The Potential Role of Dietary Intake in Explaining Postoperative Muscle Loss in Total Knee Arthoplasty (TKA)

Post-operative muscle loss has been identified as the greatest contributor to osteoarthritis patients’ long-term strength deficits, explaining 77% of muscle weakness one to three years after total knee arthroplasty (TKA) for the treatment of osteoarthritis in the knee. Essential amino acid supplementation may help reduce atrophy, but other factors could have an equally influential role. Patients’ food intake could likewise affect atrophy, and thus dietary intake must be measured in order to determine whether essential amino acids reduce muscle loss following TKA. Subjects with a minimal dietary intake could exacerbate muscle loss because fasting causes the body to break down skeletal muscle protein to liberate amino acids for use as gluconeogenic precursors in the liver. As a result, individuals with different diets may experience differing degrees of muscle atrophy. This investigation seeks to test the hypothesis that higher rates of muscle atrophy in subject groups could be explained by comparatively poorer dietary intake. For this study, subjects completed a total of three 24-hour food logs before surgery, then two, and six weeks post-TKA. During these periods, bilateral quadriceps muscle volume was determined using magnetic resonance imaging (MRI). Baseline and six-week whole-body dual-energy X-ray (DEXA) scans were also performed to compare changes in lean tissue and fat mass. Data collected indicated there was no significant difference in dietary intake between the control group and treatment group, suggesting that any muscle saved in the treatment group was a result of essential amino acid supplementation.