- Discussion: (see: dynamic instability);
- capitolunate joint has high potential for instability, since it is mainly stabilized only by the radiocapitate ligament (and captiotriquetral ligament, to a lesser degree); (see wrist ligaments);
- may result from malreduced radial styloid frx, or any condition which shortens or reduces tension in the ligament;
- often results from severe dorsiflexion injury;
- patients may note wrist clicking and pain while lifting heavy objects;
- grasping in supination may provoke symptoms;
- diff dx:
- prior to making this diagnosis, need to r/o:
- Kienbock's, scapholunate diastatsis, capitate frx, lunotriquetral diastasis;
- no VISI or DISI deformity should be present;
- Radiographs:
- lateral view of wrist;
- dorsal capitate displacement apprehension test;
- w/ patient's hand kept in a neutral position (w/ regard to flexion and extension as well as supination and pronation), the surgeon places his thumb under the capitate and attempts to force it dorsally;
- flouroscopy will confirm any dynamic instability;
- also consider taking a contralateral radiograph of the normal wrist
Chronic capitolunate instability
Central Carpal Instability - Capitate Lunate Instability Pattern. Diagnosis by Dynamic Displacement. Lousi DS, et al. Orthopedics. 1984;7(11):1693-1696.