Presentation Format: Educational poster presentation.
Purpose or Learning Objective: (1) To demonstrate that dynamic magnetic resonance imaging (MRI) assessment of the
wrist can play an important role in the evaluation of carpal instability, in particular
in scapholunate instability, and in extensor carpi ulnaris tendon instability. (2)
To describe the principal findings that need to be evaluated in the dynamic MRI study
of the wrist.
Methods or Background: Carpal instability is a complex condition in which wrist motion and/or loading produces
mechanical dysfunction, giving rise to weakness, pain, and decreased function. , Several
authors recently showed that MRI assessment of the wrist during active motion may
be valuable in the evaluation of (1) patients with clinical suspicion of carpal instability
but with absent or scarcely significant findings on conventional examinations, and
in (2) patients with wrist instability who need an additional examination, in particular
in planning for surgical treatment.
Wrist dynamic evaluation also requires a deep knowledge of the complex anatomy and
biomechanics of the wrist structures.
Results or Findings: Currently, the most used sequences in the dynamic MRI assessment of the wrist, due
to their high temporal resolution, are the balanced steady-state free precession sequence,
radiofrequency-spoiled sequence, and ultrafast gradient-echo sequence.
Dynamic MRI evaluation of the wrist, also related to clinical suspicion, is performed
during active supination/pronation, radial/ulnar deviation, “clenched fist,” and volar
flexion/dorsiflexion maneuvers.
The main findings that can be evaluated from the resulting images are distal radioulnar
joint congruity, extensor carpi ulnaris tendon translation, transverse translation
of the trapezium at the scaphotrapezium joint, capitate-to-triquetrum distance, the
scapholunate interval, and the scapholunate, radiolunate, and capitolunate angles.
These measurements can be related to lunate type, ulnar variance, and wrist kinematic
pattern to obtain an overall assessment of wrist instability.
Conclusion: Dynamic MRI study of the wrist is easy to perform and not time consuming. It can
be included in a investigative MRI protocol in suspected wrist instability. Dynamic
evaluation is very useful because resulting anatomical images enable the measurement
of metrics commonly evaluated for dynamic wrist instability, and it can also show
the presence of findings indicative of instability that cannot be seen on conventional
examination.
