Investigation about neurophysiological alterations in women with patellofemoral pain: association with performance in clinical tests and knee joint moment during functional tasks

Abstract

Patellofemoral pain (PFP) is a common reported disorder affecting mainly women. It is defined as a diffuse anterior knee pain, exacerbated by activities such as stair negotiation, squat and running. Studies have explored aspects related to the multifactorial nature of PFP, specially the biomechanical parameters that may influence the rehabilitation of these individuals. However, the correction of the biomechanical alterations found until the present moment as possible precursors to PFP do not show good prognoses in long-term, evidencing that other factors, including neurophysiological, may be involved. Thus, neurophysiological analyzes, such as the Hoffmann reflex (H-reflex), have been applied as a noninvasive experimental tool for the analysis of neurophysiology related to motor performance. Recently, studies reported changes in the H-reflex in women with PFP, which is related with pain, function and chronicity. However, no study has investigated whether alterations of this reflex may influence muscle function in these individuals during functional tasks. Moreover, neurophysiological alterations of individuals with PFP may be related with the performance in clinical tests, as they require muscle functions dependent on neurophysiological mechanisms such as power, motor control and stabilization. However, the possible relation between neurophysiological alterations and the performance in clinical tests has not been explored yet. This information is important to assist clinicians in identifying these changes in a clinical setting and to guide rehabilitation to more effective and still underused approaches. Considering the importance of this analysis to the understanding of PFP, the current project aims to investigate whether women with PFP present changes in the H-reflex compared with asymptomatic women and whether these changes are related with peak, mean, rate of force development and power of the knee extensor moment during functional tasks (stair ascent and descent, squat and step-down) and with performance in clinical tests (Single Leg Hop test, Step-down test e Y Balance test). Women with and without PFP aged between 18 to 35 years will be recruited. The volunteers will undergo an experimental protocol consisting of: 1) Vastus Medialis muscle H-reflex capture through the use of electrical stimulation on the femoral nerve while remaining relaxed in supine position; 2) Execution of clinical tests such as Single Leg Hop test, Step-down test e Y Balance test; 3) Kinematic analysis of functional tasks such as step-down, squat and stair ascent and descent through an experimental set up composed of a three-dimensional motion analysis system with 9 cameras and a force plate. Knee extensor moment calculation will be realized by ViconNexus 2.0® software and the peak, mean, rate of force development and power of the knee extensor moment will be obtained by custom-made algorithms developed in MATLAB®. Statistical analyzes will be done to investigate differences between groups (independent t test or Mann-Whitney test) and to evaluate the relation between H-reflex amplitude with knee extensor moment and the performance in clinical tests (Pearson correlation coefficient or Spearman correlation coefficient). (AU)