Acute and chronic are terms used by chartered physiotherapists in describing injuries and in this weeks blog we look to explain the terms and the differences between the two distinct types of injuries.  Although the terms are often used by lay people and patients in describing their injuries, there can be some confusion as patients, in my experience, tend to use the words to describe the severity or extent of their pain, whereas physiotherapists tend to use the terms to describe the duration or nature of the presenting injury.

Acute Injuries

Most physiotherapists categorise “acute injuries” as those having occurred in the past two weeks.  There is a defined history of when the injury started and the patient can identify this readily.  Examples of acute injuries include ankle sprains, twisted knees, or lower back strain following heavy lifting activities.  Acute, doesn’t in a physiotherapists mind describe anything in relation to the severity of pain experienced, rather that it has happened recently and there was an identifiable starting point of the injury.  Acute injuries are readily treatable and usually settle within known timeframes associated with soft tissue healing.  In general sports injuries fall into the category of acute injuries.

Acute soft tissue injuries that fail to settle quickly and drag on to between two-six weeks are sometimes categorised as sub-acute in nature.  Such injuries are at risk of becoming more chronic or long term if not treated appropriately.

Chronic Injuries

Most physiotherapists regard “chronic injuries” as those injuries having occurred greater than six weeks ago.  Many chronic injuries which present at physiotherapy clinics have lasted a great deal longer than that.  Patients often describe injuries, for example low back pain, as lasting years.  Once again chronic doesn’t refer to the severity of the pain, rather the duration or length of time that the patient has been suffering with the condition.  Common examples of chronic musculoskeletal conditions include; persistent lower back or neck pain, tendinitis, repetitive strain disorders or plantar fasciitis.  It’s often difficult for patients presenting with chronic conditions to identify a defined starting point for their symptoms.  Symptoms tend to develop over a period of time.  When asked when it started, patients tend to be vague answering for example “well before the summer” or “last year some time”.  Chronic injuries are readily treatable but the timeframe for full healing to occur is a little less clear cut than for that of acute injuries.

Chronic conditions can sometimes be exacerbated from time to time due to activity or injury.  Lower back pain is a common example of this.  Many patients present to clinic complaining that they’ve had a bad back for years but it got worse last week after shovelling snow or doing three loads of washing.  This pattern of injury is sometimes described as “acute-on-chronic” back pain.  That is an acute flare-up of a pre-existing chronic back problem.

In general injuries may be categorised as follows:




Identifiable starting point

Started less than two weeks ago


Identifiable starting point

Started greater than two weeks but less than six weeks ago

Chronic :

Difficult to identify starting point of injury

Present for greater than six weeks


Long term history of injury (Greater than six weeks)

Sudden flare up in past 2 weeks