Lateral Parapatellar Approach to Knee

Primary Indications - Trauma

Lateral Tibial Plateau Fractures

• Schatzker Type II: Split-depression of lateral plateau
• Schatzker Type III: Pure depression of lateral plateau
• Schatzker Type V: Bicondylar fracture (may use dual approach)
• Schatzker Type VI: Metaphyseal-diaphyseal dissociation

Complex Knee Trauma

• Lateral femoral condyle fractures (Hoffa fragments)
• Posterolateral corner injuries requiring repair
• Combined ligamentous and bony injuries (lateral side)

Primary Indications - Arthroplasty

Revision Total Knee Arthroplasty

• Severe valgus deformity (greater than 15 degrees)
• Lateral subluxation of patella
• Previous lateral releases with medial instability
• Need to preserve medial soft tissues

Primary TKA - Selected Cases

• Severe valgus with contracted lateral structures
• Ankylosed knee in valgus position
• Previous lateral surgical exposure

Other Indications

Lateral Compartment Pathology

• Lateral meniscus repair or transplant (open technique)
• Osteochondral defect treatment (lateral femoral condyle)
• Proximal tibiofibular joint pathology
• Tumor resection (lateral compartment)

Contraindications

Absolute

• Infection overlying proposed incision
• Compartment syndrome (relative - may need fasciotomy first)

Relative

• Previous medial approach (vascular compromise if dual)
• Severe osteoporosis (extensor mechanism fragility)
• Active smoker (wound healing concerns)

Clinical Assessment

History and Mechanism

• Trauma: valgus force, axial loading (tibial plateau)
• Arthroplasty: previous surgeries, deformity progression
• Pain localization (lateral compartment vs global)
• Functional limitations and instability symptoms

Physical Examination

• Valgus/varus alignment assessment
• Range of motion (flexion contracture, terminal extension)
• Ligamentous stability (LCL, posterolateral corner)
• Neurovascular examination (common peroneal nerve)
• Skin condition and previous scars

Imaging Protocol

Standard Radiographs

• AP and lateral knee
• Oblique views (posterolateral corner assessment)
• Full-length standing alignment films (arthroplasty cases)
• Contralateral comparison

CT Imaging - CRITICAL for Tibial Plateau

• Fine-cut (1mm) axial, coronal, sagittal reconstructions
• 3D reconstruction for fracture pattern understanding
• Identify depression depth and split displacement
• Assess articular congruity and comminution

MRI - Selected Cases

• Ligamentous injury assessment (LCL, popliteus, PLC)
• Meniscal pathology evaluation
• Osteochondral lesion characterization
• Tumor staging

Surgical Planning

Fracture Management Planning

• Fixation strategy: buttress plating vs screws
• Bone grafting needs (depression greater than 5mm)
• Meniscal repair vs resection decision
• Combined ligamentous repair planning

Arthroplasty Planning

• Constrained vs standard implants
• Soft tissue balancing strategy
• Patellar tracking assessment
• Need for augments or stems

Standard Surgical Equipment

Basic Instruments

• Standard knee arthrotomy set
• Self-retaining retractors (Hohmann, bent)
• Sharp pointed reduction forceps
• Periosteal elevators
• Electrocautery

Fracture-Specific Instrumentation

• Periarticular lateral tibial plateau plates (3.5mm locking)
• Cannulated screw sets (3.5mm, 4.0mm, 6.5mm)
• Bone graft instruments (if elevation needed)
• Arthroscopic instruments (arthroscopy-assisted option)

Arthroplasty Instrumentation

• Total knee system (primary or revision)
• Patellar eversion instruments
• Lateral release instruments
• Soft tissue balancing tools

Fluoroscopy Requirements

Imaging Equipment

• C-arm fluoroscopy unit
• Radiolucent table or leg holder
• Ability to obtain AP, lateral, and oblique views

Views Needed for Tibial Plateau

• AP: Assess reduction, screw/plate position
• Lateral: Posterior slope, sagittal reduction
• Oblique: Lateral plateau articular surface

Patient-Specific Implants

Fracture Fixation

• Lateral tibial plateau-specific plates (anatomic pre-contour)
• Raft screw constructs (subchondral support)
• Antiglide plates (simple split fractures)

Arthroplasty

• Primary vs revision TKA components
• Constrained liners (severe instability)
• Augments (bone loss)

Standard Supine Positioning

Positioning Technique

• Supine on standard operating table
• Bump under ipsilateral hip (leg in slight internal rotation)
• Leg free-draped to allow flexion/extension
• Tourniquet on proximal thigh (optional - see below)

Leg Holder Options

Option 1: Leg Holder/Post

• Side post at level of tourniquet
• Allows 90-degree flexion with gravity assistance
• Easier for patellar mobilization
• Risk of peroneal nerve compression (pad well)

Option 2: Foot of Bed

• Let leg hang off end of table when flexed
• Assistant holds leg during exposure
• More flexibility but requires extra personnel

Option 3: Leg Holder Device

• Specialized devices (e.g., spider leg holder)
• Hands-free positioning
• Allows precise knee flexion angles

Tourniquet Use

Advantages

• Bloodless field for articular reduction
• Improved visualization of fracture fragments
• Shorter operative time

Disadvantages

• Can miss vascular injury (if not deflated)
• Reperfusion bleeding at end
• Tourniquet pain limits operative time (2 hours)

Recommendation

• Use for complex articular reconstruction
• Deflate before closure to ensure hemostasis
• Avoid if vascular injury suspected

Bony Landmarks

Palpable Surface Anatomy

• Patella - mobile anteriorly
• Lateral epicondyle of femur - proximal lateral landmark
• Gerdy's tubercle - insertion of iliotibial band on tibia
• Fibular head - posterolateral, common peroneal nerve nearby
• Tibial tubercle - anterior midline

Osseous Relationships

• Lateral joint line 1-2cm distal to lateral epicondyle
• Fibular head 1-2cm distal and posterior to joint line
• Gerdy's tubercle just lateral to tibial tubercle

Neurovascular Anatomy - CRITICAL

Common Peroneal Nerve

• Course: Travels along medial border of biceps femoris
• Wraps around fibular neck 2-3cm distal to fibular head
• Branches: Divides into superficial and deep peroneal nerves
• Risk: Retraction, direct injury, compression from leg holder
• Protection: Identify early, gentle retraction, avoid posterior dissection

Superior Lateral Genicular Artery

• Origin: Popliteal artery
• Course: Runs along lateral femoral condyle
• Importance: Contributes to patella blood supply
• Risk: Ligation can contribute to patellar AVN
• Protection: Careful dissection, preserve if possible

Inferior Lateral Genicular Artery

• Runs along proximal tibia
• Usually ligated during plate application
• Collateral flow usually adequate

Popliteal Vessels

• Posterior to joint, safe distance from approach
• At risk with posterior fracture extension or hardware

Ligamentous and Soft Tissue Anatomy

Lateral Retinaculum

• Extends from vastus lateralis to lateral patella
• Incised during approach
• Important for patellar tracking (repair at closure)

Iliotibial Band (ITB)

• Inserts on Gerdy's tubercle
• May need to elevate or split for tibial exposure
• Tightness contributes to lateral patellar tilt

Lateral Collateral Ligament (LCL)

• Origin: Lateral epicondyle of femur
• Insertion: Fibular head
• Posterior to skin incision, usually not encountered
• If injured, may need repair or reconstruction

Posterolateral Corner Structures

• Popliteus tendon
• Popliteofibular ligament
• Arcuate ligament complex
• Accessed via extensile lateral exposure if needed

Muscular Anatomy

Vastus Lateralis

• Largest quadriceps component
• Reflected anteriorly during approach
• Repair critical for extensor function

Biceps Femoris

• Posterior to surgical field
• Inserts on fibular head
• Contains common peroneal nerve medially

Step 1: Skin Incision

Incision Planning

• Longitudinal incision centered over lateral patella
• Proximal extent: 5-6cm proximal to superior pole of patella
• Distal extent: Gerdy's tubercle (or 2cm distal for fracture)
• Length: 12-18cm depending on exposure needs

Skin Incision

• Sharp incision through skin and subcutaneous tissue
• Identify and preserve saphenous branches if encountered
• Achieve hemostasis with electrocautery

Subcutaneous Dissection

• Develop subcutaneous flaps medially and laterally
• Expose lateral retinaculum and vastus lateralis fascia
• Identify superior and inferior joint lines by palpation

Step 2: Arthrotomy - Lateral Parapatellar Incision

Retinacular Incision

• Incise lateral retinaculum longitudinally
• Start 1cm lateral to lateral border of patella
• Extend proximally into vastus lateralis fascia
• Extend distally to tibial tubercle level

Proximal Extension - Vastus Lateralis

• Continue incision through vastus lateralis tendon
• Extend 5-6cm proximal to patella
• Creates lateral sleeve for patellar mobilization

Distal Extension - Tibial Periosteum

• Continue incision onto proximal tibia
• Elevate periosteum from lateral tibial metaphysis
• Extend to Gerdy's tubercle (ITB insertion)

Step 3: Patellar Mobilization

Patellar Eversion

• Flex knee to 90 degrees
• Manually evert patella medially
• NOTE: More difficult than medial approach
  • Patella tilts laterally naturally
  • Tight lateral structures resist eversion
  • May need extended lateral release

Lateral Release - If Needed

• Incise superior lateral genicular vessels (risk to patella)
• Extend retinacular release proximally
• Preserve VMO attachment medially if possible

Maintain Eversion

• Keep patella everted with retractor or towel
• Protects during joint manipulation
• Allows articular surface visualization

Step 4: Joint Exposure and Assessment

Synovectomy

• Remove synovium from lateral gutter
• Improve visualization of lateral compartment
• Assess for meniscal pathology

Meniscal Management

• Evaluate lateral meniscus for tears
• Repair if possible (better outcomes than resection)
• May need to detach meniscus from capsule for exposure

Articular Surface Assessment

• Visualize lateral femoral condyle
• Assess lateral tibial plateau (fracture pattern, depression depth)
• Measure depression with depth gauge (if fracture)

Step 5: Fracture-Specific Steps (Lateral Tibial Plateau)

Fracture Reduction

Step 5a: Access Depressed Fragments

• Create cortical window in lateral metaphysis
  • 2-3cm distal to joint line
  • Anterior to fibular head
  • Size: 2x3cm
• Elevate depressed articular fragments from below
• Use bone tamp or impactor under fluoroscopic guidance
• Restore articular congruity (less than 2mm step-off)

Step 5b: Bone Grafting

• Fill metaphyseal void with bone graft
  • Autograft (iliac crest or distal femur)
  • Allograft (cancellous chips)
  • Bone graft substitute (calcium phosphate)
• Compact graft to support articular surface

Step 5c: Provisional Fixation

• Hold reduction with K-wires
• Verify articular reduction under fluoroscopy (AP, lateral, oblique)
• Adjust if needed before definitive fixation

Definitive Fixation

Plate Application

• Select lateral tibial plateau plate (anatomic pre-contour)
• Position plate on lateral tibial metaphysis
  • Proximal end just distal to joint line
  • Centered on lateral tibial shaft
• Confirm position with fluoroscopy

Screw Insertion

• Proximal screws: Subchondral raft construct
  • Multiple 3.5mm locking screws parallel to joint
  • Support elevated articular surface
  • Verify on fluoroscopy (within 5mm of joint)
• Distal screws: Diaphyseal purchase
  • Bicortical fixation
  • 3-4 screws distal to fracture

Final Assessment

• Fluoroscopy AP, lateral, oblique views
• Confirm articular reduction (less than 2mm step-off)
• Confirm hardware position (no intra-articular screws)
• ROM to assess stability (gentle - don't displace fracture)

Step 6: Arthroplasty-Specific Steps (Revision TKA)

Soft Tissue Releases

• Release contracted lateral structures (ITB, lateral retinaculum)
• Preserve medial soft tissues (MCL, pes anserinus)
• Balance flexion and extension gaps

Component Removal

• Remove previous femoral and tibial components
• Manage bone loss with augments or stems
• Preserve bone stock where possible

New Component Implantation

• Standard TKA technique
• May need constrained liner (severe instability)
• Ensure proper patellar tracking

Step 7: Wound Closure

Deep Layer

• Re-approximate lateral retinaculum with #1 absorbable suture
• Repair vastus lateralis to patellar sleeve
• Ensure watertight closure (reduce hemarthrosis)

Subcutaneous Layer

• 2-0 absorbable suture in subcutaneous tissue
• Eliminate dead space

Skin Closure

• 3-0 or 4-0 nylon interrupted or continuous suture
• May use staples (easier removal)

Drain Placement

• Consider intra-articular drain (10-12Fr)
• Remove when output less than 30mL/shift (24-48 hours)

Dressing

• Bulky compressive dressing
• Knee immobilizer (fracture cases) or CPM (arthroplasty)

Intraoperative Complications

Common Peroneal Nerve Injury (1-3%)

• Mechanism: Retraction, stretch, direct injury, compression
• Prevention:
  • Early identification and protection
  • Gentle retraction, protected with padding
  • Avoid posterior dissection beyond fibular head
  • Careful leg holder padding
• Recognition: Foot drop, numbness on dorsum of foot
• Management: Release compression, document, neuro consult

Patellar Vascular Injury

• Superior lateral genicular artery disruption
• Risk: Patellar AVN (rare but serious)
• Prevention: Preserve vessel if possible during lateral release
• Recognition: May not be apparent intraoperatively

Inadequate Exposure

• Patellar eversion difficult (tight lateral structures)
• Solution: Extended lateral release, but increases AVN risk

Early Postoperative Complications (Less than 1 month)

Wound Complications (5-8%)

• Hematoma: More common than medial approach
  • Prevention: Drain placement, hemostasis before closure
  • Management: Observation vs evacuation
• Dehiscence: Especially in obese, diabetic patients
  • Prevention: Meticulous closure, minimize tension
• Infection (less than 2%):
  • Requires irrigation, debridement
  • Hardware retention vs removal depends on stability

Neurologic Complications

• Common peroneal nerve palsy (1-3%)
  • Most recover spontaneously over 3-6 months
  • Foot drop: AFO (ankle-foot orthosis) for support
• Compartment syndrome (less than 1%):
  • High index of suspicion in trauma
  • Immediate fasciotomy if suspected

Extensor Lag (5-10%)

• Incomplete patellar eversion or quadriceps injury
• Prevention: Careful soft tissue handling, early ROM
• Management: Aggressive physical therapy

Late Complications (Greater than 1 month)

Patellar Maltracking or Instability

• Inadequate lateral closure or over-release
• May need medial imbrication or lateral reconstruction

Post-traumatic Arthritis (20-30% in fractures)

• Despite anatomic reduction
• Risk factors: articular comminution, meniscectomy
• May progress to TKA

Loss of Fixation

• Plate failure (inadequate fixation, poor bone quality)
• Screw cutout (subchondral screws too close to articular surface)

Knee Stiffness

• Prolonged immobilization
• Arthrofibrosis
• Prevention: Early ROM, aggressive PT

Immediate Postoperative Care (0-48 hours)

Positioning

• Leg elevated (reduce swelling)
• Knee immobilizer (fracture) or CPM machine (arthroplasty)
• Ice therapy (cryotherapy unit)

Pain Management

• Multimodal analgesia (opioids, NSAIDs, acetaminophen)
• Consider femoral nerve block (duration 12-24 hours)
• Avoid NSAIDs if concerned about fracture healing (controversial)

Neurovascular Checks

• Frequent checks for common peroneal nerve function
  • Ankle dorsiflexion, toe extension
  • Sensation on dorsum of foot
• Assess for compartment syndrome (trauma cases)

Drain Management

• Remove when output less than 30mL/shift
• Typically 24-48 hours

Weight-Bearing Protocol

Tibial Plateau Fractures

• Simple fractures (Schatzker I-III):
  • Toe-touch weight-bearing (TTWB) for 6-8 weeks
  • Progressive weight-bearing at 8 weeks
  • Full weight-bearing at 10-12 weeks
• Complex fractures (Schatzker V-VI):
  • Non-weight-bearing (NWB) for 8-12 weeks
  • Very gradual progression based on radiographic healing

Arthroplasty

• Weight-bearing as tolerated (WBAT) immediately
• Walker or crutches for safety first 2-4 weeks

Range of Motion Protocol

Fractures

• Week 0-2: Knee immobilizer, gentle passive ROM to 90 degrees
• Week 2-6: Remove immobilizer, progressive ROM (goal 0-120 degrees)
• Week 6+: Unrestricted ROM exercises

Arthroplasty

• Immediate CPM machine (0-90 degrees, progress daily)
• Goal 0-90 degrees by week 2, 0-110 degrees by week 6

Radiographic Follow-up

2 Weeks

• AP, lateral, oblique knee radiographs
• Assess reduction maintenance, hardware position
• Watch for early loss of fixation

6 Weeks

• Repeat radiographs before increasing weight-bearing
• Assess fracture healing (early callus formation)

12 Weeks

• Full radiographic series
• Assess union (3 of 4 cortices healed)
• Clear for full weight-bearing if healed

6 Months and 1 Year

• Long-term assessment for arthritis
• Hardware evaluation (remove if symptomatic)

Physical Therapy

Phase 1 (0-6 weeks): Protection and Early Motion

• Gentle ROM exercises (avoid varus/valgus stress)
• Quadriceps sets, straight leg raises
• Ankle pumps (DVT prophylaxis)

Phase 2 (6-12 weeks): Progressive Strengthening

• Closed-chain exercises (leg press, squats)
• Stationary bike (when ROM adequate)
• Pool therapy (buoyancy reduces joint stress)

Phase 3 (12+ weeks): Functional Restoration

• Sport-specific training
• Agility and proprioception exercises
• Return to work activities

Return to Activity

Sedentary Work: 2-4 weeks (arthroplasty), 8-12 weeks (fracture) Light Labor: 12-16 weeks Heavy Labor: 4-6 months Contact Sports: 6-9 months (fracture), avoid (arthroplasty)

Lateral tibial plateau fractures represent a significant proportion of knee trauma managed in Australian metropolitan and regional trauma centers, with mechanisms including motor vehicle accidents, motorcycle crashes, and falls from height. The Australian and New Zealand Orthopaedic Trauma Society (ANZOTS) recommends CT-based surgical planning for all displaced tibial plateau fractures (greater than 2mm articular step-off or greater than 5mm depression) to guide approach selection and fixation strategy. Most major trauma centers (Royal Melbourne Hospital, Royal Adelaide Hospital, John Hunter Hospital, Gold Coast University Hospital) have adopted lateral parapatellar approach as standard for isolated lateral tibial plateau fractures (Schatzker Types II and III), with dual approaches (lateral and medial) reserved for bicondylar patterns.

The choice between arthroscopy-assisted reduction and open lateral parapatellar approach varies by surgeon preference and patient factors in Australia. Younger patients (less than 50 years) with simple split-depression fractures increasingly undergo arthroscopy-assisted technique, which allows direct visualization of articular reduction while minimizing soft tissue disruption. However, complex fractures with severe comminution, marginal impaction, or associated posterolateral corner injuries typically require formal open lateral parapatellar exposure. Antibiotic prophylaxis follows Therapeutic Guidelines (eTG) with cefazolin 2g IV at induction, redosing every 4 hours for prolonged cases.

Weight-bearing protocols in Australia are conservative, reflecting medicolegal concerns and workers' compensation requirements. Most surgeons prescribe toe-touch weight-bearing for 8-12 weeks following lateral tibial plateau ORIF, with radiographic evidence of healing (bridging callus on 3 of 4 cortices) required before progression to full weight-bearing. Patients are counseled about post-traumatic arthritis risk (20-30% at 10 years) and the possibility of future total knee arthroplasty, with TGA-approved implants and PBS-subsidized joint replacement available through the public hospital system. Common peroneal nerve monitoring is standard perioperative practice, with detailed preoperative and postoperative neurologic examinations documented for all lateral knee approaches given the 1-3% nerve injury rate.