What are the key considerations and management strategies for patients undergoing valgus knee Total Knee Replacement (TKR) surgery?

Valgus Knee TKR Surgery: Key Technical Considerations

For valgus knee deformities in TKR, success depends on meticulous lateral soft-tissue release using a pie-crusting technique, appropriate surgical approach selection based on deformity severity, and choosing implant constraint based on the extent of medial collateral ligament insufficiency after balancing. 1, 2

Preoperative Assessment and Planning

Deformity Classification

• Grade I (5-10° valgus): Mild deformity with minimal soft tissue contracture 1
• Grade II (10-20° valgus): Moderate deformity with lateral structure tightening 1, 3
• Grade III (>20° valgus): Severe deformity with significant bone remodeling and soft tissue contracture 1, 3

Anatomical Variations to Identify

• Bone deformities: Lateral cartilage erosion, lateral condylar hypoplasia, metaphyseal femur and tibial plateau remodeling 1
• Soft tissue contractures: Lateral collateral ligament, posterolateral capsule, popliteus tendon, hamstring tendons, lateral head of gastrocnemius, and iliotibial band 1, 4
• Medial collateral ligament status: Assess for elongation or insufficiency, which determines implant constraint needs 2

Imaging Requirements

• Full-length hip-to-ankle weight-bearing radiographs for precise alignment assessment 5
• Standard anteroposterior, lateral, and axial views 5

Surgical Approach Selection

Standard Approach (Grade I-II Deformities)

• Anteromedial parapatellar approach for most valgus knees with deformity <20° 1
• Allows adequate exposure while maintaining standard surgical technique 1

Severe Deformity Approach (Grade II-III)

• Lateral parapatellar approach combined with tibial tubercle osteotomy for severe valgus (15-35°) 3
• This combination facilitates anatomical axis restoration and allows patellar realignment by displacing the osteotomized tubercle 3
• Achieved mean IKS score improvement from 44 to 91 points at 11.5-year follow-up 3
• Critical pitfall: Careful fixation of the tuberosity is mandatory to prevent proximal migration 3

Soft Tissue Release Technique

Lateral Release Sequence

• Perform preliminary lateral soft-tissue release before bone preparation 2
• Use pie-crusting technique for controlled, gradual release of tight lateral structures 2
• Release structures in sequence: iliotibial band, lateral capsule, popliteus tendon, lateral collateral ligament, lateral head of gastrocnemius 1, 4

Balancing Goals

• Achieve stable, balanced flexion and extension gaps 2
• Restore neutral mechanical axis (target: 3-7° valgus anatomical axis) 3
• Ensure mediolateral and anteroposterior stability 2

Implant Selection Strategy

Cruciate-Retaining Implants

• Use in 92% of valgus knees when adequate medial collateral ligament function is preserved after lateral release 2
• Strong evidence supports no difference between posterior-stabilized and posterior cruciate-retaining designs 6

Constrained Implants

• Reserve for severe deformities with medial collateral ligament insufficiency after soft tissue balancing 2
• Sacrifice posterior cruciate ligament when using constrained implants 2
• Required in approximately 8% of valgus TKR cases 2

Component Fixation

• Strong evidence supports using either cemented or noncemented tibial component fixation with similar outcomes 6
• Strong evidence supports either all-polyethylene or modular tibial components 6

Technical Considerations

Patellar Management

• Strong evidence shows no difference in pain or function with or without patellar resurfacing 6, 5
• However, moderate evidence supports patellar resurfacing may decrease cumulative revision surgeries after 5 years 6, 5
• In severe valgus with lateral approach, tibial tubercle osteotomy allows patellar realignment 3

Technology Use

• Do not use intraoperative navigation or robotic systems - strong evidence shows no difference in outcomes or complications 6, 7
• Do not use patient-specific instrumentation - provides no benefit over conventional instrumentation 7

Postoperative Management

Early Mobilization

• Start rehabilitation on the day of TKA to reduce hospital length of stay 5
• Strong evidence supports supervised exercise program during first 2 months improves physical function 5
• Do not use continuous passive motion - strong evidence shows no improvement in outcomes 5

Thromboprophylaxis

• Start pharmacologic prophylaxis at least 12 hours after surgery completion 6
• Continue for minimum 10-14 days, with extended prophylaxis up to 35 days for high-risk patients 8

Critical Pitfalls to Avoid

Peroneal Nerve Injury

• Monitor peroneal nerve function during correction of severe valgus deformity 4
• Excessive correction or rapid deformity correction increases nerve injury risk 4

Residual Deformity

• Only 2 of 24 knees (8%) had residual valgus >7° when using lateral approach with tibial tubercle osteotomy 3
• Inadequate lateral release is the primary cause of residual deformity 2

Instability

• Excessive lateral release without appropriate implant constraint leads to mediolateral instability 2
• Choose minimal constraint with maximum stability based on final soft tissue balance 2

Tibial Tubercle Complications

• When performing tibial tubercle osteotomy, ensure rigid fixation to prevent proximal migration 3
• Monitor for non-union, though this is rare with proper technique 3

Expected Outcomes

• Mean HSS knee score improvement from 48 to 91 at 10-year follow-up 2
• Mean tibiofemoral alignment correction from 20° valgus to 5° valgus 2
• Mean range of motion improvement from 65° to 110° 2
• All knees clinically stable in mediolateral and anteroposterior planes at long-term follow-up 2
• Infection rate approximately 3% and periprosthetic fracture rate approximately 6% at long-term follow-up 2