Electromyographyc activity of the vastus medialis oblique muscle in female patients with patellofemoral syndrome

Abstract

The patellofemoral pain syndrome (PFPS) is among the most common knee pathologies. Although its etiology is not fully known, a dysfunction of the vastus medialis oblique (VMO) muscle has been pointed out as a possible cause. This study aimed at assessing, by means of electromyography, whether one or more, among ten usual resisted exercises, might produce VMO selective activation, in view of its clinic application. Twenty female volunteers, ten with PFPS (aged 24.7±4.35) and ten healthy ones (aged 22.5±1.58) were submitted to electromyographic evaluation of VMO, vastus lateralis longus and vastus lateralis oblique (VLO) muscles during ten exercises, including open and closed kinetic chain, at different degrees of knee flexion and of hip positions. None of the exercises showed to be selective for VMO activation, but some showed selective activation of the VLO. In the PFPS group all vastii showed lesser electromyographic activity than control group, in eight of the ten exercises; the VMO/VLO ratio was also lower (0.63) in PFPS group than in control (0.82, p<0.05). Although none of the proposed exercises showed efficient to promote VMO selective activation, squatting on one foot, with medial and lateral tibia rotation, seemed appropriate for treating PFPS.