Patella tendon knee reflex

Definition:
Also known as the knee jerk, this reflex is characterised by the contraction of the quadriceps upon stretching of the patella tendon.

Test procedure:
With the patient seated or supine, the examine strikes the patella tendon of the patient’s relaxed leg. If the patient is supine, this reflex is easier to elicit with the patient’s knee in slight flexion.

Test findings (Positive & Negative results)
A positive finding is characterised by the smooth, rapid contraction of the quadriceps muscle group after it’s tendon has been struck followed by a return to the normal resting tone of that muscle group.
When performing this reflex, look out for signs of upper or lower motor neurone lesions.

Considerations:
This neurological examination is performed to assess the integrity of the L2-L3-L4 nerve roots.