Considering it is one of the most common types of knee pain, patellofemoral pain syndrome (PFPS) is a relatively poorly defined condition. Adolescents and athletes are most likely to be affected, with gradually worsening, intermittent knee pain the stereotypical presentation.
Broadly speaking, PFPS is an irritation of the contact point between the knee-cap (patellar) and the thigh bone (femur). This is known as the patellofemoral joint. The term does not imply any measurable damage to any of the structures within the knee.
Irritation arises from increased stresses through the patellofemoral joint. Raised stresses may occur during athletic activity, or may arise due to faulty biomechanics or high BMI.
It is very unusual for athletic activity alone to cause PFPS, with faulty mechanics almost always playing a part. Elite sports involving repetitive high loads on the legs, such as Olympic rowing and cycling, are the most likely to be associated with PFPS.
Typically, however, athletic activity is insufficient to cause PFPS without prior biomechanical changes.
These tend to include inward rotation of the shin bone (tibia), shortened thigh muscles (vastus lateralis, psoas and semi-membranosus), weak gluteal muscles, over extension of the knee and leaning forward of the trunk.
The overall cause of these biomechanical changes can vary, with gait changes caused by sedentary lifestyle factors very common.
Diagnosis of PFPS is usually one of exclusion. That is to say that, because it cannot be seen on scans etc, all other causes of knee pain must be ruled out to leave only PFPS as a possibility. The right diagnosis is imperative for putting in place an effective treatment plan.
PFPS is often described as growing pains due to its high frequency in adolescents. Although parents should not be overly concerned by PFPS, it is still important pain is thoroughly investigated as minor mechanical problems during growth phases can cause more severe subsequent problems if not managed properly.
Treatment usually consists of pain moderation, using ice and over the counter pain killers, followed by correction of biomechanical changes, which is best done using a combination of manipulation and soft tissue release techniques. Because the knee joint is used so regularly, treatment may need to be quite frequent at first and home exercises usually play a significant part.
If left, not only will PFPS continue to be debilitating, but the increased stresses involved will eventually lead to damage such as early onset osteoarthritis, ligament sprains and strains, and muscle and cartilage tears. These will also affect the feet, hip and spine as a result of compensatory changes.