Patellofemoral Syndrome
What is it? Patellofemoral syndrome (PFS) is somewhat of an imprecise term that encompasses the most common etiology of anterior knee pain. It has also been called chondromalacia patellae in the past, but now this term should only be used to describe a condition that show articular cartilage damage to the patella.
PFS is thought to be due to malalignment of the patella relative to the femoral trochlea that is aggravated during activities that repetitively load the patellofemoral joint, such as running, jumping and repetitive knee motions.
How does it present? Patients will often complain of anterior knee pain, that is worse when sitting in a tight space with the knee flexed (Theater Sign). They will classically get pain with walking down the stairs or down inclines and with repetitive knee activities such as running or jumping. They may also experience crepitus, or popping or snapping, around the patella.
Common exam findings: You may first want to evaluate the patient while standing to look for evidence of "patellar squinting" or evidence that the patellar are facing each other secondary to femoral anteversion. You may also find an increased Q angle or pronation or pes cavus of the feet. These malalignments may predispose your patient to PFS. On your knee exam you may find tenderness when palpating along the medial or lateral patellar facets and a positive Patellar Inhibition Test and Patellar Grind Test (the Patellar Inhibition Test is also available in Spanish; click on the "CC" icon at the bottom of the video to select the language). You many also notice a poorly developed vastus medialis oblique (VMO)(medial quadriceps) and a laterally tracking patella on flexion/extension of the knee.
Tests and Treatment: You may consider x-rays of the knee, particularly with a merchant view to rule out other bony abnormalities. Treatment generally consists of strengthening the quadriceps, particularly the VMO and a functional rehabilitation program. Patellar taping techniques can be used and patellar bracing also exists. At times orthotics may be considered if foot malalignment exists.