EP-4734843-A1 - WEARABLE DEVICE FOR MEASURING THE RESISTANCE TO PASSIVE MOVEMENT OF A HUMAN SUBJECT AFFECTED BY NEUROMUSCULAR DISORDERS, AND METHOD OF USE OF THE RESULTS OF SUCH MEASUREMENT

EP4734843A1EP 4734843 A1EP4734843 A1EP 4734843A1EP-4734843-A1

Abstract

Device adapted to be worn by a human subject, particularly a subject affected by neuromuscular disorders, for measuring a resistance to passive movement of said subject, the device comprising: • a proximal unit (102) comprising a first magneto-inertial unit, in turn comprising a three-axis accelerometer, a three-axis gyroscope, a three-axis magnetometer, said proximal unit (102) being adapted to be worn on a limb, upstream of and in proximity to an articulation of said subject; • a distal unit (103) comprising a second magneto-inertial unit, in turn comprising a three-axis accelerometer, a three-axis gyroscope, a three-axis magnetometer, and a load cell (106) for measuring the opposing force exerted by a muscle of said articulation of the subject, said distal unit (103) being adapted to be worn on said limb, downstream of and in proximity to said articulation of said subject; • a processing system (51) adapted to: o receiving measurement data of said three-axis accelerometer, three- axis gyroscope, three-axis magnetometer from said proximal unit (102) and said distal unit (103), when worn, and measurement data of said load cell (106) from said distal unit (103), when worn; o computing said measurement of resistance to passive movement by executing a software application comprising a Sensor Fusion algorithm.

Inventors

CEREATTI, Andrea
CARUSO, Marco
DERIU, Franca
Manca, Andrea
BERTULETTI, Stefano
VENTURA, Lucia

Assignees

Politecnico Di Torino
Universita' Degli Studi Di Sassari

Dates

Publication Date: 20260506
Application Date: 20240625

Claims (7)

1. Device adapted to be worn by a human subject, particularly a subject affected by neuromuscular disorders, for measuring a resistance to passive movement of said subject, the device comprising: • a proximal unit (102) comprising a first magneto-inertial unit, in turn comprising a three-axis accelerometer, a three-axis gyroscope, a three-axis magnetometer, said proximal unit (102) being adapted to be worn on a limb, upstream of and in proximity to an articulation of said subject; • a distal unit (103) comprising a second magneto-inertial unit, in turn comprising a three-axis accelerometer, a three-axis gyroscope, a three-axis magnetometer, and a load cell (106) for measuring the opposing force exerted by a muscle of said articulation of the subject, said distal unit (103) being adapted to be worn on said limb, downstream of and in proximity to said articulation of said subject; • a processing system (51) adapted to: o receiving measurement data of said three-axis accelerometer, three- axis gyroscope, three-axis magnetometer from said proximal unit (102) and said distal unit (103), when worn, and measurement data of said load cell (106) from said distal unit (103), when worn; o computing said measurement of resistance to passive movement by executing a software application comprising a Sensor Fusion algorithm.
2. Device according to claim 1, wherein said processing system comprises a program adapted to execute the following operations: • computing an orientation in three-dimensional space of said proximal unit (102) and said distal unit (103) by applying said Sensor Fusion algorithm to the data received from said proximal unit (102) and said distal unit (103); • computing the start and end of said movement, the range of motion, and the angular accelerations of said movement; • displaying said received data and/or said computed data.
3. Device according to claim 1 or 2, wherein said proximal unit (102) further comprises: • a first case bottom (11) and a first case top (12) adapted to be joined together to contain said first magneto-inertial unit; • first positioning means (74) connected to said first case bottom (11) and adapted to hold said proximal unit (102) in a fixed position on said limb.
4. Device according to claim 1 or 2 or 3, wherein said distal unit (103) further comprises: • a second case bottom (21) and a second case top (22) adapted to be joined together to contain said second magneto-inertial unit; • second positioning means (75) connected to said second case bottom (21) and adapted to hold said distal unit (103) in a fixed position on said limb.
5. Device according to claim 4, further comprising: • on said second case top (22), a bay (25) adapted to contain said load cell (106); • on said load cell (106), a clip (26) adapted to enlarge a sensitive area of said load cell (106) when applied on said limb.
6. Method suitable for using the device according to any one of claims 1 to 5, for computing said resistance to passive movement of said subject, said method comprising the following phases: • phase of characterizing said first and second magneto-inertial units, said phase being adapted to verify that the results of the operations executed by said three-axis accelerometer, three-axis gyroscope and three-axis magnetometer are consistent with the specifications provided in the respective datasheets; • phase of optimizing, or fine-tuning, parameters of said Sensor Fusion algorithm, by recording at least one acquisition of data concerning a simulation of said mobilization of said articulation; • phase of computing, by means of said Sensor Fusion algorithm, the orientation in three-dimensional space of said proximal and distal units; • phase of expressing the orientation of said distal unit relative to the orientation of said proximal unit to obtain a relative kinematics of said units; • phase of breaking up said relative kinematics to obtain an articular angle of interest through a specific sequence of Euler angles for each articulation; • phase of identifying the start and end of movement by processing data obtained from said magneto-inertial unit of said distal unit (103), applying thresholds to a signal recorded by a gyroscope; • phase of computing and identifying parameters of interest comprising said start and end of movement, range of motion, defined as the difference between the maximum value and the minimum value of said movement, angular accelerations, and force; • phase of displaying in graphical form said received data comprising linear accelerations, angular velocities, local magnetic fields, and force, as directly measured by said first and second magneto-inertial units (104, 104’) and by said load cell (106), and said computed data comprising the orientation of said proximal and distal units (102, 103), said start and end of movement, said range of motion, and said angular accelerations.
7. Method according to claim 6, wherein, during said phase of expressing the orientation, the axes of said proximal unit and of said distal unit are assumed to be aligned with, in particular parallel to, the anatomical axes on which they are positioned.

Description

TITLE WEARABLE DEVICE FOR MEASURING THE RESISTANCE TO PASSIVE MOVEMENT OF A HUMAN SUBJECT AFFECTED BY NEUROMUSCULAR DISORDERS, AND METHOD OF USE OF THE RESULTS OF SUCH MEASUREMENT. DESCRIPTION Field of the invention The present invention relates to a device, wearable by a human subject, particularly by a subject, especially a subject affected by neuromuscular disorders, which allows to assess the resistance to passive movement caused, in particular, by spastic hypertonia (spasticity) by means of the biomechanical description of the articulation of interest during the execution of a passive mobilization. The present invention also relates to a method for using the results of the measurement performed, in particular of said biomechanical description. Description of the prior art Systems are known through which a person performing mobilization of a patient’s limb provides a measurement of the perceived resistance by using, typically, semi- quantitative grading scales (e.g., Ashworth scale, modified Ashworth scale, or Tardieu scale). The main problems of such scales are their low reliability, both in kinematic and dynamic terms, due to the subjectivity of the evaluation (performed by a person) and the low sensitivity to changes in the degree of spasticity following a pharmacological or rehabilitative therapy. Typically, the involuntary activity of the spastic muscle during the test is monitored by surface electromyography (sEMG). The main problem of this solution is that recording the electromyographic activity only is insufficient to describe the motory pattern of resistance to movement. The following will illustrate some of the most relevant prior-art examples based on the above-mentioned principles. US 2016/0317066A1 describes a single unit that allows measuring the force through the use of a handle positioned on the distal side of the articulation of interest, thus physically separating the operator’s hand from the patient’s body segment. Mobilization is performed on the system, as opposed to directly on the subject, which, in addition to reducing the clinician’s sensitivity when executing the movement, may lead to movement-induced artifacts. Moreover, such a solution cannot provide the relative angle between the two limbs (proximal and distal) when, during mobilization, both limbs move. US 2013/0303947A1 describes a system for measuring electromyographic activity (EMG), force and range of motion, which is composed of two parts mutually connected by means of a mechanical joint. This system can be used on the ankle, but not on other articulations. Due to its structure, it may generate movement artifacts when performing ankle mobilization. The movement is of the “semi-rigid/semi-constrained” type. Test setup is quite complex (requiring the subject to be prepared during a preliminary experimental session), because the system needs to be adapted to the person’s anthropometric characteristics (e.g., leg length, ankle length, etc.). US 8,002,717B2 describes a non-wearable system comprising two parts, one of which is fixed, that are mutually connected by means of a joint. This system permits forcing a rotation of the joint, and hence of the articulation of interest (wrist), at a known speed, and measures the passive force exerted by the limb. This system cannot be worn and can only be used on the wrist, being unsuitable for other articulations like, for example, elbow, knee or ankle, and does not output accelerations and range of motion. In addition, the movement is not performed “directly” by the evaluator. “Biomechanical examination of a commonly used measure of spasticity” by A.D. Pandyan, C.I.M. Price, H. Rodgers, M.P. Barnes, and G.R. Johnson (doi: 10.1016/S0268- 0033(01)00084-5) describes a system including an electrogoniometer and a force sensor which was used for measuring the resistance to passive movement of the elbow articulation of 16 patients affected by ictus. This system is suitable for the elbow, but not for other articulations like, for example, wrist, knee or ankle. Furthermore, mobilization is performed on the system (handle), not on the subject. This, in addition to reducing the clinician’s sensitivity while performing the movement, may lead to movement-induced artifacts. “An Instrumented Glove for Improving Spasticity Assessment” by P. Jonnalagedda, F. Deng, K. Douglas, L. Chukoskie, M. Yip, T. Nga Ng, T. Nguyen, A. Skalsky, and H. Garudadri (doi: 10.1109/HIC.2016.7797723) describes a system consisting of a glove with foot-sensitive resistors and a magneto-inertial unit which was used to analyze the elbow articulation of 5 patients affected by cerebral paralysis. This system is suitable for the elbow and the wrist, but not for other articulations. Moreover, it cannot output the range of motion of the articulation under analysis. “Portable measurement system for the objective evaluation of the spasticity of hemiplegic patients based on the tonic stretch reflex threshold” by K.S. Kim, J.H. S