import { ContentSection, EvidenceCard, ExamCheatSheet, ExamPearl, ExamWarning, InfoCard, InfoCardGrid, MnemonicCard, OnePagerSummary, SafetyAlert, Tab, Tabs, VivaScenario, VivaScenarioSection } from '@/components/mdx' **Most commonly injured nerve at knee**. Palpable behind biceps tendon. Winds around **fibular neck** ~2-3cm distal to head. Identify and protect before deep dissection. Between **biceps femoris** (posterior) and **iliotibial band** (anterior). Both structures insert on fibular head/Gerdy's tubercle area. **LCL**, **popliteus tendon**, **posterolateral capsule**, **arcuate ligament**, **popliteofibular ligament**. Lateral tibial plateau (posterior column). **Flexing the knee** relaxes the CPN and makes dissection safer. Position the knee in 45-90° flexion during dissection around the posterolateral corner. The **posterolateral approach to the knee** provides access to the **posterolateral corner (PLC)**, lateral tibial plateau, and proximal fibula through the interval between **biceps femoris** (posterior) and **iliotibial band** (anterior). The **common peroneal nerve (CPN)** is the critical structure at risk—it wraps around the fibular neck 2-3cm distal to the head and must be identified early before deep dissection. **Knee flexion to 45-90°** relaxes the CPN and facilitates safer dissection. Primary indications include PLC reconstruction (LCL, popliteus, popliteofibular ligament), lateral tibial plateau fractures (posterior column), and peroneal nerve exploration. The approach can be extended distally for fibular access. **Indications**: - Posterolateral corner (PLC) reconstruction/repair - LCL reconstruction - Lateral tibial plateau fractures (posterior column) - Biceps tendon repair - Proximal fibula excision/biopsy - Peroneal nerve exploration **Patient Position**: - Supine with bump under contralateral hip - Lateral decubitus - Knee flexed 45-90° during dissection ### Posterolateral Knee Approach Overview The posterolateral approach provides essential exposure for the posterolateral corner (PLC), lateral tibial plateau, and peroneal nerve. **Key Concepts:** - Access to **posterolateral corner structures** (LCL, popliteus, PFL) - **Common peroneal nerve (CPN)** is critical structure at risk - Interval between **biceps femoris** and **iliotibial band** - Essential for multiligament knee injury management - Can be extended distally for proximal fibula access **Historical Context:** - PLC anatomy described by LaPrade and colleagues - Anatomic reconstruction techniques now standard - Recognition that PLC injuries often missed leading to ACL/PCL failure ### Indications | Indication | Details | |------------|---------| | PLC reconstruction | LCL, popliteus, popliteofibular ligament | | LCL repair/reconstruction | Isolated or combined injuries | | Lateral tibial plateau fracture | Posterior column access, Schatzker II, VI | | Biceps femoris avulsion | Direct repair or reconstruction | | Proximal fibula pathology | Tumor, osteomyelitis, fracture | | Peroneal nerve exploration | Palsy, entrapment, repair | | Arcuate ligament repair | Combined with PLC procedures | | Lateral capsule repair | Avulsion injuries | ### Advantages and Disadvantages **Advantages:** - Direct access to all PLC structures - Allows anatomic tunnel placement for reconstruction - Can be extended distally for fibular access - Combines well with other knee approaches - Good visualization of lateral plateau **Disadvantages:** - Common peroneal nerve at risk (most commonly injured nerve at knee) - Learning curve for anatomic identification - Limited access to medial structures - Prone positioning may be required for some techniques - Risk of lateral wound complications ### Surface Anatomy **Palpable Landmarks:** - **Fibular head**: Key landmark, palpable posterolaterally - **Biceps femoris tendon**: Inserts on fibular head - **Lateral femoral epicondyle**: LCL origin - **Iliotibial band**: Palpable anterolaterally - **Common peroneal nerve**: Palpable behind biceps **Incision Planning:** | Landmark | Position | |----------|----------| | Proximal extent | 5 cm above joint line | | Center | Over fibular head | | Distal extent | Along fibular neck | | Orientation | Curved or oblique | ### Posterolateral Corner Anatomy **Primary Stabilizers (LaPrade Classification):** | Structure | Function | |-----------|----------| | LCL (fibular collateral) | Primary varus restraint | | Popliteus tendon | External rotation restraint | | Popliteofibular ligament | Connects popliteus to fibula | **Secondary Structures:** - Arcuate ligament - Fabellofibular ligament - Posterolateral capsule - Lateral gastrocnemius tendon **Isometric Points:** - LCL femoral origin: 1.4mm proximal and 3.1mm posterior to lateral epicondyle - Popliteus: Anterior to LCL in popliteal groove ### Common Peroneal Nerve Course **Anatomical Relationships:** - Lies posterior to biceps femoris tendon at knee - Winds around fibular neck **2-3 cm distal to head** - Divides into deep and superficial branches at neck - Tethered at fibular neck (vulnerable to stretch) **CPN Safety Zone:** | Location | Distance from Fibular Head | |----------|---------------------------| | Safe zone | Proximal to fibular head | | Danger zone | 2-4 cm distal to head | | Nerve division | At fibular neck | **Clinical Pearl:** - Knee flexion relaxes the nerve - Identify CPN before any deep dissection - May need to mobilize for wider exposure ### Posterolateral Approach Variations | Variation | Description | Indication | |-----------|-------------|------------| | **Standard posterolateral** | Biceps-ITB interval | PLC reconstruction | | **Extended posterolateral** | Includes fibular neck exposure | CPN exploration, fibula access | | **Posterolateral + lateral** | Combined for plateau | Bicondylar fractures | | **Fibular head excision** | Through posterolateral | Proximal fibula tumors | **Interval Options:** - Anterior: ITB to biceps (main working interval) - Posterior: Biceps to lateral gastrocnemius (deeper access) ### PLC Injury Classification **Fanelli Classification:** | Type | Description | |------|-------------| | Type A | Fibular head avulsion | | Type B | Midsubstance tear | | Type C | Femoral avulsion | **Injury Patterns:** - Isolated PLC injury (rare, 2%) - Combined PLC + ACL (more common) - Combined PLC + PCL (knee dislocation) - Combined PLC + ACL + PCL (multiligament) **Severity:** - Grade I: Sprain, no laxity - Grade II: Partial tear, mild laxity - Grade III: Complete tear, significant laxity ### Preoperative History **Mechanism of Injury:** - Direct blow to anteromedial tibia (varus force) - Hyperextension injury - Contact sports, motor vehicle accident - Low-velocity: isolated PLC; High-velocity: multiligament **Key History Elements:** | Element | Significance | |---------|--------------| | Instability | "Giving way" with pivoting, stairs | | Pain location | Posterolateral knee | | Swelling | Often minimal with isolated PLC | | Neurological symptoms | Foot drop, numbness (CPN injury) | | Previous surgery | ACL/PCL failure may indicate missed PLC | ### Physical Examination **Observation:** - Varus thrust during gait (lateral thrust) - Recurvatum with standing - Swelling, ecchymosis posterolaterally **Palpation:** - Tenderness over fibular head - LCL along its course - Biceps femoris tendon **Neurovascular:** - **Essential**: Check CPN function - Ankle dorsiflexion, toe extension (deep peroneal) - First web space sensation - Foot eversion (superficial peroneal) ### Special Tests for PLC | Test | Technique | Positive Finding | |------|-----------|------------------| | Varus stress 30° | Varus force at 30° flexion | Increased opening = LCL tear | | Dial test | Compare ER 30° and 90° | Increased ER 30° = PLC | | Posterolateral drawer | Posterolateral translation | Increased = PLC | | Reverse pivot shift | Extension to flexion | Clunk = PLC | | External rotation recurvatum | Gravity ER and extension | Positive = PLC + possible PCL | **Dial Test Interpretation:** - Increased at 30° only: Isolated PLC - Increased at 30° and 90°: Combined PLC + PCL ### Imaging Studies **Radiographs:** | View | Finding | |------|---------| | AP | Segond fracture (pathognomonic), fibular head avulsion | | Lateral | Arcuate sign (fibular head avulsion) | | Stress views | Varus opening, increased ER | | Long leg | Varus alignment assessment | **MRI (Gold Standard):** - LCL tear: Location and quality - Popliteus tendon: Musculotendinous vs insertion - Popliteofibular ligament: Often difficult to visualize - Associated injuries: ACL, PCL, meniscal - Bone bruise pattern: Posteromedial (varus injury) ### Special Studies **Vascular Assessment:** - Mandatory for knee dislocations - CT angiography if concern - ABI (ankle-brachial index) **Nerve Conduction Studies:** - If CPN palsy present - Baseline before surgery - Helps with prognosis **EUA/Arthroscopy:** - Examine under anesthesia confirms laxity - Arthroscopy: Rule out associated injury - "Drive-through" sign lateral compartment ### Non-operative Management **Indications:** - Grade I, II injuries - Elderly, low-demand patients - Significant comorbidities **Protocol:** | Phase | Management | |-------|------------| | Acute (0-2 weeks) | Hinged brace, protected weight bearing | | Intermediate (2-6 weeks) | ROM exercises, quadriceps strengthening | | Late (6-12 weeks) | Progressive strengthening, proprioception | **Bracing:** - Hinged knee brace locked in extension initially - Progress ROM as healing occurs - Long-term lateral unloader brace if residual varus ### Operative Management **Indications:** - Grade III PLC injuries - Combined ligament injuries - Functional instability - Young, active patients **Timing:** - Acute repair: within 2-3 weeks (if reparable) - Delayed reconstruction: after 3 weeks - Combined injuries: address all ligaments **Graft Options:** | Graft | Indication | |-------|------------| | Allograft Achilles | LCL reconstruction | | Semitendinosus/gracilis | PFL, combined | | Split biceps | Popliteus reconstruction | | ITB strip | LCL augmentation | ### Surgical Technique Principles **CPN Protection:** - Identify early in approach - Knee flexion relaxes nerve - May need to mobilize nerve - Consider prophylactic release **Tunnel Placement:** - Anatomic isometric points critical - Fluoroscopic guidance helpful - Avoid tunnel convergence **Fixation:** - Interference screws in tunnels - Suture anchors for avulsions - Tension at 30-60° flexion, neutral rotation **Combined Injuries:** - Reconstruct PLC before ACL/PCL - Prevents rotational instability - Stage if needed for wound healing **Incision**: Curved incision over posterolateral knee, centered on fibular head. Approximately 8-12cm. **Interval**: Develop between **iliotibial band** (anterior) and **biceps femoris** (posterior). **CPN Identification**: **Critical first step**. Palpate CPN behind biceps tendon. Identify and protect. The nerve winds around the fibular neck 2-3cm distal to the fibular head. **Knee Flexion**: Keep knee flexed to relax CPN. **LCL**: Identified running from lateral femoral epicondyle to fibular head. **Popliteus Tendon**: Deep to LCL, courses from popliteal groove to posteromedial tibia. **Posterolateral Capsule**: Incise to access joint if needed. **Arcuate Complex**: Arcuate ligament, popliteofibular ligament identified. **Lateral Gastrocnemius**: May need to release for wider exposure distally. For PLC reconstruction, this approach allows: - Identification of torn structures - Tunnel placement in fibula and femur - Graft passage for LCL and popliteofibular ligament reconstruction - Access to lateral femoral condyle for isometric point **Common Peroneal Nerve (CPN)**: Posterior to biceps tendon, winds around fibular neck. **Most commonly injured nerve at knee**. Injury causes foot drop. Identify and protect in all cases. **Lateral Inferior Genicular Artery**: May be encountered deep in dissection. **Popliteal Vessels**: Lie medially but at risk with deep dissection toward joint. ### Common Peroneal Nerve Injury **Risk Factors:** - Preoperative CPN palsy (traction injury) - Varus malalignment - Revision surgery - Inadequate nerve protection **Presentation:** | Deficit | Nerve Affected | |---------|----------------| | Foot drop (dorsiflexion weakness) | Deep peroneal | | Toe extension weakness | Deep peroneal | | First web space numbness | Deep peroneal | | Lateral leg/foot numbness | Superficial peroneal | | Eversion weakness | Superficial peroneal | **Management:** - Observation: Most neurapraxias recover - EMG/NCS at 6 weeks, 3 months - AFO for foot drop - Exploration if no recovery at 3-6 months ### Other Complications | Complication | Incidence | Management | |--------------|-----------|------------| | Wound complications | 5-10% | Debridement, VAC if severe | | Infection | 1-2% | Antibiotics, washout | | Haematoma | 3-5% | Aspiration, drainage | | Stiffness | 5-15% | Physiotherapy, MUA | | DVT | 1-3% | Prophylaxis protocol | | Residual instability | 10-20% | Revision, brace | **Prevention:** - Meticulous hemostasis - Careful wound closure - VTE prophylaxis - Early mobilization when safe ### Graft Failure **Causes:** - Non-anatomic tunnel placement - Inadequate graft tensioning - Failure to address alignment - Missed combined injuries - Aggressive rehabilitation **Risk Factors:** - Varus alignment (unaddressed) - Combined ACL/PCL injury - High-demand activity return - Revision surgery **Management:** - Identify cause of failure - Address alignment (HTO if varus) - Revision reconstruction - Consider allograft vs autograft ### Immediate Postoperative Care **Day 0-1:** - Hinged brace locked in extension - Ice, elevation - DVT prophylaxis - Check CPN function (critical) **Protection Phase (Weeks 0-6):** | Week | Activity | |------|----------| | 0-2 | Brace locked extension, NWB or TTWB | | 2-4 | Brace 0-90°, TTWB | | 4-6 | Brace 0-120°, progress WB | **Key Points:** - Protect graft healing - Avoid varus stress - Check wound, neurovascular status ### Rehabilitation Protocol **Phase 1 (0-6 weeks):** - Quad sets, SLR (brace locked) - Patellar mobilization - No active hamstring exercises **Phase 2 (6-12 weeks):** - Progress ROM to full - Closed chain exercises - Proprioception training - Stationary cycling **Phase 3 (3-6 months):** - Full weight bearing - Progressive strengthening - Sport-specific training - Pool exercises **Return to Sport:** - Typically 9-12 months - Must pass functional testing - Gradual return to contact ### Follow-up Schedule | Timeframe | Assessment | |-----------|------------| | 2 weeks | Wound, CPN function, ROM | | 6 weeks | ROM, laxity, radiographs | | 3 months | Stability, strength, function | | 6 months | Functional testing, sport prep | | 12 months | Full assessment, return to sport | | Annually | Long-term surveillance | **Red Flags:** - New onset foot drop - Recurrent instability - Wound breakdown - Increasing pain - Loss of motion ### Functional Outcomes **PLC Reconstruction Results:** | Outcome | Result | |---------|--------| | Stability restoration | 80-90% | | Return to sport (any level) | 70-80% | | Return to previous level | 50-60% | | Patient satisfaction | 75-85% | | Residual laxity | 10-20% | **Scoring Outcomes:** - Lysholm score: Average improvement 30-40 points - IKDC: Majority achieve normal/near-normal - Tegner: Often reduced by 1-2 levels ### Acute Repair vs Reconstruction | Outcome | Acute Repair | Reconstruction | |---------|--------------|----------------| | Stability | 70-80% | 80-90% | | Stiffness | Less | More | | Technical ease | Easier | More complex | | Tissue quality | Variable | Graft dependent | | Timing | Within 2-3 weeks | Delayed OK | **Evidence:** - Recent data favors anatomic reconstruction - Repair alone has higher failure rate - Combined repair/augmentation may be optimal ### Prognostic Factors **Favorable:** - Isolated PLC injury - Acute treatment - Normal alignment - No preoperative CPN palsy - Anatomic reconstruction technique **Unfavorable:** - Combined multiligament injury - Chronic injury (more than 3 weeks) - Varus alignment (uncorrected) - CPN palsy at presentation - Previous failed surgery **Alignment Considerations:** - Address varus with HTO - Lateral compartment overload leads to failure - Correct alignment before or with PLC reconstruction ### Key Studies | Study | Year | Finding | |-------|------|---------| | LaPrade et al | 2003 | Described anatomic PLC landmarks | | Stannard et al | 2005 | Repair vs reconstruction outcomes | | Levy et al | 2010 | Anatomic reconstruction technique | | Kim et al | 2011 | Single vs double bundle PLC | | Geeslin et al | 2016 | Long-term reconstruction outcomes | **Level of Evidence:** - Mostly Level III-IV studies - Few RCTs in PLC literature - Anatomic techniques now preferred (expert consensus) - Biomechanical studies support anatomic reconstruction ### Technique Evolution **Historical:** - Early: Biceps tenodesis (non-anatomic) - 1990s: Larson technique - 2000s: Anatomic reconstruction (LaPrade) **Current Standard:** - Anatomic reconstruction of LCL + popliteus + PFL - Allograft most common for adults - Address alignment concurrently - Combined staging for multiligament **Future Directions:** - Patient-specific tunnel planning - Improved graft materials - Accelerated rehabilitation protocols - Better outcome measures for rotational stability **Q: What are the surgical indications for the posterolateral approach to the knee?** A: Primary indications: **Posterolateral corner (PLC) reconstruction**; **LCL repair/reconstruction**; **Popliteus tendon repair**; **Posterolateral tibial plateau fractures (Schatzker VI, Moore I)**; **Fibular head fractures**; **Arcuate ligament complex repair**; **Revision multiligament surgery**. Essential for addressing posterolateral rotatory instability and varus-posterolateral instability patterns. **Q: What is the key structure at risk in the posterolateral approach and how is it protected?** A: The **common peroneal nerve (CPN)** is the most critical structure. It courses around the fibular neck, approximately 2cm distal to fibular head. Protection: (1) Identify and protect nerve early in dissection; (2) Avoid excessive traction; (3) Release peroneus longus fascia to mobilize nerve if needed; (4) Maintain knee in flexion during dissection. CPN injury causes foot drop (ankle dorsiflexion, toe extension weakness) and lateral leg numbness. **Q: What are the components of the posterolateral corner (PLC)?** A: **Three main static stabilizers**: (1) **LCL (fibular collateral ligament)** - primary restraint to varus; (2) **Popliteus tendon** - resists external rotation and posterolateral translation; (3) **Popliteofibular ligament** - connects popliteus to fibular head. Additional structures: Arcuate ligament, lateral capsule, fabellofibular ligament, posterolateral capsule. The PLC resists **varus stress, external rotation, and posterior translation** of the lateral tibia. **Q: What is the interval used in the posterolateral knee approach?** A: Two main intervals: (1) **Anterior interval**: Between iliotibial band (ITB) and biceps femoris - exposes LCL, lateral femoral condyle. (2) **Posterior interval**: Between biceps femoris and lateral gastrocnemius - exposes popliteus, posterolateral capsule, fibular head. The CPN lies along posterior border of biceps, requiring identification before posterior dissection. The lateral geniculate vessels mark the joint line. **Q: How do you test for posterolateral corner insufficiency clinically?** A: **Dial test**: Prone, compare tibial external rotation at 30° and 90° knee flexion. Increased ER at 30° only = isolated PLC; at both 30° and 90° = combined PLC + PCL. **Posterolateral drawer**: Increased posterolateral translation. **Reverse pivot shift**: Knee reduced in extension, subluxes posterolaterally in flexion. **Varus stress at 30°**: Increased opening indicates LCL insufficiency. **External rotation recurvatum test**: Tibia rotates externally and knee hyperextends with gravity. ### Australian Epidemiology **Incidence:** - PLC injuries occur in 2-16% of acute knee injuries - Higher incidence in multiligament injuries - Contact sports (AFL, rugby) significant mechanism - Motor vehicle accidents common in severe cases **At-Risk Activities:** | Activity | Mechanism | |----------|-----------| | AFL/Rugby | Direct tackle, varus stress | | Motor vehicle | Dashboard injury | | Skiing | Hyperextension, rotation | | Workplace | Crush, falls | ### Australian Practice Patterns **Referral Patterns:** - Sports medicine physicians - Emergency departments - General practitioners - Often delayed presentation for isolated PLC **Training:** - FRACS training includes PLC reconstruction - Subspecialty sports surgery fellowship recommended - AOA courses on multiligament injury **Graft Availability:** - Allograft through Australian tissue banks - Autograft (hamstrings, ITB) commonly used - Some centers import specific allografts

Posterolateral Approach to the Knee

Posterolateral Approach to the Knee