Dietary Intake and its Effect on Muscle Atrophy Post Total Knee Arthroplasty

Post-operative muscle loss has been singled out as the greatest contributor to long-term strength deficits, explaining 77% of muscle weakness 1-3 years after total knee arthroplasty (TKA). One possible factor contributing to significant and rapid loss of muscle occurring within two weeks of surgery is reduced dietary intake during which our body breaks down skeletal muscle protein in order to liberate amino acids for use as gluconeogenic precursors in the liver. Therefore, inadequate dietary intake may exacerbate muscle loss following surgery. I hypothesize that subjects who maintain a protein intake ≥ .8g/kg or ≥ 2000 calories a day will experience less muscle atrophy following surgery. For this study, subjects completed a total of three 3-day food logs at baseline, 2 and 6 weeks post-TKA. Furthermore, at these same time points bilateral quadriceps muscle volume was determined using MRI. Also baseline and 6-week whole body DEXA scans were performed to determine changes in lean tissue and fat mass. Our preliminary data show at two weeks following surgery caloric and protein ingestion has decreased. Also there is a 16% decrease in lean muscle mass of the quadriceps two weeks after surgery, and this decrease may be partially explained by insufficient dietary intake.