Pivot shift test

What the test feels like

You lie on your back while the surgeon lifts your leg by the foot, turns the shin slightly inwards and pushes gently on the outside of the knee. The knee is then bent slowly from straight.

If the ACL is torn, the shin slips slightly out of position near straight and then clunks back in at around 20 to 40 degrees of bend. Many patients recognise it at once: it is the same feeling as the knee giving way when turning in football or padel. Because of that, people often tense up, and the test may only be fully reliable under anaesthesia.

What it tells the surgeon

The Lachman test shows how far the shin moves forward; the pivot shift shows how unstable the knee is when it twists, which is closer to what happens in sport. It is graded from a subtle glide to a gross clunk.

A high-grade pivot shift may point to extra damage, such as injury to the outer meniscus or the anterolateral structures, and can influence whether the surgeon adds a lateral procedure to an ACL reconstruction.

When it is done

In clinic it is often done gently or skipped in a painful knee. It is routinely checked under anaesthesia at the start of ACL surgery and again at the end to confirm stability has been restored.