What does a laterally tilted patella (kneecap) that cannot be manually corrected to a neutral position indicate, and what is the test result, negative, neutral, or positive?

Laterally Tilted Patella That Cannot Be Manually Corrected: Test Interpretation

A laterally tilted patella that cannot be manually corrected to a neutral position indicates a positive test result for patellofemoral instability, suggesting structural abnormalities in the medial stabilizing structures of the knee.

Clinical Significance

A laterally tilted patella that resists manual correction indicates:

• Structural abnormalities in the medial patellofemoral ligament (MPFL), which is the primary restraint to lateral patellar displacement
• Possible chronic lateral patellar subluxation or maltracking
• Potential patellofemoral instability requiring further evaluation

Anatomical Basis

When examining patellar position and mobility:

• Normal patella should be centrally positioned in the trochlear groove
• Ability to manually correct patellar tilt indicates functional instability
• Inability to correct tilt suggests structural changes including:
  • Tight lateral retinaculum
  • Deficient medial stabilizing structures (particularly MPFL)
  • Abnormal bony architecture of the patellofemoral joint

Diagnostic Implications

The finding of a fixed laterally tilted patella correlates with:

• Patellofemoral instability with an incidence of 1% to 12% after total knee arthroplasty, often due to internal malrotation of femoral and/or tibial components 1
• Imbalance in the extensor mechanism characterized by excessive tightness of the lateral retinaculum 1
• Component malrotation or valgus alignment of the extensor retinaculum 1

Radiographic Assessment

For further evaluation:

• Axial radiographs are recommended to demonstrate the degree of patellar tilt or subluxation 1
• Weight-bearing axial radiographs provide better assessment of patellofemoral kinematics 1
• CT is most commonly used for determining axial rotation of the femoral component when component malrotation is suspected 1

Clinical Correlation

Research has shown that:

• Patients with patellofemoral pain demonstrate significantly more lateral patellar translation (5.05 ± 3.73 mm) compared to healthy subjects (-4.93 ± 3.93 mm) at 90° of knee flexion 2
• At 90° of knee flexion, patients with patellofemoral pain show lateral spin of the patella (-10.13° ± 2.24°) while healthy subjects show medial spin (4.71° ± 1.17°) 2

Common Pitfalls in Assessment

• Visual assessment alone is inadequate for accurate diagnosis, with surgeons correctly identifying patellar maltracking in only approximately two-thirds of cases 3
• Surgeon experience does not correlate with ability to accurately identify the presence or grade of patellar maltracking 3
• Traditional lateral displacement tests may be less sensitive than distal lateral displacement tests for detecting MPFL disruption 4

Management Considerations

For patients with confirmed patellofemoral instability:

• Initial management typically includes physical therapy focusing on quadriceps strengthening
• Progressive rehabilitation protocol with immediate functional treatment rather than immobilization 5
• Consider orthopedic referral if pain persists despite 3-6 months of conservative treatment 5
• Surgical intervention may be necessary for recurrent instability or significant functional limitations

In summary, a laterally tilted patella that cannot be manually corrected represents a positive test for patellofemoral instability, warranting further evaluation with appropriate imaging and potential specialist referral depending on clinical context and impact on function.