Comparative Analysis on the Effect of Sarcopenia in Patients with Knee Osteoarthritis before and after Total Knee Arthroplasty.

Introduction: Primary sarcopenia is an age-related disease that occurs mainly in older adults, while its possibility of appearance increases with age. Secondary sarcopenia is related to the presence of a disease. At times, studies have implied a connection between various diseases and the appearance of sarcopenia. Due to pain, patients with knee osteoarthritis limit their everyday activities, leading to a decrease in muscle mass and physical function.

Purpose: This study aimed to investigate the impact of the coexistence of sarcopenia and osteoarthritis on patients' rehabilitation and symptoms, such as pain, after total knee arthroplasty, compared with patients with osteoarthritis without sarcopenia.

Methodology: This cross-sectional study material consisted of 20 patients with osteoarthritis, who were hospitalized at Papageorgiou Hospital of Thessaloniki for total knee arthroplasty from November 2021 to April 2022. The patients were evaluated for sarcopenia according to the FNIH criteria. The two groups were asked to complete the KOOS score questionnaire in order to evaluate the condition of their knee in two phases, before surgery and 3 months after surgery.

Results: The two groups, 5 sarcopenic patients and 15 non-sarcopenic, did not show a statistically significant difference in muscle strength measurements. However, the lean mass indices, ALM (15.18 ± 3.98 versus 19.96 ± 3.65, respectively; = 0.023) and ALM/height (5.53 ± 1.40 versus 6.98 ± 0.75, respectively; = 0.007) had significant differences, since the sarcopenic group showed a reduced lean mass, especially in patients with a comorbidity of cancer. Sarcopenic patients showed a smaller increase in KOOS score compared to non-sarcopenic patients before (0.38 ± 0.09 vs. 0.35 ± 0.09, respectively; = 0.312) and after surgery (0.54 ± 0.08 vs. 0.59 ± 0.10, respectively; = 0.909), but without a statistically significant difference. The score increased for both groups, with the time factor playing a greater role than the group.

Conclusions: Both the sarcopenic group and the control group did not show significant differences in their scores for the assessment of the affected limb in any of the two phases while completing the questionnaire. However, there was an improvement in their osteoarthritis symptoms before and after arthroplasty in both groups. Further research with a larger sample and longer recovery time is needed to draw more accurate conclusions and confirm the present results.