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Elbow position affects distal radioulnar joint kinematics
Eric Fu1, Guoan Li, J Sebastiaan Souer
1Hand and Upper Extremity Service and the Bioengineering Laboratory, Department of Orthopaedics, Massachusetts General Hospital, Boston, MA, USA.
The Journal of Hand Surgery
|July 7, 2009
Summary
Elbow flexion significantly impacts distal radioulnar joint motion, affecting forearm rotation and radius translation. Understanding these forearm supination-pronation changes is crucial for treating ulnar impaction and evaluating distal ulna injuries.
Area of Science:
- Orthopedics
- Biomechanics
- Radiographic Imaging
Background:
- Forearm supination-pronation involves complex distal radioulnar joint (DRUJ) kinematics.
- Previous research suggests DRUJ motion may be influenced by elbow flexion, but in vivo data is limited.
Purpose of the Study:
- To investigate the in vivo effects of elbow flexion on DRUJ kinematics.
- To test the hypotheses that ulnar variance changes with elbow flexion and forearm rotation, and that forearm rotation arc varies with elbow flexion.
Main Methods:
- Computed tomography, dual-orthogonal fluoroscopy, and 3D modeling were used to analyze radioulnar kinematics in 5 healthy subjects.
- Elbow flexion ranged from 0 to 90 degrees during forearm supination-pronation and rotation.
Main Results:
- Proximal radius translation increased with 90 degrees of elbow flexion in midpronation.
- Forearm rotation arc was significantly reduced at 0 degrees compared to 90 degrees of elbow flexion.
- The center of rotation shifted volarly and ulnarly as elbow extension increased.
Conclusions:
- Elbow position significantly influences DRUJ kinematics, primarily via forearm rotation and secondarily by elbow flexion.
- Findings are relevant for understanding ulnar impaction and radius proximal-distal translation.
- Implications exist for treating ulnar impaction, radiographic evaluation, and future biomechanical studies.
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