Comparison by ultrasound shear wave elastography of toe flexor muscle contraction during MTP flexion exercise and short-foot exercise.

BACKGROUND: The intrinsic foot muscles play an important role in medial longitudinal arch support, as well as several extrinsic foot muscles. While various strength training methods specific to intrinsic foot muscles have been conducted, these exercises are associated with certain concerns regarding their effectiveness and difficulty. We developed a new exercise for the intrinsic muscles (MTP flexion exercise). OBJECTIVE: The aim was to compare the shear modulus of the toe flexors as the muscle contraction activity during MTP flexion and short-foot exercises using ultrasound shear wave elastography. METHODS: Eleven healthy participants were included in this study. The shear modulus of the toe flexor muscles was measured during MTP flexion and short-foot exercises using ultrasound shear wave elastography. The muscle shear modulus was statistically compared between the resting phase, and during the two exercises. RESULTS: The shear modulus during MTP flexion exercise was significantly greater than in the resting phase in the abductor hallucis, flexor hallucis brevis, flexor digitorum brevis, quadratus plantae, and flexor digitorum longus. The flexor digitorum longus showed greater shear modulus during MTP flexion exercise than during short-foot exercise. CONCLUSION: MTP flexion exercise showed equivalent or greater contraction activity in certain intrinsic and extrinsic foot muscles when compared with short-foot exercise. This exercise is considered one of the training options for strengthening the intrinsic muscles of the foot.

Evaluation of the activities of the intrinsic and extrinsic muscles of the foot during toe flexion with or without interphalangeal joint flexion using ultrasound shear wave elastography.

The intrinsic muscles of the foot are important to maintain the arch of the foot and to participate in sports activities. Using ultrasound shear wave elastography, we investigated the effect of different toe flexion methods on the activity of the intrinsic and extrinsic muscles of the foot. The study included 15 healthy adults who performed toe flexion under 2 conditions: with interphalangeal (IP) joint flexion and without IP joint flexion. The applied load during flexion was 500 g. Muscle stiffness was measured in the abductor hallucis, flexor hallucis brevis, flexor digitorum brevis, quadratus plantae, flexor hallucis longus, and flexor digitorum longus muscles using ultrasound shear wave elastography. Muscle stiffness was statistically compared with IP flexion and without IP flexion (P < 0.05). The stiffness of the abductor hallucis (P < 0.0005), flexor hallucis brevis (P = 0.022), and flexor digitorum brevis muscles (P < 0.0005) was significantly greater without IP flexion than with IP flexion. In contrast, the muscle stiffness of the flexor hallucis longus (P = 0.001) and the flexor digitorum longus (P = 0.004) was significantly greater during with IP flexion than without IP flexion. This study shows that the abductor hallucis, flexor hallucis brevis, flexor digitorum brevis muscles are more active during toe flexion without IP flexion. These results suggest that the toe flexion method is important for more effective training of the intrinsic muscles of the foot.

A unique case of high-grade myofibroblastic sarcoma initially presenting with oral symptoms.

High-grade myofibroblastic sarcoma is a rare mesenchymal tumor with a high recurrence and metastatic rate. Few cases of high-grade myofibroblastic sarcomas have been reported. Herein, we report a rare case of undifferentiated, high-grade myofibroblastic sarcoma with an unclear primary site, initially presenting with oral symptoms. High-grade myofibroblastic sarcoma was diagnosed following an excisional biopsy of a gingival tumor. After this excisional biopsy, systemic imaging revealed multiple metastases in the tonsil, lung, liver, kidney, and eye. The patient underwent two cycles of chemotherapy (doxorubicin). During follow-up, the tumor progressed rapidly and metastasized to the skin of the head and neck. The patient expired three months after the initial examination.

Measurement of the median nerve strain within the carpal tunnel using a capacitance-type strain sensor: A cadaver study.

BACKGROUND: Direct and quantitative measurement of median nerve strain within the carpal tunnel has been difficult because of the technical limitations associated with conventional devices. We used capacitive sensors (C-stretch), which are thin and flexible, to measure the median nerve strain within the carpal tunnel. METHODS: We used 12 fresh frozen upper extremity specimens. The transverse carpal ligament was left in situ, and we attached the sensor to the palmar surface of the median nerve to measure the nerve strain at 60 degrees of wrist extension. The sensor measured the median nerve strain at both the carpal tunnel site and the proximal to the carpal tunnel site before and after the carpal tunnel release. The amount of nerve excursion during wrist extension was also measured with the length change of the attached suture by a digital caliper. FINDINGS: The mean median nerve strain within the carpal tunnel [8.07% (95 %CI:7.17-8.97)] was significantly higher than that proximal to the carpal tunnel [5.21% (95 %CI:4.46-5.97)] at the wrist extension. There was no significant difference of the mean nerve excursion within and proximal to the carpal tunnel. The mean nerve strain and excursion were unaffected by carpal tunnel release. INTERPRETATION: These results indicated that wrist extension position might lead to increased strain on the median nerve within the carpal tunnel compared with at the proximal to the carpal tunnel. We believe that the current study might provide new information and help us understand the pathogenesis of carpal tunnel syndrome.

Relationships between flexion strength and dexterity of the toes and physical performance.

BACKGROUND: Toe function is characterised by the strength and dexterity of toe motion. However, previous studies have mostly focused on the importance of toe strength. OBJECTIVE: This study aimed to investigate the relationships between flexion strength and dexterity of the toes and physical performance. METHODS: Twenty healthy participants were included in this study. The flexion force of each toe was measured using a digital force gauge, and the toe dexterity was evaluated using the marble pick-up and rock-paper-scissors tests. These parameters were statistically analysed in relation to physical performance, including repeated side step and balance ability, which was evaluated using centre of pressure (COP) data during single-leg standing, tiptoe standing, and single-leg drop-jumping. RESULTS: A significant correlation was found between the first toe flexion force and the total trajectory length of the COP during one-leg standing and between the time required for marble pick-up and the rock-paper-scissors score and the COP during single-leg drop-jumping. CONCLUSION: The results underscore the importance of flexion strength and dexterity of the toes in human physical performance and the necessity for the evaluation and improvement of both functions.

Tensile load on the flexor digitorum profundus tendon during palmar and lateral blocking exercises: Influence on blocking force and distal interphalangeal joint flexion angle.

STUDY DESIGN: This is a basic science research. INTRODUCTION: Isolating excursion of the flexor digitorum profundus (FDP) in zones I and II is common practice in the current management after flexor tendon repair. During this procedure, the proximal interphalangeal joint is sometimes fully extended with unmeasured external forces at the middle phalanx when the distal interphalangeal joint is actively flexed. PURPOSE OF THE STUDY: The purpose of the study was to investigate the incremental effect of external force with palmar blocking versus lateral blocking and increased angles of flexion on internal tendon forces at the repair site for a safer application of force by the treating therapist. METHODS: Eight human cadaveric fingers were studied. To simulate palmar or lateral finger blocking, a compression force of blocking was applied from 5N (510 grams) to 25N (2,550 grams) on the skin surface of the palmar or the lateral aspect of each of these middle phalanges in 5N increments. The tensile load on the FDP tendon during distal interphalangeal joint flexion from 0° to 60° was measured in 10° increments. RESULTS: During palmar blocking, the tensile load was significantly increased with increases in palmar blocking force. However, no significant increase in the tensile load on the FDP tendon was observed at any lateral blocking. DISCUSSION: Lateral blocking exercise can be performed with less tensile force on the FDP tendon when performing blocking exercise after flexor tendon injury repair. CONCLUSIONS: This study supports the concept that lateral blocking with incremental joint angles allows a safer application of force for the healing tendon.

Effective stretching positions for the posterior shoulder capsule as determined by shear wave elastography.

BACKGROUND: Stretching is often used to prevent and treat posterior shoulder capsule tightness; however, the most effective stretching positions are not clearly defined. The purpose of this study was to identify the stretching positions that specifically applied the greatest passive tension on the posterior shoulder capsule by evaluating the elastic characteristics of posterior capsules and muscles in various stretching positions using ultrasound shear wave elastography (SWE). METHODS: We evaluated 9 fresh-frozen shoulders (mean age 86.6 ± 7.7 years) without osteoarthritis or rotator cuff tears. All posterior shoulder tissues were preserved intact. Shear moduli of the middle and inferior posterior shoulder capsules and the posterior shoulder muscles were evaluated using SWE. We obtained shear modulus measurements in 9 stretching positions using a combination of glenohumeral elevation planes and angles (frontal, sagittal, scapular; -30°, 0°, 30°, 60°, respectively). A 4-Nm torque for shoulder internal rotation or horizontal adduction was applied in each position. We also measured shear moduli in the resting position (0° elevation with neutral shoulder internal/external rotation). We compared the shear moduli of all stretching and resting positions using 1-way repeated measures analysis of variance (P < .05). In addition, we compared the shear modulus in 2 positions (ie, resting and each stretching) among tissues (ie, capsules and muscles) with repeated measures using 2-way analysis of variance (P < .05). RESULTS: Shear modulus values for the middle posterior capsules in "internal rotation at 30° in scapular plane elevation" (28.7 ± 14.3 kPa, P = .01) and in "horizontal adduction at 60° of elevation" (31.1 ± 13.1 kPa, P < .001) were significantly higher than that of the resting position (11.0 ± 7.3 kPa). The shear modulus value for the inferior posterior capsule in "internal rotation at 30° of flexion" was significantly higher than that of the resting position (39.0 ± 17.3 vs. 15.4 ± 13.9 kPa, respectively; P = .004). Additionally, the shear modulus values for the posterior capsules in "internal rotation at 30° in scapular plane elevation and flexion" were significantly higher than that of the posterior shoulder muscles. CONCLUSION: Effective middle posterior shoulder capsule stretching positions were shoulder "internal rotation at 30° of scapular plane elevation" and "horizontal adduction at 60° of elevation." Shoulder "internal rotation at 30° of flexion" was the most effective position for the inferior posterior shoulder capsule. Stretching in these positions could relieve posterior shoulder capsule tightness and contribute to the prevention and treatment of throwing injuries of the shoulder.

Strain measurement of the deep layer of the supraspinatus tendon using fresh frozen cadaver: The influence of shoulder elevation.

BACKGROUND: The shoulder is a uniquely complex large joint. Effective and safe physical therapy efforts towards rehabilitating injured and repaired shoulders requires a thorough understanding of shoulder mechanics from both generalized and very specific perspectives. Numerous biomechanical studies have been published on the shoulder. None of the studies, to our knowledge, considered the strain of the deep layers of the supraspinatus tendon for scapular plane elevation. METHODS: Ten unilateral fresh-frozen human cadaveric specimens were used for the study. Scapular plane angles ranging from -10 to 30 degrees were evaluated for tensile loads, ranging from 0 to 120 Newtons, exerted on the supraspinatus tendon. Strain measurements that specifically targeted the deep layer of the supraspinatus tendon during tensile loading were recorded. FINDINGS: Strains recorded in the supraspinatus deep layer while increasing tendon force of the supraspinatus were significant for isometric gleno-humeral elevation of 30° and 20°. The response of strain to tendon force was less pronounced for 10° or less of gleno-humeral elevation. INTERPRETATION: When performing isometric shoulder exercise regimens, rotator cuff forces and both surface and deep tendon strain, relative to scapular positioning, are relevant and should be considered.

Relationship between shear modulus and passive tension of the posterior shoulder capsule using ultrasound shear wave elastography: A cadaveric study.

Although shear wave elastography (SWE) has been used to indirectly measure passive tension in muscle tissues, it is unknown whether SWE can adequately evaluate passive tension in capsule tissues. This study investigated the relationship between the shear modulus and passive tension in the posterior shoulder capsule using SWE. Ten posterior middle and ten posterior inferior shoulder capsules were dissected from ten fresh-frozen cadavers; humeral head-capsule-glenoid specimens were created from each capsule. The humeral head and glenoid were immobilized with clamps in a custom-built device. Loads (0-400 g, in 25-g increments) were applied to each capsule via a pulley system; elasticity was simultaneously measured using SWE. The elasticity-load relationship of each tested capsule was analyzed by fitting a least-squares regression line to the data. Elasticity change due to creep or hysteresis effects was evaluated by comparing the elastic modulus for a 100-g load during and after the stepwise application of the loads. The observed relationship between the shear modulus and passive capsule tension was highly linear for all twenty tested capsules (p < 0.01). The mean coefficient of determination was 0.882 ±â€¯0.075 and 0.901 ±â€¯0.050 for the posterior middle and posterior inferior capsules, respectively. There was no difference in the shear modulus between the two 100-g load assessments for both the posterior middle (p = 0.205) and posterior inferior capsules (p = 0.161). Thus, SWE is a valid and useful method for indirectly evaluating the change in the passive tension under loading in specific posterior shoulder capsule.

Measurement of strain and tensile force of the supraspinatus tendon under conditions that simulates low angle isometric elevation of the gleno-humeral joint: Influence of adduction torque and joint positioning.

BACKGROUND: Recently, supraspinatus muscle exercise has been reported to treat rotator cuff disease and to recover shoulder function. However, there have been no report on the direct measurement of strain on the supraspinatus tendon during simulated isometric gleno-humeral joint elevation. METHODS: Ten fresh-frozen shoulder specimens with the rotator cuff complex left intact were used as experimental models. Isometric gleno-humeral joint elevation in a sitting position was reproduced with low angle of step-by-step elevation in the scapular plane and strain was measured on the surface layer of the supraspinatus tendon. FINDINGS: In isometric conditions, applied tensile force of the supraspinatus tendon increased significantly with increases in adduction torque on the gleno-humeral joint. Significant increases in the strain on the layer were observed by increase in adduction torque, which were recorded in isometric elevation at -10° and 0°, but little increase in the strain was observed at 10° or greater gleno-humeral elevation. INTERPRETATION: Increased strain on the surface layer of the supraspinatus tendon was observed during isometric gleno-humeral elevation from -10 to 0°. These findings demonstrate a potential risk of inducing overstretching of the supraspinatus tendon during supraspinatus muscle exercise.

Medaka and zebrafish contactin1 mutants as a model for understanding neural circuits for motor coordination.

A spontaneous medaka ro mutant shows abnormal wobbling and rolling swimming behaviors. By positional cloning, we mapped the ro locus to a region containing the gene encoding Contactin1b (Cntn1b), which is an immunoglobulin (Ig)-superfamily domain-containing membrane-anchored protein. The ro mutant had a deletion in the cntn1b gene that introduced a premature stop codon. Furthermore, cntn1b mutants generated by the CRISPR/Cas9 system and trans-heterozygotes of the CRISPR mutant allele and ro had abnormal swimming behavior, indicating that the cntn1b gene was responsible for the ro-mutant phenotype. We also established zebrafish cntn1a and cntn1b mutants by transcription activator-like effector nucleases (TALENs). Zebrafish cntn1b but not cntn1a mutants showed abnormal swimming behaviors similar to those in the ro mutant, suggesting that Cntn1b plays a conserved role in the formation or function of the neural circuits that control swimming in teleosts. Although Cntn1-deficient mice have abnormal cerebellar neural circuitry, there was no apparent histological abnormality in the cerebellum of medaka or zebrafish cntn1b mutants. The medaka cntn1b mutants had defective optokinetic response (OKR) adaptation and abnormal rheotaxis (body positioning relative to water flow). Medaka and zebrafish cntn1b mutants are effective models for studying the neural circuits involved in motor learning and motor coordination.

Evaporation characteristics of ETBE-blended gasoline.

To reduce greenhouse gas emissions, which contribute to global warming, production of gasoline blended with ethyl tert-buthyl ether (ETBE) is increasing annually. The flash point of ETBE is higher than that of gasoline, and blending ETBE into gasoline will change the flash point and the vapor pressure. Therefore, it is expected that the fire hazard caused by ETBE-blended gasoline would differ from that caused by normal gasoline. The aim of this study was to acquire the knowledge required for estimating the fire hazard of ETBE-blended gasoline. Supposing that ETBE-blended gasoline was a two-component mixture of gasoline and ETBE, we developed a prediction model that describes the vapor pressure and flash point of ETBE-blended gasoline in an arbitrary ETBE blending ratio. We chose 8-component hydrocarbon mixture as a model gasoline, and defined the relation between molar mass of gasoline and mass loss fraction. We measured the changes in the vapor pressure and flash point of gasoline by blending ETBE and evaporation, and compared the predicted values with the measured values in order to verify the prediction model. The calculated values of vapor pressures and flash points corresponded well to the measured values. Thus, we confirmed that the change in the evaporation characteristics of ETBE-blended gasoline by evaporation could be predicted by the proposed model. Furthermore, the vapor pressure constants of ETBE-blended gasoline were obtained by the model, and then the distillation curves were developed.