Patellofemoral+Pain+Syndrome+Diagnosis

Patellofemoral Pain Syndrome (PFPS): Anterior (commonly retropatellar) knee pain that is not caused by other pathologies such as osteoarthritis, tendinopathies or soft tissue injuries (1,2)

__**Purpose:**__ To find the most reliable combination of tests and diagnostic procedures to accurately diagnose patellofemoral pain syndrome.

__Clinical Question__: What tests are the most reliable for accurately diagnosing patellofemoral pain syndrome?

__**Evidence**__

//Databases used:// Pubmed and Google Scholar //Search Terms:// //Inclusion Criteria// //Exclusion Criteria// All studies that were included were considered with caution because many studies focused on PFPS have low methodological quality (7)
 * "Diagnosis" and "Patellofemoral Pain Syndrome" or "Patellofemoral Syndrome:
 * "Diagnostic Tests" and "Patellofemoral Pain Syndrome"
 * Studies were included if they aimed to evaluate the reliability and validity of tests commonly used in diagnosing PFPS
 * Studies were included if they included tests for sensitivity and specificity of test
 * Studies that aimed to evaluate rehab interventions for PFPS or if they did not interpret the reliability of diagnostic tests.

Description of Statistics Discussed: //Likelihood Ratio//: Discriminatory measurements that refer to how many times more likely or less likely a positive test will be in an affected individual than a non-affected individual //Sensitivity//: The proportion of individuals with the condition that elicit a positive test result (7) //Specificity//: The proportion of individuals without the condition that elicit a negative test result (7)
 * Positive Likelihood Ratio (LR+): >10 indicates convincing evidence, >5 indicates strong evidence and between 2-5 indicates a small amount of evidence that a positive test will more likely be in an affected individual
 * Negative Likelihood Ratio (LR-) <.1 indicates convincing evidence, <.2 indicates strong evidence and <.5 indicates a small amount of evidence (7)
 * A negative test is more likely to rule out a condition
 * A positive test is more likely to rule in a condition

Anatomy/Biomechanics


The "Knee Joint" consists of 3 joints: Patellofemoral Pain Syndrome involves the patellofemoral joint
 * Tibiofemoral Joint
 * Proximal Tibiofibular Joint
 * Patellofemoral Joint

Other structures of the knee thought to be commonly involved include the quadriceps muscle group, surrounding retinaculum, and surrounding ligaments. (2)




 * Biomechanics**

A common problem that is thought to occur during PFPS is abnormal tracking of the patella. Normal Biomechanics: During extension, quadriceps imbalance or weakness may cause these biomechanics to be altered, although research is not conclusive on this theory. (1, 2, 8)
 * During extension: the patella glides superior and lateral
 * During flexion: the patella glides inferior and medial (8)


 * Incidence of PFPS: 10% (1) up to 25% (7) in female athletes and physically active young adults**

Common Signs/Symptoms:
//*indicates most common signs/symptoms a patients may describe//
 * Anterior knee pain**
 * Pain after prolonged sitting*: LR + 7.4 (2)
 * Pain with jumping and/or stair climbing*
 * Pain with squatting*
 * Patellofemoral pain with squatting is evident in 80% of patients with PFPS (8)
 * Pain with squatting presented the highest sensitivity (91%) in a meta-analysis by Nunes, et. al. (7)
 * Catching
 * Giving Away
 * Slipping Sensation

**Mechanism of Injury**
(1)
 * Trauma (rare)
 * Repetitive Overloading
 * Often due to an increase in activity
 * i.e. recent and intense increase in milage for runners



**Risk Factors**
(2)
 * Gender (female)
 * Age (Adolescents through young adults)
 * Malalignment of the lower extremity
 * Muscular imbalance
 * Lateral Retinaculum tightness
 * Cartilage Disruption
 * Abnormal Hip Mechanics
 * Increased Q angle

Medical Imaging

 * Medical imaging is not often used for diagnosis
 * X-ray and MRI can be used to rule out other pathologies (4)
 * EMG (9)
 * EMG is not commonly used in diagnosis of PFPS but a study by Ferrari et al. found that EMG has a high diagnostic accuracy in diagnosing PFPS[[image:kumc-ptrs-ebp/Screen Shot 2016-04-05 at 9.44.16 PM.png align="right" caption="(9)"]]
 * This was done by using 2 surface electrodes, one on the Vastus Medialis and one on the Vastus Lateralis. Activity at multiple frequencies was recorded and compared
 * This study found to have the following results related to diagnostic accuracy:
 * Specificity: .87
 * Sensitivity: .7
 * Negative Likelihood ratio (LR): (-.33)
 * Positive LR: (5.63)

Differential Diagnosis
(2)
 * Prepatellar Bursitis
 * Patellofemoral Arthritis
 * Osgood Schlatter Disease
 * Ligament Sprain/Rupture
 * Patellar Dislocation
 * Osteoarthritis
 * Patellar Tendinopathy

Objective Assessment
__Palpation__: __MMT__:
 * Tenderness on palpation of patellar edges (3)
 * Decreased quadricep strengths
 * Will not be seen in young athletes (1)
 * Resisted Quadriceps Contraction for the diagnosis of PFPS
 * LR + 2.2, Sensitivity (39%), Specificity (82%) (4)

__Functional Testing__
 * Squat Maneuver
 * Patellofemoral pain is evident in 80% of patients who are diagnosed with PFPS (5)
 * Pain with squatting presented the highest sensitivity (91%) of any functional or special test according to a meta-analysis by Nunes et. al. (7)
 * The squat test is often performed in a clinical setting because it increases load on the knee joint and therefore exacerbates the symptoms (7)
 * Eccentric Step Test
 * Patients should be barefoot, start standing on a step/box (15 cm in a study by Nijs et al, but height varies between studies). Patient places hands on hips and steps off the step slowly and as controlled as possible, stepping down with the unaffected leg, the patient then steps up with the affected leg.
 * + test: Pain on affected leg with stepping down (and stepping up)
 * LR + 2.34 (4)
 * Sensitivity (42%) and Specificity (93%) (4,7)
 * media type="youtube" key="lwms-zX5HuU" height="219" width="392"
 * (10) [|Eccentric Step Test]
 * Vastus Medialis Coordination Test
 * Patient is supine and the examiner places fist under the patient's knee. Patient is asked to extend knee into full extension without pushing down or lifting away from the examiner's fist.
 * + test: lack of full, coordinated extension (motion was not smooth or patient had to compensate)
 * LR + 2.26 (4)
 * Sensitivity (16%) and Specificity (93%) (4,7)
 * media type="youtube" key="EqokJXC6690" width="448" height="251"
 * (11) [|Vastus Medialis Coordination Test]
 * Patellar Apprehension Test
 * Not created to diagnose PFPS but often used during evaluation of PFPS
 * Patient is supine and the examiner pushes the patient's patella as lateral as possible as the hip and knee are moved into hip flexion
 * + test: patient appears apprehensive or quadriceps contract in an effort to control the patella
 * LR + 2.34 (6)... LR + 0.9-2.3 (2)
 * Nunes et al showed that most studies found a low sensitivity (7%-15%) and high specificity (89%-92%) (7)
 * media type="youtube" key="xZulxWEH-T8" width="448" height="251"
 * (12)[|Patellar Apprehension Test]
 * Patellar Tilt Test (Inferior Tilt)
 * Patient should be supine with knee in full extension. Examiner attempts to lift the borders of the patella past the horizontal plane
 * + Test: Examiner is unable to lift the affected border above the horizontal plane
 * LR + 1.1-5.3 (2)
 * Patellar Tilt has been shown to have a low sensitivity (19-43%) and higher specificity (83-92%) (7)media type="youtube" key="e0o7E5WboVY" width="448" height="251"
 * (13) [|Patellar Tilt Test]
 * Other Tests and Observations are also used to diagnose PFPS but research does not show evidence to support these tests. (LR + <2) (2)
 * [|Waldron's Test]
 * [|Clarke's Test]
 * Patellar Mobility
 * Active Instability

Interpretation of Evidence
Overall, there is no clear evidence supporting the best test for PFPS diagnosis. PFPS is a multifactorial condition, which makes it difficult to diagnose. Cook et al states that research needs to be applied with caution because studies that report high likelihood ratios showed lower methodological quality and more testing bias (2). Most evidence shows low sensitivity and higher specificity and likelihood ratios showing little to no evidence in most cases. Further research needs to be done standardizing testing procedures in order to accurately diagnose PFPS (2, 7)

With current research, it is important to rule out other possible diagnoses while diagnosing a patient with PFPS.

References
 * 1) Fredericson M, Yoon K: Physical examination and patellofemoral pain syndrome. Am J Phys Med Rehabil 2006;85:234-243.
 * 2) Cook, Chad. Best tests/clinical findings for screening and diagnosis of patellofemoral pain syndrome: a systematic review. [|Physiotherapy.] 2012 Jun;98(2):93-100
 * 3) Crossley Kay M, Callaghan Michael J, van LinschotenRobbart. Patellofemoral pain BMJ 2015; 351 :h3939
 * 4) Nijs J, Geel CV, Van der auwera C, Velde BVd. Diagnostic value of five clinical tests in patellofemoral pain syndrome. Manual Therapy. 2006. Vol 11(1). 69-77.
 * 5) Patellofemoral pain. TheBMJ web page.[]. Published 2015. Accessed 2015. Accessed April 4 2016
 * 6) Q-angle picture. Steve Jernigan PhD. Lecture Fall 2015 Kinesiology and Biomechanics.
 * 7) Nunes, Guilherme, Stapait, Eduardo, Kirsten, Michel, Noronha, Marcos, Sants, Gilmar. Clinical test for diagnosis of patellofemoral pain syndrome: Systematic review with meta-analysis. Physical Therapy in Sport. 2013. 14:55-59
 * 8) Juhn MS. Patellofemoral Pain Syndrome: A Review and Guidelines for Treatment. American Family Physician 1999;60(7):2012–2018. Available at: http://www.aafp.org/afp/1999/1101/p2012.html. Accessed April 4, 2016.
 * 9) Ferrari D, Kuriki HU, Silva CR, Alves N, Azevedo FMD. Diagnostic Accuracy of the Electromyography Parameters Associated With Anterior Knee Pain in the Diagnosis of Patellofemoral Pain Syndrome. Archives of Physical Medicine and Rehabilitation 2014;95(8):1521–1526.
 * 10) EDPT. Eccentric Step Test. YouTube 2011. Available at: https://www.youtube.com/watch?v=lwms-zx5huu. Accessed April 6, 2016.
 * 11) TUNDPT. Vastus medialis coordination test. YouTube 2012. Available at: https://www.youtube.com/watch?v=eqokjxc6690. Accessed April 6, 2016.
 * 12) CRT. Patellar Apprehension Test (CR). YouTube 2011. Available at: https://www.youtube.com/watch?v=bqysf7bzpnm. Accessed April 6, 2016.
 * 13) CRT. Patellar Tilt Test (CR). YouTube 2011. Available at: https://www.youtube.com/watch?v=e0o7e5wbovy. Accessed April 6, 2016.