title: Essential amino acid supplementation in patients following total knee arthroplasty.
abstract: BACKGROUND
  By the year 2030, 3.48 million older U.S. adults are projected to undergo total knee arthroplasty (TKA). Following this surgery, considerable muscle atrophy occurs, resulting in decreased strength and impaired functional mobility. Essential amino acids (EAAs) have been shown to attenuate muscle loss during periods of reduced activity and may be beneficial for TKA patients.
  
  
  METHODS
  We used a double-blind, placebo-controlled, randomized clinical trial with 28 older adults undergoing TKA. Patients were randomized to ingest either 20 g of EAAs (n = 16) or placebo (n = 12) twice daily between meals for 1 week before and 2 weeks after TKA. At baseline, 2 weeks, and 6 weeks after TKA, an MRI was performed to determine mid-thigh muscle and adipose tissue volume. Muscle strength and functional mobility were also measured at these times.
  
  
  RESULTS
  TKA patients receiving placebo exhibited greater quadriceps muscle atrophy, with a -14.3 ± 3.6% change from baseline to 2 weeks after surgery compared with -3.4 ± 3.1% for the EAA group (F = 5.16, P = 0.036) and a -18.4 ± 2.3% change from baseline to 6 weeks after surgery for placebo versus -6.2 ± 2.2% for the EAA group (F = 14.14, P = 0.001). EAAs also attenuated atrophy in the nonoperated quadriceps and in the hamstring and adductor muscles of both extremities. The EAA group performed better at 2 and 6 weeks after surgery on functional mobility tests (all P < 0.05). Change in quadriceps muscle atrophy was significantly associated with change in functional mobility (F = 5.78, P = 0.021).
  
  
  CONCLUSIONS
  EAA treatment attenuated muscle atrophy and accelerated the return of functional mobility in older adults following TKA.
  
  
  BACKGROUND
  Clinicaltrials.gov NCT00760383.
authors.forename: Hans C
authors.initials: HC
authors.lastname: Dreyer
authors.forename: Lisa A
authors.initials: LA
authors.lastname: Strycker
authors.forename: Hilary A
authors.initials: HA
authors.lastname: Senesac
authors.forename: Austin D
authors.initials: AD
authors.lastname: Hocker
authors.forename: Keith
authors.initials: K
authors.lastname: Smolkowski
authors.forename: Steven N
authors.initials: SN
authors.lastname: Shah
authors.forename: Brian A
authors.initials: BA
authors.lastname: Jewett
mesh_terms: D000273:Adipose Tissue / Q000473:pathology; D000368:Aged; D000601:Amino Acids, Essential / Q000008:administration & dosage*; D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects / Q000379:methods* / Q000534:rehabilitation; D019587:Dietary Supplements; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D053580:Muscle Strength; D018482:Muscle, Skeletal / Q000473:pathology / Q000503:physiopathology; D009133:Muscular Atrophy / Q000178:diet therapy / Q000473:pathology / Q000503:physiopathology; D013997:Time Factors
chemical_list: D000601:Amino Acids, Essential