Magnitude, variability and predictors of patellofemoral stress in individuals with and without patellofemoral pain during gait: A cross-sectional study

• Grant number: 23/17152-0
• Support Opportunities: Scholarships in Brazil - Master
• Start date: November 01, 2024
• End date: April 30, 2026
• Field of knowledge: Health Sciences - Physical Education
• Principal Investigator: Fernando Henrique Magalhães
• Grantee: Théo Muniz de Souza Borges da Silva
• Host Institution: Escola de Artes, Ciências e Humanidades (EACH). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

Introduction: Patellofemoral pain (PFP) is a chronic musculoskeletal disorder characterized by anterior or retro patellar pain. It has a prevalence of 25% in the general population, mainly affecting adolescents and young adults between the ages of 12 and 19. Its etiology is poorly understood, however, it is known that biomechanical alterations are commonly observed in people with PFP. The pathomechanical model of PFP suggests increased stress on the patellofemoral joint as a key alteration in the development or chronicity of PFP. Kinematic changes in the trunk and lower limb are suggested as possible causes of increased patellofemoral stress. However, there are no studies in the literature that have investigated how trunk and hip (i.e., proximal) and ankle (i.e., distal) kinematics contribute to predicting patellofemoral stress in individuals with PFP, separately and in conjunction with knee (i.e., local) kinematics. Another point that has been little elucidated in the PFP literature is how the central nervous system uses the different degrees of freedom of the trunk and lower limb to control the variability of patellofemoral stress, before and after symptom exacerbation, which can be investigated using Uncontrolled Manifold (UCM) analysis. Purposes: (1) To investigate the ability of trunk and lower limb kinematics in the three planes of movement to predict patellofemoral stress in individuals with PFP during gait; (2) To compare the magnitude and variability of patellofemoral stress, UCM_Qe of UCM_4, and UCM_ratio of individuals with and without PFP during gait; (3) To compare the magnitude of patellofemoral stress, UCM_Qe of UCM_4, and UCM_ratio of individuals with and without PFP during gait after the pain exacerbation protocol.Methods: Based on sample size calculations, 46 individuals with and without PFP will be recruited to take part in this study. The assessment of the participants will be consist of a biomechanical assessment and self-reported questionnaires. The biomechanical assessment will be carried out using a system of 5 infrared cameras, a plate force and electromyography, which will be synchronized. These data will be collected before and after symptom exacerbation using a previously established protocol. Self-reported data (e.g. pain) and questionnaires (e.g. function, level of physical activity) will also be obtained. Patellofemoral stress will be calculated based on a model used in previous studies. The variability of patellofemoral stress will be calculated using the UCM. Linear regression and mixed (2x2) analysis of covariance (ANCOVA) will be used to answer the study purposes.