OfRuggiero Corcella
In different parts of the world, solutions are being studied to try to restore movement to patients with spinal cord injuries, from neural interfaces to robotic devices. Iit of Genoa and Inail have created Twin 2,
a new exoskeleton that adapts to the patient's motor deficit
Imagine that having lost the use of his legs after a car accident, remaining paralyzed because the spinal cord suffered an injury. Imagine the pain and then the desperation for a life that promises to be all uphill. Now imagine wearing it a pair of «robotic limbs» , an exoskeleton, and to be able to walk again. Not in a hypothetical future, but today.
This is what is happening to Alex Santucci, 49 year old employee from Bologna. He is one of the “pilot” patients who accompanied technicians and researchers throughout the planning and experimentation period (also carried out at Villa Beretta in Costa Masnaga, in the province of Lecco) of «Twin 2», the latest exoskeleton model created by Rehab Tech, a joint laboratory Iit Genoa and the Inail Prosthetic Center in Vigorso di Budrio. First in the gym and then in the paths of the Montecatone Rehabilitation Institute in Imola.
Neural interfaces
To find a “therapy” capable of restoring movement to patients with spinal cord injuries, so-called neural interfaces are being studied in various parts of the world (Neuralink, that of the tycoon Elon Musk, is only the most celebrated by the media). But we are still at an experimental level. To date, therefore, exoskeletons constitute the only device that allows these patients to achieve autonomous walking.
What is an exoskeleton
What is an exoskeleton? «An artificial skeleton that complements the human one, capable of providing robotic support for the movement of the legs», as Simone Rossi and Domenico Prattichizzo explain well in the book «The artificial body» (Raffaello Cortina Editore).
How Twin 2 works
«Twin 2 is made up of a central control unit equipped with batteries that processes all the information coming from the electric motors positioned on the exoskeleton. Based on these signals, the unit processes and supplies voltage and electrical current to the motors in order to regulate the movement,” he explains Matteo Laffranchihead of the Rehab Technologies Iit Inail laboratory.
The motors activate the knee and hip joints, imposing a movement pattern on the patient's limbs that can be completely configured by the clinical staff in terms of length and type of step and walking speed. The battery has an autonomy of approximately four hours and recharges in an hour.
Configuration via app
It can be configured via an app specific for Android, installed on the tablet supplied: in particular, the graphic interface allows you to control the exoskeleton in the execution of the activities developed, of set the kinematic parameters of the movement and to choose between different ways of executing the step:
- Walkdesigned for patients with absent motor functionin which the exoskeleton imposes a walking pattern according to the programmed parameters;
- Retrainused for patients with partial impairment of the motor function of the lower limbs, i.e. able to carry out a more or less autonomous movement but with difficulty in some phases of the step. In this case the exoskeleton supports the patient's movement with more or less intensity, directing him towards an optimal reference trajectory;
- TwinCare, designed for patients with a compromise physical education partial and differentiated between the two limbsin which one leg is healthy and can move independently, while the other requires help, more or less marked, in some phases of the step.
A long research journey
The current model has a long research process behind it. «The project has its roots in the first activities that were carried out with this type of device in 2010 at the Prosthetic Center. I remember well that, at that time, on the first commercial devices we found numerous clinical and technical aspects to review to make them truly usable and therefore the ambition to create an innovative, all-Italian device developed” he says Emanuele Gruppionitechnical director of the Inail Prosthetic Center Research Area.
Patients and hospitals involved
Hospitals and patients were involved. «At the beginning of this project we had several exchanges with hospitals and patients which led to the creation of a series of key technologies to allow the use of the exoskeleton semi-autonomously to people with complete spinal cord injury. Years later, we have managed to expand the use of Twin a people with different types of motor disabilities, such as subjects with residual motor capacity – specifies Laffranchi -. We have also introduced a series of features and technologies, specifically designed for the clinical use of Twin, which allow the patient's status and therapy progress to be measured.”
The regolation
Compared to the previous example, Twin 2 offers better performance with greater engine power, lighter weight (21 kilos) and greater attention to the design of the software and structure, which makes it more adaptable to the characteristics of the wearer.
In fact, the structure is adjustable based on the physical characteristics of the patient using telescopic links placed at the level of the femur and tibia. Ankles and foot support are available in different sizes to adapt to the ergonomics of the user, whether woman or man, young or adult.
The objective is to put the individual patient and his needs at the center of the creation of the device. For this reason also the operating modes adapt to the degree of motor deficit of the person wearing it and in particular their ability to walk independently or not.
The difficulties to face
What are the biggest difficulties a patient has to overcome? «It depends on the subject – replies Laffranchi – There are people who have one complete spinal cord injury and therefore they do not have proprioception (i.e. the awareness of the position and movement of the different parts of their body, ed.). For them the main problem is not being able to feel how they are placed on the exoskeleton. So they have a hard time find balance».
«Who instead has minor damage and therefore good residual motor skills, he is able to use Twin 2 in a functional way right from the first time. For them, comfort and the possibility of harmonious movement are even more important.”
How long does a session last and what are the benefits
Twin 2 can be worn daily and each session lasts up to about an hour and a half. Assuming the upright position brings great benefits at a musculoskeletal, circulatory, psychological and functional level.digestive system of patients permanently confined to a wheelchair, and can be used in rehabilitation clinics for physiotherapy sessions.
Clinical trials in three hospitals and commercialization
After the first pilot trial, the next goal is to start clinical trials on a few dozen patients to prove the real effectiveness of Twin 2. A mandatory step to obtain the CE marking, which will take place in partnership with a company, and lead to the marketing of the model. «In 2023 we started a new Inail project with the hospitals of Montecatone, Villa Beretta, Vipiteno, the University of Bologna and Modena – Reggio Emilia – says Laffranchi -. The experimentation should start within about a year and a half and last as long.”
The world market of exoskeletons is experiencing a boom: there is talk of 419 million dollars in 2023, with a compound annual growth rate of almost 17% until 2030. But how much does a model cost? «On average between 90 and 100 thousand euros. Thanks to the great engineering and design work that has been done, however, we should be able to reduce the cost by up to 20%”, concludes the head of the Rehab Technologies Iit Inail laboratory.
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