Advanced
Technical
IVT
screw toggle
Loosening of a screw within bone, indicating loss of fixation integrity.
Full Definition
Screw toggle refers to the mechanical loosening of a screw within its bone tunnel, resulting in loss of stable fixation. This complication typically occurs due to bone resorption around the screw threads, inadequate initial purchase, or repetitive loading that exceeds the bone-screw interface strength. Screw toggle can lead to construct failure, loss of reduction, and nonunion. Radiographically, it may be evident as widening of the screw tract or change in screw position.
Usage
Usage note: Specific to loss of screw stability; distinguish from complete hardware failure or breakage.
In Context
- "Progressive screw toggle was noted on serial radiographs, necessitating revision surgery." — Complication assessment
- "Osteoporotic bone increases the risk of screw toggle in elderly patients." — Surgical planning note
Also known as
screw loosening
screw backout
Contrasted with
screw purchase
stable fixation
Don't confuse with
screw breakage
strip-out
screw migration