Study of the electromyographic activity in patellofemoral pain syndrome accompanied by secondary myofascial pain syndrome specifically affecting the popliteus muscle following dry needling: a randomized clinical trial

Objectives: Myofascial pain syndrome in the popliteus muscle may change motor control in the affected and related muscles due to changes in proprioceptive and nociceptive afferents, which can exacerbate patellofemoral pain syndrome. The primary purpose of the current study was to explore the electromyographic activity of the local and proximal muscles of the knee joint in patellofemoral pain syndrome accompanied by secondary myofascial pain syndrome specifically affecting the popliteus muscle following dry needling. Methods: Myofascial pain syndrome in the popliteus muscle may change motor control in the affected and related muscles due to changes in proprioceptive and nociceptive afferents, which can exacerbate patellofemoral pain syndrome. The primary purpose of the current study was to explore the electromyographic activity of the local and proximal muscles of the knee joint in patellofemoral pain syndrome accompanied by secondary myofascial pain syndrome specifically affecting the popliteus muscle following dry needling. Results: During step-up, the onset and offset latencies of the local and proximal muscles of the knee joint, except for the offset latency of the gluteus maximus muscle (p-value=0.162), significantly decreased in the intervention group compared to the control group (p-value<0.046). Additionally, there were no significant differences (p-value>0.116) between the groups in the amplitude ratio of the local and proximal muscles of the knee joint during both step-up and step-down. Conclusions: The present study revealed that dry needling of the popliteus muscle with secondary myofascial pain syndrome associated with patellofemoral pain syndrome constructively modified the local and proximal motor control of the knee joint during step-up.