A profile of reference data for shear modulus for lower limb muscles in typically developing children

Area of Science:

• Biomechanics
• Musculoskeletal Ultrasound
• Pediatric Physiology

Background:

• Shear wave elastography (SWE) measures muscle stiffness via shear modulus.
• Standardized methods and normative data are crucial for pediatric SWE applications.
• This study addresses the need for reference data in typically developing children.

Purpose of the Study:

• To determine the behavior of lower limb muscle shear modulus in children.
• To establish reference data and clinical assessment recommendations for pediatric SWE.
• To investigate the influence of muscle length, age, sex, and BMI on muscle shear modulus.

Main Methods:

• Forty-one typically developing children underwent SWE of four lower limb muscles (rectus femoris, biceps femoris, gastrocnemius lateralis, tibialis anterior).
• Assessments were performed at both short and long muscle lengths.
• Data were analyzed for correlations with age, sex, BMI, and Net-Longitudinal Tension Angle.

Main Results:

• Shear modulus was significantly higher at longer muscle lengths for all tested muscles (P < 0.001).
• Tibialis anterior shear modulus correlated positively with age (r = 0.39-0.42, P = 0.01).
• Shear modulus tended to increase with Net-Longitudinal Tension Angle and was higher in children than adults for some muscles.

Conclusions:

• Lower limb muscle shear modulus in children increases with muscle length and Net-Longitudinal Tension Angle.
• Reference data and standardized protocols are recommended for consistent pediatric SWE assessments.
• While age shows some correlation, further research is needed to fully understand age-related changes and other factors.