Biomechanical study of isolated radial head dislocation

Area of Science:

• Orthopedic surgery
• Biomechanics
• Anatomy

Background:

• Isolated radial head dislocation is a rare injury with an unclear pathomechanism.
• Treatment for this condition remains controversial.
• Understanding the biomechanical roles of stabilizing structures is crucial.

Purpose of the Study:

• To investigate the biomechanical contributions of the annular ligament, quadrate ligament, and interosseous membrane to proximal radioulnar joint stability.
• To evaluate the effectiveness of annular ligament reconstructions in restoring joint stability.

Main Methods:

• Utilized five fresh frozen cadaveric upper extremities.
• Reproduced radial head dislocation by sequential ligamentous structure sectioning.
• Measured radial head displacement using an electromagnetic tracking device across three forearm rotation positions.

Main Results:

• Annular ligament sectioning significantly increased lateral radial head displacement.
• Quadrate ligament sectioning led to significant posterior and lateral displacement.
• Interosseous membrane sectioning resulted in displacement in all directions and positions.
• Anatomical annular ligament reconstruction provided multidirectional stability, with noted anterior laxity in neutral rotation.

Conclusions:

• Radial head instability direction varies with soft tissue damage and forearm rotation.
• Anterior radial head dislocation may indicate more severe ligamentous injury.
• Anatomical annular ligament reconstruction offers significant proximal radioulnar joint stabilization.