Appendicular Muscle Mass, Thigh Intermuscular Fat Infiltration, and Risk of Fall in Postmenopausal Osteoporotic Elder Women

Cross-sectional area and fat infiltration of the lumbar spine muscles in patients with back disorders: a deep learning-based big data analysis

PURPOSE

Validated deep learning models represent a valuable option to perform large-scale research studies aiming to evaluate muscle quality and quantity of paravertebral lumbar muscles at the population level. This study aimed to assess lumbar spine muscle cross-sectional area (CSA) and fat infiltration (FI) in a large cohort of subjects with back disorders through a validated deep learning model.

METHODS

T2 axial MRI images of 4434 patients (n = 2609 females, n = 1825 males; mean age: 56.7 ± 16.8) with back disorders, such as fracture, spine surgery or herniation, were retrospectively collected from a clinical database and automatically segmented. CSA, expressed as the ratio between total muscle area (TMA) and the vertebral body area (VBA), and FI, in percentages, of psoas major, quadratus lumborum, erector spinae, and multifidus were analyzed as primary outcomes.

RESULTS

Male subjects had significantly higher CSA (6.8 ± 1.7 vs. 5.9 ± 1.5 TMA/VBA; p < 0.001) and lower FI (21.9 ± 8.3% vs. 15.0 ± 7.3%; p < 0.001) than females. Multifidus had more FI (27.2 ± 10.6%; p < 0.001) than erector spinae (22.2 ± 9.7%), quadratus lumborum (17.5 ± 7.0%) and psoas (13.7 ± 5.8%) whereas CSA was higher in erector spinae than other lumbar muscles. A high positive correlation between age and total FI was detected (rs = 0.73; p < 0.001) whereas a negligible negative correlation between total CSA and age was observed (rs =  - 0.24; p < 0.001). Subjects with fractures had lower CSA and higher FI compared to those with herniations, surgery and with no clear pathological conditions.

CONCLUSION

CSA and FI values of paravertebral muscles vary a lot in accordance with subjects' sex, age and clinical conditions. Given also the large inter-muscle differences in CSA and FI, the choice of muscles needs to be considered with attention by spine surgeons or physiotherapists when investigating changes in lumbar muscle morphology in clinical practice.

Lower gastrocnemius muscle stiffness, derived from elastography, is an independent factor for falls in older adults

BACKGROUND AND AIMS

It is well known that components of sarcopenia (i.e., decreased muscle strength and mass) are related to falls in older adults. However, the possible effects of changes in muscle quality on falls have not been identified. This study aimed to evaluate the changes in muscle quality reflected by muscle stiffness derived from shear-wave elastography (SWE) and its association with falls in older adults.

METHODS

A total of 101 geriatric outpatients were included in the study. Assessments of physical performance, muscle strength (handgrip strength), muscle mass (muscle ultrasonography and bioelectrical impedance analysis), and muscle stiffness of the medial head of gastrocnemius (GCM) in relaxation and passive stretching were performed. The history of falls in the previous year was questioned and recorded.

RESULTS

The median (25-75 percentiles) age of participants was 73 (69-77) years, and 66.3% (n = 67) were female. According to fall history, participants were divided into non-fallers and fallers groups, and 72 (71.3%) and 29 (28.7%) participants were in each group, respectively. The median muscle stiffness of (Emean) the GCM in passive stretching was significantly lower in the fallers group (p < 0.001), and it was significantly correlated with the number of falls in the previous year (r: - 0.274, p: 0.010). In regression analyses, the Emean value of GCM in passive stretching was significantly associated with falls independent of confounders (OR: 0.944, 95% CI 0.90-0.98, p = 0.010).

DISCUSSION AND CONCLUSION

This is the first study to reveal the relationship between falls and SWE-defined lower GCM stiffness independently of muscle mass and strength.

Association Between Skeletal Muscle Mass Index and Falls in Patients With Functional Impairment

OBJECTIVE

This study aimed to assess the association between skeletal muscle mass index and falls in patients with functional impairment.

DESIGN

This retrospective cohort study was implemented at a convalescent rehabilitation ward. Patients with no measurement of skeletal muscle mass index and bed-ridden patients were excluded from this study. Patients were dichotomized into the low skeletal muscle mass index group and the high skeletal muscle mass index group. The occurrence of fall was assessed according to skeletal muscle mass index groups.

RESULTS

Of the 327 included patients, 231 (71%) were assigned to the low skeletal muscle mass index group. In total, 66 patients (20%) experienced at least one fall, and a total of 102 falls occurred. The incidence of falls for the low skeletal muscle mass index group was not significantly greater than that for the high skeletal muscle mass index group (4.9 per 1000 patient-days vs. 4.5 per 1000 patient-days, P = 0.9). Low skeletal muscle mass index was not significantly associated with one or more incidents of falls (odds ratio [95% confidence intervals] = 0.6 [0.3-1.17]).

CONCLUSIONS

This study found that skeletal muscle mass index was not significantly associated with falls in patients undergoing convalescent rehabilitation.

Muscle strength and physical performance contribute to and improve fracture risk prediction in older people: A narrative review

Osteoporotic fractures present a major health problem with an increasing prevalence in older people. Fractures are associated with premature mortality, reduced quality of life, subsequent fracture, and increased costs. Hence, it is crucial to identify those at higher risk of fracture. Fracture risk assessment tools incorporated clinical risk factors to improve fracture predictive power over BMD alone. However, fracture risk prediction using these algorithms remains suboptimal, warranting further improvement. Muscle strength and physical performance measurements have been associated with fracture risk. In contrast, the contribution of sarcopenia, the composite condition of low muscle mass, muscle strength and/or physical performance, to fracture risk is unclear. It is uncertain whether this is due to the problematic definition of sarcopenia per se or limitations of the diagnostic tools and cut-off points of the muscle mass component. The recent position statement from the Sarcopenia Definition and Outcomes Consortium confirmed the inclusion of muscle strength and performance in the definition of sarcopenia but not DXA-assessed lean mass. Therefore, clinicians should focus on functional assessment (muscle strength and performance) rather than muscle mass, at least as assessed by DXA, as predictors of fractures. Muscle strength and performance are modifiable risk factors. Resistance exercise improves muscle parameters in the elderly, potentially leading to reduced risk of falls and fractures in the general population and in those who sustained a fracture. Therapists may consider exercise intervention to improve muscle parameters and potentially reduce the risk of fractures. The aim of this review was to explore 1) the contribution of muscle parameters (i.e., muscle mass, strength, and physical performance) to fracture risk in older adults, and 2) the added predictive accuracy of these parameters beyond the existing fracture assessment tools. These topics provide the rationale for investigating strength and physical performance interventions to reduce fracture risk. Most of the included publications showed that muscle mass is not a good predictor of fracture risk, while poor muscle strength and performance are associated with an increased risk of fracture, particularly in men, independent of age, BMD, and other risk factors for fractures. Muscle strength and performance can potentially improve the predictive accuracy in men beyond that obtained by the fracture risk assessment tools, Garvan FRC and FRAX.

Mid-life cyclists preserve muscle mass and composition: a 3D MRI study

Physical activity and a healthy lifestyle are crucial factors for delaying and reducing the effects of sarcopenia. Cycling has gained popularity in the last decades among midlife men. While the cardiovascular benefits of cycling and other endurance exercises have been extensively proved, the potential benefits of lifelong aerobic exercise on muscle health have not been adequately studied. Our aim was to quantify the benefits of cycling in terms of muscle health in middle-aged men, using magnetic resonance imaging. We ran a cross-sectional study involving two groups of middle-aged male adults (mean age 49 years, range 30-65) that underwent Dixon MRI of the pelvis. The groups consisted of 28 physically inactive (PI) and 28 trained recreational cyclists. The latter had cycled more than 7000 km in the last year and have been training for 15 years on average, while the PI volunteers have not practiced sports for an average of 27 years. We processed the Dixon MRI scans by labelling and computing the fat fraction (FF), volume and lean volume of gluteus maximus (GMAX) and gluteus medius (GMED); and measuring the volume of subcutaneous adipose tissue (SAT). We found that the cyclists group had lower FF levels, a measure of intramuscular fat infiltration, compared to the PI group for GMAX (PI median FF 21.6%, cyclists median FF 14.8%, p < 0.01) and GMED (PI median FF 16.0%, cyclists median FF 11.4%, p < 0.01). Cyclists had also larger GMAX and GMED muscles than the PI group (p < 0.01), after normalizing it by body mass. Muscle mass and fat infiltration were strongly correlated with SAT volume. These results suggest that cycling could help preserve muscle mass and composition in middle-aged men. Although more research is needed to support these results, this study adds new evidence to support public health efforts to promote cycling.

Imaging of metabolic and overload disorders in tissues and organs

Metabolic and overload disorders are a heterogeneous group of relatively uncommon but important diseases. While imaging plays a key role in the early detection and accurate diagnosis in specific organs with a pivotal role in several metabolic pathways, most of these diseases affect different tissues as part of a systemic syndromes. Moreover, since the symptoms are often vague and phenotypes similar, imaging alterations can present as incidental findings, which must be recognized and interpreted in the light of further biochemical and histological investigations. Among imaging modalities, MRI allows, thanks to its multiparametric properties, to obtain numerous information on tissue composition, but many metabolic and accumulation alterations require a multimodal evaluation, possibly using advanced imaging techniques and sequences, not only for the detection but also for accurate characterization and quantification. The purpose of this review is to describe the different alterations resulting from metabolic and overload pathologies in organs and tissues throughout the body, with particular reference to imaging findings.

From Sarcopenia to Depressive Symptoms in Elderly: A Path Analysis

BACKGROUND

Sarcopenia is an age-related progressive, generalized skeletal muscle disorder involving the accelerated loss of muscle function and muscle mass. The aim of this study was to assess the complex relationship between sarcopenia, malnutrition, cognitive impairment, physical activity, and depression in the elderly, with the potential role of quality of life as a mediator in these associations.

METHODS

A cross-sectional study was conducted on a sample (n = 298) of elderly patients admitted to Special Hospital for Rehabilitation "Termal", Vrdnik, Serbia. Sarcopenia, the risk for malnutrition, cognitive impairment, physical activity, quality of life, and depressive symptoms were measured by standardized instruments. Additional data included sociodemographic characteristics. Simultaneous assessment of the direct and indirect relationships of all determinants was performed by path analysis.

RESULTS

A total of 40% (n = 120) of the elderly were diagnosed with sarcopenia, and 42.6% had depression symptoms. The risk of malnutrition was present in 23.5%, cognitive impairment in 5.4%, and a low level of physical activity was reported in 26.2% of elderly participants. The mean reported quality of life measured by Sarcopenia and Quality of Life Questionnaire was 60 (on the scale ranging from 0 to 100; where a higher score reflects a higher quality of life). The best-fitted model (χ2/DF = 1.885, NFI = 0.987, CFI = 0.993, GFI = 0.997, RMSEA = 0.055) highlighted the mediating effect of quality of life between sarcopenia, malnutrition, cognitive impairment, lower level of physical activities and depression. According to the model, quality of life was a direct negative predictor of depressive symptoms in the elderly, while malnutrition positively affected depression.

CONCLUSIONS

The presented path model may assist rehabilitation centers in developing strategies to screen for sarcopenia and risk of malnutrition, and promote physical activity in elderly, aiming to prevent their negative effects on mental health. For the elderly currently affected by sarcopenia, we consider regenerative medicine and stem cell therapy, which, in view of their etiology, could be a potential therapeutic strategy for sarcopenia.

Fatty infiltration of hip muscles and trochanteric soft tissue thickness are associated with hip fractures in the elderly

PURPOSE

Apart from bone conditions, muscle and soft tissue parameters might also influence hip fractures. We aimed to evaluate the association between hip muscle and trochanteric soft tissue parameters and hip fractures.

METHODS

We retrospectively reviewed 60 patients with hip fractures and 114 controls without hip fractures. Cases and controls were matched for age, sex, and body mass index using propensity score matching. Muscle cross-sectional area (CSA), mean attenuation, and fatty infiltration rate (FIR) (proportion of intramuscular fat content) were measured on CT images for the gluteus maximus, the gluteus medius/minimus, and the anterior and medial compartments of the upper thigh. Trochanteric soft tissue thickness (TSTT) and femoral neck attenuation were also measured. Univariate and multivariate analyses were conducted to identify potential risk factors of hip fractures.

RESULTS

Patients with hip fractures had significantly lower femoral neck attenuation, TSTT, and CSA of the gluteus maximus and anterior compartment than controls. FIR of all hip muscle groups were significantly higher in hip fracture patients than controls. Multivariate analysis revealed that every 1% increase in FIR of medial compartment independently increased the odds of hip fractures by 23.7% (OR = 1.237, 95% CI = 1.093-1.401) and every 1 cm longer TSTT independently decreased the odds by 32.8% (OR = 0.672, 95% CI = 0.477-0.946).

CONCLUSION

Fatty infiltration of hip muscles can better discriminate hip fractures than muscle area. Increased TSTT is independently associated with low fracture risk.

Based on CT at the third lumbar spine level, the skeletal muscle index and psoas muscle index can predict osteoporosis

Background

With the increasing number of studies on osteoporosis and muscle adipose tissue, existing studies have shown that skeletal muscle tissue and adipose tissue are closely related to osteoporosis by dual-energy x-ray absorptiometry (DXA) measurement. However, few studies have explored whether the skeletal muscle and adipose tissue index measured at the lumbar spine 3 (L3) level are closely related to bone mineral density (BMD) and can even predict osteoporosis. Therefore, this study aimed to prove whether skeletal muscle and adipose tissue index measured by computed tomography (CT) images based on a single layer are closely related to BMD.

Methods

A total of 180 participants were enrolled in this study to obtain skeletal muscle index (SMI), psoas muscle index (PMI), subcutaneous fat index (SFI), visceral fat index (VFI), and the visceral-to-subcutaneous ratio of the fat area (VSR) at L3 levels and divide them into osteoporotic and normal groups based on the T-score of DXA. Spearman rank correlation was used to analyze the correlation between SMI, PMI, SFI, VFI, VSR, and BMD. Similarly, spearman rank correlation was also used to analyze the correlation between SMI, PMI, SFI, VFI, VSR, and the fracture risk assessment tool (FRAX). Receiver operating characteristic (ROC) was used to analyze the efficacy of SMI, PMI, SFI, VFI, and VSR in predicting osteoporosis.

Results

BMD of L1-4 was closely correlated with SMI, PMI, VFI and VSR (r = 0.199 p = 0.008, r = 0.422 p < 0.001, r = 0.253 p = 0.001, r = 0.310 p < 0.001). BMD of the femoral neck was only correlated with PMI and SFI (r = 0.268 p < 0.001, r = − 0.164 p-0.028). FRAX (major osteoporotic fracture) was only closely related to PMI (r = − 0.397 p < 0.001). FRAX (hip fracture) was closely related to SMI and PMI (r = − 0.183 p = 0.014, r = − 0.353 p < 0.001). Besides, FRAX (major osteoporotic fracture and hip fracture) did not correlate with VFI, SFI, and VSR. SMI and PMI were statistically significant, with the area under the curve (AUC) of 0.400 (95% confidence interval 0.312-0.488 p = 0.024) and 0.327 (95% confidence interval 0.244-0.410 p < 0.001), respectively. VFI, SFI, and VSR were not statistically significant in predicting osteoporosis.

Conclusions

This study demonstrated that L3-based muscle index could assist clinicians in the diagnosis of osteoporosis to a certain extent, and PMI is superior to SMI in the diagnosis of osteoporosis. In addition, VFI, SFI, and VSR do not help clinicians to diagnose osteoporosis well.

Knee Muscles Composition Using Electrical Impedance Myography and Magnetic Resonance Imaging

We evaluated the correlation of electrical impedance myography (EIM) measurements of knee muscles composition using Skulpt ChiselTM with MRI data retrieved from muscles segmentation. A total of 140 patients (71 females, 52 ± 21 years) underwent knee MRI, EIM with Skulpt®, and clinical evaluation (SARC-F questionnaire). MRIs were reviewed to assess the cross-sectional area (CSA) and skeletal muscle index (SMI = CSA/height2) of vastus medialis, vastus lateralis, biceps, semimembranosus, and sartorius. We tested the correlations of EIM-derived parameters [body fat-percentage (BF%) and muscle quality] with total CSA, CSA of each muscle, SMI, and SARC-F scores (0−10) using Pearson correlation coefficient. We found medium negative correlation of BF% with SMI (r = −0.430, p < 0.001) and total CSA (r = −0.445, p < 0.001), particularly with biceps (r = −0.479, p < 0.001), sartorius (r = −0.440, p < 0.001), and semimembranosus (r = −0.357, p < 0.001). EIM-derived muscle quality showed small-to-medium positive correlation with MRI measurements, ranging from r = 0.234 of biceps (p = 0.006) to r = 0.302 of total CSA (p < 0.001), except for vastus lateralis (r = 0.014, p = 0.873). SARC-F scores showed small correlations with EIM and MRI data, ranging from r = −0.132 (p = 0.121) with EIM muscle quality to r = −0.288 (p = 0.001) with CSA of vastus medialis. Hence, we observed small-to-medium correlations of muscle parameters derived from Skulpt ChiselTM with SARC-F scores and MRI parameters. We recommend using Skulpt ChiselTM with caution for assessing knee skeletal muscles composition.

Interrelationship among thigh intermuscular adipose tissue, cross-sectional area, muscle strength, and functional mobility in older subjects

The aim of this cross-sectional study was to investigate the association between lower limb strength, muscle mass and composition, and balance ability in elders. Thirthy-four older participants (Age: 65.6 ± 4.73 years; male = 10 and female = 24) were assessed for muscle strength (maximal isometric strength of knee extensors and one repetition maximum by leg press, the one repetition maximum [1RM]), balance and gait capacity (Mini-BESTest), body composition by whole-body dual energy x-ray absorptiometry (obtaining Appendicular Skeletal Muscle Mass Index, ASMMI), and magnetic resonance imaging of thigh to evaluate Intermuscular Adipose Tissue (IMAT) and muscle Cross Sectional Area (CSA). Positive correlations between 1RM and ASMMI (rs = 0.64, P < .0001) and thigh CSA (rs = 0.52, P = .0017), but not with thigh IMAT, were found. In addition, significant correlations between knee extensors strength and ASMMI (rs = 0.48, P = .004) and thigh CSA (rs = 0.49, P = .0033) and IMAT (rs = -0.35, P = .043) were observed, whereas no significant correlations between the Mini-BESTest with ASMMI, thigh CSA, and IMAT were observed. Lower limb strength positively correlated with appendicular muscle mass. Further, the maximal isometric strength of knee extensors negatively correlated with thigh IMAT in elderly patients, whereas the dynamic balance ability did not correlate with any of the morphological variables of the muscle (i.e., ASMMI, CSA, and IMAT). A reduced muscle size and strength could affect movement and reduce physical function in older patients. Improving the composition and size of muscle in elder subjects could reduce frailty and risk of falls.

Role of exercise in estrogen deficiency-induced sarcopenia

A decline in estrogen levels during menopause is associated with the loss of muscle mass and function, and it can accelerate sarcopenia. However, with the growing number of postmenopausal women due to the increase in life expectancy, the effects of estrogen on skeletal muscle are not completely understood. This article reviews the relationship between estrogen deficiency and skeletal muscle, its potential mechanisms, including those involving mitochondria, and the effects of exercise on estrogen deficiency-induced skeletal muscle impairment. In particular, mitochondrial dysfunction induced by estrogen deficiency accelerates sarcopenia via mitochondrial dynamics, mitophagy, and mitochondrial-mediated apoptosis. It is well known that exercise training is essential for health, including for the improvement of sarcopenia. This review highlights the importance of exercise training (aerobic and resistance exercise) as a therapeutic intervention against estrogen deficiency-induced sarcopenia.

Sarcopenia: imaging assessment and clinical application

Sarcopenia is a progressive, generalized skeletal muscle disorder characterized by reduction of muscle mass and strength. It is associated with increased adverse outcomes including falls, fractures, physical disability, and mortality, particularly, in elderly patients. Nowadays, sarcopenia has become a specific imaging biomarker able to predict clinical outcomes of patients. Muscle fibre reduction has shown to be an unfavourable pre-operative predictive factor in patients with cancer, and is associated with worse clinical outcomes in terms of postoperative complications, morbidity, mortality, and lower tolerance of chemoradiation therapy. Several imaging modalities, including dual-energy X-ray absorptiometry, CT, MRI, and US can be used to estimate muscle mass and quality to reach the diagnosis of sarcopenia. This article reviews the clinical implications of sarcopenia, how this condition can be assessed through different imaging modalities, and future perspectives of imaging of sarcopenia.