o Acute (e.g. duration less than 6 weeks).
o Sub-acute (e.g. duration 6–12 weeks).
o Chronic (e.g. duration more than 12 weeks).
* Although this classification is necessary for
scientific studies, it may not be useful in clinical practice
o The limits for the groups have not been
standardized. For example:
+ Sub acute is sometimes combined with the acute
category (i.e. acute is sometimes classed as a duration of less than 12 weeks).
+ Sub acute is sometimes combined with the
chronic category (i.e. chronic is sometimes classed as a duration of more than
6 weeks).
o Classification as acute or chronic is a
substantial simplification of reality, and can be misleading because:
+ Low back pain treatments tend to follow a course that fluctuates over days, weeks, and months.
It is thus not always possible to distinguish between a new acute event and an
exacerbation of a chronic process.
