Twisting Injury

For Medical Students

What It Tests

A twisting injury is a rotation of the body on a fixed or partly fixed foot. It is the commonest mechanism patients describe.

Asking about it tests whether rotational load was applied, and rotational load is what injures the menisci and the cruciates.

The same described mechanism produces different injuries depending on how much load was on the knee, how flexed it was, and how healthy the tissue was.

How It Is Performed

Ask whether the foot stayed still while the body turned, and in which direction the body went.

Ask how much weight was on the leg: fully loaded, partly, or almost none.

Ask how bent the knee was, because a twist in deep flexion loads different structures from a twist near extension.

Ask what happened immediately afterwards: whether they could continue, how fast it swelled and whether it locked. 4.2.5 covers locking.

Ask whether the knee had twisted before, since a recurrent twisting injury in a young patient raises underlying instability or patellar maltracking.

What a Positive Means

A loaded twist near extension with immediate swelling and inability to continue is an anterior cruciate rupture.

A loaded twist with pain, slower swelling and the ability to continue fits a meniscal tear. 4.9.1 covers the presentation.

A twist in deep flexion, such as rising from a squat, is a classic meniscal mechanism and can tear the posterior attachments. 4.9.9 covers root tears.

A twist on a flexed knee with the kneecap moving is a patellar dislocation. 4.2.22 covers it.

A minor twist producing significant symptoms in an older knee suggests a degenerate structure failing rather than a traumatic tear.

MRCS Level

What a Positive Means

The reasoning expected is from rotation and flexion angle to the structure, which Section 3 supplies. 3.3.14 covers kinematics during cutting.

Internal rotation of the femur on a loaded tibia near extension loads the anterior cruciate and the anterolateral structures.

Rotation with the knee flexed traps the meniscus between the condyle and the plateau, which is how it tears.

Deep flexion with rotation loads the posterior horn and its root attachment preferentially.

Rotation in a knee with a dysplastic trochlea or a lateralised tubercle displaces the patella at much lower loads, which is why a trivial twist can dislocate one patella and not another. 4.15.8 covers trochlear dysplasia.

How Good It Is

The twisting mechanism is the most commonly reported and the least specific, because it covers everything from a cruciate rupture to a sprain.

Its value comes entirely from the follow-up questions about load, flexion and aftermath, and the mechanism alone narrows very little.

Where it performs well is in excluding contact mechanisms and therefore the collaterals, which is a genuine if modest contribution.

In an older patient it performs worse still, because degenerate tissue fails under loads the patient describes as trivial, and the history understates the pathology.

FRCS Level

How Good It Is

At decision level a twisting history matters most for what it predicts about associated injury and about repairability.

A loaded twisting cruciate injury carries a meaningful chance of a repairable peripheral meniscal tear, and the window for repair is defined by the date of the twist. 4.2.9 covers onset.

A twist in deep flexion raises the root, and a root tear behaves differently from a body tear because it releases hoop tension. 4.9.9 covers it.

A recurrent twisting injury in a young patient should prompt assessment for underlying rotational laxity or patellar instability rather than treatment of each episode in isolation. 4.14.3 covers rotational laxity.

Where It Misleads

The commonest error is accepting twisting as a diagnosis-bearing mechanism, when it is the least specific history feature in this group.

The second is in the older knee, where a trivial twist is dismissed and a displaced tear or a root tear is present.

The third is attributing recurrent twisting injuries to clumsiness rather than to the instability that is causing them.

And a twisting injury in a child needs the physis considered, and a twisting injury in a hypermobile patient needs their baseline considered. 4.23.3 covers hypermobility.

Fellowship Level

Where It Misleads

In referred practice the twisting history is most useful for the knee that keeps twisting after treatment.

A reconstructed knee that twists and gives way during rotation suggests the rotational component was never addressed, which is the recurring theme of this chapter. 4.14.5 covers the patterns.

A knee that twists after meniscal resection may be mechanically different rather than unstable, because a deficient meniscus alters rotational constraint as well as load. 4.9.10 covers deficiency.

In a hypermobile patient recurrent twisting may reflect a baseline that was never normal, and the comparison that matters is with their own other knee and their own prior function. 4.23.3 covers the assessment.

In a patient with recurrent patellar dislocation the twisting history is the clue that the problem is the patella and not the tibiofemoral joint, and that mistake is common in referrals. 4.15.4 covers patellar glide.

No figure here supports these claims, under decision 023.