Ultrasound Measurement of Lateral Patellar Displacement: A Cadaveric Validation Study

Area of Science:

• Biomechanics
• Musculoskeletal Imaging
• Orthopedics

Background:

• Patellofemoral pain syndrome (PFPS) is a prevalent musculoskeletal complaint.
• Hip adduction may cause lateral patellar displacement, leading to uneven patellofemoral joint loading and pain.
• Previous ultrasound studies for measuring lateral patellar displacement lack validity data.

Purpose of the Study:

• To validate the use of ultrasound for measuring lateral patellar displacement.
• To compare ultrasound measurements with direct measurements of patellar position.

Main Methods:

• Descriptive laboratory study utilizing nine soft-fixed cadavers.
• B-mode real-time ultrasound and direct measurement were used to assess the distance between the lateral femoral condyle and the lateral patellar edge.
• Measurements were taken in neutral and 20° hip adduction positions.

Main Results:

• Mean differences between ultrasound and direct measurements were 0.27 cm (neutral) and 0.34 cm (20° adduction).
• A high Pearson correlation (0.97) and non-significant p-value (0.83) indicate no significant differences between the two measurement methods.
• Ultrasound measurements demonstrated high reliability and validity compared to direct measurements.

Conclusions:

• Ultrasound is a valid and reliable tool for assessing patellar position relative to the femoral condyle.
• The findings support the confident clinical use of ultrasound to measure lateral patellar displacement.
• This validation enhances the utility of ultrasound in diagnosing and managing conditions like PFPS.