Wrist kinematics after radiolunate arthrodesis

Area of Science:

• Orthopedic Surgery
• Biomechanics
• Hand and Wrist Anatomy

Background:

• Carpal kinematics after radiolunate and radioscapholunate arthrodesis demonstrate preserved midcarpal joint function.
• Limited biomechanical data exist on carpal kinematics following radiolunate arthrodesis.

Purpose of the Study:

• To investigate the individual motion of the scaphoid, capitate, and triquetrum after simulated radiolunate arthrodesis.
• To provide biomechanical data on wrist kinematics post-radioulnar fusion.

Main Methods:

• Simulated radiolunate arthrodesis using Kirschner wires in three fresh human cadaver wrists.
• Measured individual scaphoid, triquetrum, and capitate motion relative to the radius using photostereogrammetry and the helical axis concept.
• Assessed motion in both extension/flexion and radial-ulnar deviation before and after arthrodesis.

Main Results:

• Global wrist motion (capitate motion) reduced by 33-50% for extension/flexion and 25-43% for radial-ulnar deviation.
• Scaphoid and triquetrum motion reductions exceeded capitate motion reduction, with the triquetrum losing rotational patterns.
• The scaphoid maintained its physiological role between the distal radius and distal carpal row.

Conclusions:

• The biomechanical findings align with positive clinical outcomes of radiolunate arthrodesis in rheumatoid wrists.
• The data support the use of radiolunate arthrodesis for post-traumatic wrist conditions.