Comparison of the VMO/VL EMG Ratio and Onset Timing of VMO Relative to VL in Subjects with and without Patellofemoral Pain Syndrome

Abstract

Abstract.[Purpose] The purpose of our study was to measure the onset timing of the vastusmedialis oblique (VMO) relative to the vastuslateralis (VL) and the VMO/VL electromyographic (EMG) ratio in subjects with and without patellofemoral pain syndrome (PFPS) while they completed a functional task (stair stepping).[Subjects] Ten patients with PFPS and ten subjects without PFPS were included in this study.[Methods] The subjects performed stair stepping while surface electrodes were used to record the EMG signal amplitude of the VMO and VL.[Results] During stair ascent and descent, significant differences in VMO/VL EMG ratios were observed between participants with and without PFPS. Significant differences were also observed for the VMO-VL timing among participants with and without PFPS while ascending and descending the stairs.[Conclusion] Our findings indicate that PFPS patients have a VMO/VL imbalance and delayed onset of VMO relative to VL.

Changes in Knee Vastii Muscle Activity in Women with Patellofemoral Pain Syndrome During the Menstrual Cycle

“…The amplitude ratio between the VL and VMO muscle bellies was greater than 1 in both phases and both tasks, which means that VL activity was greater than VMO activity. This trend was expected in our patients with PFPS and was not affected by these two menstrual cycle phases. However, this ratio was significantly lower during the ovulatory than in the follicular phase, and the amplitude of VL and especially VMO activity was greater in the ovulatory phase (Figure ).…”

“…The VL/VMO amplitude ratio and differences between onset (onset VL − onset VMO) in vastii muscles were determined to investigate the presumed influence of hormonal variations on EMG activity. Toe rise and heel rock tasks have been used in previous EMG studies involving people with PFPS …”

Reliability of electromyography parameters during stair deambulation in patellofemoral pain syndrome

“…Initially, a linear envelope was applied to the signal and data were full-wave rectified and low-pass filtered at 50Hz. Automatic Onset muscle contraction was quantified as more than three standard-deviations of signal alteration for a minimum of 25ms above the baseline level of each muscle by another algorithm (Bolgla et al, 2010;Cowan, Bennell, Hodges, Crossley, & McConnell, 2001;Kim & Song, 2012). After identifying the respective values, an algorithm subtracted the VL onset from the VM, where negative differences indicated previous activation of the VM and positive differences indicated previous activation of the VL (Uliam Kuriki et al, 2011).…”

“…Several studies aim to characterize the activation pattern of the patella stabilizers muscles during stair deambulation (Cavazzuti, Merlo, Orlandi, & Campanini, 2010;Kim & Song, 2012), however, few of them present data related to the quality of these measures (Bolgla, Malone, Umberger, & Uhl, 2010;Cowan, Bennell, & Hodges, 2000;Ferrari, Kuriki, Silva, Alves, & Mícolis de Azevedo, 2014). Thereby, it is unknown which gesture has the best results of precision and reliability, yet, whether some specific EMG parameter has better accuracy depending on the gesture.…”

“…The EMG data can be analyzed in two different domains, the time and the frequency domain (Winter, 2009). The delay between vastus medialis (VM) and VL muscle onset is a classical time domain parameter investigated in individuals with PFPS due to its possible relation to the PFP etiology (Kim & Song, 2012;Pal et al, 2010;Patil, Dixon, White, Jones, & Hui, 2011; Uliam Kuriki, Mícolis de Azevedo, de Faria Negrão Filho, & Alves, 2011). On the other hand, frequency domain parameters have been currently used in studies with PFPS and promising results have been shown (Briani et al, 2015;Ferrari et al, 2014).…”