import { OnePagerSummary, ExamWarning, InfoCardGrid, InfoCard, MnemonicCard, EvidenceCard, VivaScenarioSection, VivaScenario, ExamCheatSheet, ContentSection, ExamPearl, SafetyAlert, NumberHighlightRow, NumberHighlight, Tabs, Tab, ComparisonTable } from '@/components/mdx' **Oxinium bearing surface**. Location: Femoral condyles and trochlea. Avoid scratching with metal instruments - use plastic impactors. **Popliteal neurovascular bundle**. Location: Posterior knee, 5mm from posterior capsule at 90° flexion. **Common peroneal nerve**. Location: Around fibular neck laterally. At risk with lateral retractors. **Medial collateral ligament**. Location: Medial tibia. Protect during tibial preparation with retractor placement. **Patellar tendon**. Location: Tibial tubercle insertion. Avoid excessive retraction causing avulsion. **Optimal Patient Selection for Oxinium:** 1. **Young, Active Patients (age less than 65 years)** - High lifetime demand on bearing surface - Goal: reduce polyethylene wear and osteolysis - May reduce lifetime revision risk 2. **Metal Sensitivity/Allergy** - Known nickel allergy (CoCr contains ~1% nickel) - Positive metal patch testing - History of metal jewelry reactions - Suspected hypersensitivity reactions to prior implants 3. **Revision for Metal Sensitivity** - Painful TKA with suspected metallosis - Elevated serum metal ions - Soft tissue metal reaction confirmed **Relative Indications:** - Morbidly obese patients (high wear demand) - High activity expectations - Patient preference after informed consent **Oxidized Zirconium Manufacturing:** 1. **Base Alloy Composition:** - Zirconium-2.5% niobium alloy - NICKEL-FREE (vs CoCr contains ~1% nickel) - Processed as standard metal implant 2. **Oxidation Process:** - Heating in air at 500°C for extended period - Creates ceramic oxide surface layer ~5μm thick - Monoclinic zirconium oxide (ZrO2) forms 3. **Hybrid Properties:** | Property | Oxinium | CoCr | Ceramic | |----------|---------|------|---------| | Surface | Ceramic ZrO2 | Metal | Ceramic | | Core | Metal | Metal | Ceramic | | Fracture Risk | None | None | Yes | | Hardness (Vickers) | 1300 | 400 | 2000 | | Wear Rate | Very Low | Low | Very Low | | Cost | Higher | Standard | Highest | **Surface and Wear Characteristics:** 1. **Surface Roughness (Ra):** - Oxinium: **0.01μm** (extremely smooth) - CoCr: 0.05μm - Ratio: Oxinium is **5x smoother** 2. **Wear Reduction:** - **50-90% less PE wear** vs CoCr in simulator studies - Maintains smoothness (scratch-resistant) - CoCr roughens over time → accelerating PE wear 3. **Scratch Resistance:** - Ceramic hardness prevents third-body scratching - CoCr vulnerable to bone cement, metal debris - Oxinium maintains surface properties long-term 4. **Optimal Pairing:** - **Oxinium + HXLPE = Best combination** - Further reduces wear vs conventional PE - Synergistic wear reduction effect **FRCS Key Point:** Oxinium reduces PE wear by TWO mechanisms: 1. Smoother surface - less adhesive/abrasive wear 2. Scratch resistance - maintains low wear long-term **Patient Position:** - Supine on standard operating table - Knee flexed over bolster or leg holder - Thigh tourniquet applied (inflate to 300mmHg or 100mmHg above systolic) **Surgical Approach:** - Standard medial parapatellar arthrotomy - No modification required for Oxinium vs CoCr - Same instruments and technique **Special Instrumentation:** - **Plastic impactors recommended** - avoid metal-on-Oxinium contact - Standard TKA jigs and cutting blocks - Careful handling to protect ceramic surface ### Step 1: EXPOSURE AND SOFT TISSUE RELEASE Standard medial parapatellar approach. Evert patella or sublux laterally. Release deep MCL from tibia if tight. Remove osteophytes for accurate bony landmarks. **Technical Tip:** Oxinium TKA uses IDENTICAL exposure to standard CoCr TKA. No bearing-specific modifications to approach. - Excessive patellar tendon retraction → avulsion - MCL injury from aggressive medial release ### Step 2: DISTAL FEMORAL RESECTION Intramedullary or extramedullary alignment. 5-7° valgus cut angle. Standard resection depth (8-10mm from most prominent condyle). **Technical Tip:** EXAM KEY: Same resection technique as CoCr. Alignment targets identical - mechanical axis within 3° of neutral. - Varus/valgus malalignment - Anterior notching risking fracture ### Step 3: SIZING AND ROTATION Femoral sizing per standard templating. Rotation alignment options: 1. **Transepicondylar axis** (gold standard) 2. Posterior condylar axis + 3° external rotation 3. Whiteside line (AP axis) **Technical Tip:** EXAM KEY: Oxinium sizing identical to CoCr - no adjustment needed. Transepicondylar axis preferred for rotation. - Internal rotation → patellofemoral maltracking - Undersizing → flexion instability ### Step 4: FEMORAL COMPONENT PREPARATION Anterior, posterior, and chamfer cuts. Box cut for PS or stabilized designs. Prepare for trial reduction. **Technical Tip:** EXAM KEY: Oxinium available in standard PS and CR designs - same cuts as corresponding CoCr implants. - Anterior notching → supracondylar fracture - Asymmetric chamfer cuts ### Step 5: TIBIAL RESECTION Extramedullary alignment. 0-3° posterior slope. Minimal resection (8-10mm from high side). Preserve tibial bone stock. **Technical Tip:** EXAM KEY: Standard metal tibial tray - only the femoral component is Oxinium. Same resection technique. - Varus tibial cut → medial overload - Excessive resection → bone loss ### Step 6: TRIAL REDUCTION Insert trial components. Check: - Extension gap stability (symmetric) - Flexion gap stability (symmetric) - Range of motion (0-120° target) - Patellar tracking (no-thumb test) **Technical Tip:** EXAM KEY: Same balance targets as CoCr TKA. Bearing surface does not affect soft tissue balance. - Unbalanced gaps → instability - Tight lateral retinaculum → patellar maltracking ### Step 7: OXINIUM FEMORAL COMPONENT INSERTION **CRITICAL HANDLING PRECAUTIONS:** 1. Use plastic impactors - avoid metal instruments on bearing surface 2. Handle by non-articular surfaces when possible 3. Cement technique: standard third-generation cementing 4. Pressurize cement into cancellous bone 5. Remove excess cement before polymerization **Technical Tip:** EXAM KEY: Careful handling protects ceramic surface. Scratching can occur with aggressive metal instrumentation. Use plastic/polymer impactors. - Metal instrument scratching of bearing surface - Cement interposition → loosening - Malalignment during cementation ### Step 8: TIBIAL COMPONENT AND HXLPE INSERT Standard metal tibial tray (not Oxinium). **HXLPE tibial insert preferred** - optimizes wear characteristics with Oxinium femoral. Lock insert securely. Confirm appropriate thickness. **Technical Tip:** EXAM KEY: Pair Oxinium femoral with **HXLPE insert** for maximum wear reduction. Do NOT use conventional PE - negates Oxinium advantages. - Conventional PE instead of HXLPE - Insert locking mechanism failure - Insert dislocation ### Step 9: PATELLAR RESURFACING DECISION Standard all-polyethylene patellar component if resurfacing. Maintain composite thickness (bone + component = native patella ±2mm). Oxinium trochlea provides smooth articulating surface. **Technical Tip:** EXAM KEY: Same patella resurfacing technique and indications as CoCr. All-poly cemented patella. No-thumb test for tracking. - Patellar fracture from excessive resection - Maltracking requiring lateral release ### Step 10: CLOSURE AND POST-OPERATIVE CARE Standard layered closure. Drain optional. DVT prophylaxis per protocol. Weight-bearing as tolerated. Standard TKA rehabilitation. **Technical Tip:** EXAM KEY: No bearing-specific post-operative restrictions. Standard TKA rehab protocol. Same follow-up as CoCr TKA. - VTE without prophylaxis - Stiffness from inadequate rehabilitation **Registry Data:** - AOANJRR: Oxinium TKA shows **equivalent 10-year survivorship** to CoCr - No significant difference in revision rates - Theoretical wear advantages not yet translated to clinical revision reduction **Simulator Studies:** - 50-90% reduction in volumetric PE wear vs CoCr - Maintained smoothness after simulated scratching - Superior to CoCr after third-body particle exposure **Clinical Studies:** - Metal ion levels: Lower with Oxinium - Patient-reported outcomes: Equivalent to CoCr - Cost-effectiveness: Debated - depends on long-term follow-up **FRCS Key Point:** Registry data shows equivalent outcomes to CoCr - the laboratory wear advantages have NOT yet translated to improved clinical survivorship. May require 15-20 year follow-up in young patients to demonstrate benefit. 1. Good V, et al. Reduced wear with oxidized zirconium femoral heads. J Bone Joint Surg Am. 2003;85-A Suppl 4:105-10. (Original wear studies) 2. Bourne RB, et al. A randomized clinical trial comparing oxidized zirconium to cobalt-chrome in total knee arthroplasty: A 2-year follow-up. J Arthroplasty. 2005;20(4 Suppl 2):25-28. 3. Laskin RS. An oxidized Zr ceramic surfaced femoral component for total knee arthroplasty. Clin Orthop Relat Res. 2003;416:191-196. 4. Innocenti M, et al. Metal allergy in patients undergoing total knee arthroplasty. Musculoskelet Surg. 2014;98(Suppl 1):S17-S22. 5. Kop AM, Swarts E. Corrosion of a hip stem with a modular neck taper junction: A retrieval study of 16 cases. J Arthroplasty. 2009;24(7):1019-1023. 6. Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR). Hip, Knee & Shoulder Arthroplasty Annual Report 2023. 7. Heyse TJ, et al. Oxidized zirconium versus cobalt-chromium in TKA: profilometric roughness analysis. Clin Orthop Relat Res. 2014;472(6):1904-1908. 8. Hallab NJ, et al. Metal sensitivity in patients with orthopaedic implants. J Bone Joint Surg Am. 2001;83(3):428-436. 9. Spitznagel L, et al. Oxidized zirconium versus cobalt-chromium-molybdenum in total knee arthroplasty: 10-year outcomes from the Norwegian Arthroplasty Register. J Arthroplasty. 2021;36(3):1061-1067. 10. Bergschmidt P, et al. Total knee replacement with ceramic femoral components: a national joint registry study. J Arthroplasty. 2015;30(1):61-66.

Oxidized Zirconium TKA

Oxidized Zirconium TKA