Dorsal Intercalated Segment Instability
Pronunciation: DOR-sal in-ter-KAL-ay-ted SEG-ment in-sta-BIL-i-tee
Also written as: DISI — Dorsal Intercalated Segment Instability
A specific pattern of carpal instability where the lunate bone tilts backward relative to the radius.
Full Definition
Dorsal Intercalated Segment Instability (DISI) is a form of carpal instability characterized by dorsal tilting of the lunate bone, creating abnormal alignment within the wrist. This condition typically results from injury to the scapholunate ligament, allowing the scaphoid to flex while the lunate extends. The instability pattern is identified on lateral radiographs by specific angular measurements and can lead to progressive arthritis if untreated. Understanding DISI is important for rehabilitation professionals as it influences exercise selection, splinting decisions, and functional activity modifications during wrist rehabilitation.
Usage
Usage note: Always distinguish from VISI (volar intercalated segment instability) which has opposite lunate positioning.
In Context
- "Radiographs confirmed DISI pattern with a scapholunate angle of 75 degrees." — diagnostic imaging report
- "The rehabilitation protocol was modified to avoid positions that exacerbate the DISI deformity." — therapy modification note