Kaoru Isogai

Wearable dummy to simulate joint impairment: severity-based assessment of simulated spasticity of knee joint

Physical therapists master manual examination techniques for testing impaired motor functions. We used a wearable robotic dummy joint that simulated disordered joint resistances to help physical therapists learn such techniques. This study developed a resistance model for a spasticity joint, and the dummy joint was used to present it. We assessed the simulated spasticity model using Modified Ashworth Scale (MAS), which is an evaluation criterion for spasticity seriousness that is widely used by physical therapists. The results of experiments involving two physical therapists showed that the model accurately expressed mild-to-severe symptoms of knee joint spasticity. It is expected that using the system in educational institutions for physical therapists will help students learn the typical levels of joint resistance caused by spasticity with different degrees of severity.

Wearable dummy to simulate joint impairment: Model for the discontinuous friction resistance due to arthritis

Physical therapists master manual examination techniques for testing impaired motor functions. We developed a wearable robotic dummy joint to simulate disordered joint resistances for supporting physical therapists to learn such techniques. A model to simulate discontinuous joint friction resistances due to diseases such as osteoarthritis was developed. Because such resistance originates from abnormal frictions of bones and cartilages, we used a stick-slip model to simulate the resistances. The model was validated based on the introspection of physical therapists. This study concludes that a discontinuous friction model presents forces that are perceptually similar to those typically caused by damaged or roughened joint cartilages.

Assessment of Robotic Patient Simulators for Training in Manual Physical Therapy Examination Techniques

Robots that simulate patients suffering from joint resistance caused by biomechanical and neural impairments are used to aid the training of physical therapists in manual examination techniques. However, there are few methods for assessing such robots. This article proposes two types of assessment measures based on typical judgments of clinicians. One of the measures involves the evaluation of how well the simulator presents different severities of a specified disease. Experienced clinicians were requested to rate the simulated symptoms in terms of severity, and the consistency of their ratings was used as a performance measure. The other measure involves the evaluation of how well the simulator presents different types of symptoms. In this case, the clinicians were requested to classify the simulated resistances in terms of symptom type, and the average ratios of their answers were used as performance measures. For both types of assessment measures, a higher index implied higher agreement among the experienced clinicians that subjectively assessed the symptoms based on typical symptom features. We applied these two assessment methods to a patient knee robot and achieved positive appraisals. The assessment measures have potential for use in comparing several patient simulators for training physical therapists, rather than as absolute indices for developing a standard.

Skin-fat-muscle urethane model for palpation for muscle disorders

Rehabilitation therapists are required to palpate human muscles and to correctly judge whether the hardness of tissues is abnormal or not. We developed artificial urethane models of muscles for educational purposes. Most of the earlier studies and commercial products addressed tumors caused by internal diseases. We produced several types of urethane models with different layered structures, and with fabric sheets inserted between the layers, after the measurement of the stress-strain characteristics of the skin, fat, and muscle tissues of the human gluteal region. Furthermore, 10 therapists subjectively evaluated each model concerning its similarities to the actual human gluteal region. As a result, a model that exhibited the most similar mechanical and haptic sensational properties to the actual tissue was specified. Our methods of measurement and the design of the urethane model, which includes multiple urethane layers of different hardness and fabric sheets, allowed us to create human-like muscle tissue models for palpation.

Simulated crepitus and its reality-based specification using wearable patient dummy

Physical therapists are trained in manual examination techniques to test the impaired motor functions of patients. In this study, we have introduced a wearable robotic dummy joint to simulate disordered joint resistances or behaviors to support physical therapists in learning such techniques. We developed a discontinuous joint friction model based on a stick-slip phenomenon to simulate knee joint resistances caused by crepitus, a typical symptom accompanied by osteoarthritis. Practicing therapists participated in a reality-based evaluation test and specified acceptable parameter sets to adjust the simulated crepitus for the exoskeletal patient robot. The simulated crepitus and wearable dummy joint are expected to support the training of physical therapists. Graphical Abstract

Similarities and differences in manual stretching of physical therapists for equinovarus

For equinovarus, a foot condition commonly suffered as a side effect of stroke, sustained muscle stretching is the primary form of treatment, most of which is manually performed by physical therapists (PTs). It is important to identify variations in the execution of manual stretching techniques by PTs for the standardization of therapeutic techniques. In this study, manual stretching motions performed by three PTs on one stroke survivor were analyzed in terms of foot posture and the force and torque applied to the diseased foot, which were measured through a motion capture system and instrumented foot brace. Statistical analyses based on the principal component analysis showed that many of the stretching motions of the PTs were similar in that they served to control the deformed foot. However, individual differences were observed in the force applied to the heel and the inversion and eversion torque around the ankle, suggesting that individual PTs may stretch different muscle groups. Furthermore, there are potential differences in the efficiency of stretching technique execution among PTs.

Ankle stretching rehabilitation machine for equinovarus: Design and evaluation from clinical aspects

Three-dimensional stretching is needed to treat equinovarus, which deforms the patients foot to plantarflexion, adduction, and inversion postures. We have prototyped a three-dimensional stretching machine that the patient can use for the treatment of equinovarus by him- or herself. By adopting a cable-driven mechanism with two independently controllable pneumatic actuators, the stretching machine can apply a force to the foot along the dorsiflexion direction as well as the direction combining abduction and eversion. In this study, we verified the effectiveness of a prototype stretching machine for healthy subjects. For evaluation, the muscle stiffness and maximum voluntary contraction (MVC) of plantarflexion were compared immediately before and after stretching and 10 min later. As a result, the MVC decreased after stretching, which is a clinical index for effective stretching.

Exoskeleton Simulator of Impaired Ankle: Simulation of Spasticity and Clonus

We developed a prototype of an exoskeletal patient simulator that allows clinical trainees to experience and learn about ankle disorders related to hemiplegia. The exoskeleton exerts abnormal joint torques by tendon mechanisms while realizing complex ankle movements and realistic bone and skin features. Using this exoskeleton, we simulated the resistances of spasticity and clonus, which are typical symptoms of hemiplegia. We demonstrated these two types of simulated symptoms and showed their validity.

Ankle stretching rehabilitation machine for equinovarus: Automation of eversion and flexion control

Equinovarus is a foot deformity characterized by the patients foot being at rest in an abnormally supinated state. In a clinical setting, physical therapists manually stretch the foot to a pronated state to allow the patient to retain some degree of mobility. Currently, no automated ankle stretching machine is commercially available. To tackle this issue, we have developed an automated stretching machine that controls the eversion and flexion angles of a patients deformed foot using two pneumatic actuators. We designed a proportional and integral (PI) controller to place the foot in the desired dorsiflexed position and performed a user test involving a healthy participant. Even when the initial foot position of the participant was in an equinovarus position, the foot was successfully everted and dorsiflexed to match the desired reference posture via the stretching machine. The average differences between the reference and measured foot angles at the final state were found to be within 2° for both the dorsiflexion and eversion angles. The machine replicated the reference angles with acceptable errors.

Training on Muscle Palpation Using Artificial Muscle Nodule Models

We developed a palpation simulator for training on muscle palpation techniques for myofascial pain syndrome. This simulator consisted of two layers that resemble the hardness of actual human skin-fat and muscle tissues. Furthermore, a muscle nodule model made of urethane rubber was laid in the simulator. Five participants were trained on the palpation technique for localizing the muscle nodule models, using our simulators. After the training session, they localized the muscle nodule models more definitely than before. The proposed muscle nodule palpation simulator may improve manual palpation techniques used for examining myofascial pain syndrome.