Cellular and morphological changes with EAA supplementation before and after total knee arthroplasty

Area of Science:

• Muscle physiology and cellular biology
• Sarcopenia and aging research
• Surgical recovery and rehabilitation

Background:

• Muscle atrophy is a significant concern following total knee arthroplasty (TKA), particularly in older adults.
• The cellular mechanisms underlying muscle atrophy and the potential benefits of essential amino acid supplementation (EAAs) remain unclear.
• Rapid muscle loss occurs within the first two weeks after TKA.

Purpose of the Study:

• To investigate the cellular basis of muscle atrophy and atrophy reduction in TKA patients.
• To examine the effects of essential amino acid supplementation (EAAs) on satellite cells and histological markers of inflammation, recovery, and fibrosis.

Main Methods:

• Forty-one patients (53-76 years) scheduled for TKA were randomized to ingest 20g of EAAs or placebo twice daily.
• Supplementation occurred for 7 days before TKA and for 6 weeks after surgery.
• Muscle biopsies were collected before surgery and at 1 or 2 weeks post-surgery for gene expression and immunohistochemistry analysis.

Main Results:

• EAA supplementation significantly increased satellite cells before surgery compared to placebo.
• Gene expression analysis showed differences in myogenic regulatory factors (MyoD, myogenin) between groups post-surgery.
• M1 macrophage prevalence was lower, and TNF-α levels declined faster in the EAA group post-surgery.

Conclusions:

• Pre-surgical EAA supplementation increases satellite cell numbers and promotes a more favorable inflammatory environment post-surgery.
• EAAs may play a crucial role in mitigating muscle atrophy and supporting recovery after TKA.
• These findings provide mechanistic insights into EAA's benefits and inform strategies against post-surgical sarcopenia.