The knee is the largest joint in the body and it is composed of the femur (thigh bone), tibia (leg bone), and patella (knee cap). The knee cap sits in between the sulcus of the thigh bone and articulates smoothly with it. Patellofemoral pain syndrome, commonly known as runner’s knee, is the misalignment of the knee cap against the thigh bone which may cause tracking disorders during knee movement.
What are the signs and symptoms?
The main symptom of patellofemoral pain syndrome is a diffused pain or stiffness at the knee cap and its surrounding. Pain is made worse when the knee underwent flexion and extension motion such as kneeling, climbing stairs, running, jumping and cycling. On top of that, grinding or clicking sensation also can be felt at times. Sitting in a bent knee position for too long will also trigger the pain, especially in the cinema or taking a long-haul flight.
What causes patellofemoral pain syndrome?
The most common cause of this is a poor biomechanical function of the lower limb (i.e. the way your leg function whilst walking and exercising). This can be due to a poor control around the hip and/or poor foot function (flat foot).
Other factors that may contribute to worsening of the syndrome such as:
Muscular weakness/imbalances at the front of the thigh (quadriceps)
Malalignment between the position of the knee cap and the thigh bone
Increased level of physical activities
Improper training techniques or equipment
How is it diagnosed?
Diagnosing this requires a comprehensive physical examination and gait analysis. Imaging such as X-ray is very helpful in ruling out chondromalacia patella (knee cap arthritis), which is often associated with this particular pain syndrome.