import { ComparisonTable, ContentSection, EvidenceCard, ExamCheatSheet, ExamPearl, ExamWarning, InfoCard, InfoCardGrid, MedicalImage, MnemonicCard, OnePagerSummary, SafetyAlert, Tab, Tabs, Timeline, TimelineItem, VivaScenario, VivaScenarioSection } from '@/components/mdx' {/* SECTION 1: ONE-PAGER SUMMARY */} {/* SECTION 2: EXAM WARNING */} **Always AL portal FIRST**. This is the viewing portal. Create it blind (but safely with spinal needle first). The AM portal is then created UNDER DIRECT VISION through the arthroscope. Never create AM portal blind. The **infrapatellar branch of saphenous nerve** runs transversely across the anterior knee, typically 3-5mm below the joint line. It is commonly injured during portal placement, causing anterolateral knee numbness. This is similar to open surgery. **Portals must be at joint line level**. Too proximal risks patellar surface damage; too distal risks meniscus or fat pad injury. Palpate the soft spot adjacent to the patellar tendon with the knee flexed 90 degrees. **Posterior portals risk neurovascular injury**. The popliteal artery and tibial nerve are within 5mm of the posterior capsule. Use transillumination and accessory posterior portals only when essential. {/* SECTION 3: MNEMONICS */} **Knee arthroscopy** uses a standard **two-portal technique** with the **anterolateral (AL) portal** for viewing and **anteromedial (AM) portal** for working instruments. The AL portal is placed **1cm lateral to the patellar tendon at joint line level** and is established first; the AM portal is then created **under direct visualization** 1cm medial to the patellar tendon. The **infrapatellar branch of the saphenous nerve (IPBSN)** runs transversely 3-5mm below the joint line and is commonly injured, causing anterolateral knee numbness. Portals must be at joint line level—too proximal damages the patella, too distal injures the meniscus or fat pad. **Triangulation** (working through AM while viewing through AL) is the fundamental skill. Posterior portals risk popliteal neurovascular structures and should only be used when essential. {/* SECTION 4: OVERVIEW */} **Knee arthroscopy** is one of the most commonly performed orthopedic procedures worldwide. It allows minimally invasive diagnostic and therapeutic access to all knee compartments. **Primary indications:** - Meniscal pathology (tears - repair or partial meniscectomy) - ACL/PCL reconstruction - Cartilage procedures (microfracture, debridement, OATS) - Loose body removal - Synovectomy (inflammatory arthritis, PVNS) - Lateral release for patellofemoral disorders - Diagnostic arthroscopy (when imaging inconclusive) Recent evidence (FIDELITY trial, MOSAIC trial) has questioned the role of arthroscopic partial meniscectomy in degenerative meniscal tears. For Exam, know that APM is NOT superior to sham surgery for degenerative tears but remains indicated for mechanical symptoms from acute traumatic tears and for meniscal repair in young patients. **Advantages:** - Minimally invasive with small incisions - Direct visualization of intra-articular structures - Same-day surgery in most cases - Rapid rehabilitation compared to open procedures - Can combine diagnostic and therapeutic in single procedure **Disadvantages:** - Requires specialized equipment and training - Fluid extravasation and compartment syndrome risk - Limited access to some structures without additional portals - Learning curve for complex procedures {/* SECTION 5: ANATOMY */} **Surface anatomy for portal placement:** - **Patella** - Superior pole, inferior pole, medial and lateral borders - **Patellar tendon** - From inferior patella to tibial tubercle - **Joint line** - Palpable as soft spot adjacent to patellar tendon with knee at 90 degrees - **Tibial tubercle** - 2-3cm below joint line **Portal positions (standard two-portal technique):** | Portal | Position | Purpose | |--------|----------|---------| | Anterolateral (AL) | 1cm lateral to patellar tendon, at joint line | Viewing portal | | Anteromedial (AM) | 1cm medial to patellar tendon, at joint line | Working portal | | Superolateral | 2cm above joint line, lateral | Outflow, visualization of patella | | Superomedial | 2cm above joint line, medial | Rarely used - quadriceps in the way | | Posteromedial | Posterior to MCL, at joint line | Posterior horn access, PCL surgery | | Posterolateral | Posterior to LCL, at joint line | Popliteus access, posterolateral corner | **Structures at risk:** The popliteal artery lies within 5-15mm of the posterior capsule. When creating posterior portals: (1) Always use transillumination from the anterior scope, (2) Insert spinal needle under direct vision, (3) Make only skin incision with blade then use blunt trocar, (4) Stay in the plane superficial to the capsule until visualized arthroscopically. **Intra-articular anatomy (systematic examination):** 1. **Suprapatellar pouch** - Synovium, quadriceps tendon 2. **Medial gutter** - Medial synovium, medial femoral condyle 3. **Patellofemoral joint** - Articular surfaces, tracking 4. **Medial compartment** - MFC, medial tibial plateau, medial meniscus 5. **Intercondylar notch** - ACL, PCL insertions 6. **Lateral compartment** - LFC, lateral tibial plateau, lateral meniscus 7. **Lateral gutter** - Lateral synovium, popliteus hiatus {/* SECTION 6: PREOPERATIVE PLANNING */} {/* REMOVED: 1-overview-of-collection-of-outcomes-during-the-firs.png */} **Assessment:** - Detailed history: mechanism, symptoms, mechanical vs inflammatory - Physical examination: effusion, ROM, ligament stability, meniscal tests - Document baseline neurovascular status - Identify contraindications (infection, DVT, compartment syndrome) **Imaging review:** - **X-rays**: Weight-bearing AP, lateral, Rosenberg (45 degree PA flexion), Merchant/skyline - **MRI**: Standard for most knee arthroscopy indications - meniscus, ACL, cartilage - **CT**: Rarely needed unless bony pathology or complex fracture **Consent points:** - Numbness from infrapatellar nerve injury (10-30% incidence) - Infection (less than 1%) - DVT/PE (rare but serious) - Stiffness or arthrofibrosis - Failure to resolve symptoms (especially degenerative tears) - Progression of arthritis (natural history, not caused by surgery) - Conversion to open procedure (rare) - Specific risks based on planned procedure (meniscal repair failure, etc.) **Essential equipment**: Arthroscope (4mm, 30-degree), light source, camera, pump/gravity inflow, hand instruments (probes, shavers, graspers, cutters), tourniquet (optional). **Tourniquet use is surgeon-dependent**. Benefits: bloodless field, faster surgery. Risks: tourniquet pain, potential nerve compression. Many surgeons use tourniquet only if bleeding obscures vision. {/* SECTION 7: INTERNERVOUS PLANE */} **Key Concept: There is NO true internervous plane in knee arthroscopy portals.** Unlike open surgical approaches that exploit intervals between muscles supplied by different nerves, arthroscopy uses small stab incisions through skin and capsule. The concept of "internervous plane" is not applicable to portal-based approaches. **Definition**: A surgical plane between muscles supplied by different nerves, allowing separation without denervation. **Applies to**: Open surgical approaches (medial parapatellar, posterior hip approach, etc.) **No internervous plane**: Portals are small stab incisions (5-10mm) through skin and capsule directly into the joint. **Key principle**: Minimize tissue trauma by staying at joint line, using spinal needle localization, and avoiding major neurovascular structures. **Nerve considerations for portal placement:** The **infrapatellar branch of saphenous nerve (IPBSN)** is the main nerve at risk. It emerges from beneath the sartorius muscle and runs horizontally across the anterior knee, typically passing 3-5mm below the standard portal sites. - **Injury rate**: 10-30% in various studies - **Consequence**: Anterolateral or anteromedial knee numbness - **Prevention**: Horizontal skin incisions (parallel to IPBSN), staying at joint line level, not overtight sutures When asked about internervous planes in knee arthroscopy, state: "The concept of internervous plane is not applicable to arthroscopic portals. These are small stab incisions directly through skin and capsule. The main nerve at risk is the infrapatellar branch of the saphenous nerve, which runs horizontally across the anterior knee. This is avoided by staying at joint line level and using horizontal skin incisions. Injury causes anterolateral numbness but typically resolves or is well-tolerated." {/* SECTION 8: POSITIONING AND PATIENT SETUP */} **Standard Patient Position:** - **Supine** on operating table - **Leg hanging free** off the side of the table, or - **Leg holder** device maintaining 70-90 degrees flexion - **Thigh tourniquet** if planned (inflated to 300mmHg after exsanguination) - **Lateral post** at thigh level for valgus stress (medial compartment access) - **Foot rest** or padded support **Key Setup Considerations:** 1. **Knee Position:** - Flexed 70-90 degrees for most work (suprapatellar, anterior compartments) - Near full extension for posterior horn visualization - Figure-of-4 position (hip flexion, external rotation) for lateral meniscus 2. **Access Requirements:** - Must be able to apply valgus stress (medial compartment exposure) - Must be able to apply varus stress (lateral compartment exposure) - Full flexion and extension must be possible 3. **Draping:** - Free drape the entire lower extremity - Include thigh in field for tourniquet - Impermeable drape to contain fluid **Advantages**: Gravity assists flexion, easy to apply varus/valgus stress, simple setup. **Disadvantages**: Surgeon must stabilize leg, may be awkward for prolonged cases. **Advantages**: Hands-free stabilization, consistent positioning, easier for long cases. **Disadvantages**: Cost, setup time, may limit positioning options for some procedures. **Positioning for Specific Procedures:** - **Meniscal repair**: Leg hanging with ability to flex deeply (90-120 degrees) - **ACL reconstruction**: Leg holder often preferred for consistent positioning during graft passage - **Posterior horn work**: Near-extension increases posterior visualization - **Loose body removal**: May need multiple position changes to access all compartments {/* SECTION 9: SURGICAL TECHNIQUE */} ### Standard Two-Portal Technique **Step 1: Joint Distension (optional)** - Insert spinal needle superolaterally into suprapatellar pouch - Inject 30-60mL saline to distend joint - Alternatively, distend after AL portal with pump **Step 2: Anterolateral Portal (Viewing)** Palpate the soft spot 1cm lateral to the patellar tendon at the level of the inferior pole of the patella. The knee should be flexed 70-90 degrees. Insert 18g spinal needle through the soft spot, aiming for the intercondylar notch. Confirm intra-articular position by aspirating fluid if joint distended. Make horizontal stab incision with 11-blade, 5-10mm long, centered on the needle entry point. Horizontal incision is parallel to IPBSN. Insert blunt trocar with sheath, aiming toward intercondylar notch. Feel the capsule give way as you enter the joint. Do NOT force. Remove trocar, insert 4mm 30-degree arthroscope. Connect camera, light source, and inflow. Confirm intra-articular position. **Step 3: Anteromedial Portal (Working) - UNDER DIRECT VISION** From AL portal, look toward the medial compartment. Identify the medial femoral condyle, anterior horn of medial meniscus, and fat pad. Insert spinal needle under direct visualization 1cm medial to the patellar tendon at joint line level. Watch the needle enter the joint on screen. The needle should enter above the anterior horn of medial meniscus, avoiding fat pad entrapment. Adjust entry point if needed before skin incision. Make horizontal stab incision over needle, 5-10mm long. Remove needle and keep incision open. Insert blunt trocar through the portal under direct vision. Can use portal cannula or work with instruments directly. The AM portal must be created under direct arthroscopic vision. Blind AM portal placement risks injury to the anterior horn of the medial meniscus, articular cartilage, or fat pad. Always localize with spinal needle first and visualize the needle entering the joint. The working portal position is confirmed, and instruments can now be triangulated. ### Systematic Joint Examination A complete diagnostic arthroscopy follows a standardized examination routine to avoid missing pathology. **Recommended Examination Sequence:** 1. **Suprapatellar Pouch** - Assess for synovitis, loose bodies, suprapatellar plica - Examine quadriceps tendon insertion 2. **Medial Gutter** - Medial synovium, medial plica - Medial femoral condyle articular surface 3. **Patellofemoral Joint** - Patellar articular surface (all facets) - Trochlea articular surface - Patellar tracking with knee extension 4. **Medial Compartment (apply valgus stress)** - Medial femoral condyle weight-bearing surface - Medial tibial plateau - Medial meniscus (anterior horn, body, posterior horn) 5. **Intercondylar Notch** - ACL (AM and PL bundles) - PCL (through the notch, limited view) - Notch osteophytes or impingement 6. **Lateral Compartment (apply varus stress)** - Lateral femoral condyle - Lateral tibial plateau - Lateral meniscus (anterior horn, body, posterior horn, popliteal hiatus) 7. **Lateral Gutter** - Lateral synovium - Popliteus tendon in the hiatus 8. **Posterior Compartments (if indicated)** - Through intercondylar notch or with posterior portals - PCL tibial insertion - Posterior horns from inside-out Document all findings systematically. Video or photo documentation of key pathology is standard of care. Note meniscal tear location using zones (red-red, red-white, white-white) and clock positions (6 to 12 o'clock). Document cartilage lesions using ICRS or Outerbridge grading. Complete systematic examination before beginning any therapeutic procedures. ### Accessory Portals When Needed **Superolateral Portal** - **Position**: 2-3cm above joint line, lateral to quadriceps tendon - **Indication**: Outflow, patellofemoral visualization, loose body removal from suprapatellar pouch - **Technique**: Create under direct vision from AL portal **Superomedial Portal** - **Position**: 2-3cm above joint line, medial - **Indication**: Rarely used - quadriceps muscle in the way - **Alternative**: Most procedures can use superolateral or far medial AM portal **Posteromedial Portal** - **Position**: 1cm posterior to MCL, at joint line - **Indication**: Posterior horn medial meniscus repair, PCL reconstruction, posterior loose bodies - **Safety**: Saphenous vein and nerve anterior; popliteal vessels posterior - **Technique**: MUST use transillumination and spinal needle under direct vision **Posterolateral Portal** - **Position**: 1cm posterior to LCL, at joint line - **Indication**: Popliteus repair, posterolateral corner surgery, posterior horn lateral meniscus - **Safety**: Common peroneal nerve at risk if placed too posterior - **Technique**: Spinal needle under direct vision, transillumination essential **All posterior portals carry significant neurovascular risk.** Protocol: 1. Transilluminate from anterior scope to identify vasculature 2. Insert spinal needle under direct arthroscopic visualization 3. Make only skin incision with blade 4. Use blunt dissection through subcutaneous tissue 5. Enter capsule with blunt trocar under direct vision 6. If any uncertainty, abort posterior portal and use alternative technique **Transpatellar Tendon Portal (Central Portal)** - **Position**: Through the patellar tendon substance - **Indication**: ACL femoral tunnel drilling (all-inside technique) - **Controversy**: Risk of tendon damage, patellar tendonitis - **Alternative**: Far AM portal now often preferred Consider the risk-benefit ratio carefully before creating accessory portals. ### Closure **Portal Closure:** - Remove all instruments and confirm hemostasis - Irrigate joint thoroughly to remove debris - Express fluid from joint by flexing knee - Close skin only - capsule not closed - Suture options: 3-0 or 4-0 nylon/Prolene, Steri-strips, or dermabond - Sterile dressing and compression bandage **Postoperative Care:** - Ice elevation and compression for first 48 hours - Weight bearing as tolerated (most simple arthroscopies) - Range of motion exercises immediately - DVT prophylaxis per institutional protocol - Suture removal at 7-10 days Recovery depends on procedure performed: - **Diagnostic arthroscopy/loose body**: 1-2 weeks to normal activities - **Partial meniscectomy**: 2-4 weeks - **Meniscal repair**: 4-6 months (protect repair) - **ACL reconstruction**: 9-12 months (sport-specific) - **Microfracture**: 6-8 weeks non-weight-bearing, 6 months to sport **Final Checks:** - All instruments accounted for (count confirmed) - No tourniquet time exceeded limits - Operative findings documented - Patient counseled on postoperative expectations Rehabilitation protocol should be procedure-specific and communicated clearly. {/* SECTION 10: EXTENSILE OPTIONS */} When standard two-portal arthroscopy provides insufficient access, several options exist: **1. Additional Anterior Portals** - **Far medial/lateral portals**: For ACL femoral tunnel drilling, improved triangulation - **Trans-notch visualization**: Insert scope through one side, work from opposite **2. Posterior Portals (see above)** - Posteromedial and posterolateral when required - Use transillumination for safety **3. Inside-Out and Outside-In Techniques** - **Meniscal repair needles**: Pass inside-out for posterior horn suturing - **Outside-in repair**: For anterior and middle third meniscal tears **4. Mini-Open Conversion** - If arthroscopic procedure fails, can extend portal to small arthrotomy - Example: Mini-open meniscal repair at posterior horn **5. Pump Pressure Optimization** - Increase pump pressure (up to 60mmHg) for bleeding control - Use with caution - compartment syndrome risk with extravasation {/* SECTION 11: COMPLICATIONS */} **Compartment Syndrome - Key Points:** - **Cause**: Fluid extravasation through capsular defect into calf or thigh - **Risk factors**: Prolonged surgery, high pump pressures, capsular tears - **Recognition**: Increasing leg swelling, pain out of proportion, tense compartments - **Prevention**: Monitor leg compartments, limit pump pressure, limit OR time - **Treatment**: Immediate fasciotomies - orthopedic emergency During knee arthroscopy, periodically palpate the calf and thigh for swelling. If significant extravasation is detected, lower pump pressure, consider switching to gravity inflow, and expedite the procedure. Postoperatively, monitor for compartment syndrome symptoms. **Instrument Breakage:** - Shavers, graspers, and other instruments can break intra-articularly - Always perform instrument count before and after procedure - Broken fragments require immediate retrieval - loose body causing damage - May require additional portals or mini-open approach {/* SECTION 12: EVIDENCE BASE */} {/* REMOVED: 2-overview-of-the-recruitment-flow-in-the-knee-arthr.png */} {/* SECTION 13: VIVA SCENARIOS */} {/* SECTION 14: MCQ POINTS */} {/* REMOVED: 4-overview-of-the-full-analysis-set-for-study-aims-1.png */} **Q: Which portal should be established first during knee arthroscopy?** A: The **anterolateral portal** is always established first as the viewing portal. The anteromedial portal is then created under direct arthroscopic vision. Never create the AM portal blind. **Q: What nerve is most commonly injured during knee arthroscopy, and what is the consequence?** A: The **infrapatellar branch of the saphenous nerve (IPBSN)** is injured in 10-30% of cases, causing anterolateral knee numbness. Prevention: horizontal skin incisions, staying at joint line level. **Q: According to the FIDELITY trial, what is the role of arthroscopic partial meniscectomy for degenerative meniscal tears?** A: The FIDELITY trial showed **APM is no better than sham surgery** for degenerative meniscal tears. Non-operative management with physiotherapy is recommended first-line. **Q: How is compartment syndrome prevented during knee arthroscopy?** A: Monitor pump pressure (keep less than 60mmHg), periodically palpate leg compartments for swelling, limit operative time, and recognize capsular tears that increase extravasation risk. **Q: Which zone of the meniscus has the best healing potential and why?** A: The **red-red (peripheral) zone** has the best healing potential due to its blood supply from the perimeniscal capillary plexus. The red-white (middle) zone has intermediate potential, while the white-white (central) zone has poor healing due to avascularity. **Q: What are the two main positioning options for knee arthroscopy, and when is each preferred?** A: **Supine with leg hanging** (60-90° flexion) is preferred for most procedures - allows gravity to open joint. **Supine with leg support** is used for ACL reconstruction when tibial tunnel drilling requires stable position. Both options should maintain thigh support. {/* SECTION 15: AUSTRALIAN CONTEXT */} {/* REMOVED: 3-expected-distribution-per-450-patients-recruited-d.png */} Knee arthroscopy is one of the most common orthopedic procedures in Australia with over 100,000 procedures performed annually. However, rates have declined significantly following publication of high-quality RCTs (FIDELITY, METEOR) demonstrating limited benefit for degenerative meniscal tears compared to sham surgery or physiotherapy. Australian practice has shifted toward meniscal repair over resection in younger patients with traumatic tears, aligned with international guidelines. The Australian orthopaedic community has been at the forefront of implementing evidence-based practice changes, with many surgeons now offering structured rehabilitation as first-line treatment for degenerative tears. This represents a significant shift from historical practice patterns and aligns with recommendations from the Royal Australasian College of Surgeons regarding informed consent for procedures with limited evidence of efficacy. Consent considerations in Australia must include explicit discussion of evidence regarding degenerative tears, documentation that non-operative management was offered and declined, and realistic expectation setting regarding outcomes given the natural history of osteoarthritis progression. For Orthopaedic Operative Surgery station, you must be able to describe portal placement in detail: patient positioning, AL portal first (landmarks, technique), AM portal under direct vision, systematic joint examination sequence, and common complications. Know the evidence regarding APM for degenerative tears and be prepared to discuss non-operative alternatives. {/* SECTION 16: EXAM CHEAT SHEET */}

Knee Arthroscopy Approach

Knee Arthroscopy Approach