Comparison of patellar height ratio between different knee flexion angles in patients with patellofemoral pain syndrome

Abstract

Abstract Patellofemoral height is a measurement to determine the abnormality of the patellofemoral joint. This study aims to find the appropriate knee flexion angle and patella height ratio in patients with patellofemoral pain syndrome (PFPS) and assess inter- and intra-rater reliability. 27 patellofemoral pain syndrome patients (36 knees) with a sex distribution of 5 males and 22 females, averaging 38.78 ± 11.71 years of age. Lateral knee flexion angles at 0, 30, and 60 degrees were measured in the lateral decubitus position to calculate the patellar height ratio. All parameters (Insall‒Salvati, Modified Insall‒Salvati, Caton-Deschamps, Blackburne-Peel, and knee flexion angle) were significantly higher at 0 degrees than at 30 and 60 degrees of knee flexion. The Caton-Deschamps ratio was also significantly higher at 30 degrees than at 60 degrees of knee flexion. However, all of the patellar height ratios that were significant were not clinically significant. The inter- and intrarater reliability of the patellar height ratios were moderate to good (ICC = 0.506–0.889, 0.667–0.888 as ordered).