import { OnePagerSummary, ExamWarning, InfoCardGrid, InfoCard, MnemonicCard, EvidenceCard, VivaScenarioSection, VivaScenario, ExamCheatSheet, ContentSection, ExamPearl, SafetyAlert, NumberHighlightRow, NumberHighlight, Tabs, Tab, ComparisonTable } from '@/components/mdx' **Common peroneal nerve**. Location: Around fibular neck, 2-3cm from lateral joint line. At HIGH RISK with lateral releases and retraction. Protect with bent-knee positioning and gentle retraction. **Popliteal neurovascular bundle**. Location: Posterior knee, 5mm from posterior capsule at 90° flexion. Protect with careful posterior capsule release and avoid deep retractors. **Lateral collateral ligament**. Location: Lateral femoral epicondyle to fibular head. Release from femur if needed - preserve fibular attachment for some constraint. **Medial collateral ligament**. Location: Medial femoral epicondyle to proximal tibia. PROTECT - attenuated in valgus knees. Avoid medial retraction and aggressive manipulation. **Lateral genicular artery**. Location: Courses around lateral femoral condyle. May be injured with lateral release - have diathermy ready for hemostasis. **Krackow Classification of Valgus Deformity:** | Type | Deformity | Characteristics | Management | |------|-----------|-----------------|------------| | **I** | 10-15° | Correctable with varus stress, minimal lateral contracture | Minimal release, CR may be possible | | **II** | 15-25° | Partially correctable, moderate lateral contracture | Sequential lateral release, PS common | | **III** | greater than 25° | Fixed, severe lateral contracture, MCL attenuated | Extensive release, often CCK required | **Key Pathology in Valgus Knee:** - **Lateral side CONTRACTED**: ITB, LCL, popliteus, posterolateral capsule - **Medial side ATTENUATED**: MCL stretched, may be incompetent - Lateral femoral condyle often hypoplastic - Lateral tibial plateau worn - Patella may be laterally subluxed **FRCS Key Point:** Assess PASSIVE correctability - if deformity corrects to neutral with gentle varus stress, Type I or II. If fixed, Type III. **Indications for TKA in Valgus:** 1. **Primary Osteoarthritis with Valgus** - Lateral compartment OA predominant - Secondary to anatomic valgus 2. **Inflammatory Arthritis** - Rheumatoid arthritis commonly causes valgus - Often bilateral, severe deformity 3. **Post-traumatic Deformity** - Malunion of lateral tibial plateau fracture - Lateral condyle fracture malunion 4. **Previous HTO Overcorrection** - Lateral closing wedge overcorrected to valgus **Contraindications:** - Active infection - Severe extensor mechanism dysfunction - Neuropathic joint (relative) - Severe vascular insufficiency **Medial Parapatellar Approach:** - Familiar to all surgeons - Adequate for Types I and II - May require extensive lateral retraction - Higher risk of medial soft tissue damage in valgus **Lateral Parapatellar Approach:** - Better access to lateral structures - Ideal for Type III valgus - Preserves blood supply to extensor mechanism - No tibial tubercle osteotomy needed - May be unfamiliar to some surgeons **Subvastus Approach:** - Minimizes extensor mechanism disruption - Difficult exposure in severe valgus - Not recommended for significant deformity **FRCS Key Point:** For severe valgus (Type III), consider LATERAL parapatellar approach - allows direct access to tight lateral structures and protects attenuated MCL. **Patient Position:** - Supine on standard operating table - Knee flexed over bolster or leg holder - Thigh tourniquet applied - Ensure full flexion and extension possible intraoperatively **Key Considerations:** - Preoperative standing long-leg alignment views essential - Templating to assess bone loss laterally - Prepare constrained components (CCK, RHK) in room - Warn patient of potential for higher constraint preoperatively **Special Instrumentation:** - Standard TKA instruments - Pie-crusting needle (18G or similar) - Laminar spreaders for gap assessment - Constrained implant options available ### Step 1: EXPOSURE AND DEFORMITY ASSESSMENT Approach (medial or lateral parapatellar based on severity). Sublux or evert patella. Document fixed vs correctable deformity. Assess passive correction with gentle varus stress. Document Krackow Type. **Technical Tip:** EXAM KEY: Assess deformity BEFORE bone cuts. If passively correctable to neutral = Type I/II. If fixed = Type III. This determines release strategy. - Excessive medial retraction damaging attenuated MCL - Forced correction causing MCL rupture ### Step 2: INITIAL BONE CUTS - TIBIAL RESECTION Perform tibial cut FIRST in valgus knees. Use extramedullary guide. Cut perpendicular to mechanical axis (0° varus/valgus). Avoid excessive resection - preserve bone stock. Reference off lateral (higher) plateau. **Technical Tip:** EXAM KEY: In valgus, tibial cut FIRST allows better assessment of deformity. Cut perpendicular to mechanical axis. The medial plateau is LOWER - do not under-resect medially. - Varus tibial cut creating medial overload - Excessive medial resection ### Step 3: DISTAL FEMORAL RESECTION Intramedullary guide with appropriate valgus correction angle. In valgus knee, may need LESS valgus (3-5° instead of 5-7°) as anatomic valgus already present. Remove distal femoral bone. Check extension gap with laminar spreader. **Technical Tip:** EXAM KEY: Valgus knees often have LESS anatomic valgus correction needed. If setting at standard 5-7°, may under-resect lateral and over-resect medial. Consider reducing valgus cut angle. - Over-resection of medial femoral condyle - Under-correction due to standard valgus angle ### Step 4: EXTENSION GAP ASSESSMENT With trials in place, assess extension gap balance. In valgus knee, expect LATERAL tightness. Document asymmetry (medial vs lateral gap difference). Plan lateral release based on gap asymmetry. **Technical Tip:** EXAM KEY: Document gap asymmetry in mm. Rule of thumb: each 1mm of lateral release adds ~1° of correction. Plan releases systematically. - Underestimating lateral contracture - Proceeding without documenting gap asymmetry ### Step 5: LATERAL RELEASE SEQUENCE - PHASE 1 **ITB Pie-Crusting:** - Make multiple percutaneous stab incisions through ITB at joint line level - Use 18G needle or #11 blade - Space stabs 5mm apart - Releases 2-3mm per puncture - Safe distance from CPN (remains proximal to fibular head) **Technical Tip:** EXAM KEY: Pie-crusting = SAFE, CONTROLLED lengthening of ITB. Multiple small releases add up. Each puncture releases ~2-3mm. Recheck balance after each set. - CPN injury if stabs too distal/posterior - Over-release causing lateral instability ### Step 6: LATERAL RELEASE SEQUENCE - PHASE 2 **Posterolateral Capsule Release:** - If ITB pie-crusting insufficient - Release posterolateral capsule from lateral tibial plateau - Use electrocautery staying on bone - Releases the arcuate complex **Popliteus Release:** - Release popliteus tendon from FEMORAL origin - Preserves tibial attachment for some constraint - Releases tight lateral flexion gap **Technical Tip:** EXAM KEY: Release from FEMUR first (LCL, popliteus) - preserves their tibial attachments which provide residual lateral constraint. Order: ITB → PLC → Popliteus → LCL. - Popliteal vessel injury with aggressive posterior release - CPN injury with lateral retraction ### Step 7: LATERAL RELEASE SEQUENCE - PHASE 3 **LCL Release (if needed):** - Release LCL from FEMORAL epicondyle - Subperiosteal elevation with cautery - Preserves fibular attachment - Significant release - may create lateral laxity **Lateral Epicondylar Osteotomy (LAST RESORT):** - Osteotomize entire lateral epicondyle with LCL/popliteus attached - Allow to slide distally - May require fixation or accept malunion - Indicates severe deformity - consider CCK **Technical Tip:** EXAM KEY: Lateral epicondylar osteotomy = LAST RESORT. If needed, indicates severe deformity requiring CCK constraint. Release sequence is critical: ITB → PLC → Popliteus → LCL → Osteotomy. - Massive lateral instability requiring CCK/RHK - CPN at risk with epicondylar osteotomy ### Step 8: FEMORAL ROTATION AND SIZING Size femoral component. Set rotation using transepicondylar axis (most reliable in valgus). Posterior condylar axis UNRELIABLE in valgus (hypoplastic lateral condyle). Make anterior, posterior, chamfer cuts. **Technical Tip:** EXAM KEY: In valgus, posterior condylar axis unreliable due to lateral condyle hypoplasia. Use TRANSEPICONDYLAR AXIS for rotation. Avoid internal rotation → patella maltracking. - Internal rotation from using posterior condylar axis - Patella maltracking ### Step 9: GAP BALANCING AND CONSTRAINT SELECTION Check flexion and extension gaps. Goal: symmetric rectangular gaps. If residual lateral laxity greater than 10°, consider CCK. If collateral incompetence bilateral, consider RHK. **Constraint Ladder for Valgus:** 1. **CR (cruciate-retaining)** - Type I, balanced after minimal release 2. **PS (posterior-stabilized)** - Type II, balanced after moderate release 3. **CCK (constrained condylar)** - Type III, residual instability greater than 10° 4. **RHK (rotating hinge)** - Severe bilateral laxity, MCL incompetence **Technical Tip:** EXAM KEY: Accept slight residual valgus (2-3°) rather than overcorrect to varus. Varus overcorrection causes rapid medial wear and poor outcomes. - Under-constraining → postoperative instability - Over-constraining → accelerated wear, loosening ### Step 10: COMPONENT INSERTION AND CLOSURE Cement components with standard technique. Final check of balance, ROM, and patellar tracking. Repair lateral retinaculum if lateral approach used. Layered closure. Consider hinged brace if borderline stability. **Post-operative:** - Weight-bearing as tolerated - Hinged brace for 6 weeks if concern for instability - Standard DVT prophylaxis - Physiotherapy focusing on quadriceps strength **Technical Tip:** EXAM KEY: If any concern about stability, use hinged brace for 6 weeks postoperatively. Document intraoperative stability clearly. - Patella maltracking - check no-thumb test - VTE without prophylaxis **Key Studies:** - **Krackow et al. (1991)**: Original classification of valgus deformity - guides surgical planning - **Whiteside (2002)**: Systematic lateral release sequence - established ITB → PLC → Popliteus → LCL order - **Ranawat et al. (2005)**: Lateral epicondylar osteotomy technique for severe valgus **Registry Data (AOANJRR 2023):** - TKA for valgus OA has similar survivorship to varus OA when properly balanced - Higher revision rate if inappropriate constraint selected - CCK has slightly higher loosening rates than PS - use only when required **FRCS Key Point:** Valgus TKA has equivalent outcomes to varus TKA when properly balanced and appropriate constraint selected. Key is systematic release and protecting the attenuated MCL. 1. Krackow KA, et al. Primary total knee arthroplasty in patients with fixed valgus deformity. Clin Orthop Relat Res. 1991;273:9-18. (Original classification) 2. Whiteside LA. Selective ligament release in total knee arthroplasty of the knee in valgus. Clin Orthop Relat Res. 1999;367:130-140. 3. Ranawat AS, et al. The lateral femoral epicondyle osteotomy technique: a novel approach for correcting severe valgus deformity. Clin Orthop Relat Res. 2005;440:166-171. 4. Elkus M, et al. Total knee arthroplasty for severe valgus deformity. J Bone Joint Surg Am. 2004;86:2671-2676. 5. Mullaji AB, et al. Computer-assisted navigation in total knee arthroplasty for severe valgus deformity. J Arthroplasty. 2007;22:1028-1034. 6. Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR). Hip, Knee & Shoulder Arthroplasty Annual Report 2023. 7. Rossi R, et al. Total knee arthroplasty in the valgus knee: a systematic review. J Arthroplasty. 2014;29:1207-1211. 8. Clarke HD, et al. Valgus deformity in total knee arthroplasty: technique and results. J Knee Surg. 2004;17:94-101. 9. Favorito PJ, et al. Total knee arthroplasty in the valgus knee. J Am Acad Orthop Surg. 2002;10:16-24. 10. Lombardi AV Jr, et al. The knee in the valgus deformity: a historical review with a contemporary solution. J Arthroplasty. 2016;31:S34-S38.

Total Knee Arthroplasty for Valgus Deformity

Total Knee Arthroplasty for Valgus Deformity