Amino Acid Supplementation May Help Prevent Muscle Wasting After Orthopedic Surgery, but Additional Studies Are Warranted: A Systematic Review of Randomized Clinical Trials

Background: Essential amino acid (EAA) supplementation, including conditionally essential amino acid (CEAA) and branched-chain amino acids (BCAA) supplementation, has been suggested as a mechanism to optimize patient outcomes by counteracting the atrophy associated with orthopedic procedures. Purpose: We sought to investigate the effect of EAA supplementation in the perioperative period on patients undergoing orthopedic and spine surgery, specifically whether it is associated with (1) reductions in postoperative muscle atrophy and (2) improved postoperative function including range of motion, strength, and mobility. Methods: We conducted a systematic review of the literature. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were used, and the protocol was registered in the Prospective Register of Systematic Reviews (PROSPERO) database (CRD42023447774). Studies of interest were prospective, placebo-controlled, randomized clinical trials (RCTs) published between 2002 and 2023 evaluating the impact of EAA supplementation on patients undergoing orthopedic and spine surgery. Results: Ten RCTs evaluating EAA supplementation in trauma, adult reconstruction, and spine surgery were identified; half of these focused on adult reconstruction. The EAA supplementation dose (3.4-20 g), frequency (daily to 3 times per day), and duration (14-49 days) varied widely across studies. Seven studies reported parameters relating to muscle size and/or composition, with 3 studies reporting superior muscle size/composition in patients receiving perioperative EAA supplementation, when compared with controls. Three studies reported favorable mobility outcomes for patients receiving EAA. Meta-analysis was prohibited by variation in measurement and outcome variables across the studies. Conclusions: Pooled data from level I studies supports the use of EAA, BCAA, and CEAA supplementations across several orthopedic subspecialties. However, significant heterogeneity exists in the quantity, duration, and content of EAA administered. Further prospective studies are needed to determine optimal/standardized parameters for supplementation.