Anterior knee pain or Patellofemoral knee pain one of the most common sources of knee pain.
This is probably the most common knee pain that we see in the clinic and can be a source of pain for a wide range of age groups; from adolescents right up to the oldest of children – those in their 70’s and beyond.
This is probably one of the reasons it has so many names but really comes down to pain behind the patella.
It is often caused by irritation to the cartilage at the back of the patella as well as the surrounding soft tissues.
in this blog we have a quick look at what the function of your patella is and why it may cause you a problem.,
What does the patella do and why do we need one ?
Well it helps reduce the amount of effort we need to straighten the knee by about 33-50%. It does this by increasing the lever arm of the muscle tendon unit (that all went a bit physics didn’t it?).
So it helps us be much more efficient in the movement of our leg and reduces the amount of energy we need to do the things we take for granted such as squatting, going up or down stairs, etc.
Here is how it works to make the knee more efficient.
Anatomy of the Patella
It’s a sesamoid bone which means it is formed and contained within the tendon attaching the quads to the tibia (lower leg bone).
The under surface of the patella is a V shape and has some of the thickest cartilage in the body and this allows smooth movement on the femur which has a U-shaped cartilage covered groove when we bend and straighten the knee.
It also helps the knee tolerate the forces that are put through the joint when we squat to sit, go up and down stairs, walk or run.
This animation below gives you a good idea of the structure and function of the patella.
When your knee is straight there is no contact between the patella and the femur and that is why you can move it from left to right quite easily with your fingers, especially when the thigh muscles are relaxed.
As you bend the knee the patella starts to slide into the femoral groove at about 20 degrees and stays in the groove until 70-80 degrees flexion.
So the maximum contact between the patella and the femur occurs in the 20 – 80 degree range which is exactly the range the knee is in when we go up and down stairs or squatting to a chair.
Patellofemoral or anterior knee pain and how it presents
Pain will occur when there is injury to the cartilage on the patella when we bend the knee.
If we can identify where in the range of movement the pain occurs (where in your bend the pain begins) then we can have a good guess where the problem on the patella is. This then gives us good info in where the best ranges of motion to train the knee are.
Patellofemoral pain can be divided into 4 categories;
Stability type patellofemoral knee pain:
This type of knee pain is most common in younger age groups and has a higher incidence in females.
It is usually caused by weakness of the muscles surrounding the knee and hip that then leads to altered movements when we walk, run, climb or descend stairs and squat.
It may also be associated with movement issues at the foot.
As well as getting the muscles stronger it is important to retrain the movements that cause you the most pain such as squatting or stepping down. It may also be important to look at improving running style or walking technique if these are problem activities.
Compressive type patellofemoral knee pain:
Especially common in age groups over 40 and is more related to the outer edge of the patella being squashed against the cartilage of the long thigh bone , (femur). This is usually associated with tightness of the muscles around the knee as well as some hip related weakness and can respond to hands on physiotherapy.
Post surgery patellofemoral pain :
Not a common problem but if someone has had knee surgery and has not been able to straighten the knee fully this can cause irritation of the knee cap due to sustained compressive forces placed upon it. Similar in its treatment to the compressive type knee pain.
Traumatic patellofemoral pain:
Thankfully we don’t see a lot of this but any direct blow to the knee cap with the knee in a flexed position can create irritation to the cartilage on the back of the knee cap.
What is the best treatment for anterior or patellofemoral pain ?
In our next blog we go in depth about about the different causes of patellofemoral pain and our top tips to get rid of this condition and what treatment may suit you.
.If you have any problems with your knee feel free to book in to see one of our team to get you back on track.