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OrthoVellum

© 2026 OrthoVellum. For educational purposes only.

Not affiliated with the Royal Australasian College of Surgeons.

Back to Operative Surgery
Adult Reconstruction

Total Knee Arthroplasty for Valgus Deformity

Comprehensive surgical technique guide for TKA in valgus knee including Krackow classification, lateral release sequence, soft tissue balancing, and component selection - FRCS exam preparation

Core Procedure
advanced
By OrthoVellum Medical Education Team

Reviewed by OrthoVellum Editorial Team

Orthopaedic clinicians and medical editors • Published by OrthoVellum Medical Education Team

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High Yield Overview

TOTAL KNEE ARTHROPLASTY FOR VALGUS DEFORMITY

Medial or lateral parapatellar approach | Systematic lateral release | Balance before resection

ArthroplastySubspecialty
10Key Steps
5Danger Zones
90-120minDuration

Critical Must-Knows

  • Valgus = LATERAL structures contracted, MEDIAL structures attenuated
  • Krackow classification: Type I (10-15°), Type II (15-25°), Type III (greater than 25°)
  • PROTECT the MCL - it is attenuated and fragile in valgus knees
  • Systematic lateral release: ITB pie-crusting → PLC → popliteus → LCL → lateral epicondylar osteotomy
  • CPN at HIGH RISK with lateral releases - avoid aggressive retraction

Examiner's Pearls

  • "
    Lateral parapatellar approach preferred by some for better access to lateral structures
  • "
    Pie-crusting = multiple percutaneous stab incisions to lengthen ITB at joint line
  • "
    Release from FEMUR first (LCL, popliteus) - preserves lateral tibial attachment for constraint
  • "
    CCK (varus-valgus constrained) if greater than 10° residual instability after balancing
  • "
    Avoid over-correction - slight residual valgus (2-3°) acceptable vs overcorrection to varus
Mnemonic

LATERAL - Valgus Release Sequence

L
Lateral retinaculum and ITB pie-crusting first
A
Arcuate complex (posterolateral capsule) release
T
Tendon of popliteus from femoral origin
E
External (lateral) collateral ligament from femur
R
Reconsider constraint if still unbalanced
A
Avoid CPN injury with all lateral maneuvers
L
Last resort: lateral epicondylar osteotomy
Mnemonic

TYPE - Krackow Classification

T
Type I (10-15°) - Correctable, minimal release needed
Y
Yardstick Type II (15-25°) - Moderate, sequential release
P
Progressive Type III (greater than 25°) - Severe, extensive release ± CCK
E
Evaluate passively - correctability determines type

Critical Danger Structures

Danger 1

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.

Danger 2

Popliteal neurovascular bundle. Location: Posterior knee, 5mm from posterior capsule at 90° flexion. Protect with careful posterior capsule release and avoid deep retractors.

Danger 3

Lateral collateral ligament. Location: Lateral femoral epicondyle to fibular head. Release from femur if needed - preserve fibular attachment for some constraint.

Danger 4

Medial collateral ligament. Location: Medial femoral epicondyle to proximal tibia. PROTECT - attenuated in valgus knees. Avoid medial retraction and aggressive manipulation.

Danger 5

Lateral genicular artery. Location: Courses around lateral femoral condyle. May be injured with lateral release - have diathermy ready for hemostasis.

Classification and Indications

Krackow Classification of Valgus Deformity:

TypeDeformityCharacteristicsManagement
I10-15°Correctable with varus stress, minimal lateral contractureMinimal release, CR may be possible
II15-25°Partially correctable, moderate lateral contractureSequential lateral release, PS common
IIIgreater than 25°Fixed, severe lateral contracture, MCL attenuatedExtensive 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

Exam Pearl

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

Exam Pearl

FRCS Key Point: For severe valgus (Type III), consider LATERAL parapatellar approach - allows direct access to tight lateral structures and protects attenuated MCL.

Positioning and Preparation

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

Operative Technique

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.

Exam Pearl

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.

Dangers at this step

  • 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.

Exam Pearl

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.

Dangers at this step

  • 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.

Exam Pearl

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.

Dangers at this step

  • 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.

Exam Pearl

Technical Tip: EXAM KEY: Document gap asymmetry in mm. Rule of thumb: each 1mm of lateral release adds ~1° of correction. Plan releases systematically.

Dangers at this step

  • 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)

Exam Pearl

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.

Dangers at this step

  • 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

Exam Pearl

Technical Tip: EXAM KEY: Release from FEMUR first (LCL, popliteus) - preserves their tibial attachments which provide residual lateral constraint. Order: ITB → PLC → Popliteus → LCL.

Dangers at this step

  • 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

Exam Pearl

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.

Dangers at this step

  • 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.

Exam Pearl

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.

Dangers at this step

  • 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

Exam Pearl

Technical Tip: EXAM KEY: Accept slight residual valgus (2-3°) rather than overcorrect to varus. Varus overcorrection causes rapid medial wear and poor outcomes.

Dangers at this step

  • 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

Exam Pearl

Technical Tip: EXAM KEY: If any concern about stability, use hinged brace for 6 weeks postoperatively. Document intraoperative stability clearly.

Dangers at this step

  • Patella maltracking - check no-thumb test
  • VTE without prophylaxis

Complications

ComplicationRecognitionPreventionManagement

Evidence and Outcomes

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

Exam Pearl

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.

Exam Viva Scenarios

Practice these scenarios to excel in your viva examination

VIVA SCENARIOStandard

EXAMINER

"You are performing a TKA on a 65-year-old woman with rheumatoid arthritis and a fixed 20° valgus deformity. After bone cuts, the lateral extension gap is 15mm and medial is 22mm. Describe your approach to balancing."

EXCEPTIONAL ANSWER
This is a Krackow Type II valgus deformity with significant lateral contracture (7mm gap asymmetry). My approach would be systematic lateral release. First, I would perform ITB pie-crusting at the joint line level using an 18-gauge needle, making multiple stab incisions 5mm apart. I would reassess the gap after each set of punctures. If insufficient, I would release the posterolateral capsule from the lateral tibial plateau. Next, I would release the popliteus tendon from its femoral origin - this particularly addresses the tight flexion gap. If still unbalanced, I would release the LCL from the lateral femoral epicondyle. Throughout, I would protect the CPN by maintaining knee flexion and avoiding aggressive lateral retraction. My goal is symmetric gaps with neutral alignment. I would accept 2-3° residual valgus rather than risk overcorrection. If greater than 10° residual laxity persists after release, I would use a CCK design.
KEY POINTS TO SCORE
Krackow Type II requires systematic release
ITB pie-crusting first - safe, controlled
Release from femur (LCL, popliteus) - preserves tibial attachment
Reassess after each release - avoid over-release
CCK if greater than 10° residual laxity
COMMON TRAPS
✗Releasing MCL (already attenuated in valgus)
✗Aggressive lateral retraction injuring CPN
✗Over-correcting to varus (causes rapid medial wear)
✗Not having constrained implants available
LIKELY FOLLOW-UPS
"What if the patient develops foot drop on day 1 postoperatively?"
VIVA SCENARIOStandard

EXAMINER

"A patient develops foot drop on post-operative day 1 after TKA for severe valgus deformity. How do you assess and manage this?"

EXCEPTIONAL ANSWER
This is likely common peroneal nerve palsy, a recognized complication of valgus TKA due to the proximity of the CPN to the lateral structures being released. Immediate assessment includes: removing any compressive dressings, flexing the knee to 30-40° to reduce tension on the nerve, and performing a thorough neurological examination documenting motor function (ankle dorsiflexion, toe extension, eversion) and sensory distribution (lateral leg, dorsum of foot). I would differentiate from epidural-related weakness if regional anaesthesia was used. Management depends on findings. If complete palsy, I would arrange urgent MRI to exclude hematoma. If no compressive lesion, observation is appropriate as most peroneal palsies after TKA are neurapraxia and recover over 12-18 months. I would provide an AFO to prevent foot drop contracture and refer to physiotherapy. If no recovery by 12 months, nerve conduction studies and possible exploration/neurolysis would be considered.
KEY POINTS TO SCORE
CPN palsy recognized complication of valgus TKA
Immediate: remove dressings, flex knee to reduce tension
Exclude compressive hematoma with MRI if complete palsy
Most are neurapraxia - observe for 12-18 months
AFO prevents equinus contracture
COMMON TRAPS
✗Missing epidural-related weakness
✗Not excluding compressive hematoma
✗Premature surgical exploration
✗Not providing AFO - leads to contracture
LIKELY FOLLOW-UPS
"What preventive measures should you take to avoid CPN injury in valgus TKA?"
VIVA SCENARIOStandard

EXAMINER

"During TKA for Type III valgus, you perform extensive lateral releases but there remains 15° of lateral laxity in extension. What is your management?"

EXCEPTIONAL ANSWER
With 15° of lateral laxity after extensive release, this represents significant collateral incompetence requiring increased constraint. I would first confirm the release was appropriate and not excessive - checking that releases were done systematically from ITB through to LCL from femur. If the MCL is competent, I would use a CCK (constrained condylar knee) design, which provides varus-valgus constraint through the tall post engaging the intercondylar housing. If there is also MCL incompetence (bilateral collateral laxity), I would consider a rotating hinge knee which provides complete coronal plane constraint. I would counsel the patient preoperatively about the possibility of needing constraint, and I always have constrained options available in theatre for severe valgus cases. Important to document the intraoperative instability and rationale for constraint level selected.
KEY POINTS TO SCORE
Greater than 10° lateral laxity requires CCK
CCK provides varus-valgus constraint via post/housing
Bilateral collateral laxity → consider rotating hinge
Always have constrained options available for severe valgus
Document instability and rationale for constraint
COMMON TRAPS
✗Using PS in the setting of significant collateral laxity
✗Not having CCK/RHK available preoperatively
✗Overcorrecting to varus trying to tension lateral side
✗Not warning patient preoperatively about possible constraint
LIKELY FOLLOW-UPS
"What are the disadvantages of using a CCK compared to PS?"

References

  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.

TKA for Valgus Deformity - Exam Summary

High-Yield Exam Summary

Key Pathology

  • •Valgus = LATERAL contracted, MEDIAL attenuated
  • •Tight: ITB, LCL, popliteus, posterolateral capsule
  • •Stretched: MCL (fragile, protect throughout)
  • •Lateral femoral condyle often hypoplastic

Krackow Classification

  • •Type I: 10-15°, correctable, minimal release
  • •Type II: 15-25°, partially correctable, sequential release
  • •Type III: greater than 25°, fixed, extensive release ± CCK

Lateral Release Sequence

  • •1. ITB pie-crusting at joint line (safest, controlled)
  • •2. Posterolateral capsule (arcuate complex)
  • •3. Popliteus from femoral origin
  • •4. LCL from lateral femoral epicondyle
  • •5. LAST: Lateral epicondylar osteotomy (rare)

Constraint Selection

  • •CR: Type I, balanced after minimal release
  • •PS: Type II, balanced after moderate release
  • •CCK: Type III, greater than 10° residual laxity
  • •RHK: Bilateral collateral incompetence

Critical Exam Points

  • •Protect CPN - knee flexion, gentle retraction
  • •Protect MCL - attenuated, do NOT release
  • •Accept 2-3° residual valgus (better than varus overcorrection)
  • •Transepicondylar axis for rotation (posterior condylar unreliable)

Key Complications

  • •CPN palsy - most recover (neurapraxia), AFO needed
  • •Residual instability - consider CCK revision
  • •Overcorrection to varus - causes rapid medial wear
  • •Patella maltracking - from internal rotation

LATERAL Mnemonic

  • •L - Lateral retinaculum and ITB pie-crusting
  • •A - Arcuate complex (PLC) release
  • •T - Tendon of popliteus from femur
  • •E - External (lateral) collateral from femur
  • •R - Reconsider constraint if still unbalanced
  • •A - Avoid CPN injury
  • •L - Last resort: epicondylar osteotomy
Quick Stats
Complexityadvanced
Reading Time50 min
Updated2025-12-26
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