession (if CR knee):

• Can "pie crust" PCL (multiple small releases)
• Consider converting to PS design if severe

Avoid:

• Excessive posterior tibial slope (increases instability)
• Undersizing femoral component (worsens flexion gap balance)

Soft Tissue Balancing - Flexion Gap

Flexion Gap Assessment

Flex knee to 90°:

• Insert spacer blocks (same thickness as extension gap)
• Apply varus and valgus stress
• Assess medial and lateral opening

Goal: EQUAL to extension gap

• Extension gap = Flexion gap = "Balanced knee"
• Both gaps rectangular (equal medial/lateral)
• Thickness equals planned poly insert

Flexion Gap TIGHT

Causes:

• Femoral component too large (AP dimension)
• Insufficient posterior femoral resection
• Tight posterior capsule
• Flexed femoral component (excessive posterior slope on distal cut)

Solutions:

1. Downsize femoral component (most common solution)
2. More posterior femoral resection (check anterior notching first!)
3. Posterior capsular release
4. Thinner poly insert (affects both gaps)

Flexion Gap LOOSE

Causes:

• Femoral component too small (AP dimension)
• Excessive posterior femoral resection
• PCL deficiency or excessive recession (if CR knee)

Solutions:

1. Upsize femoral component (most common solution)
2. Thicker poly insert (affects both gaps)
3. More constrained implant (if cannot balance with above)
4. Augment posterior femoral condyles (rarely needed in primary)

PCL Balancing (CR Designs)

PCL tension assessment:

• Should be snug but not tight at 90° flexion
• Too tight: Limits flexion, increases contact stress
• Too loose: Paradoxical anterior slide, instability

Adjust if needed:

• Too tight: Recession (pie crust technique) or convert to PS
• Too loose: Thicker poly or convert to PS

Medial-Lateral Flexion Gap Balance

Assess with knee at 90°:

• Should be equal medial and lateral opening
• Slightly more opening than extension gap acceptable

If asymmetric:

• Medial tight/lateral loose: Internal rotation of femoral component (revise rotation)
• Lateral tight/medial loose: Excessive external rotation (revise rotation)
• Can also use collateral releases but prefer correct rotation first

Trial Components

Insert Trial Components

Trial femoral component:

• Correct size and rotation determined above
• Should sit flush on all cuts without rocking
• No anterior overhang or notching

Trial tibial baseplate:

• Size to cover tibial cut without excessive overhang (<2mm)
• Keel or stem aligned with tibial axis
• Stable on tibial cut

Trial polyethylene insert:

• Thickness determined from gap balancing
• Lock into tibial baseplate
• Standard (CR/PS) or higher constraint as needed

Comprehensive Trial Assessment

1. ALIGNMENT:

• Mechanical axis check: Alignment rod from femoral head to center of ankle
• Should pass through center of knee (or slightly medial)
• Correct any malalignment before final implantation

2. STABILITY:

• Extension (0°): Varus/valgus stress - should be stable (minimal opening)
• Mid-flexion (30-60°): Stable throughout range
• Flexion (90°): Small amount laxity acceptable but no gross instability
• Anterior-posterior: Drawer test at 90° (CR should be snug, PS stable)

3. RANGE OF MOTION:

• Extension: Should achieve 0° (no flexion contracture)
• Flexion: Target minimum 120° (ideally matches or exceeds pre-op)
• Smooth motion throughout range without catching or impingement

4. PATELLAR TRACKING:

• "No thumb test": Remove thumb pressure, patella should track centrally through full ROM
• At 30° flexion: Patella should be centered (not lateral subluxation)
• At 90° flexion: Patella should engage trochlea centrally
• If maltracking: Check femoral rotation first, lateral release last resort

5. JOINT LINE RESTORATION:

• Measure from medial epicondyle to joint line: should be within 8mm of anatomic
• Measure from fibular head to joint line laterally
• Elevation >8mm: Patella baja, extensor lag, poor function
• Lowering: Patella alta, instability (rare)

6. FLEXION-EXTENSION GAP BALANCE:

• Recheck with spacer blocks throughout ROM
• Should remain equal and rectangular
• No opening >2mm with stress
• No tightness limiting motion

7. SOFT TISSUE BALANCE:

• Equal tension medial and lateral
• No excessive laxity or tightness
• Smooth motion without sudden opening/closing

If any parameter unsatisfactory: REVISE before final implantation

Patellar Preparation

Patellar Resurfacing Decision

ALWAYS resurface if:

• Inflammatory arthritis (RA, psoriatic arthritis, ankylosing spondylitis)
• Significant patellar wear or eburnation
• Patellofemoral symptoms preoperatively
• Patellar maltracking or subluxation
• Young active patient expecting high function

Selective resurfacing (surgeon preference):

• Minimal patellar wear
• Good tracking
• Older, low-demand patient
• Patient preference after counseling

Rarely not resurface:

• Very thin patella (<15mm) - resurfacing risks fracture
• Severe patellar dysplasia (may not accommodate button)

Resurfacing Technique

Measure patellar thickness:

• Native thickness: typically 24-26mm
• Measure with caliper
• Goal: Restore native thickness (bone + button = 24-26mm)

Patellar resection:

• Use patellar clamp to stabilize patella
• Resect to leave 12-15mm residual bone (MINIMUM 12mm)
• Cut should be parallel to anterior surface
• Avoid over-resection (<12mm increases fracture risk)

Prepare for patellar button:

• Drill holes for 3 pegs (or central peg depending on design)
• Match drill to implant system
• Depth stops to avoid perforation through anterior cortex

Trial patellar button:

• Insert trial button
• Median ridge should align with trochlear groove (center of trochlea)
• Check rotation: Lateral facet should align with lateral trochlea
• Check no overhang or malposition

Check patellofemoral thickness:

• Compare native thickness to resected bone + button thickness
• Should be equal or within 2mm of native
• Overstuffing causes pain, stiffness, reduced ROM
• Understuffing rare with proper technique

Final Component Cementation

Bone Preparation

Pulsatile lavage:

• Irrigate all bone surfaces with 3L minimum pulsatile lavage
• Removes debris, blood, fat
• Better cement penetration

Dry bone surfaces:

• Suction device and dry sponges
• Bone should be dry but not desiccated
• Some surgeons use hydrogen peroxide for hemostasis (controversial - may impair cement penetration)

Final check:

• Remove all debris and soft tissue
• Expose cancellous bone
• Check sizing one final time

Cement Mixing

3rd generation antibiotic cement:

• Vacuum mixing system (reduces porosity)
• Gentamicin typically (40mg per 40g cement powder)
• Mix according to manufacturer guidelines (usually 2 minutes)
• Mixing in cooled environment prolongs working time

Working time:

• Doughy phase ideal for insertion (not too liquid, not too firm)
• Typically 3-5 minutes working time after mixing
• Have all components ready before mixing cement

Cement Application and Component Insertion

Order of insertion:

1. Tibial component FIRST (better cement penetration in supine position with knee flexed)
2. Femoral component SECOND
3. Patellar button THIRD (if resurfacing)

Tibial component:

• Apply cement to tibial cut surface (thin layer)
• Apply cement to underside of tibial baseplate
• Pressurize cement into cancellous bone with finger or cement gun
• Insert tibial component in correct rotation and alignment
• Hold under firm pressure (can use spacer blocks and knee flexion to maintain pressure)

Femoral component:

• Apply cement to all femoral cut surfaces (distal, anterior, posterior, chamfers)
• Apply cement to femoral component
• Pressurize cement into cancellous bone
• Insert in correct rotation (verify rotation marks)
• Hold under firm pressure
• Flex knee to apply pressure

Patellar button (if resurfacing):

• Apply cement to patellar cut surface
• Apply cement to peg holes
• Insert button ensuring correct rotation (median ridge alignment)
• Hold under firm pressure (patellar clamp helps)

Cement Cure

Remove excess cement:

• Remove ALL excess cement immediately (while still soft enough to remove but polymerized enough not to smear)
• Most critical: Posterior cement (can cause impingement, popliteal vessel compression, wear particles)
• Use curettes, rongeurs to remove excess
• Check anterior, posterior, medial, lateral gutters

Snap trial poly:

• Protect articulating surfaces during cement cure
• Apply pressure to components
• Maintain correct alignment

Hold position:

• Maintain pressure on components 8-12 minutes (cement cure time)
• Knee flexed to 20-30° during cure
• Remove excess cement as it extrudes

After cement cure:

• Remove trial poly
• Check final cement interdigitation
• Remove any remaining cement debris
• Final irrigation

Final Polyethylene Insertion

Remove trial poly:

• Carefully unlock from tibial baseplate

Final irrigation:

• Copious irrigation with 3L minimum pulsatile lavage
• Remove all cement debris and bone fragments
• Particulate debris causes third-body wear

Insert final polyethylene:

• Correct thickness from trialing
• Lock securely into tibial baseplate
• Verify locked (pull test)

Final comprehensive check:

1. Full ROM: 0° extension to 120° flexion minimum
2. Stability: Varus/valgus stress at 0° and 90° - stable
3. Patellar tracking: Centrally throughout ROM, no thumb test
4. No impingement: Deep flexion smooth, no posterior impingement
5. Leg alignment: Mechanical axis confirmed through knee center
6. Smooth motion: No catching or clicking throughout ROM

Tourniquet Release and Hemostasis

Release tourniquet:

• After cement cure and final checks
• OR after closure (surgeon preference)
• Have vasopressors ready (hypotension common)

Achieve meticulous hemostasis:

• Identify bleeding vessels
• Electrocautery for hemostasis
• Avoid excessive cautery (tissue damage, delayed healing)

Tranexamic acid (TXA):

• Consider intra-articular injection 1-3g in 100mL saline
• Proven to reduce blood loss by 30-50%
• Leave in joint 5 minutes then drain
• Contraindications: Previous VTE, coronary stents <1 year, stroke

Closure

Capsular Closure - CRITICAL

Medial parapatellar arthrotomy:

• Repair with interrupted #1 Vicryl sutures
• Critical for extensor mechanism integrity
• Ensure strong repair at tibial tubercle (site of avulsion risk)
• Tension-free closure (no excessive tightness limiting flexion)

Running closure option:

• Some surgeons prefer running #1 Vicryl
• Ensure secure knots proximally and distally

Check patella:

• Reduce patella back into trochlear groove
• Should sit centrally without lateral subluxation

Deep Layer

Subcutaneous closure:

• 2-0 Vicryl to subcutaneous tissues
• Minimize dead space
• Avoid excessive tension

Skin Closure

Subcuticular closure:

• 3-0 or 4-0 Monocryl running subcuticular
• Better cosmesis than staples
• Equal infection rates to staples

Skin glue or Steri-Strips:

• Reinforce closure
• Waterproof dressing

Drains (controversial):

• Author does NOT routinely use drains (increased infection risk, no benefit in modern TKR with TXA)
• If used: Remove at 24 hours, <400mL output

Dressing

Sterile dressing:

• Absorptive dressing
• Waterproof outer layer
• Leave in place 48-72 hours

Compression:

• TED stockings or compression bandage
• Reduces swelling

Ice:

• Cryotherapy pads if available
• Reduces pain and swelling