Functional hyper-extension deficit of the knee and patellar dimple sign in patellofemoral pain syndrome. A preliminary study

Abstract

Introduction: The aim of this study was to investigate the presence of two new signs in patellofemoral pain syndrome (PFPS). Methods: Twenty-three patients with unilateral patellofemoral pain were participated. The study was designed with each subject acting as their own internal control by using the unaffected limb for comparison. The pain level during squat & stair up-down, functional hyper-knee-extension lack, absence of the patellar dimple sign, and Kujala patellofemoral score were measured in patients. Results: All patients had an unclear and weak patellar dimple sign. Mean pain level during the squat was 7.13±2.54. The functional hyper-knee-extension lack was 4.39±1.23° in the affected side while was-3.91±1.37° in the unaffected side. Conclusion: This study is the first to demonstrate absence of the patellar dimple sign and functional hyperextension lack in patients with patellofe moral pain syndrome. It is suggested that future studies might look at the effect of functional hyperextension knee exercises and look at the longer term fol