ATTENUATING MUSCLE ATROPHY USING ESSENTIAL AMINO ACID SUPPLEMENTATION BEFORE AND AFTER TOTAL KNEE ARTHROPLASTY

Abstract

C. Policar1, L. Wheary1, M. Barnes1, J. Agtarap1, E. Owen2, T. Kirkpartick2, A. Poluso2, M. Bremer2, L. Strycker3, K. Smolkowski3, B. Lantz4, S. Shah4, C. Mohler4, B. Jewett4, J. Muyskens1, H. Dreyer1 1University of Oregon; 2Slocum Research and Education Foundation; 3Oregon Research Institute;4Slocum Center for Orthopedics and Sports Center, Eugene, OR PURPOSE: The demand for total knee arthroplasty (TKA) is projected to increase nearly seven-fold to 3.4 million surgeries performed annually in the U.S. by 2030. A proof-of-principle report by our group recently showed that essential amino acid (EAA) supplementation before and after TKA was successful in mitigating muscle atrophy after surgery vs.Placebo. The present investigation, conducted with a larger number of subjects having a wider age range (50-80 vs.60-80 y) and under the care of more surgeons, sought to repeat that study. METHODS: Using a double-blind placebo-controlled randomized clinical trial, 39 older adults (age 50-80 y) having TKA were randomized to ingest either 20 g of EAA (n = 19) or Placebo (n = 20) 2x/d between meals for 1 wk before, and 6 wk after TKA. At baseline, 2 wk post-TKA and 6 wk post-TKA, an MRI was obtained to determine mid-thigh muscle and adipose tissue volume; MRI scans were obtained at the Lewis Center for Neuroimaging. RESULTS: At 6 wk post-TKA, quadriceps muscle atrophy was significantly greater in the Placebo group in the operative leg quadriceps (-13.4%±1.9 [M±SE] change from baseline for Placebo vs.-8.5%±2.5 for EAA;p= .033) and in the non-operative leg quadriceps (-7.2%±1.4 change for Placebo vs.-1.5%±1.6 for EAA; p = .014). Similar results were found for the hamstrings, in the operative leg (-12.2%±1.4 change for Placebo vs.-7.4%±2.0 for EAA;p = .036) and in the non-operative leg (-7.5%±1.5 change for Placebo vs.-2.1%±1.3 for EAA;p = .005). Effect sizes (d) were .34, .68, .41, and .67 for operative quadriceps, non-operative quadriceps, operative hamstrings, and non-operative hamstrings, respectively. CONCLUSIONS: Twice-daily ingestion of 20 g of EAA for 7 d before and 42 d after (49 d total) TKA demonstrated muscle-sparing effects in the operative and non-operative quadriceps and hamstrings at 6 wk post-TKA. NIA:R01AG04640