import { ContentSection, EvidenceCard, ExamCheatSheet, ExamPearl, ExamWarning, InfoCard, InfoCardGrid, MnemonicCard, OnePagerSummary, SafetyAlert, Tab, Tabs, VivaScenario, VivaScenarioSection } from '@/components/mdx' **Standard TKA arthrotomy**. Incision through or adjacent to **vastus medialis** insertion on patella. Then along medial patellar border and medial to patellar tendon. For TKA, patella is **everted laterally** to expose joint. May need **lateral retinacular release** if tight. Subvastus avoids splitting quadriceps. **At risk with distal medial extension**. Saphenous nerve accompanies great saphenous vein along medial knee and leg. Injury causes medial leg numbness. The approach provides access to **medial collateral ligament** for repair or imbrication. **Pes anserinus** (sartorius, gracilis, semitendinosus) is landmark distally. The **anteromedial approach to the knee** is the standard exposure for **total knee arthroplasty (TKA)**, utilising the **medial parapatellar arthrotomy**. This is **not a true internervous plane**—the incision passes through or adjacent to vastus medialis. The patella is **everted laterally** to expose the joint; lateral retinacular release may be needed if tight. Variations include **subvastus** (muscle-sparing, passes under VM) and **midvastus** (splits VM). The **saphenous nerve and great saphenous vein** are at risk with distal extension—injury causes medial leg numbness. The **pes anserinus** (Sartorius, Gracilis, Semitendinosus—"Say Grace before Tea") is the key distal landmark providing access to MCL. **Indications**: - Total knee arthroplasty (most common) - Unicompartmental knee arthroplasty - Medial tibial plateau fractures - MCL repair/reconstruction - Medial meniscus surgery (open) - Arthrotomy for infection **Patient Position**: Supine with knee flexed to 90° over edge of table or supported. ### Anteromedial Knee Approach Overview The anteromedial approach to the knee provides versatile exposure for various knee procedures, from arthroscopic portals to open procedures including total knee arthroplasty. **Key Concepts:** - Standard approach for **total knee arthroplasty** (medial parapatellar variant) - **Not a true internervous plane** - passes through or adjacent to vastus medialis - Provides access to **medial compartment**, MCL, and medial meniscus - Can be combined with other approaches for multiligament reconstruction - Variations include subvastus and midvastus for TKA **Historical Context:** - Medial parapatellar arthrotomy described by Insall for TKA - Subvastus approach developed to preserve extensor mechanism - Midvastus represents compromise between exposure and muscle sparing ### Indications | Indication | Details | |------------|---------| | Total knee arthroplasty | Primary, revision TKA (medial parapatellar) | | Unicompartmental knee arthroplasty | Medial UKA access | | Medial tibial plateau fractures | ORIF of Schatzker I-IV | | MCL repair/reconstruction | Acute or chronic MCL injuries | | ACL reconstruction | Hamstring graft harvest, tunnel drilling | | Medial meniscus surgery | Open meniscal repair, meniscectomy | | Loose body removal | Medial compartment access | | Tibial eminence fractures | Open fixation in adults | | Arthrotomy for infection | Irrigation and debridement | | Synovectomy | Inflammatory arthropathy | ### Advantages and Disadvantages **Advantages:** - Familiar, reproducible approach for most knee surgeons - Excellent exposure of entire joint (femur, tibia, patella) for TKA - Extensile - can extend proximally or distally as needed - Direct access to medial structures (MCL, medial meniscus) - Allows patellar eversion for TKA **Disadvantages:** - Disrupts VMO insertion (medial parapatellar variant) - Risk to saphenous nerve with distal extension - May affect patellar tracking if not closed properly - Limited lateral compartment access - Infrapatellar branch of saphenous nerve often transected ### Surface Anatomy **Palpable Landmarks:** - **Patella**: Central reference point - **Patellar tendon**: From inferior patella to tibial tubercle - **Tibial tubercle**: Distal extent of incision - **Medial femoral condyle**: Palpable medially - **Medial joint line**: At level of inferior patella - **VMO muscle belly**: Visible superomedially **Incision Planning:** | Landmark | Position | |----------|----------| | Proximal extent | 5-10 cm above patella (TKA) | | Central portion | Medial to patella | | Distal extent | Tibial tubercle or beyond | | Orientation | Midline or slightly medial | ### Surgical Layers **Superficial Layer:** - Skin, subcutaneous tissue - Prepatellar bursa (may require excision) - Saphenous vein branches **Intermediate Layer:** - Quadriceps tendon and expansion - Vastus medialis obliquus (VMO) - Medial retinaculum - Patellar tendon **Deep Layer:** - Joint capsule - Synovial membrane - Fat pad (may need partial excision) **Plane of Dissection:** - No true internervous plane - Incision through/adjacent to VMO insertion - Arthrotomy along medial patella border ### Key Anatomical Structures | Structure | Relevance | |-----------|-----------| | Vastus medialis obliquus | Split or lifted in arthrotomy | | Medial retinaculum | Incised for joint entry | | Infrapatellar fat pad | Partial excision improves exposure | | Saphenous nerve | At risk distally | | Infrapatellar branch | Often transected at joint line | | Great saphenous vein | Posterior, at risk distally | | MCL | Deep to approach, accessed by extension | | Pes anserinus | Distal landmark (SGS) | | Medial meniscus | Visible on capsulotomy | **Pes Anserinus Order (superficial to deep):** - **S**artorius - most superficial - **G**racilis - middle - **S**emitendinosus - deepest ### Anteromedial Approach Variations | Variation | Description | Best Indication | |-----------|-------------|-----------------| | **Medial Parapatellar** | Standard TKA arthrotomy through/near VMO | Primary and revision TKA | | **Subvastus** | Under VMO, muscle sparing | TKA in selected patients | | **Midvastus** | Split VMO, compromise approach | TKA with limited exposure | | **Mini-incision** | Limited exposure for minimally invasive | UKA, selected TKA | | **Anteromedial portal** | Arthroscopic portal at joint line | Arthroscopy, ACL | | **Extended anteromedial** | Distal extension along tibia | Plateau fractures, MCL | **Selection Criteria:** - Patient factors: obesity, ROM, deformity - Procedure type: TKA vs UKA vs trauma - Surgeon experience and preference - Previous incisions on medial knee ### Approach Comparison for TKA | Feature | Medial Parapatellar | Subvastus | Midvastus | |---------|---------------------|-----------|-----------| | VMO integrity | Disrupted | Preserved | Partially preserved | | Exposure | Excellent | Limited | Moderate | | Technical ease | Easiest | Most difficult | Intermediate | | Patellar tracking | Good | Possibly better | Good | | Recovery | Standard | Possibly faster | Intermediate | | Conversion rate | N/A | Higher | Lower | | Obese patients | Yes | Difficult | Possible | | Stiff knees | Yes | No | Limited | **Evidence Summary:** - No consistent difference in long-term outcomes - Subvastus may have faster early recovery - Medial parapatellar remains gold standard for most surgeons ### Preoperative History **Key History Elements:** - Previous knee surgery or incisions - Skin quality and soft tissue condition - History of DVT/PE or anticoagulation - Corticosteroid or immunosuppressant use - Diabetes and healing concerns **Factors Affecting Approach Choice:** | Factor | Preferred Approach | |--------|-------------------| | Primary TKA, standard patient | Medial parapatellar | | Young patient, concern for recovery | Consider subvastus | | Obese patient | Medial parapatellar | | Previous medial incision | Use existing incision | | Stiff knee, limited ROM | Medial parapatellar | | Valgus deformity | Lateral approach consideration | ### Physical Examination **Key Examination Findings:** - **Skin**: Scars, trophic changes, vascularity - **Soft tissue**: Swelling, effusion, skin mobility - **Range of motion**: Flexion, extension contracture - **Alignment**: Varus/valgus deformity - **Patellar tracking**: Lateral tilt, subluxation **Specific Assessments:** - Previous incision location and quality - VMO bulk and function - Quadriceps strength - Patellar mobility and J-sign - Vascular status (pulses, capillary refill) ### Surgical Planning **Approach Selection Algorithm:** | Scenario | Recommended Approach | |----------|---------------------| | Standard primary TKA | Medial parapatellar | | Revision TKA | Medial parapatellar (may need tibial tubercle osteotomy) | | UKA (medial) | Mini-medial parapatellar | | Medial plateau fracture | Extended anteromedial | | MCL reconstruction | Anteromedial with distal extension | | ACL reconstruction | Anteromedial portal or small incision | **Patient Positioning:** - Supine with knee flexed 90° over table edge - Foot of bed dropped or leg holder - Tourniquet applied to upper thigh (if used) - Ensure full flexion and extension achievable ### Imaging Studies **Standard Preoperative Imaging:** | Study | Purpose | |-------|---------| | Weight-bearing AP radiograph | Assess alignment, joint space | | Lateral radiograph | Tibial slope, patella alta/baja | | Skyline/Merchant view | Patellofemoral joint, tracking | | Long leg alignment | Mechanical axis for TKA planning | **Additional Imaging (Selected Cases):** - **MRI**: Soft tissue pathology, MCL injury, meniscal disease - **CT**: Complex deformity, bone loss, previous hardware - **Vascular studies**: If peripheral vascular disease suspected ### Laboratory Investigations **Preoperative Labs (TKA):** - Full blood count - Urea, electrolytes, creatinine - Coagulation studies (if anticoagulated) - HbA1c (diabetic patients, target below 8%) - ESR/CRP (if infection concern) **Infection Workup (if concern):** - Joint aspiration for cell count, culture - Synovial fluid WBC greater than 3000 concerning - Alpha-defensin if available ### Surgical Setup **Patient Positioning:** - Supine on standard operating table - Knee flexed 90° over edge of bed - Leg holder or foot of bed dropped - Ensure hip and ankle freely mobile **Equipment:** | Item | Purpose | |------|---------| | Tourniquet | Bloodless field (thigh, 250-300 mmHg) | | Leg holder | Maintain flexion, free movement | | Bump under hip | Neutral rotation | | Bovie cautery | Hemostasis | | Retractors | Hohmann, bent Hohmann for exposure | ### Technical Tips **Key Steps:** 1. Mark patella borders before incision 2. Full-thickness flaps to reduce devascularization 3. Protect patellar tendon during arthrotomy 4. Adequate proximal release for patella eversion 5. Flex knee to 90° after eversion **Exposure Enhancement:** - Partial fat pad excision - Lateral retinacular release (if tight) - Proximal quadriceps snip (revision) - Tibial tubercle osteotomy (severe stiffness) **Avoid:** - Thin skin flaps - Excessive traction on patella - Forceful patella eversion (risk avulsion) - Distal extension without protecting saphenous nerve ### Wound Closure **Closure Technique:** | Layer | Suture | |-------|--------| | Capsule/VMO | #1 Vicryl or Ethibond | | Deep dermis | 2-0 Vicryl | | Skin | Staples, subcuticular, or Monocryl | **Key Points:** - Repair VMO/quad tendon meticulously - Test patella tracking with trial - No lateral subluxation in extension - Drain if significant ooze (optional) - Sterile dressing, compression wrap **Incision**: Midline skin incision or slightly medial (anterior midline for TKA). From 5cm above patella to tibial tuberosity. **Arthrotomy**: Incise joint capsule along medial patellar border: - Start proximally in quadriceps tendon (may split vastus medialis obliquus near its insertion) - Continue along medial patella - Then medial to patellar tendon **Patella Eversion**: After releasing soft tissue attachments, evert patella laterally. May need **lateral retinacular release** if difficult to evert. **Exposure**: Provides excellent exposure of entire joint (femur, tibia, patella) for TKA. **Subvastus Approach**: Muscle-sparing. **Technique**: Dissect beneath vastus medialis rather than through it. Lift VMO off intermuscular septum. Enter joint under VMO. **Advantages**: Preserves quadriceps mechanism. May have faster recovery, less pain. **Disadvantages**: More technically demanding. Limited exposure. May need to convert to MPP. **Distal Extension** (for medial plateau, MCL): Extend incision distally along subcutaneous border of tibia. **Saphenous Nerve and Vein**: At risk. Runs with great saphenous vein which lies posteriorly. Stay anterior to avoid. **Pes Anserinus**: Landmark for distal extent. Contains sartorius, gracilis, semitendinosus. **MCL Access**: Expose MCL from epicondyle to tibial insertion. **Saphenous Nerve**: Accompanies great saphenous vein. At risk with distal extension. Injury causes numbness over medial knee and leg. **Infrapatellar Branch of Saphenous Nerve**: Small branch running anterior to MCL. Often transected in TKA. Causes small area of lateral patellar numbness (usually well-tolerated). **Patellar Tendon**: Can be damaged during eversion if technique poor. Risk of avulsion. ### Early Complications | Complication | Incidence | Prevention | |--------------|-----------|------------| | Wound dehiscence | 1-2% | Careful closure, no tension | | Haematoma | 2-3% | Meticulous hemostasis, consider drain | | Superficial infection | 1-2% | Prophylactic antibiotics, aseptic technique | | DVT | 1-2% (with prophylaxis) | VTE prophylaxis protocol | | Patellar tendon injury | Rare | Careful technique, protect tendon | **Management Principles:** - Early recognition and intervention - Wound issues: early wound care, may need debridement - Haematoma: aspiration if tense, rule out bleeding disorder - Infection: antibiotics, may need washout ### Late Complications | Complication | Incidence | Management | |--------------|-----------|------------| | Numbness (infrapatellar nerve) | 30-70% | Usually well-tolerated, counsel preop | | Medial leg numbness (saphenous) | 1-5% | Avoid with careful technique | | Patellar tracking issues | 2-5% | Lateral release, revision if severe | | Stiffness | 3-7% | Physiotherapy, MUA if needed | | Extensor mechanism weakness | Variable | Depends on approach variant | **Numbness Counselling:** - Infrapatellar branch injury almost universal in TKA - Causes numbness lateral to incision - Usually well-tolerated and not functionally significant ### Approach-Specific Complications **Medial Parapatellar:** - VMO damage affecting patella tracking - Risk of lateral subluxation if not closed well - Usually heals without long-term sequelae **Subvastus:** - Higher conversion rate to standard approach - May not achieve adequate exposure - Potential VMO avulsion **Distal Extension:** - Saphenous nerve injury (numbness medial leg) - Great saphenous vein injury (bleeding, haematoma) - Pes anserinus damage **Prevention:** - Careful surgical technique - Stay anterior when extending distally - Identify and protect saphenous structures ### Immediate Postoperative Care **Day 0-1:** - Compression dressing - Ice therapy - Elevation above heart level - DVT prophylaxis (LMWH or other per protocol) - Analgesia (multimodal approach) **Wound Management:** | Timeframe | Action | |-----------|--------| | Day 1-2 | Check dressing, ensure no excessive bleeding | | Day 2-3 | Remove drain if present | | Day 10-14 | Suture/staple removal | | Week 2-6 | Scar massage when healed | **VTE Prophylaxis:** - Mechanical: TED stockings, foot pumps - Chemical: LMWH or aspirin per protocol - Duration: 2-6 weeks depending on risk ### Rehabilitation Protocol **Phase 1 (Week 0-2):** - Weight bearing as tolerated (TKA) - Quadriceps sets, straight leg raises - CPM if used (controversial) - ROM exercises **Phase 2 (Week 2-6):** - Progress ROM to 90° flexion - Gait training without aids - Progressive strengthening - Stairs training **Phase 3 (Week 6-12):** - Full ROM goal (0-120°) - Return to normal activities - Low-impact exercise - Avoid high-impact until 3-6 months ### Follow-up Schedule | Timeframe | Assessment | |-----------|------------| | 2 weeks | Wound check, ROM, early function | | 6 weeks | Radiographs, ROM, strength, gait | | 3 months | Function, return to activities | | 12 months | Outcome scores, radiographs | | Annually | Long-term surveillance | **Red Flags:** - Increasing pain after initial improvement - Wound breakdown, drainage - Fever, systemic symptoms - Sudden loss of ROM - Calf pain, swelling (DVT concern) ### Functional Outcomes **TKA Outcomes (Any Approach):** | Metric | Result | |--------|--------| | Pain relief | 90-95% significant improvement | | ROM | Average 115° flexion | | Patient satisfaction | 85-90% | | Return to function | 3-6 months typical | | Sports (low-impact) | 6-12 months | **Factors Affecting Outcome:** - Preoperative function and ROM - Patient expectations and motivation - Surgical technique and alignment - Implant design and fixation - Rehabilitation compliance ### Approach Comparison Outcomes | Outcome | MPP | Subvastus | Midvastus | |---------|-----|-----------|-----------| | Early ROM | Standard | Faster | Intermediate | | Pain (early) | Standard | Less | Intermediate | | Quad strength (6w) | Reduced | Preserved | Intermediate | | Long-term function | Excellent | Excellent | Excellent | | Complications | Low | Low | Low | **Evidence Summary:** - Meta-analyses show modest early benefit for subvastus - No significant difference at 1 year or beyond - Surgeon experience more important than approach - Patient selection key for subvastus success ### Implant Survival (TKA) **AOANJRR Data:** | Time | Cumulative Revision Rate | |------|--------------------------| | 1 year | 1.0-1.5% | | 5 years | 3-4% | | 10 years | 5-6% | | 15 years | 7-8% | **Revision Reasons:** - Loosening: 25-30% - Infection: 20-25% - Pain: 15-20% - Instability: 10-15% - Patellofemoral problems: 5-10% **Note:** Approach type not independently associated with revision risk in registry data. ### Key Studies **Approach Comparison RCTs:** | Study | Comparison | Finding | |-------|------------|---------| | Berstock 2018 (Cochrane) | MPP vs Subvastus | No clinically important difference | | Xie 2012 (Meta) | MPP vs Subvastus | Early benefits subvastus, no long-term difference | | Liu 2014 (Meta) | MPP vs Midvastus | Similar outcomes | | Pongcharoen 2013 | MPP vs Subvastus | Faster early recovery subvastus | **Evidence Level:** - Multiple RCTs and meta-analyses available - Level I evidence: No significant long-term difference between approaches - Surgeon experience and patient selection more important **Infrapatellar Nerve:** - Mistry 2016: Nerve transection in 100% TKA - Sensory deficit well-tolerated in most patients - Does not correlate with functional outcomes ### Guidelines and Recommendations **Approach Selection (Expert Consensus):** - No single approach superior for all patients - Medial parapatellar: gold standard, most versatile - Subvastus: consider in younger, thinner patients - Midvastus: reasonable compromise **AAOS Guidelines (TKA):** - Strong evidence for TKA in OA - No specific approach recommended - Surgeon experience critical **NICE Guidelines:** - Standard TKA approach not specified - Focus on outcomes, not approach - Patient-centred decision making **Australian Guidelines:** - AOANJRR: monitors outcomes by implant, not approach - No approach-specific recommendations **Q: What are the surgical indications for the anteromedial approach to the knee?** A: Primary indications: **ACL reconstruction** (hamstring or BTB graft harvest and femoral tunnel drilling); **Medial meniscus repair**; **MCL repair/reconstruction**; **Medial tibial plateau fractures**; **Tibial eminence fractures**; **Loose body removal**. Often combined with anterolateral approach for multiligament reconstruction. Provides direct access to medial compartment, posteromedial capsule, and medial meniscus. **Q: What are the key anatomical structures at risk during the anteromedial knee approach?** A: **Infrapatellar branch of saphenous nerve**: Crosses surgical field, causes painful numbness if injured (avoid by staying close to patella); **Saphenous nerve and vein**: At risk with distal extension along medial border; **MCL superficial fibers**: Divided in some approaches; **Medial inferior genicular artery**: Lies along medial joint line; **Pes anserinus tendons** (sartorius, gracilis, semitendinosus): Protect during distal extension. **Q: What is the interval used in the anteromedial knee approach?** A: The approach uses the interval between **medial border of patellar tendon and VMO (vastus medialis obliquus)**. Incision extends from medial patella margin, along medial patellar tendon border, to tibial tubercle. For ACL surgery, extend distally to access hamstring tendons. The **medial retinaculum and capsule** are incised to enter the joint. Deep dissection may require release of the coronary ligament for meniscal access. **Q: How does the anteromedial approach differ from the medial parapatellar approach for TKA?** A: **Anteromedial (mini)**: Smaller incision, stays lateral to VMO, limited exposure, used for arthroscopy portals, meniscal surgery, ACL. **Medial parapatellar (standard TKA)**: Extends through VMO tendon, allows patellar eversion, provides full exposure of knee joint for arthroplasty. The medial parapatellar is more extensile but disrupts VMO insertion, potentially affecting quadriceps function and patellar tracking. **Q: What are the advantages and limitations of the anteromedial arthroscopy portal?** A: **Advantages**: Provides working access to medial compartment; Allows ACL graft passage; Good angle for tibial tunnel drilling; Meniscal suture placement. **Limitations**: Limited visualization compared to lateral portal; Risk to infrapatellar nerve branch; Instrument crowding with multiple portals. Portal placed just medial to patellar tendon, at joint line level, with knee flexed 90°. Transillumination helps avoid vessels. ### Australian Epidemiology **TKA Statistics (AOANJRR 2023):** - Approximately 70,000 TKAs performed annually - Median age: 69 years - Female predominance: 56% - Primary indication: Osteoarthritis (97%) - Most common approach: medial parapatellar (exact numbers not tracked) **Registry Monitoring:** - AOANJRR tracks implant survival, not surgical approach - Overall revision rate: 5.6% at 10 years - Best performing implants identified annually ### Australian Practice Patterns **Approach Preferences:** - Medial parapatellar: Most common (estimated greater than 80%) - Subvastus: Used by subset of surgeons - Midvastus: Less common - Lateral: Rare, selected valgus cases **Training:** - FRACS trainees learn medial parapatellar as standard - Subvastus/midvastus exposure varies by training institution - AOA courses include approach variations **Prosthesis Selection:** - Approach does not dictate prosthesis choice - Most surgeons have preferred implant systems - AOANJRR publishes best-performing combinations

Anteromedial Approach to the Knee

Anteromedial Approach to the Knee