Common knee symptoms

When speaking to the doctor or physiotherapist being able to describe the exact symptoms will help with diagnosis.

Page updated July 2023 by Dr Sheila Strover (Clinical Editor)

If there has been an injury, the mechanism of the injury, assessed together with any symptoms, determines which anatomical part is likely involved. It might have been a twisting injury, a direct blow to the side, back or front of the knee, or an 'hyperextension' injury (bent backwards).

Immediate pain, rapid balloon-like swelling and incapacity suggests a disrupted vascular structure within the knee capsule, such as a cruciate ligament, or meniscus, or bone.

Structures outside the capsule (eg collateral ligament) may have less dramatic symptoms when injured.

Pain in the absence of injury
Evaluating stiffness
Feeling uncertain about stability
Funny noises in the knee
Is the joint an odd shape?

Pain in the absence of injury

Pain may occur in the absence of injury, but still be very specific in nature - it can be gnawing in nature, like arthritic pain, or can be sharp and catching, like pain from a plica. The doctor will need to ask details about the exact nature of the pain and what type of movement brings it on.

Pain is often experienced at the front of the knee - so-called 'anterior knee pain' - and this may have several causes which need to be carefully investigated.

Evaluating stiffness

If the knee is inflamed and full of fluid it may feel stiff, but stiffness may also be caused by a true mechanical block to full movement. The physiotherapist's role is to optimise movement in the knee, reducing internal fluid, massaging adhesions and improving muscle strength. If there is a mechanical block to movement, like a bone spur or arthrofibrosis, then it may require surgery to achieve full motion.

If the knee cab be fully bent, but when trying to straighten the joint it suddenly seems to find a mechanical block, then this is called 'locking'.

Feeling uncertain about stability

Wearing away of the joint cartilage or the meniscus may cause a general wobbliness of the knee, but ligament tears are likely to cause instability in a particular direction.

A bit of broken joint cartilage or a loose flap of a torn meniscus can suddenly get caught temporarily between the bones in the knee, causing a sudden painful stumble which is called 'catching'.

Very often it is someone else who notices that your knee thrusts outwards with each step. This is called 'lateral thrust'. This can be due to a lack of the knee meniscus 'spacer' on one side. It is an issue which needs to be taken seriously as it means that the problem is still relatively early, when an intervention like an osteotomy or a meniscus transplant may restore function and prevent further damage.

Funny noises in the knee

A common knee noise is 'crepitus' which sounds like 'rice krispies' and can be felt with a hand on the knee. Other noises may include snapping or clunking.

Is the joint an odd shape?

Bow legs is a more permanent situation where one is unable to bring knees together without spreading the feet. Usually there are arthritic changes in the knee. Knock knees are the opposite.