Patent Publication Number: US-2023149256-A1

Title: Wearable local muscle vibratory stimulator

Description:
PRIORITY CLAIM 
     This application claims the priority benefit of U.S. Provisional Patent Application Ser. No. 63/005,029 filed Apr. 3, 2020, the disclosure of which is incorporated herein by reference in its entirety. 
    
    
     GOVERNMENT INTEREST 
     This invention was made with government support under Grant Number W81XWH-15-1-0287 awarded by the Department of Defense. The government has certain rights in the invention. 
    
    
     TECHNICAL FIELD 
     The subject matter described herein relates to vibratory stimulation of muscles for rehabilitation of orthopaedic injuries and disease. 
     BACKGROUND 
     In the fields of rehabilitation of orthopaedic injuries and disease, it is desirable to stimulate muscle and sensory functions related to joints to increase the effectiveness of the rehabilitation and reduce behaviors that could lead to degradation of joint function. Some injuries, such as anterior cruciate ligament (ACL) injuries, disrupt sensory information that is sent to the central nervous system and alter the drive/motor output from the nervous system to the quadriceps muscle. Because the graft that is used to reconstruct the ACL does not restore the native sensory function and possibly because of learned maladaptive behaviors, this scenario can persist for years following injury and surgery. Because the quadriceps muscle is critical for attenuating forces during routine activities, such as walking, declines in the function of this muscle are thought to contribute to altered loading of joint tissues (e.g., cartilage) and high risk of knee osteoarthritis following knee injuries. 
     Applying vibratory stimulation combination with rehabilitation has been shown to improve the effectiveness of physical rehabilitation. However, some conventional vibratory stimulation devices are hand held and must be applied by the clinician while the patient is stationary. Such devices are unable to be used while the patient is participating in rehabilitation activities. 
     Another type of conventional vibratory stimulator device delivers vibration to the patient via a concentrated tip applicator with a small contact area (e.g., point stimulators) that is best suited for isolated stimulation of muscle spasms/trigger points and small muscles (e.g., in the hand). Such devices are unsuitable for rehabilitating large muscles, such as the quadriceps. 
     Yet another problem with conventional vibratory stimulators is the inability to easily adjust parameters, such as frequency, acceleration, and duration of vibratory stimulation. The inability to adjust these parameters makes such devices less suitable for targeted therapy. 
     Accordingly, in light of these difficulties, there exists a need for a wearable local muscle vibration stimulator that is adjustable and suitable for applying vibratory stimulus to large muscles, such as the quadriceps. 
     SUMMARY 
     A wearable local muscle vibratory stimulator includes a frame including a concave surface for conforming to a treatment surface of a subject. The stimulator further includes an electromagnetic oscillator located in the frame for applying vibratory stimulus to the treatment region of the subject located beneath the treatment surface. The stimulator further includes a waveform generator coupled to the oscillator for generating an electrical signal that causes the electromagnetic oscillator to oscillate. The stimulator further includes an accelerometer coupled to the oscillator for measuring frequency and acceleration of oscillation of the oscillator. The stimulator further includes a controller user interface for receiving user input regarding a desired frequency and acceleration of oscillation of the oscillator. The stimulator further includes a controller coupled to the oscillator and the accelerometer for receiving measurements of frequency and acceleration of oscillation of the oscillator from the accelerometer and controlling the frequency and acceleration of oscillation of the oscillator to minimize a difference between the desired frequency and acceleration of oscillation of the oscillator and the frequency and acceleration of oscillation measured by the accelerometer. The stimulator further includes means for securing the frame to the subject so that the oscillator is wearable. 
     The subject matter described herein may be implemented in hardware, software, firmware, or any combination thereof. As such, the terms “function” “node” or “module” as used herein refer to hardware, which may also include software and/or firmware components, for implementing the feature being described. In one exemplary implementation, the subject matter described herein may be implemented using a computer readable medium having stored thereon computer executable instructions that when executed by the processor of a computer control the computer to perform steps. Exemplary computer readable media suitable for implementing the subject matter described herein include non-transitory computer-readable media, such as disk memory devices, chip memory devices, programmable logic devices, and application specific integrated circuits. In addition, a computer readable medium that implements the subject matter described herein may be located on a single device or computing platform or may be distributed across multiple devices or computing platforms. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1 A  is an image of a wearable local muscle vibratory stimulator; 
         FIG.  1 B  is an image of the wearable local muscle vibratory stimulator of  FIG.  1    illustrating a printed circuit board and battery components; 
         FIG.  2    is an image of a closeup view of a frame for a wearable local muscle vibratory stimulator; 
         FIGS.  3 A and  3 B  are images of an electromagnetic oscillator for a local muscle vibratory stimulator; 
         FIG.  4    is an image of a printed circuit board for a local muscle vibratory stimulator; 
         FIG.  5    is a drawing of a computer screen shot of a graphical user interface for controlling operation of a local muscle vibratory stimulator; 
         FIGS.  6 A and  6 B  are images of a subject wearing a local muscle vibratory stimulator; 
         FIG.  7    is a bottom perspective view of an oscillator holder of a frame for a local muscle vibratory stimulator; 
         FIG.  8    is a top perspective view of an oscillator holder of a frame for a local muscle vibratory stimulator; 
         FIG.  9    is a bottom perspective view of an accelerometer holder for a frame for a local muscle vibratory stimulator; 
         FIG.  10    is a top perspective view of an accelerometer holder for a frame for a local muscle vibratory stimulator; 
         FIGS.  11 A and  11 B  are perspective views of an alternate implementation of a local muscle vibratory stimulator illustrating different control and measurement communications interfaces and frame configurations; 
         FIG.  12    is a perspective view of an alternate implementation of a local muscle vibratory stimulator illustrating different control and measurement communications interfaces and different accelerometer locations; 
         FIG.  13    is a block diagram illustrating exemplary electronic components of a local muscle vibratory stimulator; 
         FIG.  14    is a schematic diagram illustrating electrical connections between components of a local muscle vibratory stimulator; and 
         FIG.  15    is a flow chart illustrating exemplary steps for using a local muscle vibratory stimulator during physical rehabilitation or exercise. 
     
    
    
     DETAILED DESCRIPTION 
     The subject matter described herein includes a wearable local muscle vibratory stimulator.  FIG.  1 A  is an image of a prototype implementation of a local muscle vibratory stimulator. In  FIG.  1 A , a local muscle vibratory stimulator  100  includes a frame  102  holding an electromagnetic oscillator  104  that oscillates to deliver vibratory stimulus to a subject via the frame. This vibratory stimulus is similar to the mechanics of a reflex hammer when evaluating the tendon-tap/knee-jerk reflex clinically in that it creates rapid changes in quadriceps length, thus exciting the muscle via the muscle spindle system. 
     A wearable bag  106  contains control circuitry for controlling oscillator  104 . Straps  108  are threaded through frame  102  for attaching frame  102  to a subject so that stimulator  100  can be worn by the subject and operated while the subject is participating in physical rehabilitation activities. In one example, straps  108  may be sized to secure frame  102  to a subject&#39;s thigh for enhancing rehabilitation of a quadriceps muscle. 
       FIG.  1 B  illustrates stimulator  100  of  FIG.  1 A  with control unit circuit board  110  and power supply  112  removed from bag  106 . Control unit circuit board  110  includes components for controlling oscillations of oscillator  104 . In the illustrated example, a wired connection  114  connects control unit circuit board  110  to oscillator  104  and to an accelerometer  116 . Accelerometer  116  measures the frequency and acceleration of oscillation of oscillator  104 .  FIG.  2    is a closeup view of frame  102 , oscillator  104 , and accelerometer  116 . In the illustrated example, frame  102  includes an accelerometer holder  118  and an oscillator holder  120 . 
       FIGS.  3 A and  3 B  are images of electromagnetic oscillator  104 . In the illustrated example, electromagnetic oscillator  104  is an audio speaker. However, the subject matter described herein is not limited to using an audio speaker. Any oscillator capable of generating and delivering vibratory stimulus to a subject along a single axis is intended to be within the scope of the subject matter described herein. 
       FIG.  4    is an image of control unit circuit board  110  of the prototype implementation illustrated in  FIGS.  1 A,  1 B, and  2   . Control unit circuit board  110  includes a controller, an amplifier, and a waveform generator, the operation of which will be described in detail below. In addition, although in the examples illustrated in  FIGS.  1 A and  1 B , control unit circuit board  110  is separate from frame  102 , the subject matter described herein is not limited to such an implementation. In an alternate implementation, control unit circuit board  110  and the components mounted on control unit circuit board  110  as well as power supply  112  may be miniaturized and attached to or incorporated within frame  102 . 
       FIG.  5    is a diagram illustrating a controller user interface for varying frequency, force, and duration of oscillations by oscillator  104 . In the illustrated example, controller user interface  121  includes a first graphical tool  122  for controlling frequency, a second graphical tool  124  for controlling acceleration, a third graphical tool  126  for controlling duration of treatment, and a fourth graphical tool  128  for activating and deactivating oscillator  104 . Controller user interface  121  further includes a treatment status display area  129  that displays an indication that treatment is in progress and that includes a timer that indicates an amount of time remaining in the current treatment. 
     In one example, controller user interface  121  is displayable on a user&#39;s mobile device. As such, control unit circuit board  110  may include a communications interface, such as a Bluetooth interface, for connecting to the user&#39;s mobile device so that controller user interface  121  may be used to remotely provide control input to a controller for controlling frequency and acceleration of oscillation of oscillator  104 . For example, a physician or physical therapist may use controller user interface  121  to set and vary frequency, force or acceleration, and duration of oscillations by oscillator  104  while the subject is participating in physical rehabilitation or exercise activity. 
     The input received via controller user interface  121  will be provided as desired input to the controller. The frequency and acceleration of oscillation by oscillator  104  measured by accelerometer  116  will be provided as measurement input to the controller. The controller will generate a control signal to oscillator  104  to minimize a difference or error between the desired frequency and acceleration of oscillation and the measured frequency and acceleration of oscillation. 
       FIGS.  6 A and  6 B  illustrate the wearing of vibratory stimulator  100  by a human subject during physical exercise and/or rehabilitation activity. In the illustrated example, vibratory stimulator  100  is secured to the subject&#39;s thigh for applying vibratory stimulus to the subject&#39;s quadriceps muscle. Bag  106  containing the control electronics is secured to the subject&#39;s waist. 
       FIG.  7    is a bottom perspective view of oscillator holder  120 . In  FIG.  7   , oscillator holder  120  includes a concave surface  130  for conforming to a surface of a subject&#39;s thigh. Oscillator holder  120  further includes strap guides  131  to which straps  108  are secured. In use, concave surface  130  is worn transversally with respect to the long axis of the quadriceps muscle. Vibratory stimulation is delivered mechanically through concave surface  130  into the subject&#39;s muscle. 
       FIG.  8    illustrates a top perspective view of oscillator holder  120  where oscillator holder  120  includes a central recess  132  for holding oscillator  104  (not shown in  FIG.  8   ). When oscillator  104  is positioned in recess  132 , vibrations generated by oscillator  104  are transferred via mechanical conduction through concave surface  130  into the subject&#39;s thigh. In one example, oscillator  104  delivers vibratory stimulation along a single axis in the anterior-posterior direction with regard to the muscle being treated. 
       FIG.  9    is a bottom perspective view of accelerometer holder  118 , and  FIG.  10    is a top perspective view of accelerometer holder  118 . In  FIG.  9   , accelerometer holder  118  includes a plate  134  that is securable to oscillator holder  120  via tabs  136  through which fasteners, such as screws, are inserted. Plate  134  also includes a central aperture  138  for holding an accelerometer or for allowing a connector to connect to corresponding pins or sockets for communicating control signals to oscillator  104 . 
       FIGS.  11 A and  11 B  illustrate an alternate implementation of local muscle vibratory stimulator with a different frame configuration and a different control and measurement communication interface from the prototype implementation illustrated in  FIGS.  1 A and  1 B . In  FIG.  11 A , concave lower surface  130  of oscillator holder  120  includes a central aperture  140  to reduce the weight of local muscle vibratory stimulator and to allow direct contact between oscillator  104  and the subject. In addition, local muscle vibratory stimulator  100  includes a communication interface  142  for communicating control signals to oscillator  104  and for communicating measurement signals from accelerometer  116  to controller printed circuit board  110 . In the illustrated example, communication interface  142  is a female connector for connecting to a male 9-pin audio connector  144 . Using a single communication interface for communicating control signals to oscillator  104  and measurement signals from accelerometer  116  reduces the weight and complexity of stimulator  100  over implementations with separate communication interfaces for control and measurement signals. 
       FIG.  12    illustrates an alternate implementation of local muscle vibratory stimulator  100  with separate communication interfaces for measurement and control signals and alternate locations for accelerometer  116 . In  FIG.  12   , local muscle vibratory stimulator  100  includes control communication interface  142 A for connecting to a control signal connector  144 A and a measurement communication interface  142 B for connecting to a measurement communications connector  144 B. In the illustrated example, control communication interface  142 A is a female ¼ inch audio connector for connecting to male ¼ inch audio connector, and measurement communication interface  142 B comprises a female USB connector for connecting to a male USB connector. 
       FIG.  12    also illustrates alternate locations for accelerometer  116 . In  FIG.  12   , accelerometer  116  is located on an outside edge of frame  102 . In an alternate implementation, indicated by the red arrow in  FIG.  12   , accelerometer  116  may be located at or near the center of accelerometer holder  118  adjacent to the center of oscillator  104 . 
       FIG.  13    is a block diagram illustrating exemplary electronic components of wearable local vibratory muscle stimulator. In  FIG.  13   , the components include oscillator  104 , an accelerometer  116  previously described. A waveform generator  150  provides an electronic signal for controlling oscillation of oscillator  104 . An amplifier  152  amplifies a signal output from waveform generator  150  to a level suitable for inducing vibrations of oscillator  104 . In one example, amplifier  152  may be an audio amplifier. A controller  154  receives frequency and acceleration measurements from accelerometer  116  as well as control input from user interface  121 . Controller  154  provides output to waveform generator  150  to control the frequency and acceleration of oscillation based on the control inputs. 
       FIG.  13    also illustrates measurement communication interface  142 B connecting accelerometer  116  to controller  154 , and control communication interface  142 A for connecting amplifier  152  to oscillator  104 . A user control communication interface  155  may be provided to communicate control signals between controller user interface  121  and controller  154 . In one example, user control communication interface  155  may be a wireless interface, such as a Bluetooth interface. 
       FIG.  14    is an electrical schematic diagram of the electronic components of the local muscle vibratory stimulator. In the illustrated example, power supply  112  supplies energy to the various electronic components. A voltage regulator  158  regulates the voltage output from power supply  112 . Waveform generator  150  provides a signal that is output via a digital to analog converter (DAC)  156  to amplifier  152 . The output signal from amplifier  152 , which in the illustrated example is an operational amplifier, is used to drive oscillator  104 . In one example, the signal used to drive oscillator  104  is a sine wave with a frequency and acceleration set based on control and measurement inputs to controller  154 . Controller  154  provides control input to waveform generator  150  based on measurements received from accelerometer  116  and control inputs received from controller user interface  121  (not shown in  FIG.  14   ). 
       FIG.  15    is a flow chart illustrating an exemplary process for using wearable local muscle vibratory stimulator  100  to delivery vibratory stimulus to a subject while the subject is participating in physical rehabilitation and/or exercise activity. Referring to  FIG.  15   , in step  160 , wearable local muscle vibratory stimulator  100  is attached to a subject. For example, frame  102  may be attached to a treatment surface of a subject by securing frame  102  to the treatment surface via straps  108 . 
     In step  162 , the process includes having the subject perform physical rehabilitation or exercise activity. In step  164 , the process includes, while the subject is performing the physical rehabilitation or exercise activity, operating the stimulator to deliver vibratory stimulation to the subject. For example, a physician or physical therapist may activate, via controller user interface  121 , stimulator  100  to deliver vibratory stimulus to the treatment region beneath the treatment surface of the subject while the subject is participating in physical rehabilitation or exercise activity. 
     In step  166 , the process includes receiving, via the controller user interface, desired frequency and acceleration of oscillations of oscillator  104  to enhance the therapeutic benefits of the physical rehabilitation or exercise activity. For example, the physician or physical therapist may utilize graphical tool  122  to set the frequency of oscillations of oscillator  104  and graphical tool  124  to set the acceleration of oscillations of oscillator  104 . 
     In step  168 , the process includes controlling the frequency and acceleration of oscillation of the oscillator to minimize a difference in the frequency and acceleration of oscillation set by the user and the frequency and acceleration of oscillation measured by the accelerometer. For example, controller  154  may receive control input from controller user interface  121  and measurements from accelerometer  116  and produce an output signal to waveform generator  150  to minimize an error or difference between the desired frequency and acceleration of oscillation of oscillator  104  and the measured frequency and acceleration of oscillation of oscillator  104 . 
     It will be understood that various details of the presently disclosed subject matter may be changed without departing from the scope of the presently disclosed subject matter. Furthermore, the foregoing description is for the purpose of illustration only, and not for the purpose of limitation.