Supplemented amino acids may enhance the walking recovery of elderly subjects after hip fracture surgery

Interventions to improve outdoor mobility among people living with disabilities: A systematic review

Background

Around 15% of the global population live with some form of disabilities and experience worse health outcomes, less participation in the community and are part of fewer activities outside the home. Outdoor mobility interventions aim to improve the ability to move, travel and orient outside the home and could influence the number of activities outside the home, participation and quality of life. However, outdoor mobility interventions may also lead to harm like falls or injuries or have unforeseen effects which could lead to mortality or hospitalization.

Objectives

To assess the efficacy of interventions aiming to improve outdoor mobility for adults living with disabilities and to explore if the efficacy varies between different conditions and different intervention components.

Search Methods

Standard, extensive Campbell search methods were used, including a total of 12 databases searched during January 2023, including trial registries.

Selection Criteria

Only randomized controlled trials were included, focusing on people living with disabilities, comparing interventions to improve outdoor mobility to control interventions as well as comparing different types of interventions to improve outdoor mobility.

Data Collection and Analysis

Standard methodological procedures expected by Campbell were used. The following important outcomes were 1. Activity outside the home; 2. Engagement in everyday life activities; 3. Participation; 4. Health-related Quality of Life; 5. Major harms; 6. Minor harms. The impact of the interventions was evaluated in the shorter (≤6 months) and longer term (≥7 months) after starting the intervention. Results are presented using risk ratios (RR), risk difference (RD), and standardized mean differences (SMD), with the associated confidence intervals (CI). The risk of bias 2-tool and the GRADE-framework were used to assess the certainty of the evidence.

Main Results

The screening comprised of 12.894 studies and included 22 studies involving 2.675 people living with disabilities and identified 12 ongoing studies. All reported outcomes except one (reported in one study, some concerns of bias) had overall high risk of bias. Thirteen studies were conducted in participants with disabilities due to stroke, five studies with older adults living with disabilities, two studies with wheelchair users, one study in participants with disabilities after a hip fracture, and one study in participants with cognitive impairments. Skill training interventions versus control interventions (16 studies) The evidence is very uncertain about the benefits and harms of skill training interventions versus control interventions not aimed to improve outdoor mobility among all people living with disabilities both in the shorter term (≤6 months) and longer term (≥7 months) for Activity outside the home; Participation; Health-related Quality of Life; Major harms; and Minor harms, based on very low certainty evidence. Skill training interventions may improve engagement in everyday life activities among people with disabilities in the shorter term (RR: 1.46; 95% CI: 1.16 to 1.84; I 2 = 7%; RD: 0.15; 95% CI: -0.02 to 0.32; I 2 = 71%; 692 participants; three studies; low certainty evidence), but the evidence is very uncertain in the longer term, based on very low certainty evidence. Subgroup analysis of skill training interventions among people living with disabilities due to cognitive impairments suggests that such interventions may improve activity outside the home in the shorter term (SMD: 0.44; 95% CI: 0.07 to 0.81; I 2 = NA; 118 participants; one study; low certainty evidence). Subgroup analysis of skill training interventions among people living with cognitive impairments suggests that such interventions may improve health-related quality of life in the shorter term (SMD: 0.49; 95% CI: 0.12 to 0.88; I 2 = NA; 118 participants; one study; low certainty evidence). Physical training interventions versus control interventions (five studies) The evidence is very uncertain about the benefits and harms of physical training interventions versus control interventions not aimed to improve outdoor mobility in the shorter term (≤6 months) and longer term (≥7 months) for: Engagement in everyday life activities; Participation; Health-related Quality of Life; Major harms; and Minor harms, based on very low certainty evidence. Physical training interventions may improve activity outside the home in the shorter (SMD: 0.35; 95% CI: 0.08 to 0.61; I 2 = NA; 228 participants; one study; low certainty evidence) and longer term (≥7 months) (SMD: 0.27; 95% CI: 0.00 to 0.54; I 2 = NA; 216 participants; one study; low certainty evidence). Comparison of different outdoor mobility interventions (one study) The evidence is very uncertain about the benefits and harms of outdoor mobility interventions of different lengths in the shorter term (≤6 months) and longer term (≥7 months) for Activity outside the home; Engagement in everyday life activities; Participation; Health-related Quality of Life; Major harms; and Minor harms, based on very low certainty evidence. No studies explored the efficacy of other types of interventions.

Authors’ Conclusions

Twenty-two studies of interventions to improve outdoor mobility for people living with disabilities were identified, but the evidence still remains uncertain about most benefits and harms of these interventions, both in the short- and long term. This is primarily related to risk of bias, small underpowered studies and limited reporting of important outcomes for people living with disabilities. For people with disabilities, skill training interventions may improve engagement in everyday life in the short term, and improve activity outside the home and health-related quality of life for people with cognitive impairments in the short term. Still, this is based on low certainty evidence from few studies and should be interpreted with caution. One study with low certainty evidence suggests that physical training interventions may improve activity outside the home in the short term. In addition, the effect sizes across all outcomes were considered small or trivial, and could be of limited relevance to people living with disabilities. The evidence is currently uncertain if there are interventions that can improve outdoor mobility for people with disabilities, and can improve other important outcomes, while avoiding harms. To guide decisions about the use of interventions to improve outdoor mobility, future studies should use more rigorous design and report important outcomes for people with disabilities to reduce the current uncertainty.

The Role of Amino Acid Supplementation in Orthopaedic Surgery

The nutritional status of patients undergoing orthopaedic surgery has started to garner increasing attention in published literature. Notable previous evidence has demonstrated the negative effect of malnutrition on outcomes after orthopaedic procedures. Although there has been increased recognition of malnutrition as a risk factor for suboptimal outcomes, the use of nutritional supplementation to mitigate those risks is not well understood. The purpose of this review of most current literature on the topic is to introduce and elucidate the role of amino acid supplementation as a countermeasure to muscle loss and improvement of nutritional status in orthopaedic patients to improve results and outcomes after orthopaedic surgery.

Nutrition in Surgery: An Orthopaedic Perspective

➤ Malnutrition is common among subsets of patients undergoing orthopaedic surgery and is associated with an increased risk of postoperative complications.➤ Serum proteins, in particular, albumin, may be used in the evaluation of nutritional status.➤ Anthropometric measurements and surveys also play a role in the evaluation of nutritional status.➤ Increased energy and nutrient requirements due to surgical procedures necessitate increased caloric and protein intake in the perioperative period, which may be achieved through diet or supplementation.➤ Evidence supports the use of protein-calorie, amino acid, and immunonutrition supplements. Vitamin D supplementation is an area of further consideration.➤ Diet restriction, activity alterations, pharmacotherapy, and bariatric surgery are all safe, effective approaches to weight loss, although the optimal timing and magnitude of preoperative weight loss require further investigation.

International Society of Sports Nutrition Position Stand: Effects of essential amino acid supplementation on exercise and performance

Position Statement: The International Society of Sports Nutrition (ISSN) presents this position based on a critical examination of literature surrounding the effects of essential amino acid (EAA) supplementation on skeletal muscle maintenance and performance. This position stand is intended to provide a scientific foundation to athletes, dietitians, trainers, and other practitioners as to the benefits of supplemental EAA in both healthy and resistant (aging/clinical) populations. EAAs are crucial components of protein intake in humans, as the body cannot synthesize them. The daily recommended intake (DRI) for protein was established to prevent deficiencies due to inadequate EAA consumption. The following conclusions represent the official position of the Society: 1. Initial studies on EAAs' effects on skeletal muscle highlight their primary role in stimulating muscle protein synthesis (MPS) and turnover. Protein turnover is critical for replacing degraded or damaged muscle proteins, laying the metabolic foundation for enhanced functional performance. Consequently, research has shifted to examine the effects of EAA supplementation - with and without the benefits of exercise - on skeletal muscle maintenance and performance. 2. Supplementation with free-form EAAs leads to a quick rise in peripheral EAA concentrations, which in turn stimulates MPS. 3. The safe upper limit of EAA intake (amount), without inborn metabolic disease, can easily accommodate additional supplementation. 4. At rest, stimulation of MPS occurs at relatively small dosages (1.5-3.0 g) and seems to plateau at around 15-18 g. 5. The MPS stimulation by EAAs does not require non-essential amino acids. 6. Free-form EAA ingestion stimulates MPS more than an equivalent amount of intact protein. 7. Repeated EAA-induced MPS stimulation throughout the day does not diminish the anabolic effect of meal intake. 8. Although direct comparisons of various formulas have yet to be investigated, aging requires a greater proportion of leucine to overcome the reduced muscle sensitivity known as "anabolic resistance." 9. Without exercise, EAA supplementation can enhance functional outcomes in anabolic-resistant populations. 10. EAA requirements rise in the face of caloric deficits. During caloric deficit, it's essential to meet whole-body EAA requirements to preserve anabolic sensitivity in skeletal muscle.

Loss of Muscle Mass and Strength After Hip Fracture: an Intervention Target for Nutrition Supplementation

PURPOSEOF REVIEW

To summarize what is known about the deleterious effect of hip fracture on muscle mass and strength as well as the scientific evidence for post-surgical nutrition supplementation to maintain muscle and improve function.

RECENT FINDINGS

This review provides a discussion of the relationship between muscle mass, strength, and physical function following hip fracture, briefly describes the approaches to measuring lean mass, discusses prevalence of sarcopenia and malnutrition among older men and women with hip fracture, and reviews the effects of essential amino acids on muscle. Loss of muscle mass and strength following hip fracture is substantial with consequences for recovery of functional independence. EAA-based nutrition supplementation, which directly effects muscle, has potential to improve outcomes.

Substantial Loss of Skeletal Muscle Mass Occurs After Femoral Fragility Fracture

BACKGROUND

Femoral fragility fractures in older adults can result in devastating loss of physical function and independence. Skeletal muscle atrophy likely contributes to disability. The purpose of this study was to characterize the change in skeletal muscle mass, investigate the relationship with malnutrition and physical function, and identify risk factors for skeletal muscle loss.

METHODS

Adults ≥65 years of age who were treated with operative fixation of an isolated femoral fragility fracture were enrolled in this multicenter, prospective observational study. Skeletal muscle mass was assessed within 72 hours of admission using multifrequency bioelectrical impedance analysis, which was repeated at 6 weeks, 3 months, and 6 months. Sarcopenia was defined by sex-specific cutoffs for the appendicular skeletal muscle mass index. The Mini Nutritional Assessment was used to measure nutritional status at the time of injury. Physical function was measured using the Patient-Reported Outcomes Measurement Information System (PROMIS) Physical Function domain. Linear mixed models were used to evaluate changes in skeletal muscle mass and PROMIS Physical Function scores over time and to evaluate factors associated with skeletal muscle mass changes.

RESULTS

Ninety participants (74% female) with a mean age of 77.6 ± 9.0 years were enrolled. At the time of injury, 30 (33%) were sarcopenic and 44 (49%) were at risk for malnutrition or had malnutrition. Older age was associated with lower skeletal muscle mass (age of ≥75 versus <75 years: least squares mean [and standard error], -3.3 ± 1.6 kg; p = 0.042). From the time of injury to 6 weeks, participants lost an average of 2.4 kg (9%) of skeletal muscle mass (95% confidence interval [CI] = ‒3.0 to ‒1.8 kg; p < 0.001). This early loss did not recover by 6 months (1.8 kg persistent loss compared with baseline [95% CI = ‒2.5 to ‒1.1 kg]; p < 0.001). Participants with normal nutritional status lost more skeletal muscle mass from baseline to 6 weeks after injury compared with those with malnutrition (1.3 kg more loss [standard error, 0.6 kg]; p = 0.036). A 1-kg decrease in skeletal muscle mass was associated with an 8-point decrease in the PROMIS Physical Function (model parameter estimate, 0.12 [standard error, 0.04]; p = 0.002).

CONCLUSIONS

We found that older adults with femoral fragility fractures lost substantial skeletal muscle mass and physical function. Participants with adequate baseline nutrition actually lost more muscle mass than those who were malnourished, indicating that future investigations of interventions to prevent muscle loss should focus on older adults regardless of nutritional status.

LEVEL OF EVIDENCE

Prognostic Level II . See Instructions for Authors for a complete description of levels of evidence.

Use of Conditionally Essential Amino Acids and the Economic Burden of Postoperative Complications After Fracture Fixation: Results from a Cost Utility Analysis

Objective

To measure the economic impact of conditionally essential amino acids (CEAA) among patients with operative treatment for fractures.

Methods

A decision tree model was created to estimate changes in annual health care costs and quality of life impact due to complications after patients underwent operative treatment to address a traumatic fracture. The intervention of interest was the use of CEAA alongside standard of care as compared to standard of care alone. Patients were required to be aged ≥18 and receive the surgery in a US Level 1 trauma center. The primary outcomes were rates of post-surgical complications, changes in patient quality adjusted life years (QALYs), and changes in cost. Cost savings were modeled as the incremental costs (in 2022 USD) of treating complications due to changes in complication rates.

Results

The per-patient cost of complications under CEAA use was $12,215 compared to $17,118 under standard of care without CEAA. The net incremental cost savings per patient with CEAA use was $4902, accounting for a two-week supply cost of CEAA. The differences in quality-adjusted life years (QALYs) under CEAA use and no CEAA use was 0.013 per person (0.739 vs 0.726). Modeled to the US population of patients requiring fracture fixations in trauma centers, the total value of CEAA use compared to no CEAA use was $316 million with an increase of 813 QALYs per year. With a gain of 0.013 QALYs per person, valued at $150,000, and the incremental cost savings of $4902 resulted in net monetary benefit of $6852 per patient. The incremental cost-effectiveness ratio showed that the use of CEAA dominated standard of care.

Conclusion

CEAA use after fracture fixation surgery is cost saving. Level of Evidence: Level 1 Economic Study.

Conditionally Essential Amino Acid Supplementation Reduces Postoperative Complications and Muscle Wasting After Fracture Fixation: A Randomized Controlled Trial

BACKGROUND

Postoperative complications and substantial loss of physical function are common after musculoskeletal trauma. We conducted a prospective randomized controlled trial to assess the impact of conditionally essential amino acid (CEAA) supplementation on complications and skeletal muscle mass in adults after operative fixation of acute fractures.

METHODS

Adults who sustained pelvic and extremity fractures that were indicated for operative fixation at a level-I trauma center were enrolled. The subjects were stratified based on injury characteristics (open fractures and/or polytrauma, fragility fractures, isolated injuries) and randomized to standard nutrition (control group) or oral CEAA supplementation twice daily for 2 weeks. Body composition (fat-free mass [FFM]) was measured at baseline and at 6 and 12 weeks postoperatively. Complications were prospectively collected. An intention-to-treat analysis was performed. The relative risk (RR) of complications for the control group relative to the CEAA group was determined, and linear mixed-effects models were used to model the relationship between CEAA supplementation and changes in FFM.

RESULTS

Four hundred subjects (control group: 200; CEAA group: 200) were enrolled. The CEAA group had significantly lower overall complications than the control group (30.5% vs. 43.8%; adjusted RR = 0.71; 95% confidence interval [CI] = 0.55 to 0.92; p = 0.008). The FFM decreased significantly at 6 weeks in the control subjects (-0.9 kg, p = 0.0205), whereas the FFM was maintained at 6 weeks in the CEAA subjects (-0.33 kg, p = 0.3606). This difference in FFM was not seen at subsequent time points.

CONCLUSIONS

Our results indicate that CEAA supplementation has a protective effect against common complications and early skeletal muscle wasting after operative fixation of extremity and pelvic fractures. Given the potential benefits of this inexpensive, low-risk intervention, multicenter prospective studies in focused trauma populations are warranted.

LEVEL OF EVIDENCE

Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.

Essential amino acid supplementation is associated with reduced serum C-reactive protein levels and improved circulating lymphocytes in post-acute inflamed elderly patients

Background

Persistent systemic inflammation leads to multidistrectual body dysfunctions. Attenuation of inflammation may improve patients’ functional and life prognoses. We hypothesized that essential amino acids (EAAs) given to elderly patients in rehabilitation after acute diseases may be associated with a reduced inflammatory state. Therefore, this retrospective study investigated whether the supplementation of EAAs – modulators of immune competence – was associated with a reduced inflammation rate in elderly patients.

Methods

The medical records of 282 patients admitted to the rehabilitation (rehab) institute after acute index events (surgery or medical diseases) (age: 81.18 ± 8.58 years; females: 67.9%) were analyzed.

Results

46 patients (16.3% of the entire population) had received EAA supplements (S), whereas the remaining 236 patients had not (N-S). Systemic inflammation (I) (serum C-reactive protein (CRP) > 0.5 mg/dL) was present in 67.4% of the I-S group and 57.2% of the I-N-S group. During rehab, the I-S group (but not the I-N-S group) showed a reduction in CRP levels (p = 0.03) and an increase in circulating lymphocytes (p = 0.035), immune cells of the adaptive immune system. C-reactive protein levels remained virtually unchanged in non-inflamed patients who received supplements but increased in non-inflamed patients who did not receive supplements (p = 0.05). Stratified for developed infections, CRP levels reduced in S patients (p = 0.008) but did not in N-S patients.

Conclusion

EAA supplementation was associated with reduced inflammation in both inflamed and infected patients. In addition, EAA supplementation was associated with increased circulating lymphocytes in inflamed patients.

Clinical Practice Guideline for Postoperative Rehabilitation in Older Patients With Hip Fractures

OBJECTIVE

The incidence of hip fractures is increasing worldwide with the aging population, causing a challenge to healthcare systems due to the associated morbidities and high risk of mortality. After hip fractures in frail geriatric patients, existing comorbidities worsen and new complications are prone to occur. Comprehensive rehabilitation is essential for promoting physical function recovery and minimizing complications, which can be achieved through a multidisciplinary approach. Recommendations are required to assist healthcare providers in making decisions on rehabilitation post-surgery. Clinical practice guidelines regarding rehabilitation (physical and occupational therapies) and management of comorbidities/complications in the postoperative phase of hip fractures have not been developed. This guideline aimed to provide evidence-based recommendations for various treatment items required for proper recovery after hip fracture surgeries.

METHODS

Reflecting the complex perspectives associated with rehabilitation post-hip surgeries, 15 key questions (KQs) reflecting the complex perspectives associated with post-hip surgery rehabilitation were categorized into four areas: multidisciplinary, rehabilitation, community-care, and comorbidities/complications. Relevant literature from four databases (PubMed, EMBASE, Cochrane Library, and KoreaMed) was searched for articles published up to February 2020. The evidence level and recommended grade were determined according to the grade of recommendation assessment, development, and evaluation method.

RESULTS

A multidisciplinary approach, progressive resistance exercises, and balance training are strongly recommended. Early ambulation, weigh-bearing exercises, activities of daily living training, community-level rehabilitation, management of comorbidities/complication prevention, and nutritional support were also suggested. This multidisciplinary approach reduced the total healthcare cost.

CONCLUSION

This guideline presents comprehensive recommendations for the rehabilitation of adult patients after hip fracture surgery.

Pre- and Post-Surgical Nutrition for Preservation of Muscle Mass, Strength, and Functionality Following Orthopedic Surgery

Nutritional status is a strong predictor of postoperative outcomes and is recognized as an important component of surgical recovery programs. Adequate nutritional consumption is essential for addressing the surgical stress response and mitigating the loss of muscle mass, strength, and functionality. Especially in older patients, inadequate protein can lead to significant muscle atrophy, leading to a loss of independence and increased mortality risk. Current nutritional recommendations for surgery primarily focus on screening and prevention of malnutrition, pre-surgical fasting protocols, and combating post-surgical insulin resistance, while recommendations regarding macronutrient composition and timing around surgery are less established. The goal of this review is to highlight oral nutrition strategies that can be implemented leading up to and following major surgery to minimize atrophy and the resultant loss of functionality. The role of carbohydrate and especially protein/essential amino acids in combating the surgical stress cascade and supporting recovery are discussed. Practical considerations for nutrient timing to maximize oral nutritional intake, especially during the immediate pre- and post- surgical periods, are also be discussed.

Simultaneous hip and upper-limb fractures are associated with lower Geriatric Nutritional Index scores than isolated hip fractures: a cross-sectional study of 858 women

BACKGROUND AND AIMS

Factors associated with simultaneous fractures at hip and upper limb have scarcely been investigated. Our aim was to assess the association between Geriatric Nutritional Risk Index (GNRI) scores and concurrent upper-limb fractures in women with a fall-related hip fracture.

METHODS

We investigated 858 of 907 women admitted to our Physical and Rehabilitation Medicine ward following a fall-related hip fracture.

RESULTS

GNRI scores were significantly lower in the 41 women with a simultaneous upper-limb fracture than in the 817 with an isolated hip fracture: median (interquartile range) were 85.9 (80.6-94.1) ad 90.3 (83.4-98.0), respectively, in the two groups (p = 0.021). After adjustment for age, height, body mass index, 25-hydroxyvitamin D, parathyroid hormone, femoral-neck bone mineral density, cognitive impairment, neurologic impairment and type of hip fracture we confirmed a significant association between GNRI scores and the concomitant upper-limb fractures (p = 0.001). The adjusted odds ratio for suffering a concomitant fracture was 7.53 (95% CI from 1.79 to 31.72; p = 0.006) for the 190 women of the GNRI lowest class (GNRI score < 82) versus the 213 women of the highest class (GNRI score > 98).

CONCLUSIONS

Data show that GNRI scores were significantly lower in the subgroup of women with hip fracture and concurrent upper-extremity fracture than in the controls with isolated hip fracture. Although caution is needed in interpreting our results due to the cross-sectional design of the study, we suggest that low GNRI scores may have a role in the genesis of the concurrent fractures.

Targeting Multiple Mitochondrial Processes by a Metabolic Modulator Prevents Sarcopenia and Cognitive Decline in SAMP8 Mice

The age-dependent declines of skeletal muscle and cognitive functions often coexist in elderly subjects. The underlying pathophysiological mechanisms share common features of mitochondrial dysfunction, which plays a central role in the development of overt sarcopenia and/or dementia. Dietary supplementation with formulations of essential and branched-chain amino acids (EAA-BCAA) is a promising preventive strategy because it can preserve mitochondrial biogenesis and function. The senescence-accelerated mouse prone 8 (SAMP8) is considered an accurate model of age-related muscular and cognitive alterations. Hence, we aimed to investigate the progression of mitochondrial dysfunctions during muscular and cognitive aging of SAMP8 mice and to study the effects of a novel EAA-BCAA-based metabolic modulator on these changes. We evaluated body condition, motor endurance, and working memory of SAMP8 mice at 5, 9, 12, and 15 months of age. Parallel changes in protein levels of mitochondrial respiratory chain subunits, regulators of mitochondrial biogenesis and dynamics, and the antioxidant response, as well as respiratory complex activities, were measured in the quadriceps femoris and the hippocampus. The same variables were assessed in 12-month-old SAMP8 mice that had received dietary supplementation with the novel EAA-BCAA formulation, containing tricarboxylic acid cycle intermediates and co-factors (PD-0E7, 1.5 mg/kg/body weight/day in drinking water) for 3 months. Contrary to untreated mice, which had a significant molecular and phenotypic impairment, PD-0E7-treated mice showed preserved healthy body condition, muscle weight to body weight ratio, motor endurance, and working memory at 12 months of age. The PD-0E7 mixture increased the protein levels and the enzymatic activities of mitochondrial complex I, II, and IV and the expression of proliferator-activated receptor γ coactivator-1α, optic atrophy protein 1, and nuclear factor, erythroid 2 like 2 in muscles and hippocampi. The mitochondrial amyloid-β-degrading pitrilysin metallopeptidase 1 was upregulated, while amyloid precursor protein was reduced in the hippocampi of PD-0E7 treated mice. In conclusion, we show that a dietary supplement tailored to boost mitochondrial respiration preserves skeletal muscle and hippocampal mitochondrial quality control and health. When administered at the early onset of age-related physical and cognitive decline, this novel metabolic inducer counteracts the deleterious effects of precocious aging in both domains.

Role of dietary protein and exercise on biomarkers of immune activation in older patients during hospitalization

The aim of this study was to examine the effect of short-term protein supplementation (aiming to consume 1.2 g protein/kg body weight per day) combined with moderate resistance training on 3 days of the week on tryptophan-kynurenine metabolism in 40 older patients with hip fracture. Secondary outcomes for physical recovery were hand-grip strength and chair-rise score. Older patients with hip fracture exhibited higher degrees of immune activation, detected by increased neopterin and kynurenine to tryptophan levels compared with reference values for healthy elderly with no significant differences between those who received the exercise-protein intervention compared to the control. Increasing dietary protein intake during hospitalization did not alleviate the Th1-type immune response in the elderly patient. On the other hand, muscularity per se may affect immune activation responses following injury, as improvements in maximum hand-grip strength with the intervention were related to decreases in neopterin levels.

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

Investigate the underlying cellular basis of muscle atrophy (Placebo) and atrophy reduction (essential amino acid supplementation, EAAs) in total knee arthroplasty (TKA) patients by examining satellite cells and other key histological markers of inflammation, recovery, and fibrosis. Forty-one subjects (53-76 yr) scheduled for TKA were randomized into two groups, ingesting 20 g of EAAs or placebo, twice-daily, for 7 days before TKA and for 6 wk after surgery. A first set of muscle biopsies was obtained from both legs before surgery in the operating room, and patients were randomly assigned and equally allocated to have two additional biopsies at either 1 or 2 wk after surgery. Biopsies were processed for gene expression and immunohistochemistry. Satellite cells were significantly higher in patients ingesting 20 g of essential amino acids twice daily for the 7 days leading up to surgery compared with Placebo (operative leg P = 0.03 for satellite cells/fiber and P = 0.05 for satellite cell proportions for Type I-associated cells and P = 0.05 for satellite cells/fiber for Type II-associated cells.) Myogenic regulatory factor gene expression was different between groups, with the Placebo Group having elevated MyoD expression at 1 wk and EAAs having elevated myogenin expression at 1 wk. M1 macrophages were more prevalent in Placebo than the EAAs Group. IL-6 and TNF-α transcripts were elevated postsurgery in both groups; however, TNF-α declined by 2 wk in the EAAs Group. EAAs starting 7 days before surgery increased satellite cells on the day of surgery and promoted a more favorable inflammatory environment postsurgery.NEW & NOTEWORTHY Clinical studies by our group indicate that the majority of muscle atrophy after total knee arthroplasty (TKA) in older adults occurs rapidly, within the first 2 wks. We have also shown that essential amino acid supplementation (EAAs) before and after TKA mitigates muscle atrophy; however, the mechanisms are unknown. These results suggest that satellite cell numbers are elevated with EAA ingestion before surgery, and after surgery, EAA ingestion positively influences markers of inflammation. Combined, these data may help inform further studies designed to address the accelerated sarcopenia that occurs in older adults after major surgery.