Understanding positive flexion tests

A flexion test involves compression of joints and soft tissues through forced bending of the limbs

Flexion tests of both the fore- and hindlimbs are common diagnostic tools, particularly used for the purposes of pre-purchase examination. Many of us have heard the words ‘failed flexion test’ or ‘positive flexion test’ when looking into buying or selling a horse, but what do these terms really mean? What is the significance of these results and how seriously should we be taking them?

What is a flexion test?

Simply put, a flexion test involves various joints and soft tissue structures of the lower limbs of the horse being stretched and/or compressed for a brief period of time by forcibly bending the limb. After the test the horse is immediately trotted off and observed for any signs of lameness.

Flexion tests are not unlike what you may experience if someone asked you to crouch for a minute or so and then run off immediately. You would usually be able to run off with no problem, but sometimes you may experience some soreness or pain or stiffness in a joint or tissue when you first try to run; you might even limp slightly, at least for the first few steps. If you had a known injury, for example a knee problem, you would do very badly on a flexion test. Therefore, as in humans, an abnormal response to a flexion test could be highlighting a serious problem (like a knee injury), but could also occur even in a normal limb either because the test was performed differently or overzealously, or simply because the horse was stiff or hadn’t warmed up properly.

What can a flexion test do?

Flexion tests are marked on a positive score of one to five

Flexion tests are screening tests. They aim to identify any lameness that is not necessarily visible in the usual gaits. Flexion tests can therefore screen for subclinical problems that are not necessarily an issue currently, but may become an issue at some later stage in the horse’s life.

Flexion tests can therefore identify which limb or limbs have issues. The tests cannot specifically locate the issue, but they can reveal the need for further investigations of the limbs and joints. Nerve blocks, ultrasounds and x-rays are all worth considering after a positive flexion test.

Text: Dr Lizzie Harrison

The full article appears in the April issue of HQ (121) > Shop now