Wrist instability can be due to various causes and depending upon its behavior, wrist instability can be of many types.
A wrist is considered stable when the modifications brought about by the various forces acting on it are restored when the said forces stop to act.
In contrast, the alteration of one or more of the structures responsible for stability lead to preclusion of the restoration of the order and leads to misalignment and decrease in performance of the organ.
This happens when takes wrist is damaged by trauma, chronic inflammation or anatomical alterations like ulnar variance and and neoplasms.
Carpal instability often depends on capsular integrity and on the interosseous ligaments. It can be
- Dynamic instability – This occurs in incomplete injury. The wrist maintains normal alignment at rest but will collapse under applied load
- Static Instability – This occur in complete injury to the structure involved. This kind would show abnormal intercarpal alignment on static radiographs
Further, carpal instability is said to be of following types. Each link would take you to the details of the particular instability
The carpus moves ulnar wards. It occurs mostly in rheumatoid arthritis and Madelungs’s deformity
Non dissociative carpal instability [CIND]
Instability occurs between the rows of the carpus
- Capitolunate instability
- Mid-carpal instability
Dissociative instability [CID]
Instability occurs between the individual bones of the row.
- Scapholunate instability
- Lunotriquetral dissociation
As a matter of example all untreated dislocations and displaced fractures are examples of carpal instability. Not all instabilities are painful to begin with.
Complex Carpal Instability[CIC]
CID and CIND coexist as in lunate dislocation
Adaptive Carpal Instability [CIA]
The instability do not reside in the carpus but is due to sequelae of radial fractures with dorsal displacement in the epiphyseal region.
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