Abstract
Introduction
Isolated midcarpal motion during radioulnar deviation could be approximated to be a rotation in a plane of a radiodorsal/ulnopalmar rotation of the wrist, which may coincide with a motion plane of one of the most essential human wrist motions, known as the dart-throwing motion. This has been studied before in normal volunteers using Magnetic Resonance Imaging to study in vivo kinematics of the midcarpal joint in the wrists of normal volunteers. We present the early results of use of biaxial flexible electrogoniometer to study the range of motion in patients with four-corner fusion.
Methods
Ten patients with four-corner fusion for SLAC/SNAC wrist were assessed to study flexion-extension, radial-ulnar deviation, and circumduction motions using flexible electrogoniometers. Opposite unaffected wrist was studied to provide normal data. Angle-angle curves (Lissajous's figures) were generated to study the area under the curve and comparison with the normal wrists and also to study the deviation from the neutral axis. Five normal volunteers were also studied to calculate the area under the curve and the axis of deviation during circumduction of the wrist.
Results
The coupling action of mid-carpal motion was revealed as obliquity of the axis of motion with extension combined with radial deviation in normal wrists. This was lost in patients with four-corner fusion as revealed with decrease of obliquity in Lissajous's figures from 19 degrees to 5 degrees. There was 80% reduction in the area in the curve of the figures in comparison to normal wrists (4000 to 960 degree-degrees).
Discussion
Electrogoniometer and Lissajous's figures provide a useful method of assessment of range of motion in patients with four-corner fusion. They could be used in future for comparison with patients undergoing limited wrist fusion to study the disability experienced and for counselling regarding the postoperative limitation in activities of daily living experienced by these patients.
