Patellofemoral pain syndrome (PFPS): "Runners knee".

Patellofemoral pain syndrome (PFPS), often referred to as “runner’s knee”, is one of the most common knee conditions in endurance sports, especially those requiring running activity. It is a general descriptor for anterior knee pain related to a spectrum of patellofemoral joint disorders. The post will cover current concepts in regards to the causes, history, risk factors, diagnosis and treatment of the PFPS.
The pathogenesis of the PFPS is not fully understood, but in orthopaedic sports medicine, the most common reasons for anterior knee pain are overuse, patellofemoral malalignment, and trauma. Pain may be caused by increased subchondral bone stress attributed to the stress of articulation or from cartilaginous lesions on the patella or distal femur. Most clinicians believe that PFPS results from abnormal patella tracking that leads to excessive compressive stress to the patellar facets.History includes pain in the anterior knee that is related to repetitive loading of the joint while running, jumping, or cycling; pain during climbing or descending stairs or hills; and pain related with prolonged sitting with the knees flexed.

Physical examination may reveal patellofemoral malalignment, tenderness at the patellofemoral facets, pain on patellofemoral compression test, crepitus on active extension, and a positive “J” sign (curvilinear lateral tracking of the patella with contraction of quadriceps). Imaging may include radiography and/or computed tomography/MRI. Radiography (sunrise or merchant view) often normal but may show lateral tilt or subluxation of patella. Computed tomography and MRI usually not indicated but may reveal patellar malalignment or chondromalacia. PFPS must be differentiated from tibiofibular subluxation, Osgood- Schlatter disease, Patellar Stress Fracture, Sinding-Larsen-Johansson Syndrome, patellofemoral arthritis, plica syndrome, patellar tendinitis, bone tumors, or bursitis.

Factors that might contribute to PFPS include: EMG VL- VMO onset timing difference, foot abnormalities (pes cavus, pes planus, geu varum, genu varus), gastrocnemius tightness, generalized joint/ligamentous laxity, hamstring tightness, hip musculature weakness, ITB tightness, increased Q-angle (recently questioned), quadriceps tightness/weakness, decreased patellar mobility.

Most patients with PFPS respond well to conservative interventions and evidence supports the use of exercise for the treatment of PFPS. Based on this clinical theory, the aim for interventions used for the treatment of PFPS is to improve patella tracking and reduce abnormal stress to patellofemoral joint structures. Specific vastus medialis obliquus (VMO) and general quadriceps exercises represent the most commonly used intervention. Other intervention strategies include: patellar taping, patellar bracing, knee bracing, hip strengthening exercises, foot orthosis, relative rest and activity modification, icing, NSAIDs, quadriceps/ITB stretching. Cyclists should consider change in seat height, cycling position, or pedal/cleat system. Runners should consider modifications in landing technique.

What are your experiences with patients suffering from PFPS? Which interventions works best in your opinion?