Study of bone mineral density of runners and non runners with and without patellofemoral pain

Abstract

Patellofemoral pain is a musculoskeletal disorder characterized by the presence of pain around or behind the patella during functional or activities of daily living. It is the most common disorder reported by runners and affects approximately 23% of the general population. Individuals with PFD have alterations that can influence the distribution or amount of mechanical loads in the patellofemoral and tibiofemoral joints, such as reduced knee extensor and flexor torque, hip abductor and hip extensor torque; increased knee valgus; increased Body Mass Index (BMI) and reduced physical activity level. Since the bone responds to mechanical loads applied to it, these changes can influence the Bone Mineral Density (BMD) of the patella, proximal tibia and distal femur of individuals with PFP. Another factor that can influence the BMD of individuals with PFP is running due to the mechanical impact generated on the knee joint. Studying changes in knee BMD is important as it is associated with the development of osteoarthritis. However, there are few studies in the literature that have investigated the BMD of the patella, proximal tibia and distal femur in men and women, runners and non-runners, with PFP. Furthermore, there is no information in the literature on how much these characteristics predict, individually and in combination, the BMD of subpopulations of individuals with PFP (men, women and runners). This study, therefore, has the objective of investigating the BMD of the patella, proximal tibia and distal femur in men, women and runners with and without PFP. It will also be investigated to what extent hip and knee muscle torque, knee frontal plane projection angle, physical activity level and BMI predict patellar, proximal tibia and distal femur BMD in men, women and runners with PFP. One hundred eighty-four male and female runners and non-runners with and without PFP aged between 18 and 35 years will be recruited to participate in this study. Physical activity level, knee frontal plane projection angle, BMI and muscle torque will be evaluated through questionnaire, 2D kinematics, scale with stadiometer and manual dynamometer, respectively. The BMD will be obtained through double emission bone densitometry (DEXA). The BMD of the patella, proximal tibia and distal femur will be compared between groups using a three-way Analysis of Variance (ANOVA) (group X sex X race), or the non-parametric correspondent. Multivariate linear regressions (or non-parametric correspondent) will be calculated to determine the ability of isometric torque of hip and knee muscles, knee frontal plane projection angle, physical activity level and BMI of predicting the BMD. (AU)