Association between upper limb muscle quality and knee osteoarthritis in dynapenia: an observational cross-sectional study.

Neurological and skeletal muscle properties are suggested causes of dynapenia. This study aimed to evaluate the relationship between upper limb muscle quality (grip strength/upper extremity muscle mass) and knee osteoarthritis in dynapenia, and to identify dynapenia-associated factors. Elderly individuals who responded to a public call for screening in Wakasa Town, Fukui Prefecture between June 2019 and November 2021 were included. The analysis included 433 participants (304 women aged 76.0 ± 7.1 years). Examination comprised (consecutively) a basic interview, physical function measurement, body composition measurement, and explanation of results. Dynapenia was observed in 67 patients. Binomial logistic regression analysis revealed that age, upper limb muscle quality score, and knee osteoarthritis were independent factors for dynapenia. Receiver operating characteristic analysis of the relationship between dynapenia and upper limb muscle quality showed an area under the curve of 0.806 (95% confidence interval: 0.658-0.953) for men (cut-off value, 14.3 kg/kg) and 0.849 for women (95% confidence interval: 0.858-0.968; cut-off value, 14.0 kg/kg). In conclusion, age, upper limb muscle quality, and knee osteoarthritis were independent factors of dynapenia. We demonstrated that upper limb muscle quality has good accuracy in detecting dynapenia in both men and women.