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).Conclusion. EAA treatment attenuated muscle atrophy and accelerated the return of functional mobility in older adults following TKA.Trial registration. Clinicaltrials.gov NCT00760383.

Leucine-Enriched Amino Acid Ingestion after Resistance Exercise Prolongs Myofibrillar Protein Synthesis and Amino Acid Transporter Expression in Older Men

“…Collectively, these findings emphasize the importance of sufficient postexercise Leu/protein ingestion as a strategy to enhance the preservation and/or recovery of muscle function in older adults undergoing exercise training or exercise-based therapies for rehabilitation. Indeed, ingestion of an EAA mixture containing 3.6 g of Leu in combination with rehabilitation was shown recently to improve recovery from total knee replacement in older adults (41). However, whether an equivalent dose (Leu content) of intact protein is necessary to sustain MyoPS requires additional investigation (42).…”

p53 and ATF4 mediate distinct and additive pathways to skeletal muscle atrophy during limb immobilization

“…This causes weakness, which in turn delays recovery (2,4). Physical therapy is often employed to enhance recovery of muscle mass and strength but is frequently insufficient for complete recovery (15,43,45,61). Nutritional or pharmacological therapies to prevent muscle atrophy during immobilization would be ideal, but current approaches are often not effective enough to completely prevent muscle atrophy.…”

Tourniquet Use During Knee Replacement Surgery May Contribute to Muscle Atrophy in Older Adults

“…Using MRI, we have measured a 14% reduction in quadriceps volume within 2 weeks of TKA (9). This corresponds to a loss rate of 1% per day.…”

“…This corresponds to a loss rate of 1% per day. In contrast, at 6 weeks after surgery we have measured a total change in quadriceps volume of −18% in the same patients (9). In other words, ~80% of the muscle atrophy occurred within the first 14 days of surgery (Figure 1).…”