The patient lies comfortably. With the knee out-stretched and relaxed the ankles are raised; in this position locking can be detected.

Generalised ligament laxity, seen by eliciting recurvatum, should be checked against the range of movement at the elbow, the metacarpophalangeal joint of the fingers and the wrist looking for hyperextension.

Unilateral recurvatum arouses suspicion of a cruciate ligament tear and posterolateral capsular injury.

Posterolateral rotatory instability is checked; this is a subtle test used where there is abnormal external rotation of the tibia with the knee ‘sitting’ slightly varus and rotated externally while in hyperextension. This is due to a tear in the arcuate complex and lateral collateral ligament, called ‘external rotational recurvatum’.