Background <p>The age-related muscle weakness known as dynapenia severely exacerbates functional impairment and disability risk when comorbid with knee osteoarthritis (KOA).The epidemiological profile of this coexisting condition within specific clinical populations remains underexplored. This study aimed to investigate the prevalence and influencing factors of dynapenia among middle-aged and elderly patients with KOA, providing epidemiological evidence for the development of targeted prevention and management strategies.</p> Methods <p>This cross-sectional study employed a convenience sampling approach. Participants were recruited from patients diagnosed with KOA in the outpatient and inpatient departments of three tertiary hospitals in Guangdong Province, China, from December 2023 to September 2024. Investigators collected detailed demographic characteristics and disease-related information from all enrolled patients,and identified dynapenia by measuring handgrip strength (HGS) and muscle mass in patients with KOA.</p> Results <p>Among middle-aged and elderly patients with KOA, 173 individuals had dynapenia, with an overall prevalence rate of 27.03%, indicating that this disease is common in patients with KOA. Binary logistic regression analysis identified that age, education level, diabetes, and gout were closely associated with the occurrence of dynapenia.</p> Conclusions <p>As far as we know, this is one of the earliest studies to specifically investigate the prevalence and influencing factors of dynapenia in middle-aged and elderly patients with KOA. These findings underscore the importance of integrating routine muscle strength assessment into clinical practice, along with targeted interventions involving resistance training, nutritional optimization, and comorbidity management for this population.</p>