Patellofemoral stress syndrome is typified by anterior knee pain and related symptoms. It has no clear cause and is often seen in active individuals such as runners.
Patellofemoral stress syndrome (PSS) is a disorder that shows up with gradual onset anterior knee pain . The disease affects females more than males and is also commonly seen in those who participate in sports . It is usually associated with overuse or increased stress on the patellofemoral joint, which in turn might be caused by activities such as running, lunges, squats, climbing stairs, or abnormalities in the structures that support the joint . A recent increase or a change in daily actions may be noted. There is no direct pathological etiology in the joint or cartilage, thus other possible factors of knee pain should be investigated and ruled out before the diagnosis can be made  . Features such as swelling are not characteristic of PSS and their presence also alludes to a different causative agent for the pain. The differential diagnoses include infection, dislocation or subluxation of the joint and a history of traumatic injury.
The main sign of PSS is dull or sharp pain around the knee, and patients may indicate this by motioning the circumference around the anterior knee, the latter is called the circle sign. Extended periods of flexion of the knees also worsen the discomfort. This is known as the theater sign. Other possible features are crepitus, stiffness, weakness at the knee and loss of function. A history of trauma or previous surgery may be recorded. It is thought by some that PSS and development of osteoarthritis are linked .
Entire Body System
- Anterior Knee Pain
UW Health's Sports Medicine doctors in Madison, Wisconsin, treat a wide range of common athletic injuries, including patellofemoral stress syndrome, or anterior knee pain. [uwhealth.org]
The onset of anterior knee pain is usually gradual. [integrativehealthcare.org]
AKP, anterior knee pain BMD, bone mineral density MTSS, medial tibial stress syndrome PFPS, patellofemoral pain syndrome diffuse uptake patellofemoral pain scintigraphy tibia Statistics from Altmetric.com AKP, anterior knee pain BMD, bone mineral density [bjsm.bmj.com]
Patellofemoral stress syndrome (PFSS) is a broad, nondescript term used in sports medicine to describe anterior knee pain when the true etiology is multifactorial or unknown. [doctorabel.us]
- Quadriceps Muscle Weakness
muscle weakness, specifically the vastus medialis (inner quad), and/or gluteus muscle weakness, specifically the gluteus medius Poor alignment with the three bones that are found at the knee, including the femur (thigh bone), tibia (shin bone) and the [uwhealth.org]
- Restless Legs Syndrome
Legs Syndrome Sciatica Knee Surgery Knee Arthroscopy Knee Replacement Call PhysioWorks Book Online [physioworks.com.au]
A diagnosis of PSS is often made clinically because it consists of a group of symptoms that are not directly associated with a disease process . Other diagnostic modalities are employed mainly to exclude alternative sources of pain and to assess the factors contributing to the stability of the joint.
Investigations are usually done if there is a positive history of a risk factor, such as injury or prior surgery. They are also advised if there are symptoms that are not consistent with or typical to PSS. The following studies are examples:
- Radiography: This is taken in several planes, in order to assess the joint adequately. X-rays are useful in detecting fractures, bone tumors, infections such as osteoarthritis and effusion. Abnormality in the alignment of the joint may be found, however, it is not specific to PSS as it may be present in individuals who are asymptomatic  .
- Joint aspiration: Useful when an effusion is suspected.
- Arthroscopy: To visualize joint cartilage and structures.
- Magnetic resonance imaging (MRI) and computerized tomography (CT) scanning are not routine exams. MRI may be useful if abnormalities such as softening of the cartilage, fractures and other injuries are present. It assists in visualizing edema within the bone marrow.
- Witvrouw E, Werner S, Mikkelsen C, Van Tiggelen D, Berghe L Vanden, Cerulli G. Clinical classification of patellofemoral pain syndrome: guidelines for non-operative treatment. Knee Surg Sports Traumatol Arthrosc. 2005;13(4):122–130.
- Kannus P, Natri A, Paakkala T, Jarvinen M. An outcome study of chronic patellofemoral pain syndrome. Seven-year follow-up of patients in a randomized, controlled trial. J Bone Joint Surg Am. 1999;81(3):355–363.
- Barton CJ, Menz HB, Levinger P, Webster KE, Crossley KM. Greater peak rearfoot eversion predicts foot orthoses efficacy in individuals with patellofemoral pain syndrome. Br J Sports Med. 2011;45(9):697–701.
- Al-Hakim W, Jaiswal PK, Khan W, Johnstone D. The non-operative treatment of anterior knee pain. Open Orthop J. 2012;6:320–326.
- Boling M, Padua D, Marshall S, Guskiewicz K, Pyne S, Beutler A. Gender differences in the incidence and prevalence of patellofemoral pain syndrome. Scand J Med Sci Sports. 2010;20(5):725–730.
- Myer GD, Ford KR, Barber Foss KD, et al. The incidence and potential pathomechanics of patellofemoral pain in female athletes. Clin Biomech (Bristol, Avon). 2010;25(7):700–707.
- Bolgla LA, Malone TR, Umberger BR, Uhl TL. Reliability of electromyographic methods used for assessing hip and knee neuromuscular activity in females diagnosed with patellofemoral pain syndrome. J Electromyogr Kinesiol. 2009;20(1):142-147.
- Elias DA, White LM. Imaging of patellofemoral disorders. Clin Radiol. 2004;59(7):543-557.
- Natri A, Kannus P, Jarvinen M. Which factors predict the long-term outcome in chronic patellofemoral pain syndrome? A 7-yr prospective follow-up study. Med Sci Sports Exerc. 1998;30(11):1572-1577.