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The posterior parietal cortex plays an important role in postural stability by adapting to changes in input from the visual, vestibular, and proprioceptive systems. However, little is known regarding whether transcranial electrical stimulation of the posterior parietal cortex affects reactive postural responses. This study aimed to investigate changes in physical control responses to anodal and cathodal transcranial direct current stimulation and transcranial random noise stimulation of the right posterior parietal cortex using a simultaneous inertial measurement unit. The joint movements of the lower limb of 33 healthy volunteers were measured while standing on a soft-foam surface with eyes closed during various stimulation modalities. These modalities included anodal, cathodal transcranial direct current stimulation, and sham stimulation in Experiment 1, and transcranial random noise and sham stimulations in Experiment 2. The results showed that cathodal stimulation significantly decreased the joint angular velocity in the hip rotation, ankle inversion-eversion, and abduction-adduction directions compared to anodal or sham stimulation in Experiment 1. In contrast, there were no significant differences in physical control responses with transcranial random noise stimulation coeducation in Experiment 2. These findings suggest that transcranial electrical stimulation of the right posterior parietal cortex may modulate physical control responses; however, the effect depends on the stimulus modality.

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BACKGROUND: Medial meniscal extrusion (MME) is the medial displacement of the meniscus, which extends beyond the tibial margin. Studies have shown an association between MME and knee pain and that surgical treatment can reduce the extent of MME. Here, we describe the beneficial effects of physical therapy as a feasible conservative treatment for MME. METHODS: Data of 30 patients with knee osteoarthritis who underwent stretching of the semimembranosus tendon and passive range of motion (ROM) exercises twice a week for 8 weeks were retrospectively analyzed. MME was the measured distance between the medial meniscus and the line connecting the medial borders of the femur and tibia using ultrasound. Ultrasound findings of surrounding tissues, including the deep posterior bundle of the medial collateral ligament (dMCL), were recorded. Additionally, knee extension ROM was measured, and inner knee pain when walking was evaluated using a numerical rating scale. RESULTS: There were significant improvements between the baseline and 8 weeks for MME in the non-weight-bearing position (3.6 ± 0.3 mm vs. 3.0 ± 0.4 mm), MME in the weight-bearing position (4.3 ± 0.4 mm vs. 3.8 ± 0.5 mm), ROM (-12.3° ± 4.1° vs. -3.1° ± 3.8°), and knee pain (7.0 ± 0.9 vs. 1.1 ± 1.4) (each p < 0.001). In almost all cases in which the knee extension ROM improved, the dMCL was bulging at the baseline; after 8 weeks, the dMCL was flattened, suggesting ligament tension on ultrasound imaging. CONCLUSION: Stretching of the semimembranosus tendon and passive ROM exercises may reduce the extent of MME in patients with knee osteoarthritis. The ultrasound findings suggest that improvement in knee extension ROM may have led to the re-acquisition of MCL tension, which may have influenced MME reduction. Therefore, physical therapy may be a feasible conservative treatment for the reduction of MME.

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The ligaments are believed to have a role in stabilizing joints and regulating joint motion. Here, we propose a novel function of the calcaneofibular ligament (CFL), which stabilizes the ankle joint. In human bipedal locomotion, the peroneal muscles maintain mediolateral stability and prevent involuntary ankle inversion. To investigate the functional relationship between the peroneal longus tendon (PLT), brevis tendon (PBT), and CFL, we quantitatively analyzed the positional changes of the tendons by using a contactless three-dimensional optical scan system. Eighteen cadaveric specimens were included in the study. Interestingly, with increased tension of the CFL, the tendons significantly moved toward the lateral direction (P < 0.001), compared with their position when the CFL was detached. The actual lift amount reached 2.0 ± 0.8 mm for the PLT and 1.9 ± 1.0 mm for the PBT. These results strongly suggest that a tensed CFL can lift the peroneal tendons and may act as a "tensioner" for the effective transmission of muscle contraction. This phenomenon contributes to postural control, especially in regaining balance on uneven terrain, and provides a new perspective for the exercise methods or understanding the ankle joint instability due to sprains.

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Objective: Noisy galvanic vestibular stimulation (nGVS) is an effective method for stabilizing posture; however, little is known regarding the detailed muscle activity and joint movement in the standing posture. This study aimed to clarify the changes in the lower limb muscle activity and joint angular velocity by nGVS intervention using the simultaneous assessment method of inertial measurement units and surface electromyography (EMG). Methods: Seventeen healthy participants were assessed for their physical responses under four conditions (standing on a firm surface with eyes-open/eyes-closed, and a foam surface with eyes-open/eyes-closed) without stimulation (baseline) and with stimulation (sham or nGVS). Noise stimuli were applied for 30 s at a level below the perceptual threshold. The body control response was evaluated using EMG activity and angular velocity of the lower limbs. Result: Regarding the change from baseline for each parameter, there was a significant interactive effect of EMG activity in the muscle type × intervention and EMG activity and angular velocity in the condition × intervention. Post hoc analysis revealed that the angular velocity was significantly decreased in the abduction-adduction direction in the standing on a foam surface with eyes-closed condition compared to that with eyes-open in the nGVS intervention. Conclusion: Our results suggest that nGVS altered physical responses in different standing postural conditions. The present study is exploratory and therefore the evidence should be investigated in future studies specifically target those muscle activities and joint motion parameters.

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OBJECTIVES: In post-stroke patients, shifts in the center of gravity may affect joint movement patterns of the paraplegic lower limb during walking. The impact of changes in ankle dorsiflexion angle and trailing limb angle due to slight weight-shifting is unknown. This study aimed to investigate the effect of the abovementioned parameters on gait characteristics measured by trunk acceleration. MATERIALS AND METHODS: During walking, the ankle dorsiflexion angle and trailing limb angle were assessed using two-dimensional motion analysis. Shifts in the center of gravity were assessed to evaluate symmetry, regularity, and sway of trunk movements by calculating the harmonic ratio, autocorrelation coefficient, and root mean square using a wearable trunk accelerometer. RESULTS: Ankle dorsiflexion angle showed a significant negative correlation with the root mean square of the anteroposterior axis (r = -0.460, p = 0.005). Trailing limb angle was significantly correlated with the autocorrelation coefficient of the vertical axis (r = 0.585, p < 0.001) and root mean square of the vertical (r = -0.579, p < 0.001), mediolateral (r = -0.474, p = 0.004), and anteroposterior axes (r = -0.548, p = 0.001). Trailing limb angle was a significant predictor (autocorrelation coefficient vertical axis, p = 0.001; root mean square vertical axis, p = 0.001; mediolateral axis, p = 0.007; anteroposterior axis, p = 0.001). CONCLUSIONS: Trailing limb angle can indicate the acquisition of forward propulsion during walking; an increase in it may contribute to improvements of the regular vertical movement ability and stability of the center of gravity sway.

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Jiggling exercise is a conservative treatment for hip osteoarthritis, which involves continuous shaking of the foot and leg in small oscillations while seated. Previous studies have shown beneficial effects of jiggling exercises for outpatients with advanced- and terminal-stage hip osteoarthritis when performed for longer than 1 year, including increases in joint space width and remission of symptoms. We aimed to use the data from our own treatment to evaluate the short-term impact of intensive jiggling exercises on inpatients with hip osteoarthritis to further examine the clinical utility of this exercise. This retrospective case series study included nine patients (57 ± 12 years) with nine hip joints with advanced- or terminal-stage hip osteoarthritis who performed continuous daily jiggling exercises, beginning from day of hospitalization to 6 months post-discharge. Jiggling exercise was performed seated, using the KENKO YUSURI® automated heel vibrating machine at 3.3-5.0 Hz. The patients were also instructed against weight-bearing during hospitalization. The values of radiographic joint space width and Japanese Orthopaedic Association hip score for pain at hospital admission, discharge, and at the 6-month post-discharge checkup were evaluated. Although the hospitalization period and daily time spent performing the jiggling exercise varied in each case (27-98 days and 2-6 hours, respectively), the joint space width increased in all patients and there was an improvement in the hip pain scores in eight patients. The mean values of the minimum joint space width and hip pain scores at discharge were the highest compared to those at hospital admission and 6 months post-discharge. Our results suggest that intensive jiggling exercise for inpatients with advanced- and terminal-stage hip osteoarthritis leads to earlier improvement in joint space width and pain. Daily jiggling exercise for an adequate duration or in combination with non-weight-bearing practices may be a feasible conservative treatment for hip osteoarthritis.

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[Purpose] To assess the influence of plantar sensory input and task guidance produced by a protrusion on lower limb joint dynamics during gait by changes in muscle activity and two-dimensional motion analysis. The protrusion seals on the soles of the feet, named "Perceptual Stimulus Protrusion" were used in this study. [Participants and Methods] In this study, 40 and 42 healthy adults were recruited for muscle activity and two-dimensional analysis, respectively. In addition to walking without perceptual stimulus protrusion ("Control" condition), the testing conditions included attachment of the protrusion to the heel ("Heel Condition") and the hallucal ("Hallucal Condition"). As task guidance, participants were orally instructed how to walk for each conditions. The muscle activities of the rectus femoris, vastus medialis, tibialis anterior, and medial head of the gastrocnemius were measured. The two-dimensional analysis was compared with the angle of ankle dorsiflexion and plantarflexion, the toe height during the swing phase between the test conditions, respectively. [Results] In the Heel Condition, the tibialis anterior and vastus medialis activity in the stance and swing phases, toe height, and angle of ankle dorsiflexion and plantarflexion increased. In the Hallucal Condition, tibialis anterior activity during the stance and swing phases, gastrocnemius activity during the stance phase, toe height, and angle of ankle plantarflexion increased. [Conclusion] Plantar sensory input and task guidance using perceptual stimulus protrusion influences active motion control. Therefore, the application of this procedure can be expected to support motion guidance, such as gait and load practice.

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The lateral ligament complex of the ankle is involved in a large proportion of ankle sprains. The calcaneofibular ligament (CFL) is often involved in severe injuries. The purpose of this study was to evaluate the anatomical variation and laterality of the CFL to improve our understanding of the mechanisms of CFL-related injuries. This study utilized 110 paired ankles from 55 formalin-fixed Japanese cadavers (33 male and 22 female). The length and width of the CFL and the angle created by the CFL and long axis of the fibula (CF angle) were measured after exposing the CFL by careful dissection from the surrounding tissues. The results revealed that each parameter exhibited a wide range of values and showed unique patterns of frequency distribution, among which only the length was normally distributed. Among the parameters, only the CF angle showed no significant correlation with the other parameters. Analysis of laterality revealed that the mean left CF angle was significantly greater than the value on the opposite side (p < 0.05) and that the values of the bilateral CF angle showed no significant correlation at the individual level. The present results revealed not only detailed information regarding the CFL morphology, but also inter- and intra-individual laterality regarding the CFL traveling angle. It is likely that the differences in the quality and quantity of mechanical stress against each leg may have caused this morphologic laterality of the CFL.

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[Purpose] To study the effect that limbering up of the muscles attached to the pelvis has on muscle strength of the trunk and upper and lower extremities, which are not being exercised, and to investigate the possibilities for clinical application. [Subjects and Methods] A total of 152 healthy adult men. Sthenometry was conducted using a handheld dynamometer to assess the effect of limbering up of the upper gluteus maximus, hamstrings, and internal abdominal oblique muscles attached to thoracolumbar fascia on the trunk and upper and lower extremities. The exercises were slowly performed 20 repetitions. Subjects were divided into AB group (n=49) measuring abdominal and back muscle strength, K group (n=42) measuring knee flexor and extensor strength, and S group (n=61) measuring shoulder flexor and external rotator strength and compared to non-exercising controls. [Results] In the exercise groups, exercising either gluteus maximus or hamstrings significantly increased the strength of abdominal and back muscles; exercising gluteus maximus increased knee extensor strength, and exercising the abdominal internal oblique muscle significantly increased knee flexor strength; and shoulder flexor strength significantly increased after exercising gluteus maximus versus controls. [Conclusion] This may be useful in rehabilitation of injuries to the trunk and upper and lower extremities.