Temporal Activation of Core Muscles and Vasti in Isolated Patellofemoral Osteoarthritis during Stair-Stepping: A Case-Control Study

Background. Patellofemoral osteoarthritis (PF OA) is a leading cause of significant pain and disability of the knee joint. Stair climbing dysfunction is commonly reported in this cohort. Objectives. To compare the temporal muscle activation between females with PF OA and healthy controls during stair ascent and decide whether there is a link between altered core activity and Patellofemoral osteoarthritis. Methods. A comparative observational study was conducted on 31 females with PF OA and 11 healthy ones. The electromyographic onset times of vasti, gluteus medius (GM), multifidus, and transversus abdominus (TrA) muscles were measured during the initiation of the stair ascending task. Results. A non-significant difference was detected between females with PF OA and controls regarding the onset times of all tested muscles except for the multifidus muscle, which significantly delayed activation in the PF OA group. Conclusion. Females with patellofemoral osteoarthritis showed a significantly delayed multifidus activation during ascending stairs which indicated the neuromotor dysfunction of core muscles compared to healthy controls. Core stability may be of clinical significance in managing patients with patellofemoral osteoarthritis. Prospective longitudinal studies are recommended for prioritizing the dysfunction.