Patellofemoral pain syndrome is an umbrella term for all peripatellar and retropatellar pain. A number of intra-articular and extra-articular components of the knee can be the source of pain. It is interesting to note that articular cartilage cannot directly be a source of pain as it is avascular and anueral. However a cartilage lesion may lead to chemical or mechanical synovial irritation. PFPS has traditionally been considered to be a self limiting condition however it may predispose to the development of patellofemoral osteoarthritis so it should not be neglected in hopes of a natural resolution.
When the knee is flexed from an extension position, the patella moves along a medial-lateral course along the femoral trochlea. During flexion, the patella moves medially and comes to lie within the intercondylar notch until 130degrees of flexion, when it starts to move laterally again. Loaded knee flexion activities subject the PFJ to forces ranging from 0.5 times body weight for walking to seven times body weight for stair climbing. Balanced activity in the VMO and vastus lateralis are required to maintain optimal alignment and tracking of the patella when we bend and straighten our knee.
PFPS is likely to be initiated by increased or unaccustomed loads. Extrinsic load is created by the body’s contact with the ground. The number of loading cycles and frequency of loading are also important. When an individual experiences an increase in the magnitude of the patella femroal joint load due to a higher volume or higher training intensity, this may overload the patellofemoral joint sufficiently to initiate pain. Intrinsic factors that can influence patella tracking may be considered remote or local. Remote factors include femoral rotation, tibial rotation, knee valgus and subtalar pronation. Local factors that influence patella movement include patella position, soft tissue tension and neuromuscular control of the medial and lateral components of the vasti.
Management Strategy and Treatment
As clinicians, it is important for us to assess the contribution of various extrinsic and intrinsic factors to the development of patellofemoral pain. We will assess the patient in both static positions and functional activities. Once a potential contributing factor has been identified, we will investigate the mechanisms that may require intervention. We will treat patellofemoral pain using an integrated management approach which includes
Our first priority of treatment is to reduce pain. Rest from the aggravating activity usually suffices but it may require ice and taping to have an immediate pain-relieving affect. The aim of taping is to correct the abnormal position of the patella in relation to the femur, helping to speed up the onset timing of the VMO relative to the vastus lateralis.
To address the extrinsic factors, the patients will have to reduce the load on the patellofemoral joint and training loads, volume and intensity will have to be addressed. Addressing intrinsic factors will be based on clinical assessment and thus must be individualized for each person. Remote intrinsic factors may be addressed through hip muscle retraining, improving musculotendinous compliance or foot orthoses. Local intrinsic factors may be addressed with techniques that improve lateral soft tissue compliance, generalized quadriceps strengthening or vasti retraining.
Because patellofemoral pain syndrome may predispose to the development of patellofemoral osteoarthritis, treatment will aim not only to reduce pain and symptoms, but also to address all contributing factors.