Fig. 2.

Study design. Bilateral biopsies were obtained in the operating room, before total knee arthroplasty (TKA) surgery began, after 7 days of twice-daily ingestion of 20 g of essential amino acid supplement (EAA) or placebo, and at 1 and 2 wk post-TKA (random allocation). Supplements were not taken on the day of surgery, but continued the next day through the end of the trial at 6 wk post-TKA. The rationale for post-TKA biopsy time points was to determine the cell level changes occurring at week 1 and week 2 after TKA, when MRI data from our previously published clinical trial showed that 80% or more of the total muscle atrophy measured at week 6 after TKA. Additionally, the parent study included analysis of functional outcomes, blood analysis, and MRI analysis for 6 wk following surgery, but the results of these measures have been or will be reported in other articles.