Patellofemoral pain syndrome
What is patellofemoral pain syndrome?
Knee pain is very common in teenagers and young adults, with as
many as 1 in 3 young adults experiencing problems at some time or
other. Often this is caused by the kneecap (patella) moving outside
of its normal groove.
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Symptoms of patellofemoral pain syndrome
The main symptoms are pain and a scratching, grinding or
clicking sensation (known as crepitus). The effect of these
symptoms on everyday life varies from time to time and from person
to person.
The pain is felt in the front of your knee, around and behind
the kneecap. It can sometimes be quite severe and everyday
movements like walking up and down stairs can make it worse. At
other times it may be felt as a dull ache after you have been
sitting for any length of time. The pain often makes it difficult
to kneel or squat. It’s often aggravated by running and therefore
often occurs during or after sport.
Changes in the surface of the cartilage can produce a scratching
or grating sensation from the kneecap, which may be heard, when you
bend or straighten the knee. Many people have the grating sensation
but without any pain.
What causes patellofemoral pain syndrome?
The kneecap (patella) lies in a groove at the front of the lower
end of the thigh bone (femur) and is shaped to move up and down in
the groove when you bend or straighten your knee. If the kneecap
moves out of its groove this can put excessive pressure on the
cartilage lining the side of the groove and a small area on the
back of the kneecap. The pressure can lead to changes in a small
area of cartilage where the kneecap meets the thigh bone, which can
lead to knee pain.
It may be a combination of factors that causes the kneecap to
move outside its groove but most important is the balance of the
quadriceps muscles. Often the muscle on the inside of the knee is
weaker than the muscle at the outside, whic results in the kneecap
moving outwards when the knee is bent.
What is the outlook?
The outlook is very good. In most cases the knee will get better
by itself, without needing any treatment. There is no link between
this kind of knee pain and genaralised arthritis later on in
life.
How is patellofemoral pain syndrome diagnosed?
Your doctor will make a diagnosis based on your symptoms and a
physical examination of your knee.
To check for any changes behind the kneecap that could be
causing the pain and crepitus, your doctor may ask you to tighten
your thigh muscles while s/he holds your kneecap down, as this will
reproduce the pain.
Occasionally increased fluid in the joint can cause swelling so
your doctor will also check for this.
What tests are there?
Blood tests do not help in diagnosing patellofemoral pain
syndrome, and x-rays aren’t usually helpful as cartilage doesn’t
show up on x-rays. Only occasionally, if you have received a blow
to your knee, is imaging likely to be needed.
Patellofemoral pain syndrome treatments
The condition very often gets better on its own without any
treatment, though the symptoms may sometimes persist for several
years. However, painkilling drugs and physiotherapy can help to
reduce the pain.
Drugs
Simple painkillers such as paracetamol can help to reduce
pain.
Exercise and physiotherapy
It’s important to keep the quadriceps (thigh) muscles strong and
balanced to keep the kneecap in the right position.
A physiotherapist will assess your knee and decide why the
kneecap is moving out of alignment and which exercises will best
correct this maltracking. S/he will also ensure that you are doing
the exercises properly and safely.
It will take at least 6 weeks of doing these exercises several
times a day for a total of 30 minutes a day before the muscle
imbalance is corrected. It may take some time after that before the
pain completely settles down.
Your physiotherapist may also use adhesive tape, applied to the
kneecap, to control the tracking of the kneecap and provide pain
relief.
Self-help and daily living
Patellofemoral pain syndrome need not interfere with your
day-to-day life or schooling. You may need to take care
with certain sports for a time if they make the pain worse.
However, exercise is a very important part of your treatment
and complete rest is not recommended.
Exercise
Complete rest will lead to weakness of the thigh muscles, so
it’s important to exercise. Swimming is an excellent form of
exercise for people with knee pain, although doing a lot of
breaststroke can sometimes make the pain worse. Sports like
football, rugby or cross-country running should be avoided if they
make the pain worse, although it should be possible to resume these
once the muscle imbalance is corrected.
Read more general advice and specific
exercises that will help you keep active.
Quadriceps contractions and straight leg raises will be helpful
if carried out regularly, but your physiotherapist may recommend
alternative or additional exercises.
School
There’s no need to stay away from school, though you may have to
make arrangements to make sure you don’t overtax your knee. If the
walk to school, certain sports or climbing stairs make the pain
worse talk to your head teacher about your knee problem.