The knee cap (patella-femoral) joint refers to a specific part of the knee joint. Medically, the knee cap is known as the patella and the thigh bone as the femur.

The patella is connected to the quadriceps tendon at the top of the patella. The quadriceps tendon attaches to the quadriceps muscle which attaches to the pelvis.

The patella tendon goes from the bottom of the knee cap to the top front of the shin bone (tibia). When the quadriceps muscle contracts it shortens and pulls the knee cap which in turn pulls on the front of the shin bone, which causes the knee to straighten. As this happens the knee cap must slide smoothly across the groove at the lower end of the thigh bone.

In order for the normal frictionless tracking to occur there must be balance between all the tissues above, below and particularly either side. If this tracking is unbalanced or off line there will be abnormal shearing stress causing pain, friction or grating sensation.

When the knee cap is slightly off centre in its groove there are various labels that the condition may be given. Overall, all the different diagnostic names have one thing in common - an abnormal centering of the knee cap in its groove. If this is left untreated, then it can lead to many problems later.

Fortunately, most of these syndromes that result in pain around the front of the knee cap can be helped considerably without surgical intervention.