Contraction of the Deep Hip Muscles Contributes to Hip Capsulo-Ligamentous Complex Tension In Vivo

Area of Science:

• Biomechanics
• Musculoskeletal anatomy
• Sports medicine

Background:

• Anterior hip muscles like the iliocapsularis, rectus femoris, and gluteus minimus attach to the hip capsulo-ligamentous complex.
• These muscles may enhance anterior hip stability by increasing capsulo-ligamentous complex tension via contraction.
• In vivo evidence verifying this tension increase has been lacking.

Purpose of the Study:

• To determine if deep hip muscle contractions elevate hip capsulo-ligamentous complex tension.
• To identify which specific muscles exert the most influence on capsulo-ligamentous complex tension changes.

Main Methods:

• Twenty-eight healthy young adults participated.
• Shear wave elastography measured shear elastic moduli (G) of the capsulo-ligamentous complex and specific muscles (iliocapsularis, rectus femoris, gluteus minimus).
• Measurements were taken during isometric hip flexion, abduction, adduction, knee extension, and rest.

Main Results:

• Hip capsulo-ligamentous complex tension (G) was significantly higher during hip abduction compared to rest (p=0.008).
• Multiple regression analysis indicated that changes in the iliocapsularis' G were the sole significant predictor of capsulo-ligamentous complex tension changes (R²=0.412, p=0.009).
• This suggests a tension transfer mechanism between muscles and the capsulo-ligamentous complex.

Conclusions:

• Isometric hip abduction increases hip capsulo-ligamentous complex tension, supporting the concept of muscle-ligament tension transfer.
• The iliocapsularis muscle plays a crucial role in transmitting tension to the hip capsulo-ligamentous complex.
• Findings have implications for understanding hip stability and injury mechanisms.