Causes of Anterior Knee Pain
Patello-Femoral Pain Syndrome
PFPS is caused by a range of problems, all of which lead to abnormal wear/loading on the back of the patella (knee cap). These include the following disorders.
When the knee bends, the patella tracks through the groove in the front of the femur (thigh bone). Depending on a variety of factors, this tracking can go to one side, usually the outside, causing uneven wear and irritation of the joint surfaces.
In CMP there is a softening and then cracking/fissuring of the articular cartilage on the back of the patella. This occurs when there is a long standing irritation of the knee joint. It can be from a problem with the patella, but can also result from other knee injuries.
Patella Alta describes the condition where the knee cap is both smaller and higher than usual. This results in increased stress as the load through the knee is passing through a smaller area.
Osgood Schlatter Disease
Osgood Schlatter Disease is an inflammation of the growth plate at the insertion of the patellar tendon onto the front of the shin bone. OS is only found in adolescents. It is common in children who play a lot of sport, but not always. It occurs in girls between the ages of 8 and 12, and in boys between the ages of 12 and 15. After these ages the growth plate is fused and can longer be a source of pain.
Sometimes called Jumper’s Knee, Patellar Tendonitis is inflammation of the large tendon attaching the knee cap to the shin bone. As the name suggests it is common in people who play jumping sports such as basketball or netball. It will also occur in track and field athletes.
Pre-Patellar Bursitis is usually associated with kneeling hence it sometimes being referred to as Housemaid’s Knee. It describes the swelling of the bursa in the front of the knee. Bursas are found in many places in the body where there is tendon passing over bone, or other sources of friction. They can become severely swollen when inflamed.
Less common than Osgood Schlatter Disease but presenting in the same types of patient, SLJD is inflammation of the junction between the lower pole of the patella and the patellar tendon. It is only found in children and adolescents and is associated with jumping and kneeling.
Hip Joint Pathology
Sometimes knee pain isn’t really coming from the knee at all. The hip joint can refer pain into the front of the knee, often without any obvious symptoms in the hip itself. Patients will often describe pain just above the knee cap, sometimes with pain through the front of the thigh. There are serious hip joint problems in adults and children that need to be excluded when the presenting symptom is Anterior Knee Pain. Therefore it is important that any examination for anterior knee pain also involves at least a cursory inspection of the hip joint to rule out problems higher up.