What is Patellofemoral Syndrome (PFS) ?
Anterior knee pain normally noticed during weight bearing or activities that involve knee bending like squatting, kneeling, hopping, running or using the stairs. It starts gradually during activity then ultimately become painful even at rest. You can also experience kneecap pain when you are in sustained knee bend during prolonged period of sitting in a chair, which is experienced by office workers or those who drive for longer time during the day.
Why it happens ?
In normal situation your patella normally glides up and down through the femoral groove. As your knee is bent, pressure between your kneecap and the groove increases. When the patella does not ride normally through the groove, but miss tracks & travels more to one side this retropatellar pressure is further increased, making it rub against the femur. Repeated lateral side rubbing will cause trauma & lead to kneecap pain, joint irritation and eventually degeneration of your patella joint surface.
The most common cause of patellar malalignment is an abnormal muscle imbalance and poor biomechanical control. If there is a muscle imbalance between the quadriceps muscles: vastus lateralis (VL), which pulls your patella up and outwards, and the vastus medialis oblique (VMO), which is the only quadriceps muscle that pulls your kneecap up and slightly in, then your patella will track laterally in the groove. Sometimes people are born with abnormal alignment or have a knee groove that is too shallow, allowing the patella to dislocate. In other cases, patella malalignment can also be caused by direct trauma to the knee or post-operative swelling. Poor foot posture (flat feet) and weak hip control muscles can result in a lateral deviation of your patella. Patellofemoral pain syndrome is more common during adolescence, because the long bones are growing faster than the muscles, tendons and ligaments, putting abnormal stresses on the joints. Active children who do not stretch the appropriate muscles are predisposed to patellar malalignment.
Researchers have confirmed that physiotherapy intervention is a very effective short and long-term solution for kneecap pain. PFS sufferers will be pain-free within six weeks of starting a physiotherapist guided rehabilitation program for patellofemoral pain syndrome. The aim of treatment in phase one of rehabilitation is to reduce your pain, inflammation & restore patella movement in the short-term. Phase two consist of muscle work to regain balance between VMO & VL & correct the cause to prevent it returning in the long-term. There is no specific time frame for when to progress from each stage to the next. For those who fail to respond, surgery may be required to repair associated injuries such as severely damaged or arthritic joint surfaces.