Clinical test for diagnosis of patellofemoral pain syndrome: Systematic review with meta-analysis

Abstract

The high incidence and diversity of factors attributed to the etiology of patellofemoral pain syndrome (PFPS) makes the diagnosis of this problem somewhat complex and susceptible to misinterpretation. Currently, there is not a defined set of procedures considered as ideal to diagnose PFPS. To investigate the diagnostic accuracy of clinical and functional tests used to diagnose PFPS through a systematic review. We searched relevant studies in the databases Medline, CINAHL, SPORTDiscus and Embase. The QUADAS score was used to assess the methodological quality of the eligible studies. We analyzed data that indicated the diagnostic properties of tests, such as sensibility, specificity, positive (LR+) and negative (LR−) likelihood ratio, and predictive values. The search identified 16,169 potential studies and five studies met the eligibility criteria. The 5 studies analyzed 25 tests intending to accurately diagnose PFPS. Two tests were analyzed in two studies and were possible to perform a meta-analysis. Within the five studies included, one study had high methodological quality, two studies had good methodological quality and two studies had low methodological quality. Two tests, the patellar tilt (LR+ = 5.4 and LR− = 0.6) and squatting (LR+ = 1.8 and LR− = 0.2), had values that show a trend for the diagnosis of PFPS (LR+ >5.0 and LR− <0.2), however their values do not represent clear evidence regarding diagnostic properties as suggested in the literature (LR+ >10 and LR− <0.1). Future diagnostic studies should focus on the sample homogeneity and standardization of tests analyzed so future systematic reviews can determine with more certainty the accuracy of the tests for diagnosis of PFPS.

Introduction

In the absence of other intra-articular disorders, there is currently consensus that anterior knee pain, which limits activities of daily living that demand knee flexion such as climbing and descending stairs, squatting or remaining seated, is defined as patellofemoral pain syndrome (PFPS) (Bohnsack, Hurschler, Demirtas, Rühmann, Stukenborg-Colsman, & Wirth, 2005; Bohnsack et al., 2009; Loudon, Wiesner, Goist-Foley, Asjes, & Loudon, 2002; Reid, 1993; Thomeé, Augustsson, & Karlsson, 1999). There is a high incidence of this condition among physically active populations; it affects 8.75% of the individuals involved in intense physical training and has a significant impact on their occupational activities (Wills, Ramasamy, Ewins, & Etherington, 2004). Besides the series of factors that negatively contributes to symptom reduction, there is a diversity of terms used to classify the types of PFPS. This diversity may lead to an erroneous evaluation and it could consequently influence treatment. Some terms have been used synonymously to classify individuals reporting symptoms in the knee region, such as chondromalacia patellae, patellar arthralgia, patellar pain and patellofemoral syndrome.

Even when analyzed within the general population, PFPS has an incidence between 15 and 25% (Boling, Padua, Marshall, Guskiewicz, Pyne, & Beutler, 2010; Tállay et al., 2004; Wood, Muller, & Peat, 2011) and is more predominant among female adolescents and physically active young adults (Boling, Padua, Marshall, Guskiewicz, Pyne, & Beutler, 2009; Ivković, Franić, Bojanić, & Pećina, 2007; Myer et al., 2010; Tenforde, Sayres, McCurdy, Collado, Sainani, & Fredericson, 2011). Several factors have been linked to PFPS, including a decrease in quadriceps strength (Lankhorst, 2011; Pattyn et al., 2011), decreased flexibility (Miyamoto, Soriano, & Cabral, 2010; Piva et al., 2006), asynchrony in the electrical activity between the vastus medialis oblique and the vastus lateralis longus muscles (Santos, Ries, Sperandio, Say, Pulzatto, & Monteiro-Pedro, 2011), rotations between the femur and the tibia (Boling et al., 2009; Levinger, Gilleard, & Coleman, 2007), excessive subtalar pronation (Boling et al., 2009), and alterations in the position of the patella (Hunter et al., 2007; Ward & Powers, 2004).

The high incidence and diversity of factors attributed to the etiology of PFPS make its diagnostics complex and susceptible to errors of interpretation. Currently, there is not a defined set of procedures considered as ideal to diagnose PFPS. However, Fredericson and Yoon (2006) recommend an association of tests and functional evaluations to aid in the diagnosis of PFPS. Even though a number of studies have proposed tests for diagnosing PFPS, the comparative validity of these tests is not clear. Thus, the objective of this study is to investigate, as a systematic review, the accuracy of these clinical and functional tests for diagnosing PFPS.