Enhanced echo intensity in vastus medialis is associated with worsening of functional disabilities and symptoms in patients with knee osteoarthritis: a 3 years longitudinal study

A cross-sectional study on peroneal muscle echogenicity changes and their effects on balance functions in individuals with chronic ankle instability

This study investigated the relationship between peroneal muscle echogenicity and balance function in individuals with chronic ankle instability (CAI). While prior research has examined peroneal muscle activity, reaction time, and balance, the impact of echogenicity-an indicator of myosteatosis/fibrosis-remained underexplored. Cross-sectional study. Sixty-two adults with CAI were included. Peroneal muscle size, echogenicity, and stiffness were assessed using ultrasound. Dynamic balance was evaluated via the Y balance test (YBT), and static postural control was evaluated during lateral step-down (LSDT) and single-leg stance test (SLST). Eversion strength was assessed with a dynamometer. The relationship between muscle characteristics and balance was assessed using canonical correlation and stepwise linear regression. Individuals with increased peroneal muscle echogenicity had reduced muscle size, poorer eversion strength, and poorer balance. Eversion strength is positively associated with YBT scores across all echogenicity levels and negatively associated with posture parameters during the LSDT in moderate echogenicity. Peroneal longus stiffness was positively associated with YBT in severe echogenicity and posture parameters during the SLST. Increased peroneal muscle echogenicity is associated with poorer eversion strength and stiffness, resulting in poorer balance performance. Improving the peroneal muscle quality may enhance functions in the CAI condition.

Artificial intelligence-based analysis of lower limb muscle mass and fatty degeneration in patients with knee osteoarthritis and its correlation with Knee Society Score

PURPOSE

Lower-limb muscle mass reduction and fatty degeneration develop in patients with knee osteoarthritis (KOA) and could affect their symptoms, satisfaction, expectation and functional activities. The Knee Society Scoring System (KSS) includes patient reported outcome measures, which is widely used to evaluate the status of knee function of KOA. This study aimed to clarify how muscle mass and fatty degeneration of the lower limb correlate with the KSS in patients with KOA.

METHODS

This study included 43 patients with end-stage KOA, including nine males and 34 females. Computed tomography (CT) images of the lower limb obtained for the planning of total knee arthroplasty were utilized. Ten muscle groups were segmented using our artificial-intelligence-based methods. Muscle volume was standardized by dividing by their height squared. The mean CT value for each muscle group was calculated as an index of fatty degeneration. Bivariate analysis between muscle volume or CT values and KSS was performed using Spearman's rank correlation test. Multiple regression analysis was performed, and statistical significance was set at p  < 0.05.

RESULTS

Bivariate analysis showed that the functional activity score was significantly correlated with the mean CT value of all muscle groups except the adductors and iliopsoas. Multiple regression analysis revealed that the functional activities score was significantly associated with the mean CT values of the gluteus medius and minimus muscles and the anterior and lateral compartments of the lower leg (β = 0.42, p = 0.01; β = 0.33, p = 0.038; and β = 0.37, p = 0.014, respectively).

CONCLUSION

Fatty degeneration, rather than muscle mass, in the lower-limb muscles was significantly associated with functional activities score of the KSS in patients with end-stage KOA. Notably, the gluteus medius and minimus and the anterior and lateral compartments of the lower leg are important muscles associated with functional activities.

MRI-based analysis of thigh intramuscular fat and its associations with age, sex, and BMI using data from the osteoarthritis initiative data

The degree of thigh intramuscular fat in individuals without OA is fundamental for distinguishing natural variations in intramuscular fat from pathological changes. The goals of this study were to estimate the degree of thigh intramuscular fat in individuals without radiographic OA or frequent pain and assess the associations of age, sex, and BMI with the degree of intramuscular fat. Individuals without knee or hip radiographic OA, without total knee/hip arthroplasty, and without frequent knee/hip pain were selected from the OAI database (n = 710). Goutallier Grades (GGs) of the quadriceps and hamstring muscles were assessed based on 3 T MR images on a scale from 0 (normal muscle) to 4 (more fat than muscle). The associations between demographic variables and GG outcomes were evaluated using mixed effects models. The most prevalent GGs among the muscles were Grades 1 and 2; Grade 4 was infrequent (< 1%). Greater BMI (p < 0.001) and age (p < 0.001) were each associated with greater GG. Women had greater GG than men (greatest difference in the vastus medialis: coeff. = 0.214, p < 0.001). At lower BMI, women had greater intramuscular fat than men; at higher BMI, men had greater intramuscular fat than women (p = 0.029 for BMI-sex interaction). While individuals without radiographic OA or frequent pain generally had low thigh intramuscular fat, higher BMI and age were associated with greater intramuscular fat, and GGs were greater in women than men. The relationship between BMI and intramuscular fat was sex-dependent. Thus, demographic variables must be considered when evaluating intramuscular fat.

Differences in fatty infiltration in thigh muscles and physical function between people with and without knee osteoarthritis and similar body mass index: a cross-sectional study

BACKGROUND

People with knee osteoarthritis (OA) may have more thigh intermuscular and intramuscular adipose tissue (interMAT and intraMAT, respectively) compared to those without knee OA. Literature has not considered differences in body mass index (BMI) in the context of comparing intraMAT and interMAT between individuals with and without knee OA, matched for BMI (± 1 kg/m²). This study aims to compare interMAT and intraMAT, along with physical function (including knee extension strength), between individuals with and without knee osteoarthritis, matched by BMI.

METHODS

Participants aged ≥ 40 years with symptomatic and radiological knee OA group (grade 2 and 3 on the Kellgren and Lawrence (KL) scale) were included in the affected group, while those with no knee pain and no radiological knee OA changes were included in the unaffected group. No participants were lost to assessment, ensuring complete data analysis for all participants. We used independent t-test and mean difference (95% CI) to compare thigh intraMAT and interMAT volume, self-reported measures (WOMAC questionnaire), physical function measures, and knee extension strength between groups.

RESULTS

Forty-six participants were analyzed (23 in each group). The affected group had significantly higher intraMAT compared to the unaffected group (p < 0.05), but no differences were observed for interMAT. Self-reported outcomes and physical function measures were worse in the affected group, as was knee extension strength.

CONCLUSION

People with knee OA present higher levels of intraMAT and poorer physical function compared to those without knee OA. These findings highlight the need for further research to explore the clinical significance of intraMAT and its potential impact on physical function in this population.

Degeneration of the cartilage quality is correlated with a higher intramuscular fat infiltration of the vastus medialis in older adults with pre-to-mild knee osteoarthritis

PURPOSE

To quantitatively verify whether degeneration in the quality of the medial femoral cartilage is correlated with muscle volume loss and intramuscular adipose tissue (IntraMAT) infiltration in quadriceps using magnetic resonance imaging (MRI).

METHODS

Of the 66 older adult participants ≥60 years old (74.5 ± 6.9 years), 29 were female. All participants were patients with pre-to-mild knee osteoarthritis. Muscle volume and IntraMAT infiltration of the four individual muscles, the rectus femoris (RF), vastus medialis (VM), vastus intermedius, and vastus lateralis were assessed, using proton density-weighted and 2-point Dixon MR images. Based on the MRI T2 mapping, the T2 relaxation times of the weight-bearing surface of the medial femoral cartilage were calculated. Simple linear regression analyses were performed, evaluating the correlations between the T2 relaxation time of the medial femoral cartilage and quadriceps muscle volume and IntraMAT. Multiple linear regression analysis using a stepwise method was performed, determining which indicators of the four individual muscles correlated with cartilage quality degeneration.

RESULTS

Simple linear regression analyses revealed that a longer T2 relaxation time of the medial femoral cartilage was positively correlated with IntraMAT infiltration of the entire quadriceps muscle, RF, and VM, however not with the quadriceps muscle volume. Multiple linear regression analysis revealed that VM IntraMAT was particularly correlated with the extension of T2 relaxation time of the medial femoral cartilage.

CONCLUSIONS

In older adults with pre-to-mild knee osteoarthritis, IntraMAT infiltration of the quadriceps muscles, particularly of the VM was correlated with degeneration in the quality of the medial femoral cartilage.

High expression of transcription factor EGR1 is associated with postoperative muscle atrophy in patients with knee osteoarthritis undergoing total knee arthroplasty

BACKGROUND

Muscle atrophy is a typical affliction in patients affected by knee Osteoarthritis (KOA). This study aimed to examine the potential pathogenesis and biomarkers that coalesce to induce muscle atrophy, primarily through the utilization of bioinformatics analysis.

METHODS

Two distinct public datasets of osteoarthritis and muscle atrophy (GSE82107 and GSE205431) were subjected to differential gene expression analysis and gene set enrichment analysis (GSEA) to probe for common differentially expressed genes (DEGs) and conduct transcription factor (TF) enrichment analysis from such genes. Venn diagrams were used to identify the target TF, followed by the construction of a protein-protein interaction (PPI) network of the common DEGs governed by the target TF. Hub genes were determined through the CytoHubba plug-in whilst their biological functions were assessed using GSEA analysis in the GTEx database. To validate the study, reverse transcriptase real-time quantitative polymerase chain reaction (qRT-PCR), enzyme-linked immunosorbent assay (ELISA), and Flow Cytometry techniques were employed.

RESULTS

A total of 138 common DEGs of osteoarthritis and muscle atrophy were identified, with 16 TFs exhibiting notable expression patterns in both datasets. Venn diagram analysis identified early growth response gene-1 (EGR1) as the target TF, enriched in critical pathways such as epithelial mesenchymal transition, tumor necrosis factor-alpha signaling NF-κB, and inflammatory response. PPI analysis revealed five hub genes, including EGR1, FOS, FOSB, KLF2, and JUNB. The reliability of EGR1 was confirmed by validation testing, corroborating bioinformatics analysis trends.

CONCLUSIONS

EGR1, FOS, FOSB, KLF2, and JUNB are intricately involved in muscle atrophy development. High EGR1 expression directly regulated these hub genes, significantly influencing postoperative muscle atrophy progression in KOA patients.

Clinical Application of Skeletal Muscle Quantity and Quality Assessment Using Bioelectrical Impedance and Ultrasound Images

A decline in muscle strength is a key factor responsible for physical dysfunction in older individuals. Both loss of muscle quantity and quality are associated with muscle strength decline. While the gold standard method for evaluating muscle mass and quality is magnetic resonance imaging, it is not suitable for clinical settings because of the measurement and analysis costs. Bioelectrical impedance analysis (BIA) and B-mode ultrasonography are clinically useful alternatives for skeletal muscle assessment owing to their feasibility and noninvasiveness. The recent advancements in the techniques for BIA and ultrasonography have improved their accuracy in assessing skeletal muscle quantity and quality, making them useful in detecting age-related and disease-specific alterations. This review comprehensively analyzes the advantages of using BIA and ultrasound imaging for assessing skeletal muscle quantity and quality and detecting muscle degeneration. We summarize the recent findings regarding age-related changes in muscle characteristics and the associations of muscle degeneration with physical dysfunction in patients with knee osteoarthritis. Furthermore, we discuss the clinical application of skeletal muscle assessment using BIA and ultrasound for evaluating training effects and exercise prescription.

Association of Muscle Quality and Pain in Adults With Symptomatic Knee Osteoarthritis, Independent of Muscle Strength: Findings From a Cross-Sectional Study

OBJECTIVE

Knee osteoarthritis (OA) is a leading cause of chronic pain in adults and shows wide interindividual variability, with peripheral and central factors contributing to the pain experience. Periarticular factors, such as muscle quality (eg, echo intensity [EI] and shear wave velocity [SWV]), may contribute to knee OA pain; however, the role of muscle quality in OA symptoms has yet to be fully established.

METHODS

Twenty-six adults (age >50 years) meeting clinical criteria for knee OA were included in this cross-sectional study. Quantitative ultrasound imaging was used to quantify EI and SWV in the rectus femoris of the index leg. Pearson correlations followed by multiple linear regression was used to determine associations between muscle quality and pain, controlling for strength, age, sex, and body mass index.

RESULTS

EI and SWV were significantly associated with movement-evoked pain (b = 0.452-0.839, P = 0.024-0.029). Clinical pain intensity was significantly associated with SWV (b = 0.45, P = 0.034), as were pressure pain thresholds at the medial (b = -0.41, P = 0.025) and lateral (b = -0.54, P = 0.009) index knee joint line, adjusting for all covariates. Pain interference was significantly associated with knee extension strength (b = -0.51, P = 0.041).

CONCLUSION

These preliminary findings suggest that EI and SWV may impact knee OA pain and could serve as malleable treatment targets. Findings also demonstrate that muscle quality is a unique construct, distinct from muscle strength, which may impact pain and treatment outcomes. More research is needed to fully understand the role of muscle quality in knee OA.

Sitting vs. supine ultrasound measurements of the vastus medialis: correlations with MRI measurements and age considerations

BACKGROUND

Muscle thickness (MT) and echo intensity (EI) measurements are ultrasound alternatives to magnetic resonance imaging (MRI) for evaluating muscle quantity and quality. The vastus medialis (VM) is a clinically important muscle, and assessment methods that most accurately reflect its quantity and quality are required. This study aimed to examine the correlation between MT and EI measured in the supine and sitting postures with corresponding MRI-measured muscle quantity and quality indices.

METHODS

In total, 134 adults (91 older and 43 young) participated in this study. Ultrasound images of the VM were acquired in the supine and sitting postures, and MT and EI were measured. The cross-sectional area (CSA), muscle volume (MV), and intramuscular adipose tissue (intraMAT) of the VM were evaluated from MRI images using T1-weighted and Dixon methods. Pearson's coefficients were used to quantify the correlation strength amongst pairs of dependent variables. Meng's test was used to test for correlation coefficient differences between the two measurement postures (supine and sitting).

RESULTS

The correlation coefficients amongst MT, CSA, and MV were significantly higher in the sitting posture than in the supine posture. EI measured in the supine and sitting postures correlated significantly with intraMAT, and in young individuals, these correlation coefficients were significantly higher in the sitting posture than in the supine posture.

CONCLUSIONS

These findings suggest that assessment of VM muscle quantity in the sitting posture is superior for young and older individuals, and assessment of VM muscle quality in the sitting posture is most effective in younger individuals.

A higher intramuscular fat in vastus medialis is associated with functional disabilities and symptoms in early stage of knee osteoarthritis: a case-control study

BACKGROUND

The characteristics of muscle degeneration in individual quadriceps in early knee osteoarthritis (OA) and the association of muscle quantity and quality on knee dysfunction remain unclear. This study aimed to clarify the characteristics of muscle degeneration in individual quadriceps muscles in early knee OA and elucidate the association of muscle volume and intramuscular adipose tissue (intraMAT) with knee dysfunction, including functional disabilities, symptoms, and joint morphology.

METHODS

Fifty participants were categorized into early knee OA and healthy control groups. 3.0 T magnetic resonance imaging (MRI) using T1-weighted and Dixon methods and 3D SPACE in the thigh muscle and knee joint regions was performed. Quadriceps muscle volume, intraMAT, and whole-organ MRI score (WORMS) were assessed. The Knee Society Score (KSS) was used to evaluate functional disabilities and knee symptoms. Univariate analysis of variance was conducted with covariates to clarify the differences in muscle volume and intraMAT between the two groups. Multiple linear regression analyses were performed using the KSS function and symptom subcategories and WORMS as dependent variables and muscle volume, intraMAT, and the presence of early knee OA as independent variables, such as potential confounders.

RESULTS

The quadriceps intraMAT, especially in the vastus medialis (VM), was significantly higher in patients with early knee OA than in healthy controls. The VM intraMAT, not muscle volume, was significantly associated with KSS function [B =  - 3.47; 95% confidence interval [CI], - 5.24 to - 1.71; p < 0.001] and symptom scores [B =  - 0.63; 95% CI, - 1.09 to - 0.17; p = 0.008], but not with WORMS.

CONCLUSION

These findings suggest that higher VM intraMAT is characteristic of quadriceps muscle degeneration in early knee OA and its increase is associated with functional disabilities and symptoms.