Asymmetry in CT Scan Measures of Thigh Muscle 2 Months After Hip Fracture: The Baltimore Hip Studies

Acute Sarcopenia: Mechanisms and Management

BACKGROUND

Acute sarcopenia refers to the swift decline in muscle function and mass following acute events such as illness, surgery, trauma, or burns that presents significant challenges in hospitalized older adults.

METHODS

narrative review to describe the mechanisms and management of acute sarcopenia.

RESULTS

The prevalence of acute sarcopenia ranges from 28% to 69%, likely underdiagnosed due to the absence of muscle mass and function assessments in most clinical settings. Systemic inflammation, immune-endocrine dysregulation, and anabolic resistance are identified as key pathophysiological factors. Interventions include early mobilization, resistance exercise, neuromuscular electrical stimulation, and nutritional strategies such as protein supplementation, leucine, β-hydroxy-β-methyl-butyrate, omega-3 fatty acids, and creatine monohydrate. Pharmaceuticals show variable efficacy.

CONCLUSIONS

Future research should prioritize serial monitoring of muscle parameters, identification of predictive biomarkers, and the involvement of multidisciplinary teams from hospital admission to address sarcopenia. Early and targeted interventions are crucial to improve outcomes and prevent long-term disability associated with acute sarcopenia.

Effects of Multicomponent Home-Based Intervention on Muscle Composition, Fitness, and Bone Density After Hip Fracture

BACKGROUND

Mechanistic factors on the pathway to improving independent ambulatory ability among hip fracture patients by a multicomponent home-based physical therapy intervention that emphasized aerobic, strength, balance, and functional training are unknown. The aim of this study was to determine the effects of 2 different home-based physical therapy programs on muscle area and attenuation (reflects muscle density) of the lower extremities, bone mineral density (BMD), and aerobic capacity.

METHODS

Randomized controlled trial of home-based 16 weeks of strength, endurance, balance, and function exercises (PUSH, n = 19) compared to seated active range-of-motion exercises and transcutaneous electrical neurostimulation (PULSE, n = 18) in community-dwelling adults >60 years of age within 26 weeks of hip fracture.

RESULTS

In PUSH and PULSE groups combined, the fractured leg had lower muscle area and muscle attenuation and higher subcutaneous fat than the nonfractured leg (p < .001) at baseline. At 16 weeks, mean muscle area of the fractured leg was higher in the PUSH than PULSE group (p = .04). Changes in muscle area were not significantly different when compared to the comparative PULSE group. There was a clinically relevant difference in change in femoral neck BMD between groups (p = .05) that showed an increase after PULSE and decrease after PUSH. There were generally no between-group differences in mean VO2peak tests at 16-week follow-up, except the PUSH group reached a higher max incline (p = .04).

CONCLUSIONS

The treatment effects of a multicomponent home-based physical therapy intervention on muscle composition, BMD, and aerobic capacity were not significantly different than an active control intervention in older adults recovering from hip fracture.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT01783704.

Development of soft tissue asymmetry indicators to characterize aging and functional mobility

Introduction: The aging population poses significant challenges to healthcare systems globally, necessitating a comprehensive understanding of age-related changes affecting physical function. Age-related functional decline highlights the urgency of understanding how tissue composition changes impact mobility, independence, and quality of life in older adults. Previous research has emphasized the influence of muscle quality, but the role of tissue composition asymmetry across various tissue types remains understudied. This work develops asymmetry indicators based on muscle, connective and fat tissue extracted from cross-sectional CT scans, and shows their interplay with BMI and lower extremity function among community-dwelling older adults. Methods: We used data from 3157 older adults from 71 to 98 years of age (mean: 80.06). Tissue composition asymmetry was defined by the differences between the right and left sides using CT scans and the non-Linear Trimodal Regression Analysis (NTRA) parameters. Functional mobility was measured through a 6-meter gait (Normal-GAIT and Fast-GAIT) and the Timed Up and Go (TUG) performance test. Statistical analysis included paired t-tests, polynomial fitting curves, and regression analysis to uncover relationships between tissue asymmetry, age, and functional mobility. Results: Findings revealed an increase in tissue composition asymmetry with age. Notably, muscle and connective tissue width asymmetry showed significant variation across age groups. BMI classifications and gait tasks also influenced tissue asymmetry. The Fast-GAIT task demonstrated a substantial separation in tissue asymmetry between normal and slow groups, whereas the Normal-GAIT and the TUG task did not exhibit such distinction. Muscle quality, as reflected by asymmetry indicators, appears crucial in understanding age-related changes in muscle function, while fat and connective tissue play roles in body composition and mobility. Discussion: Our study emphasizes the importance of tissue asymmetry indicators in understanding how muscle function changes with age in older individuals, demonstrating their role as risk factor and their potential employment in clinical assessment. We also identified the influence of fat and connective tissue on body composition and functional mobility. Incorporating the NTRA technology into clinical evaluations could enable personalized interventions for older adults, promoting healthier aging and maintaining physical function.

Acute Sarcopenia after Elective and Emergency Surgery

Sarcopenia is an increasingly recognised condition of loss of muscle mass and function. The European Working Group on Sarcopenia in Older People 2 (EWSOP2) updated their definition in 2018, emphasising the importance of low muscle strength in diagnosis. Acute sarcopenia has been arbitrarily defined as sarcopenia lasting less than 6 months. This review highlights the pathophysiology involved in muscle wasting following surgery, focussing on hormonal factors, inflammation, microRNAs, and oxidative stress. Biomarkers such as GDF-15, IGF-1 and various microRNAs may predict post-surgical muscle loss. The impact of existing sarcopenia on various types of surgery and incident muscle wasting following surgery is also described. The gaps in research found include the need for longitudinal studies looking in changes in muscle strength and quantity following surgery. Further work is needed to examine if biomarkers are replicated in other surgery to consolidate existing theories on the pathophysiology of muscle wasting.

Trunk Muscle Composition 2 Months After Hip Fracture: Findings From the Baltimore Hip Studies

OBJECTIVE

To determine if hip fracture patients would have smaller cross-sectional area (CSA) and lower radiological attenuation (suggesting greater fat infiltration) in all trunk muscles as compared to older adults without hip fractures.

DESIGN

Cross-sectional analysis of computed tomography (CT) scans.

SETTING

Clinical imaging facility.

PARTICIPANTS

Forty-one white participants (19 men, 22 women) from the Baltimore Hip Studies seventh cohort at 2 months postfracture were compared to 693 white participants (424 men, 269 women) from the Health, Aging and Body Composition (Health ABC) study at the year 6 visit (N=734).

INTERVENTION

Not applicable.

MAIN OUTCOME MEASURES

Trunk muscle CSA and attenuation values were obtained from a single 10-mm, axial CT scan completed at the L4-L5 disc space in each participant.

RESULTS

The hip fracture cohort had significantly smaller CSA for all trunk muscles (range: 12.1%-38% smaller) compared to the Health ABC cohort (P<.01), with the exception of the rectus abdominus muscle in men (P=.12). But, hip fracture patients, particularly female patients, had higher attenuation levels (lower intramuscular fat) in all trunk muscles (P<.0001).

CONCLUSIONS

Findings are consistent with atrophy of the trunk muscles in the hip fracture population without a high level of intramuscular fat. Future work should evaluate the role of trunk muscle composition in the functional recovery of older adults after hip fracture.

The Comparative Associations of Ultrasound and Computed Tomography Estimates of Muscle Quality with Physical Performance and Metabolic Parameters in Older Men

Estimates of muscle tissue composition may have greater prognostic value than lean body mass levels regarding health-related outcomes. Ultrasound provides a relatively low cost, safe, and accessible mode of imaging to assess muscle morphology. The purpose of this study was to determine the construct validity of muscle echogenicity as a surrogate measure of muscle quality in a sample of older, predominantly African American (AA) participants. We examined the association of rectus femoris echogenicity with mid-thigh computed tomography (CT) scan estimates of intra- and intermuscular adipose tissue (IMAT), basic metabolic parameters via blood sample analysis, muscle strength, and mobility status. This observational study was conducted at a federal medical center and included 30 community-dwelling men (age, 62.5 ± 9.2; AA, n = 24; Caucasian, n = 6). IMAT estimates were significantly associated with echogenicity (r = 0.73, p < 0.001). Echogenicity and IMAT exhibited similar associations with the two-hour postprandial glucose values and high-density lipoproteins values (p < 0.04), as well as grip and isokinetic (180°/s) knee extension strength adjusted for body size (p < 0.03). The significant relationship between ultrasound and CT muscle composition estimates, and their comparative association with key health-related outcomes, suggests that echogenicity should be further considered as a surrogate measure of muscle quality.