SARCOPENIA VERSUS GONARTHROSE:RELATION BETWEEN THE BODY COMPOSITION AND THE STRUCTURAL SEVERITY OF THE KNEE OSTEOARTHRITIS

Background: Sarcopenia is initially defined as the involuntary loss of age-related muscle mass. Body composition has been rarely studied during osteoarthritis. The aim: of this study was to determine the relationship between the body composition and the structural severity of the knee osteoarthritis. Methods: We enrolled 100 patients with knee osteoarthritis of all stages. Lean mass and fat mass were measured by absorptiometry (DXA). The skeletal mass index (SMI) was defined as appendicular lean mass /height squared, and the sarcopenia in our patients was defined according to the International Working Group on Sarcopenia (IWGS) by a threshold lower than 5.67 kg/m 2., Pain and function have been assessed using the WOMAC, and the radiographic severity was evaluated by knee x-rays according to the Kallgren-Lawrence classification. Results: Two groups were defined by severity based on the Kellgren - Lawrence classification mild knee osteoarthritis as group 1 (stage 1 and 2 n = 45) and severe knee osteoarthritis as group 2 (stage 3 and 4 n =55). The mean body fat and lean mass were 39.68±,7.44Kg and 38.89±4.5Kg in group 1 and 2 respectively. The fat and lean mass indices were 15.698±3.07Kg/m2 and 15.66±1.93Kg/m2 respectively. Our study found that sarcopenia is related to the severity of knee osteoarthritis (p<0.001). In univariate analysis and in multivariate analysis, decreased lean mass (sarcopenia) was associated with history of fracture (p <0.05) Sarcopenia was not associated with WOMAC pain. Conclusion: Our study found that the low lean mass index was significantly associated to the radiographic severity of knee OA.