Purpose: The aims of this study were to evaluate the diagnostic accuracy of common physical examination and functional evaluation tests, and to determine a set of tests with the highest diagnostic accuracy for diagnosing patellofemoral pain syndrome (PFPS) in patients with anterior knee pain.
Methods: Based on careful evaluation of clinical findings and imaging methods by orthopedic physicians, 162 patients with anterior knee pain were classified into two groups of PFPS and non-PFPS. The physical examination and functional tests were performed by two physiotherapists. The accuracy of these measures was determined by calculating sensitivity, specificity, area under the receiver operating characteristic (ROC) curve (AUC), likelihood ratio (LR), and predictive value (PV).
Results: Our results showed the most sensitive tests in identifying patients with PFPS were as follows: eccentric step test [0.82 (95%CI: 0.72-0.89)]; palpation test [0.81(95%CI: 0.70-0.88)]; and prolonged sitting [0.73 (95%CI: 0.62-0.82)]. The palpation test, patellar tilt test, eccentric step test, navicular drop test, squatting, and stair descending tests had an acceptable accuracy (AUC ≥ 70). The strongest combination of the physical examination and functional tests included pain severity between 3 and 10 during stair descending test and pain severity between 6 and 10 during prolonged sitting test. This combination showed a positive LR of 19.47 (95% CI: 6.36-59.65) and a posttest probability of 95%.
Conclusion: Our findings provide evidence for the good accuracy of the palpation test, patellar tilt test, eccentric step test, navicular drop test, squatting, and stair descending and prolonged sitting tests for diagnosing PFPS. Also, the combination of stair descending test and prolonged sitting test could be very useful for ruling in PFPS patients.
Keywords: Patellofemoral pain syndrome; functional tests; physical examination; sensitivity; specificity.