What is the importance of body mass index for individuals with patellofemoral pain? An investigation of movement pattern, aspects of muscular function and psychological factors

Abstract

An altered Patellofemoral Joint (PFJ) load, particularly when associated with biomechanical and muscular impairments that affects movement pattern, has been identified as the key mechanism for the development and chronicity of Patellofemoral Pain (PFP). In this context, the excess of body mass, which can be estimated from a person's Body Mass Index (BMI), may overload PFJ. In addition, other non-mechanical factors such as quality of life and psychological factors, which are related to PFP prognosis, are negatively affected by excess body mass in many different musculoskeletal disorders. However, there is a lack of studies of the influence of the BMI in PFP. Therefore, the aim of this study is to compare quality of life, psychological factors, aspects of muscle function and movement patterns during double leg squat, single leg squat and step-down tasks of women with PFP according to their BMI (normal weight vs. overweight vs. obesity). Women with PFP aged 18 to 35 years will be recruited and divided into three groups: PFP normal weight, PFP overweight and PFP obesity. In order to characterize the sample, self-reported function, physical activity level and pain level will be initially obtained using the Anterior Knee Pain Scale (AKPS), Baecke and Visual Analog Pain Scale (VAS) questionnaires, respectively. Then, the experimental protocol will consist of 3 stages, on different days: (1) assessment of psychological factors (by Tampa Scale for Kinesiophobia and Pain Catastrophizing Scale), quality of life (by SF-36), and movement pattern of the trunk, pelvis, hip, knee and rearfoot in the frontal and sagittal planes during double leg squat, single leg squat and step-down (by three-dimensional movement system); (2) assessment of aspects of muscle function - peak torque of knee extensors and hip abductors (using an isokinetic dynamometer); and (3) assessment of aspects of muscle function - rate of torque development of knee extensors and hip abductors (using an isokinetic dynamometer). Statistical analysis will consist of comparing the study variables between groups using a one-way ANOVA (three factors). In addition, functional data analysis will be used to evaluate the differences between the groups in the kinematics of the trunk, pelvis, hip, knee and rearfoot in the frontal and sagittal planes, during the entire period of task execution (double leg squat, single leg squat and step-down). Significance level will be set at p <0.05. (AU)