INTRODUCTION
Osteoarthritis (OA) is one of the most common joint disorders worldwide . The knee is the most common symptomatic joint in osteoarthritis. In epidemiological studies conducted in various regions of the world, it has been reported that 10-30% of people over the age of 65 have symptomatic knee OA (1, 2).
The elderly population is increasing in the world and constitutes the majority of the population, especially in developed countries. As people age, they are more likely to suffer from the problems. The term sarcopenia was first used by Irwin Rosenberg to describe the loss of muscle mass associated with ageing (3). Today sarcopenia is defined as a syndrome characterized by the general and progressive loss of skeletal muscle mass and strength. Sarcopenia contributes to several adverse health outcomes, including loss of mobility and independence, reduced quality of life, fall and fracture risk, frailty, and mortality(3, 4). Many factors contribute to the development of sarcopenia. These include the aging process itself, deficiencies in the optimal diet, immobility / sedentary life, chronic diseases, and the use of many medications (3).
It has been found that the development of sarcopenia is faster in patients with OA, and this has been found to be associated with increased inflammatory cytokines in OA (5). TNF-α and IL-1β play an important role in the increase in protein catabolism, which explains the muscle loss that leads to a decrease in physical activity in individuals with joint pain (6, 7). In this study, the presence of sarcopenia in patients with knee OA is evaluated multidimensionally using clinical, ultrasonographic and biochemical parameters. In this respect, the relation between OA and sarcopenia was aimed to be investigated as well as the most practical, easily accessible and inexpensive method for investigating sarcopenia was aimed to be identified.