Mechanical strains passing through the acetabular labrum modify its shape during hip motion: an anatomical study

Area of Science:

• Orthopedic biomechanics
• Hip joint anatomy
• Surgical implications

Background:

• The mechanical function of the hip labrum during hip motion is not well understood.
• The acetabular labrum's role in hip joint stability and function requires further investigation.

Purpose of the Study:

• To investigate the morphological variations of the acetabular labrum during hip adduction to abduction movement.
• To analyze femoro-labral strains in response to these movements.
• To test the hypothesis that labral deformation is linked to strain variations.

Main Methods:

• An ex vivo anatomical study using ten fresh-frozen human cadaver hemi-pelvises.
• Sagittal splitting of hemi-pelvises and rigid mounting on a test platform.
• Application of a 700 N load and unidirectional adduction/abduction movement of the acetabulum over a fixed femur.
• Strain analysis using captors on the acetabular edge.

Main Results:

• Labral length decreased, edge angle increased, and sectional area decreased significantly from 20° to 40° of abduction (p=0.001).
• Femoro-labral strains peaked at 40° abduction and were minimal at 30° adduction (p=0.001).
• Morphological changes correlated with strain variations.

Conclusions:

• The hip labrum undergoes significant morphological changes during hip motion, reflecting strain transfer to the femoral head.
• The acetabular labrum has a direct mechanical role in hip joint function.
• Surgical resection of the hip labrum may negatively impact hip biomechanics by altering strain distribution.