Reliability and Validity Measures of the Patellofemoral Subscale Koos-Pf in the Greek Patients with Patellofemoral Pain

Background: Patellofemoral pain (PFP) is one of the most common multifactorial musculoskeletal pathologies affecting the knee joint. The prevalence of PFP in the general population ranges from 11% to 17%, with higher rates observed in specific groups such as females, runners, military personnel, and young athletes. To assess symptoms associated with PFP, the Patellofemoral subscale (KOOS-PF) was developed, consisting of 11 questions that evaluate pain, stiffness, and quality of life. The KOOS-PF scale has already been validated and shown to be reliable in both Spanish and Arabic. Objectives: The aim of this study was to assess the reliability and validity of the KOOS-PF scale in the Greek language among the Greek population with Patellofemoral pain. Methods: Fifty-five participants aged 18-65 years who suffered from PFP were evaluated in two phases on the 1st and 3rd days regarding the reliability and validity of the measures of KOOS-PF in the Greek language. Construct validity was assessed using the Knee Outcome Survey scale - Activities of Daily Living Scale (KOS-ADLS). Reliability was measured through Repeated measurements (test-retest) using intraclass coefficient correlation (ICC), standard error (SEM) and smallest detectable change (SDD. Internal consistency was evaluated using Cronbach’s coefficient a. The significance level was set at 5% (α=0.05). Results: The KOOS-PF measures showed high internal consistency reliability (Cronbach's alpha 0.87, p=0.05) and high test-retest reliability (ICC=0.95, p=0.05, SEM= 3.7, SDC=13.57). Additionally, the Greek version of the KOOS-PF exhibited high construct validity when correlated with the KOS-ADLS scale (r=0.72, p=0.001). Conclusions: The KOOS-PF scale was displayed high reliability and construct validity for measuring Patellofemoral pain in the Greek population.