Exploring the association between the knee injury and osteoarthritis outcome score-patellofemoral subscale and lower extremity kinematics and strength in individuals with patellofemoral pain

Abstract

Introduction To assess the association between Knee Injury and Osteoarthritis Outcome Score-Patellofemoral subscale (KOOS-PF) and two-dimensional single-leg squat kinematics and lower extremity isometric strength in individuals with patellofemoral pain. Methods Seventy-five individuals with patellofemoral pain completed this cross-sectional laboratory study. Participants completed the KOOS-PF. Lateral trunk motion, pelvic drop, hip frontal plane projection angle, and knee frontal plane projection angle were assessed during a single leg squat using two-dimensional motion analysis. Peak isometric hip abduction, hip extension, and knee extension strength were evaluated using a hand-held dynamometer. Pearson correlations were used to estimate the association of the KOOS-PF with 2D SLS kinematics and lower extremity isometric strength. Separate linear regressions were also conducted, controlling for sex, age, and BMI to assess the relationship between variables. Significance was set at P < .05 for all statistical tests. Results 75 participants (51 females; 24 males, age: 24 ± 5 years, height: 167.9 ± 10.0 cm, mass: 73.7 ± 18.2 kg) were enrolled and data from all participants were included in the analyses. No significant linear associations were observed between the KOOS-PF and measures of two-dimensional squatting kinematics (−.07≤r ≤ .01; P > .05) or between the KOOS-PF and lower extremity isometric strength (−.04≤r ≤ .04; P > .05) in individuals with patellofemoral pain. Conclusions The KOOS-PF was not linearly associated with frontal plane squatting kinematics or lower extremity isometric strength in individuals with patellofemoral pain. The lack of significant linear associations suggests that clinicians should evaluate and consider self-reported, kinematics, and strength measurements when assessing individuals with patellofemoral pain.