Developing a Novel Prosthetic Hand with Wireless Wearable Sensor Technology Based on User Perspectives: A Pilot Study.

Myoelectric hands are beneficial tools in the daily activities of people with upper-limb deficiencies. Because traditional myoelectric hands rely on detecting muscle activity in residual limbs, they are not suitable for individuals with short stumps or paralyzed limbs. Therefore, we developed a novel electric prosthetic hand that functions without myoelectricity, utilizing wearable wireless sensor technology for control. As a preliminary evaluation, our prototype hand with wireless button sensors was compared with a conventional myoelectric hand (Ottobock). Ten healthy therapists were enrolled in this study. The hands were fixed to their forearms, myoelectric hand muscle activity sensors were attached to the wrist extensor and flexor muscles, and wireless button sensors for the prostheses were attached to each user's trunk. Clinical evaluations were performed using the Simple Test for Evaluating Hand Function and the Action Research Arm Test. The fatigue degree was evaluated using the modified Borg scale before and after the tests. While no statistically significant differences were observed between the two hands across the tests, the change in the Borg scale was notably smaller for our prosthetic hand (p = 0.045). Compared with the Ottobock hand, the proposed hand prosthesis has potential for widespread applications in people with upper-limb deficiencies.

Role of the medial agranular cortex in unilateral spatial neglect.

Unilateral spatial neglect (USN) results from impaired attentional networks and can affect various sensory modalities, such as visual and somatosensory. The rodent medial agranular cortex (AGm), located in the medial part of the forebrain from rostral to caudal direction, is considered a region associated with spatial attention. The AGm selectively receives multisensory input with the rostral AGm receiving somatosensory input and caudal part receiving visual input. Our previous study showed slower recovery from neglect with anterior AGm lesion using the somatosensory neglect assessment. Conversely, the functional differences in spatial attention across the entire AGm locations (anterior, intermediate, and posterior parts) are unknown. Here, we investigated the relationship between the severity of neglect and various locations across the entire AGm in a mouse stroke model using a newly developed program-based analysis method that does not require human intervention. Among various positions of the lesions, the recovery from USN during recovery periods (postoperative day; POD 10-18) tended to be slower in cases with more rostral lesions in the AGm (r = - 0.302; p = 0.028). Moreover, the total number of arm entries and maximum moving speed did not significantly differ between before and after AGm infarction. According to these results, the anterior lesions may slowly recover from USN-like behavior, and there may be a weak association between the AGm infarct site and recovery rate. In addition, all unilateral focal infarctions in the AGm induced USN-like behavior without motor deficits.

Estimation of center of pressure information by smartphone sensors for postural control training.

Postural control training based on physical information is a common rehabilitation training method for patients with movement disorder. This research aims to verify the feasibility of using one smartphone embedded sensors to estimate CoP (Center of Pressure) displacement to take postural control training. We tested the reliability of smartphone sensor by motion capture system based on the following two CoP calculation models: (1) one-link inverted pendulum model; (2) two-link inverted pendulum model. We compared the estimation results with real CoP values measured by force plate. Sway training experiment was conducted under two tasks conditions: feet apart and feet together. The results show that data obtained from smartphone sensors is capable of representing human body CoM (Center of Mass) information. These two models can roughly estimate CoP displacement; and the results suggested that the two-link model performed better than one-link model. The estimation error between smartphone and real value is 0.70 - 2.01 cm in feet apart task and 1.03 - 1.12 cm in feet together task with two-link model.Clinical Relevance- This study verified the performance of smartphone in estimating CoP displacement for postural control training.

Analysis of the Relationship Between Muscle Tones and Abnormal Postures in a Computational Model.

Patients with Parkinson's disease (PD), a neurodegenerative disorder, exhibit a characteristic posture known as a forward flexed posture. Increased muscle tone is suggested as a possible cause of this abnormal posture. For further analysis, it is necessary to measure muscle tone, but the experimental measurement of muscle tone during standing is challenging. The aim of this study was to examine the hypothesis that "In patients with PD, abnormal postures are those with a small sway at increased muscle tones" using a computational model. The muscle tones of various magnitudes were estimated using the computational model and standing data of patients with PD. The postures with small sway at the estimated muscle tones were then calculated through an optimization method. The postures and sway calculated using the computational model were compared to those of patients with PD. The results showed that the differences in posture and sway between the simulation and experimental results were small at higher muscle tones compared to those considered plausible in healthy subjects by the simulations. This simulation result indicates that the reproduced sway at high muscle tones is similar to that of actual patients with PD and that the reproduced postures with small sway locally at high muscle tones in the simulations are similar to those of patients with PD. The result is consistent with the hypothesis, reinforcing the hypothesis.Clinical relevance- This study implies that improving the increased muscle tone in patients with PD may lead to an improved abnormal posture.

Analysis of abnormal posture in patients with Parkinson's disease using a computational model considering muscle tones.

Patients with Parkinson's disease (PD) exhibit distinct abnormal postures, including neck-down, stooped postures, and Pisa syndrome, collectively termed "abnormal posture" henceforth. In the previous study, when assuming an upright stance, patients with PD exhibit heightened instability in contrast to healthy individuals with disturbance, implying that abnormal postures serve as compensatory mechanisms to mitigate sway during static standing. However, limited studies have explored the relationship between abnormal posture and sway in the context of static standing. Increased muscle tone (i.e., constant muscle activity against the gravity) has been proposed as an underlying reason for abnormal postures. Therefore, this study aimed to investigate the following hypothesis: abnormal posture with increased muscle tone leads to a smaller sway compared with that in other postures, including normal upright standing, under the sway minimization criterion. To investigate the hypothesis, we assessed the sway in multiple postures, which is determined by joint angles, including cases with bended hip joints. Our approach involved conducting forward dynamics simulations using a computational model comprising a musculoskeletal model and a neural controller model. The neural controller model proposed integrates two types of control mechanisms: feedforward control (representing muscle tone as a vector) and feedback control using proprioceptive and vestibular sensory information. An optimization was performed to determine the posture of the musculoskeletal model and the accompanied parameters of the neural controller model for each of the given muscle tone vector to minimize sway. The optimized postures to minimize sway for the optimal muscle tone vector of patients with PD were compared to the actual postures observed in these patients. The results revealed that on average, the joint-angle differences between these postures was <4°, which was less than one-tenth of the typical joint range of motion. These results suggest that patients with PD exhibit less sway in the abnormal posture than in other postures. Thus, adopting an abnormal posture with increased muscle tone can potentially serve as a valid strategy for minimizing sway in patients with PD.

Effect of experimentally induced plantar pain on trunk posture during gait.

[Purpose] Plantar pain is associated with the prevalence of low back pain. Therefore, it is reasonable to assume that some kind of physical change should be occurring in the trunk due to plantar pain. However, the physical effect of plantar pain on the trunk remains unknown. We evaluated the effect of plantar pain on trunk posture during gait. [Participants and Methods] Ten healthy volunteers participated in the present study. Participants walked under two conditions: without pain and with pain. In the with pain condition, we set pain-inducing devices to the right foot to induce plantar pain during stance phase. By using 3D motion analysis system, the angles of the head, thorax, and pelvis segments, as well as the neck, trunk, bilateral hip, bilateral knee, and bilateral ankle joints, were measured. We analyzed the angle data throughout the gait cycle by using one-dimensional statistical parametric mapping. [Results] The anterior trunk tilt was observed in the right stance phase. [Conclusion] The anterior trunk tilt observed in the with pain condition may be a burden on the trunk. Our results presented one of the possible reasons for increased prevalence of low back pain in the plantar pain patients.

Effect of Trunk Solution® on hemodynamics in the supplementary motor area during walking.

[Purpose] Humans keep their trunks vertical while walking. This defining characteristic is known as upright bipedalism. Research on the neural control of locomotion indicates that not only subcortical structures, but also the cerebral cortex, especially the supplementary motor area (SMA), is involved in locomotion. A previous study suggested that SMA may contribute to truncal upright posture-control during walking. Trunk Solution® (TS) is a trunk orthosis designed to support the trunk in decreasing the low back load. We hypothesized that the trunk orthosis might reduce the burden of truncal control on the SMA. The objective of this study was, therefore, to determine the effect of trunk orthosis on the SMA during walking. [Participants and Methods] Thirteen healthy participants were enrolled in the study. We measured the hemodynamics of the SMA during walking with functional near-infrared spectroscopy (fNIRS). The participants performed two gait tasks on a treadmill: (A) independent gait (usual gait) and (B) supported gait while wearing the TS. [Results] During (A) independent gait, the hemodynamics of the SMA exhibited no significant changes. During (B) gait with truncal support, the SMA hemodynamics decreased significantly. [Conclusion] TS may reduce the burden of truncal control on the SMA during walking.

Effect of Sway Frequency on the Joint Angle and Center of Pressure in Voluntary Sway.

Voluntary sway is the periodic movement of one's body back and forth. The study aimed to clarify the effects of sway frequency on center of pressure and joint angle during voluntary sway. We measured 10 unrestricted voluntary sway conditions with different frequencies and natural pace conditions. The frequencies ranged from 0.1 to 1 Hz in 0.1-Hz increments. The joint angles and centers of pressure during voluntary sway were compared between the conditions. The joint angle amplitude of the trunk and knee were greater in the slow frequency condition than in the fast frequency condition. The trunk and knee joint angles during voluntary sway were considered to change according to the sway frequency.

Peak vertical ground force of hand-knee crawling in human adults.

[Purpose] Fall risk is immanent in humans because they are bipedal. Bipedalism has transited from quadrupedalism in both evolutional and developmental contexts. Past studies have measured the peak vertical ground force of forelimbs and hindlimbs in quadrupedalism; and revealed that load dominancy shifted from forelimbs to hindlimbs during evolution. The dominance of hindlimb peak vertical ground force allows forelimb freedom and is considered important for locomotor evolution toward bipedalism. With this consideration, we hypothesize that hindlimb peak vertical ground force is dominant in human adults when they designedly crawl in a quadrupedal manner. [Participants and Methods] Six healthy human adults crawled on their hands and knees over a pressure platform. We calculated the peak vertical ground force of their hands and knees by integrating the pressure of the contact area of each limb. [Results] The mean knee peak vertical ground force at 0.694 (per body weight) was significantly higher than that of the hand at 0.372 (per body weight). The mean hand/knee peak vertical ground force ratio was 0.536; therefore, it was -0.624 on the natural logarithmic scale. [Conclusions] Our findings on human adults are compatible with existing considerations on locomotor evolution toward bipedalism. Our findings contribute to the comprehensive understanding of human locomotion.

Muscle synergy analysis yields an efficient and physiologically relevant method of assessing stroke.

The Fugl-Meyer Assessment is widely used to test motor function in stroke survivors. In the Fugl-Meyer Assessment, stroke survivors perform several movement tasks and clinicians subjectively rate the performance of each task item. The individual task items in the Fugl-Meyer Assessment are selected on the basis of clinical experience, and their physiological relevance has not yet been evaluated. In the present study, we aimed to objectively rate the performance of task items by measuring the muscle activity of 41 muscles from the upper body while stroke survivors and healthy participants performed 37 Fugl-Meyer Assessment upper extremity task items. We used muscle synergy analysis to compare muscle activity between subjects and found that 13 muscle synergies in the healthy participants (which we defined as standard synergies) were able to reconstruct all of the muscle activity in the Fugl-Meyer Assessment. Among the standard synergies, synergies involving the upper arms, forearms and fingers were activated to varying degrees during different task items. In contrast, synergies involving posterior trunk muscles were activated during all tasks, which suggests the importance of posterior trunk muscle synergies throughout all sequences. Furthermore, we noted the inactivation of posterior trunk muscle synergies in stroke survivors with severe but not mild impairments, suggesting that lower trunk stability and the underlying activity of posterior trunk muscle synergies may have a strong influence on stroke severity and recovery. By comparing the synergies of stroke survivors with standard synergies, we also revealed that some synergies in stroke survivors corresponded to merged standard synergies; the merging rate increased with the impairment of stroke survivors. Moreover, the degrees of severity-dependent changes in the merging rate (the merging rate-severity relationship) were different among different task items. This relationship was significant for 26 task items only and not for the other 11 task items. Because muscle synergy analysis evaluates coordinated muscle activities, this different dependency suggests that these 26 task items are appropriate for evaluating muscle coordination and the extent of its impairment in stroke survivors. Overall, we conclude that the Fugl-Meyer Assessment reflects physiological function and muscle coordination impairment and suggest that it could be performed using a subset of the 37 task items.

Interaction of the Left-Right Somatosensory Pathways in Patients With Thalamic Hemorrhage: A Case Report.

Neural plasticity compensates for the loss of motor function after stroke. However, whether neural plasticity occurs in the somatosensory pathways after stroke is unknown. We investigated the left-right somatosensory interaction in two hemorrhagic patients using a paired somatosensory evoked potentials (p-SEPs) recorded at CP3 and CP4, which was defined as an amplitude difference between the SEPs of paired median nerve stimulations to both sides and that of single stimulation to the affected side. Patient 1 (61-year-old, left thalamic hemorrhage) has a moderate motor impairment, severe sensory deficit, and complained of pain in the affected right upper limb. Patient 2 (72-year-old, right thalamic hemorrhage) had slight motor and sensory impairments with no complaints of pain. Single SEPs (s-SEPs) were obtained by stimulation of the right and left median nerves, respectively. For paired stimulations, 1 ms after the first stimulation to the non-affected side, followed by a second stimulation to the affected side. In patient 1, a s-SEP with stimulation to the non-affected side and a p-SEP were observed in CP4. However, a s-SEP was not observed in either hemisphere with stimulation to the affected side. On the other hand, in patient 2, a s-SEP in CP3 with stimulation to the non-affected side and in CP4 with stimulation to the affected side were observed; however, a p-SEP was not observed. In addition, to investigate the mechanism by which ipsilateral median nerve stimulation enhances contralateral p-SEP in patient 1, we compared the SEP averaged over the first 250 epochs with the SEP averaged over the second 250 epochs (total number of epochs recorded: 500). The results showed that in the patient 1, when the bilateral median nerve was stimulated continuously, the habituation did not occur and the response was larger than that of the s-SEP with unilateral median nerve stimulation. In the current case report, the damage to the thalamus may cause neuroplasticity in terms of the left-right interaction (e.g., left and right S1). The somatosensory input from the affected side may interfere with the habituation of the contralateral somatosensory system and conversely increase the response.

Contralateral and Ipsilateral Interactions in the Somatosensory Pathway in Healthy Humans.

Hyper-adaptability, the ability to adapt to changes in the internal environment caused by neurological disorders, is necessary to recover from various disabilities, such as motor paralysis and sensory impairment. In the recovery from motor paralysis, the pre-existing neural pathway of the ipsilateral descending pathway, which is normally suppressed and preserved in the course of development, is activated to contribute to the motor control of the paretic limb. Conversely, in sensory pathways, it remains unclear whether there are compensatory pathways which are beneficial for the recovery of sensory impairment due to damaged unilateral somatosensory pathways, such as thalamic hemorrhage. Here, we investigated the interaction between the left and right somatosensory pathways in healthy humans using paired median nerve somatosensory evoked potentials (SEPs). Paired median nerve SEPs were recorded at CP3 and CP4 with a reference of Fz in the International 10-20 System. The paired median nerve stimulation with different interstimulus intervals (ISIs; 1, 2, 3, 5, 10, 20, 40, 60, and 100 ms) was performed to test the influence of the first stimulus (to the right median nerve) on the P14, P14/N20, and N20/P25 components induced by the second stimulus (left side). Results showed that the first stimulation had no effect on SEP amplitudes (P14, P14/N20, and N20/P25) evoked by the second stimulation in all ISI conditions, suggesting that there might not be a neural connectivity formed by a small number of synapses in the left-right interaction of the somatosensory pathway. Additionally, the somatosensory pathway may be less diverse in healthy participants.

The Progress of the Gait Impairment and Brain Activation in a Patient with Post-stroke Hemidystonia.

OBJECTIVE: We explore the effects of body weight-supported (BWS) treadmill training, including the change of cortical activation, on a patient with post-stroke hemidystonia. PATIENT: The patient was a 71-year-old man with left thalamus hemorrhage. His motor symptoms indicated slight impairment. There was no overactive muscle contraction in the supine, sitting, or standing positions. During his gait, the right initial contact was the forefoot, and his right knee showed an extension thrust pattern. These symptoms suggested that he had post-stroke hemidystonia. METHODS: The patient performed BWS treadmill training 14 times over 3 weeks. The effects of the BWS training were assessed by a step-length analysis, electromyography and functional magnetic resonance imaging (fMRI). RESULTS: The patient's nonparetic step length was extended significantly in the Inter-BWS (p<0.001) and Post-BWS (p=0.025) periods compared to the Pre-BWS session. The excessive muscle activity of the right gastrocnemius medialis in the swing phase was decreased at the Inter-BWS, Post-BWS, and follow-up compared to the Pre-BWS session. The peak timing difference of the bilateral tibialis anterior muscle became significant (p<0.05) on the first day of the intervention. The fMRI revealed that the cortical areas activated by the motor task converged through the intervention (p<0.05, family-wise error corrected). CONCLUSION: These results suggest that there was improvement of the patient's symptoms of post-stroke hemidystonia due to changes in the brain activity during voluntary movement after BWS intervention. Body weight-supported treadmill training may thus be an effective treatment for patients with poststroke hemidystonia.

Multiple patterns of infant rolling in limb coordination and ground contact pressure.

Infants acquire the ability to roll over from the supine to the prone position, which requires body coordination of multiple degrees of freedom under dynamic interactions with the ground. Although previous studies on infant rolling observed kinematic characteristics, little is known about the kinetic characteristics of body segments in contact with the surface. We measured the ground contact pressure under the arms, legs, head, and proximal body segments using a pressure mat and their displacements using a three-dimensional motion capture system. The data obtained from 17 infants aged 9-10 months indicated that most of them showed 2-4 of 6 highly observed movement patterns, including 1 axial rolling, 2 spinal flexion, and 3 shoulder girdle leading patterns. The arms and legs had small contributions to the ground contact pressure in the axial rolling and spinal flexion patterns. The ipsilateral leg in relation to the rolling direction was involved in supporting the body weight in only 1 shoulder girdle leading pattern. The contralateral leg showed large peak pressure to push on the floor before rolling in 3 shoulder girdle leading patterns. The results indicate that infants can produce multiple rolling-over patterns with different strategies to coordinate their body segments and interact with the floor. The results of the analysis of the movement patterns further suggest that few patterns correspond to those reported in adults. This implies that infants generate unique motor patterns by taking into account their own biomechanical constraints.

Kinematic changes in goal-directed movements in a fear-conditioning paradigm.

In individuals with a musculoskeletal disorder, goal-directed reaching movements of the hand are distorted. Here, we investigated a pain-related fear-conditioning effect on motor control. Twenty healthy participants (11 women and 9 men, 21.7 ± 2.7 years) performed a hand-reaching movement task. In the acquisition phase, a painful electrocutaneous stimulus was applied on the reaching hand simultaneous with the completion of reaching. In the subsequent extinction phase, the task context was the same but the painful stimulus was omitted. We divided the kinematic data of the hand-reaching movements into acceleration and deceleration periods based on the movement-velocity characteristics, and the duration of each period indicated the degree of impairment in the feedforward and feedback motor controls. We assessed the wavelet coherence between electromyograms of the triceps and biceps brachii muscles. In the acquisition phase, the durations of painful movements were significantly longer in both the acceleration and deceleration periods. In the extinction phase, painful movements were longer only in the acceleration period and higher pain expectation and fear were maintained. Similarly, the wavelet coherence of muscles in both periods were decreased in both the acquisition and extinction phases. These results indicate that negative emotional modulations might explain the altered motor functions observed in pain patients.

Experience of After-Effect of Memory Update Reduces Sensitivity to Errors During Sensory-Motor Adaptation Task.

Motor learning is the process of updating motor commands in response to a trajectory error induced by a perturbation to the body or vision. The brain has a great capability to accelerate learning by increasing the sensitivity of the memory update to the perceived trajectory errors. Conventional theory suggests that the statistics of perturbations or the statistics of the experienced errors induced by the external perturbations determine the learning speeds. However, the potential effect of another type of error perception, a self-generated error as a result of motor command updates (i.e., an aftereffect), on the learning speeds has not been examined yet. In this study, we dissociated the two kinds of errors by controlling the perception of the aftereffect using a channel-force environment. One group experienced errors due to the aftereffect of the learning process, while the other did not. We found that the participants who perceived the aftereffect of the memory updates exhibited a significant decrease in error-sensitivity, whereas the participants who did not perceive the aftereffect did not show an increase or decrease in error-sensitivity. This suggests that the perception of the aftereffect of learning attenuated updating the motor commands from the perceived errors. Thus, both self-generated and externally induced errors may modulate learning speeds.

Ipsilesional spatial bias after a focal cerebral infarction in the medial agranular cortex: A mouse model of unilateral spatial neglect.

Unilateral spatial neglect is a disorder of higher brain function that occurs after a brain injury, such as stroke, traumatic brain injury, brain tumor, and surgical procedures etc., and leads to failure to attend or respond to stimuli presented to the side contralateral to the lesioned cerebral hemisphere. Because patients with this condition often have other symptoms due to the presence of several brain lesions, it is difficult to evaluate the recovery mechanisms and effect of training on unilateral spatial neglect. In this study, a mouse model of unilateral spatial neglect was created to investigate whether the size of the lesion is related to the severity of ipsilesional spatial bias and the recovery process. Focal infarction was induced in the right medial agranular cortex (AGm) of mice via photothrombosis. After induction of cerebral infarction, ipsilesional spatial bias was evaluated for 9 consecutive days. The major findings were as follows: (1) unilateral local infarction of the AGm resulted in ipsilateral bias during internally guided decision-making; (2) the lesion size was correlated with the degree of impairment rather than slight differences in the lesion site; and (3) mice with anterior AGm lesions experienced lower recovery rates. These findings suggest that recovery from ipsilesional spatial bias requires neural plasticity within the anterior AGm. This conditional mouse model of ipsilesional spatial bias may be used to develop effective treatments for unilateral spatial neglect in humans.

Gait Training Using a Wearable Robotic Device for Non-Traumatic Spinal Cord Injury: A Case Report.

INTRODUCTION: We aimed to report the clinical evaluation results of gait training with the Honda Walking Assist Device® (HWAT) in a patient with spinal cord injury (SCI). PATIENTS AND METHODS: A 63-year-old male with SCI (grade D on the American Spinal Injury Association Impairment Scale) underwent 20 HWAT sessions over 4 weeks. The self-selected walking speed (SWS), mean step length, cadence, 6-minute walking test (6MWT), Walking Index for SCI score, SCI Functional Ambulation Inventory gait score, American Spinal Injury Association Impairment Scale grade, neurological level, upper and lower extremity motor scores, modified Ashworth Scale, Penn Spasm Frequency Scale, and Spinal Cord Independence Measure version III were measured on admission, at the start of HWAT, at 2 and 4 weeks post-HWAT, and at discharge. Three-dimensional kinematic gait analysis and electromyographic assessments were performed before and after HWAT. RESULTS: The patient safely completed 20 HWAT sessions. We found improvements above the clinically meaningful difference in SWS and 6MWT as well as increased hip extension, ankle plantar- and dorsi-flexion range of motion and increased hip extensor, abductor, adductor, and ankle plantar flexor muscle activity. DISCUSSION: The SWS improved more markedly during the HWAT intervention, exceeding the minimal clinically important difference (0.10 to 0.15 m/s) in walking speed for people with SCI until discharge. Moreover, the 6MWT results at 2 weeks after the start of HWAT exceeded the cutoff value (472.5 m) for community ambulation and remained at a similar value at discharge. CONCLUSION: The walking distance (6MWT) and the walking speed (SWS) both demonstrated clinically important improvements following 20 treatment sessions which included HWAT.

Influence of a Foot Insole for a Down Syndrome Patient with a Flat Foot: A Case Study.

Background and Objectives: Patients with Down syndrome have many orthopedic problems including flat foot. Insertion of an insole for a flat foot provides support to the medial longitudinal arch; thus, insole therapy is often used to treat a flat foot. However, the influence of an insole insertion on the knee joint kinematics for a patient with Down syndrome is unknown. This study aimed to elucidate the influence of an insole for a flat foot on the knee kinematics during gait for a patient with Down syndrome. Materials and Methods: The subject was a 22-year-old male with Down syndrome who had a flat foot. The knee joint angle during the gait was measured using a 3D motion capture system that consisted of eight infrared cameras. Results: The gait analysis demonstrated a reduction in the knee flexion angle during double knee action. The knee valgus and tibial internal rotation angles also decreased during the loading response phase while wearing shoes that contained the insole. Conclusions: As the angle of the knee joint decreased during the gait, it was considered that the stability of the knee joint improved by inserting the insole. In particular, there was a large difference in the tibial internal rotation angle when the insole was inserted. It is thus hypothesized that the insole contributes to the rotational stability of the knee joint. This study suggests that knee stability may improve and that gait becomes more stable when a Down syndrome patient with a flat foot wears an insole.

Use of malleoli as an indicator for flatfoot in patients with Down syndrome: development of a simple and non-invasive evaluation method through medial longitudinal arch.

[Purpose] Flatfoot often presents in patients with Down syndrome, and it can be diagnosed using a simple radiograph. Consequently, due to radiograph limitations, alternative non-invasive testing must be determined. Conventionally, arch height ratio can be used for evaluation of the medial longitudinal arch, where the foot is evaluated by detecting the navicular bone on the foot surface. However, detection of the navicular tuberosity is difficult and even though the detection is relatively straightforward for patients without intellectual disability, measuring navicular bone is more difficult in patients with intellectual disability, such as those who have Down syndrome and are uncooperative with a tester. Therefore, we evaluated arch height ratio using the malleoli instead of the navicular bone to determine whether malleoli testing was appropriate for patients with Down syndrome that have an intellectual disability. [Participants and Methods] We conducted a retrospective study of 16 pairs of feet in 16 patients with Down syndrome, diagnosed with flatfoot. The height to the centre of the talo-navicular joint and that of the malleoli from the sole were measured on radiographs using weight-bearing conditions. [Results] The age range was 5.2 to 25.3 years. There was a correlation between the height of the navicular bone and that of the medial and lateral malleoli. [Conclusion] We conclude that the medial and lateral malleoli can substitute navicular bone as a landmark diagnosis test for flatfoot. Considering the close physical distance between the medial malleolus and navicular bone, and the association between the tibia and medial longitudinal arch, the medial malleolus may provide a better landmark in patients with Down syndrome with it being potentially less invasive for uncooperative patients.