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Jiraporn Sri-on,1 Sommapan Rueanthip,2 Alissara Vanichkulbodee,3 Thitiwan Paksopis,1 Chatbhaudin Chetanasilpin2 1Geriatric Emergency Medicine Unit, The Department of Emergency Medicine, Vajira Hospital, Navamindradhiraj University, Bangkok, Thailand; 2The Department of Emergency Medicine, Vajira Hospital, Navamindradhiraj University, Bangkok, Thailand; 3Ultrasound Emergency Unit, The Department of Emergency Medicine, Vajira Hospital, Navamindradhiraj University, Bangkok, ThailandCorrespondence: Jiraporn Sri-on, Geriatric Emergency Medicine Unit, The Department of Emergency Medicine, Vajira Hospital, Navamindradhiraj University, 681 Samsen road, Dusit, Bangkok, 10300, Thailand, Tel +66 896840010, Email Jiraporn.rew@gmail.comPurpose: This study aimed to determine the validity of ultrasonographic measurement of the rectus femoris muscle (RFM) thickness as a screening tool for low appendicular muscle mass (ASM) to diagnose sarcopenia and to determine the cut-off point of RFM thickness in the Thai population.Patients and methods: We enrolled 857 community-dwelling adults aged 60 years and older who were diagnosed with sarcopenia using the Asian Working Group for Sarcopenia-2019 algorithm. The RFM thickness was measured using ultrasonography and compared with bioelectrical impedance analysis (BIA) data. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were evaluated, and the area under the receiver operating curve (AUROC) was used to determine the accuracy of the test.Results: A total of 857 participants were included in the study. Overall, when the cut-off values of RFM thickness of ≤ 1.1 cm were used for male and ≤ 1 cm for female, the highest sensitivity for sarcopenia diagnosis was 90.9% and specificity was 92.2%. The PPV was 76.6, and the NPV was the highest at 97.3. The highest sensitivity for the diagnosis of severe sarcopenia was 92.5% and specificity was 97.4%. The AUROC of the cut-off point of RFM thickness for the diagnosis of sarcopenia was 0.92 (95% confidence interval [CI], 0.89− 0.94); for severe sarcopenia, it was 0.95 (95% CI, 0.92− 0.98).Conclusion: Measuring RFM thickness using ultrasonography is a feasible and reliable screening test for sarcopenia, and the cut-off values of ≤ 1.1 cm for male and ≤ 1 cm for female showed the highest accuracy for confirming low ASM in the Thai population.Keywords: sarcopenia, rectus femoris muscle, ultrasonography, bioelectrical impedance

Abstract Background Ultrasonography (US) is a feasible and accessible method for the measurement of skeletal muscle mass. This technique presents acceptable intra-rater reliability; however, there are a few reports on its inter-rater reliability. Additionally, relative reliability should equally be inspected to determine the presence of systematic errors. Therefore, this study aimed to investigate the intra- and inter-rater reliabilities and absolute reliability of rectus femoris muscle thickness as measured using US. Methods The participants included in our study comprised 12 healthy young men (26.5 ± 3.9 years. Rectus femoris muscle thickness was measured from the right side of the thigh using US by two trained physical therapists. Inter- and intra-rater reliabilities were determined using the intraclass correlation coefficient (ICC) (1, 1) and ICC (2, 1) methods, respectively. Absolute reliability was evaluated using Bland − Altman analysis. Additionally, we calculated the minimal detectable change at the 95% level of confidence (MDC95). Result According to the results of the Bland − Altman analysis, no fixed or proportional errors were present. The ICC (1, 1) was 0.95, and the ICC (2, 1) was 0.70. The MDC95 values of rectus femoris thickness for the intra- and inter-rater reliabilities were 2.0 mm and 4.3 mm, respectively. Conclusions In our study, intra- and inter-rater reliabilities were measured at “excellent” and “moderate” levels in the healthy individuals based on a previously defined scale. Moreover, we determined the measurement error for quantifying rectus femoris thickness. Therefore, the measurement of rectus femoris thickness using US could be considered applicable in clinical research.

Handheld ultrasound has great potential in resource-limited areas, and can improve healthcare for rural populations. Single-channel ultrasound has been widely used in many clinical ultrasound applications, and optical tracking is considered accurate and reliable. In this study, we developed a 10 MHz lead magnesium niobate–lead titanate (PMN-PT) dual-element ultrasound transducer combined with a miniature optical position tracker, and then measured the rectus femoris of the thigh, upper arm, and cheek muscles. Compared to single-element transducers, dual-element transducers improve the contrast of near-field signals, effectively reduce noise, and are suitable for measuring curved surfaces. The purpose of position tracking is to calculate the location of the ultrasound transducer during the measurement process. By utilizing positioning information, 2D ultrasound imaging can be achieved while maintaining structural integrity. The dual-element ultrasound scanner presented in this study can enable continuous scanning over a large area without a scanning width limitation. The custom-made dual-element ultrasound scanner has the advantage of being a portable, reliable, and low-cost ultrasound device, and is helpful in popularizing medical care for remote villages.

Pyomyositis affecting the muscles around the hip may present with characteristics similar to those bof septic arthritis, which are challenging to diagnose due to their rare and vague presentation. Herein, we present a 35-day-old –male nfant with fever, restriction of hip and right limp movement and magnetic resonance imaging finding indicating rectus femoris pyomyositis.

Background: Cancer-related malnutrition is still unrecognized and undertreated in clinical practice. The morphofunctional assessment of disease-related malnutrition (DRM) is a new approach that focuses on evaluating changes in body composition and function. The aim of this study is to evaluate the prognostic value of classic and emerging assessment of malnutrition at 12-months survival in cancer patients. Methods. We conducted a prospective study on cancer outpatients. Bioelectrical impedance with phase angle (PhA), nutritional ultrasound by rectus femoris cross-sectional area (RFCSA), hand grip strength, and “Timed Up and Go Test” (TUG) were evaluated as predictors of mortality. Results. Fifty-seven patients were included. The non-survivors had lower PhA values than the survivors (4.7° vs. 5.4°; p < 0.001), and we had the same results with RFCSA 2.98 cm2/m2 vs. 4.27 cm2/m2 (p = 0.03). Cut-off points were identified using the ROC (receiver operating characteristic) curves for PhA (≤5.6° cancer patients, ≤5.9° men, ≤5.3° women), RFCSA (≤4.47 cm2/m2 cancer patients, ≤4.47° men, ≤2.73° women) and rectus femoris-Y-axis (RF-Y-axis; ≤1.3 cm cancer patients, ≤1.06 men, ≤1 women). In multivariate logistic regression analysis, we found that high PhA was significantly associated with a lower mortality hazard ratio (HR: 0.42 95% CI: 0.21–0.84, p = 0.014). Likewise, high RFCSA was associated with a decrease in mortality risk in the crude model (HR: 0.61 95% CI: 0.39–0.96, p = 0.031). This trend was also maintained in the adjusted models by the confounding variables. Conclusions. Low PhA and RFCSA values are significant independent predictors of mortality in cancer patients. These cut-off points are clinical data that can be used for nutritional assessment and the prediction of clinical outcomes.

The pendulum test assesses quadriceps spasticity by dropping the lower leg of a relaxed patient from the horizontal position and observing limb movement. The first swing excursion (FS) decreases with increasing spasticity severity. Our recent simulation study suggests that the reduced initial swing results from muscle short-range stiffness and its interaction with reflex hyper-excitability. Short-range stiffness emerges from the thixotropic behavior of muscles where fiber stiffness upon stretch increases when the muscle is held isometric. Fiber stiffness might thus be higher during the first swing of the pendulum test than during consecutive swings. In addition, it has recently been suggested that muscle spindle firing reflects fiber force rather than velocity and therefore, reflex activity might depend on fiber stiffness. If this hypothesized mechanism is true, we expect to observe larger first swing excursions and reduced reflex muscle activity when the leg is moved rather than kept isometric before release, especially in patients with increased reflex activity. We performed the pendulum test in 15 children with cerebral palsy (CP) and 15 age-matched typically developing (TD) children in two conditions. In the hold condition, the leg was kept isometric in the extended position before release. In the movement condition, the leg was moved up and down before release to reduce the contribution of short-range stiffness. Knee kinematics and muscle activity were recorded. Moving the leg before release increased first swing excursion (p < 0.001) and this increase was larger in children with CP (21°) than in TD children (8°) (p < 0.005). In addition, pre-movement delayed reflex onset by 87 ms (p < 0.05) and reduced reflex activity as assessed through the area under the curve of rectus femoris electromyography (p < 0.05) in children with CP. The movement history dependence of pendulum kinematics and reflex activity supports our hypothesis that muscle short-range stiffness and its interaction with reflex hyper-excitability contribute to joint hyper-resistance in spastic CP. Our results have implications for standardizing movement history in clinical tests of spasticity and for understanding the role of spasticity in functional movements, where movement history differs from movement history in clinical tests.

We aimed to uncover which rectus femoris strain injury types affect regional activation within the rectus femoris. The rectus femoris has a region-specific functional role; the proximal region of the rectus femoris contributes more than the middle and distal regions during hip flexion. Although a history of strain injury modifies the region-specific functional role within the rectus femoris, it was not obvious which rectus femoris strain injury types affect regional activation within it. We studied 12 soccer players with a history of rectus femoris strain injury. Injury data were obtained from a questionnaire survey and magnetic resonance imaging. To confirm the region-specific functional role of the rectus femoris, surface multichannel electromyographic signals were recorded. Accordingly, eight legs had a history of central tendon injury, four had a history of myofascial junction injury, and four had a healed strain injury. When the injury was limited to the central tendon, the region-specific functional role disappeared. The region-specific functional role was confirmed when the injury was outside the central part. The neuromuscular function was also inhibited when the longitudinal range of the injured region was long. Our findings suggest that a central tendon injury with a long injury length impairs regional neuromuscular activation of the rectus femoris muscle.

Electromechanical delay (EMD) was described as a time elapsed between first trigger and force output. Various results have been reported based on the measurement method with observed inconsistent results when the trigger is elicited by voluntary contraction. However, mechanomyographic (MMG) sensor placed far away on the skin from the contracting muscle was used to detect muscle fiber motion and excitation-contraction (EC) coupling which may give unreliable results. On this basis, the purpose of this study was to detect EMD during active muscle contraction whilst introducing an ultrafast ultrasound (US) method to detect muscle fiber motion from a certain depth of the muscle. Time delays between onsets of EMG-MMG, EMG-US, MMG-FORCE, US-FORCE and EMG-FORCE were calculated as 20.5 ± 4.73 ms, 28.63 ± 6.31 ms, 19.21 ± 6.79 ms, 30.52 ± 8.85 ms and 49.73 ± 6.99 ms, respectively. Intrarater correlation coefficient (ICC) was higher than MMG when ultrafast US was used for detecton of the Δt EMG-US and Δt US-FORCE, ICC values of 0.75 and 0.70, respectively. Synchronization of the ultrafast ultrasound with EMG and FORCE sensors can reveal reliable and clinically useful results related to the EMD and its components when muscle is voluntarily contracted. With ultrafast US, we detect onset from the certain depth of the muscle excluding the tissues above the muscle acting as a low - pass filter which can lead to inaccurate time detection about the onset of the contracting muscle fibers. With this non-invasive technique, understanding of the muscle dynamics can be fascilitated.