1I. INTRODUCTION

The Myotonometer measures force-displacement characteristics of muscle and other tissues located

beneath the measuring probe. The force applied by the user with the probe is perpendicular to the

muscle. Myotonometric measurements obtained during a muscle contraction are able to quantify

strength because muscle stiffness increases proportionally to muscle activation and torque

production. Tone, compliance, hardness, and stiffness are all terms associated with force-

displacement or length-tension muscle characteristics. Preferred terminology differs among clinicians,

scientists and engineers. Following are definitions of terms associated with myotonometric

measurements.

Muscle compliance is an intrinsic property of muscle in which tension within the muscle increases

during lengthening without a change in the neural drive to the muscle.

Stiffness is the magnitude of force necessary to cause tissue displacement (the inverse of

compliance).

Tone is defined clinically as a muscles resistance to passive stretch. Muscle tone reflects the

relative influences of the mechanical-elastic characteristics of muscular and connective tissues, and

the reflexive drive to the muscle. Hypertonia, an excessive resistance to passive stretch, is one

characteristic of spasticity. Hypotonia accompanies other medical disorders and diseases.

Spasticity is a motor disorder characterized by velocity-dependent hypertonia and accentuated

tendon reflexes.

Spastic Paresis typically infers the presence of spasticity and associated positive and negative

sensorimotor phenomena. Among the negative phenomena associated with spasticity is muscle

paresis (weakness).

For reading ease, the manual will use the term "tone" rather than compliance, stiffness, or hardness.

2. 1Fig. 1

The Myotonometer was developed to quantify muscle tone and paresis. Protocols also permit

quantification of the level of severity of the spastic paretic condition. Valid and reliable quantifiable

measures of muscle tone are obtained easily and quickly. Clinical trials have shown that

myotonometric measurements can distinguish between injured and non-injured muscles (even years

post injury) and quantify muscle imbalances. The Myotonometer can also quantify differences

between individuals with upper motor neuron involvement from non-disabled individuals as well as

distinguishing between ipsi- and contra-lesional extremities. Intra- and inter-rater reliabilities are

extremely high. Measurements of muscle strength/paresis correlate very well with surface

electromyography (EMG) and joint torque outputs. A summary of these results and a publication list

are available on our website, www.neurogenic.com.

The Myotonometer assesses the amount of resistance a muscle exerts against a probe as the probe

is pushed in a direction perpendicular to the muscle fibers. The amount of resistance is directly

proportional to muscle tone.

Figure 1 shows the general operation of

the probe. The probe is the mechanical

part of the Myotonometer and sends

information pertaining to force and tissue

displacement to the computer. (1) Inner

probe (2) Plexiglas collar (3) Inner shaft

(4) Handle. The user grasps the handle

and applies downward pressure

perpendicular to the muscle. As pressure

is applied, the inner probe pushes into

the muscle whereas the Plexiglas collar

remains relatively motionless on the skin

surface. Specialized transducers monitor

ongoing pressure changes with the

accompanying changes in displacement

between the inner probe (1) and outer

collar (2).

3Fig. 2

CBA

kg

mm

Figure 2 shows, schematically, the relationship between tissue displacement and its tension/elasticity.

The tissue to be measured consists of the skin layer (s), the muscle (m), and bone (b) (Fig.2A). The

User, by applying downward pressure with the Myotonometer, compresses the underlying tissues.

The depth of penetration (L) (the difference in displacement between the inner probe and the

external Plexiglas collar) is measured at pre-programmed force levels (selected by the User; see

section 3.1.7) (Fig. 2B).

An activated/contracted muscle, which has higher tone than a relaxed muscle would be characterized

by a steep slope when plotted on a length-tension curve (1) because it provides more resistance to

the pressure of the probe. In contrast, a relaxed muscle would be characterized by gently sloping

curve or a curve that "shifts to the right" (Fig. 2C).

The Myotonometer is programmed to take 8 length-tension measurements per recording. The

default setting = force levels from 0 to 2.0 kg in steps of .25 kg.

4II. DEVICE SPECIFICATIONS

The Myotonometer allows users to:

- select desired procedure (resting tone, contraction, fixed force) to measure muscle properties

- reject measurements when appropriate

- obtain statistical characteristics of measured values

- store and analyze information

- obtain quantifiable measures of resting tone

- obtain quantifiable measures of muscle paresis

- obtain quantifiable measures that can indicate relative levels of spasticity

- group data together (e.g. combine pre-drug trials from various testing days)

- export data to other programs such as Excel, Paint and Systat

Technical specifications of the device:

Electric current (mA):

in measuring mode.................................15

in "off" mode..............................0.001

The precision of measuring mechanical values:

pressure (kg)......................................................... 0.05

displacement (mm).................................................. 0.1

Computer Requirements

computer processor 80486DX4 or higher

RAM 8 MB

hard disk 0.6 GB

screen 800X600 High Color(16 bit)

Windows 95/98

free serial or USB port.

data format...........................................RS232;

Electrical safety:

in accordance with ICO-601-1 (Medical electrical equipment, Part 1, General safety

requirements).

5III. MYOTONOMETER OPERATION

1. Connection of the Device to the Computer.

1.1 The probe cable is permanently connected to the electronic casing. The cable from the electronic

casing has a 9-pin connection to the serial or USB port of the computer (port COM1 or COM2). With

desktop-computers the mouse often occupies the COM1 port. You may need to manually change to

the COM2 port, if the computer does not automatically recognize the device. Do not connect the

device until you have installed the software.

2. Software installation.

2.1. Insert CD-ROM into the computer. If the CD does not initiate automatically, Press "Start" in the

left-hand bottom corner of the screen:

- choose the lower line: "Run"

enter the letter of your CD-ROM drive (e.g. D:\ or E:\) followed by the following:

D:\myotonometer\setup.exe

The installation procedure will start automatically. The view of the screen in the process of installation

is shown in Figure 3. The program will cue you to insert all necessary program disks. After program

installation, select Start; Programs; Myotonometer; Myotonometer (Fig.4).

2.2. Connect the cable from the electronic casing to the USB-port of your computer. See calibration

procedures in section 2.4.

2.3. Initiate the program operation from Programs menu, as shown on Figure 4 (Start Programs

Myotonometer Myotonometer). On initial program starting, if the computer recognizes the

presence of the Myotonometer on the COM-port, a screen appears (Fig.5), prompting the user to

calibrate the unit to ensure that the Myotonometer has not been damaged during shipping.

6Fig. 5

Fig. 3. Fig. 4.

2.4. Calibration: This screen (Fig. 5) allows the user to calibrate the Myotonometer. For this

purpose, the enclosed mouse-pad is to be used. Place the Myotonometer probe on the top of the

pad. Place one hand on top of the probe so that you can exert downward pressure and hold the

Plexiglas collar steady. Press downward gently until the sound signal is generated. This procedure

must be repeated three times.

After each testing cycle, a blue graph is plotted, as shown on Figure 6 (1). If the graph does not

Fig. 4

7Fig. 8

extend beyond limits, shown by red dash lines, the condition of the sensors has not changed since

manufacturer's testing. If the generated graph exceeds limits (see Fig. 6[2]) this would indicate either

testing procedure error or damage to the Myotonometer during shipping. If errors are detected (Fig.

7), the test procedure is to be repeated carefully several times. Make sure the Plexiglas collar

remains in contact with the mouse-pad at all times and the inner probe returns all the way to the

collar following each testing session. (See calibration procedures for further details.) If errors persist

after 3 to 4 testing attempts, the unit needs to be returned to Neurogenic Technologies, Inc.

Fig.6

2.5. In rare cases, if a computer configuration differs

from established standards, the program will not be able

to recognize the device. If this occurs an error window

appears (Fig.8) after a time delay of 15 30 seconds.

You will then need to manually select the desired

Comport. Click on desired Comport and select "Detect

Again.' Opening window will then appear (Fig. 9). Click

the left mouse button and the Main Window (Fig. 10) will appear. You are now ready to begin

taking Myotonometer measurements

Fig. 7

8Fig. 10.

-

3. Selecting Patient and Measurement Conditions

3.1 Patient Information Data collection begins with the entering of patient/subject information.

When the Main Window appears (Fig. 10) select "New Client". You will then see the

window "Client" (Fig.11) and the window "Body" (Fig.12). The blinking cursor within

"Name" makes it possible to enter the patient's name or subject code number from the

keyboard. It is recommended that you avoid long words as it can create later difficulties while

working with the database.

3.2 Any additional information (e.g. condition,

date etc.) can be entered and stored in

"Notes".

3.3 It is then necessary to select the muscles

and conditions you wish to measure. Move

the cursor to the red silhouetted figure in

the window and click with the left mouse

button. This will activate the Body

window (Fig. 12).

3.4. Selection of muscles and

conditions: First, choose the muscle to be measured by clicking on the appropriate gray

box associated with the muscle (Fig. 12).

3.5. After choosing the part of the body, (e.g. Arm right), a window with a more detailed

picture of a particular body part will be shown (Fig.13). Select the specific muscle.

Fig. 9

9Fig. 11

Fig. 12

Fig. 13. Fig. 14.

3.6. After choosing the muscle, the window "Muscle Dialog" appears (Fig. 14). There are three

possible conditions:

Activation" = muscle contraction (a maximal voluntary contraction is recommended)

"Relaxation" = resting muscle tone

"Fixed Force" is selected if you wish to obtain a measurement at a known and pre-prescribed

level of muscle contraction. For instance, the patient could hold a 5-pound weight or could

isometrically contract against a hand-held dynamometer to a certain force level. If this option is

selected, you must also enter the value in the box to the right.

10

Use the left mouse button to click on the desired conditions. A check mark will appear for each

selected condition. Upon completing the description of the conditions, press "OK". The "Client"

window will appear (Fig. 15) and in the section "Muscles" the name of the muscle and condition will

be listed. If needed, choose the next muscle for investigation by clicking on the red-silhouetted

figure and repeat the procedure described above. In this way you will be able to compile a list of

muscles to be measured. The section "Muscles" will then show the list of muscles and conditions

(Fig.15).

3.7 Selection of Probe Forces: The User can set the amount of maximum pressure exerted

by the probe during testing. This is done within the Force section of the Client window

(Fig. 15). The default setting is 2 kg in .25 kg steps. In some instances (e.g. children,

debilitated individuals) the 2 kg force is too high and can be uncomfortable. In these

cases, enter values of 1 or 1.5 kg in th Force window. It is important to note that

Fig. 15Fig. 16measurements obtained during di

cannot be combined or compared inefferent force values (e.g. 1.0 and 2.0 kg)

the Analysis portion of the program.

11

Fig. 18.

Fig. 17

3.8 After you have completed all your selections

within the Client window, left mouse click "Save."

The information you have entered (patient name,

notes, list of muscles and conditions, and test

force) will be stored in the database. The same

window will re-appear with the "Measure" button

highlighted (Fig.16). By clicking on it you will

progress to the measurement mode. But, if you wish just to make a preliminary list of muscles and

conditions without immediately performing any measurements, click "Close", after which the window

"Client" will disappear and the Main Window will appear. After that you can exit the program or

insert information about another patient.

4 Measurement Procedures

4.1. If you want to initiate a measurement session directly after entering patient information, click

"Measure" in the window "Client" (Fig.16). The window "Measure" will open (Fig.17). Patient

information will be displayed.

4.2. Click Measure A window with a table and a chart will appear on the screen (Fig. 19). The

title above the window indicates the name of the muscle, and the condition (relax, contract) in

which it is to be measured.

4.3. Use of the Probe: Before initiating a measurement with the probe, the patient is asked to

contract or relax the muscle (dependent on desired condition).

12

Fig. 19

The probe should be gently

pressed against the surface of the

skin overlying the desired muscle.

Pressure should be exerted

perpendicular to the muscle. It is

recommended that the user apply

the pressure within a 2-3 second

time period. When the pressure

reaches 2 kg a sound will occur

signaling the end of the

measurement. Several

repetitions are needed for each

measurement in order for an

average to be calculated. A

minimum of 5 to 8 repetitions is

recommended. Any number of repetitions can be selected with the Options button within the

"Main Menu" window (Fig.10). You must exit out of the program and re-enter to set and save any

changes made in this window

4.4. After each probe measurement, the table and graph will immediately display the results. The

table displays the depth of the plunging rod (mm) at 8 different pressures (e.g. from 0.25 kg to 2.0

kg). The graph reflects these numbers. After every measurement a new line of the table and an

additional curve is displayed. The red curve is the average of all measurements taken during the

session; black curves of each individual measurement.

4.5. The User should look at the graph after each probe measurement. Measurements

that deviate substantially from pervious measurements might indicate a source of error. For instance,

perhaps the patient's condition has changed (e.g. they contracted the muscle during a relaxed trial)

or the probe head slipped off the muscle.

4.6. Deleting Measurements: If a measurement differs greatly from previous measurements,

results should be deleted. There are several ways to accomplish this:

1) Pressing the button at the top of the probe will delete only the last trial taken.

13

2) Left mouse click on "Reset Measure" will also delete last measure.

3) Clicking "Reset All Measures" will delete all measurements taken to that point.

4) At the end of a testing session the window "Save Measure" will appear. If many errors

have occurred, select "Remeasure" and all trials will be deleted and program will

automatically put you back in measure mode to repeat your measurements.

4.7. Automatic Deletion of Trials: It is possible to have the program automatically delete

individual measurements that deviate + 2 standard deviations from the average. This is done

by left clicking on "Exclude" located above the table (Fig.19) prior to taking measurements.

4.8. If there are long time delays between measurements after the initiation of the measuring

mode, the program will produce intermittent sound signals. This is done to remind the

user that the unit is still on and using power. Exiting measurement mode as soon as

measurements are completed will ensure long battery life. Batteries should last for one year

of intensive work.

4.9. After completing a cycle of measurements, a window will appear (Fig.19) asking if the data

are to be saved (Save) or deleted ("Remeasure").

4.10. After data have been saved, another measurement window will appear with the next muscle

or condition listed. Measurement procedures are then repeated.

4.11. A tone will signal the end of the testing session. Results are automatically saved and the user

can either exit the program or immediately analyze and printout the results by opening the

Analysis part of the program.

14

5 Analysis

5.1. The Analysis program allows:

- data analysis in numerical and graphical form for a particular muscle or for a group of muscles.

- calculation of statistical parameters of a chosen muscle or group.

- summation of data from groups of muscles or conditions

- calculation of percent differences between tonograms of selected measurements.

- calculation of Area Under the Curve of any length-tension curve.

- the saving of data as text (table) or graph.

- Printout of data as text or graph.

- exporting of data files in formats for import into other software packages (e.g. Excel, Systat,

Paint)

- importing of data for analysis from other Myotonometer units and computers

5.2. It is not necessary to have the Myotonometer connected while doing data analysis. At the

start of the program (Fig. 8), select Work without device" if this is what you wish to do.

When this mode is chosen the button Measure in Main Window is not activated.

5.3. In order to initiate analysis, left click on Analysis in the Main Window. The Analysis

window (Fig.20) will appear. The User will be cued to select either "Display Measurements" or

"Display Groups of Measurements" "Display Measurements' is used when you have no need to

combine data into a different group name. "Display Groups of Measurements allows the User to

merge data files and create a new group name for analysis (e.g. combining pre or post treatment

intervention data).

15

5.4. "Display Measurements" Left mouse clicking on "Display Measurements" (Fig.20) will bring

up another window, "Measurements for Analysis." From here it is necessary to choose the file for

analysis and drag it into the right-sided window. To do this, highlight the desired file, then, while

keeping the left mouse button depressed, use your mouse to move the file icon into the right

window. Once the icon is located anywhere within the window, release the left mouse button and the

file will be rewritten into this window. The file to be analyzed can come from any level within the

tree of file: names (e.g. patient name; part of the body; muscle; condition). Once you have done

this, a smaller window "Analysis of Measurements" (Fig.21) will be displayed.

Fig. 20

Fig.21

16

5.4.1 "Analysis of Measurements" (Fig.21) window allows you to select the desired analysis

function and display.

"Display Graph of Selected Muscles" Left clicking this button will display your selected

data files in graph format (Fig.22).

"Display Table of Selected Muscles" will display data in table format with averages given

of each force measurement. Area Under the Curve (AUC) calculation is also given for each line. See

Figures 24 and 25.

"Calculate % of Difference of Area" will compare each set of data and calculate the %

difference between each (e.g. the % difference between relaxed biceps brachii vs. contracted biceps

b

m

su

th

ar

enrachii). This window will also provide a statistical com

"Calculate Area Under the Curve" will ca

easurement selected.

"Summate Selected Muscles" will combine

mmated data (a single line on a graph with standard

e data displayed in Figure 27 was summated and th

e limited to displaying and summating 10 individua

tered, the message Too many graphs" appears.

"Cancel" will bring you back to "Analysis" wind

Fig.22parison of the % differences.

lculate area under the curve (AUC) for each

all selected measurements and display as

deviations and a table) (Fig.28). For instance,

en automatically displayed as Figure 28. You

l trials. When more than 10 tonograms are

ow (Fig.20).

Fig. 23

17

Fig. 24 Fig. 25

Fig. 26

Fig. 27 Fig. 28

5.5 All of the windows allow switching among the windows by clicking on the buttons located

at the bottom of each window. Buttons to save or printout data are also located at the bottom of

each window. When the button "Save" is pressed, a window appears (Fig.23) that will allow you to

save your data. It is recommended that you place your data in a folder designated "Data." The

graphic files will be saved in .BMP format and table/text files in .TXT format. You will not be able to

pull these data up again from within the Myotonus program.

18

5.6 "Display Groups of Measurement" allows the user to merge data files and create a new

group name for analysis (e.g. combining pre or post treatment intervention data). First, click and

drag all files to be combined into the right window. For instance, you might want to combine all

muscle activation patient data taken prior to a treatment intervention. Once all files are listed in the

right window, click "Add Group" located on the far right of the window. An example is shown in

Figure 29.

Once this is done, the "Analysis of Groups of Measurements" window becomes active and all

operations necessary for analysis are the same as described above.

5.7 Remove group" To remove a group from your list in the right window it is necessary to

highlight the file to be deleted by left mouse clicking on it. Then, press the button Remove

group.

5.7.1 Remove All Groups will remove all groups. Highlighting is not necessary

Fig. 29

19

Fig. 31

Fig. 30

6.1 Exporting Files: It is possible to export data to another user or another computer by using the

"Export" button located on the

Main Window (Fig.30). First,

highlight the desired file to be

exported. Then, left mouse click

on "Export." The "Saving" window

will appear and you can designate

the location where you would like

the file to be saved. Clicking on

"Save" completes the procedure.

Fig. 31

6.2 Importing Files: To import Myotonometer data from another source, click "Import" and then

highlight and "Open" desired. The file will automatically be listed on the Main Menu.

6.3 If a duplicate file name exists, the program will automatically assign the same name but a

different number to the data file. For instance, you might try to import a file named "test" from a

floppy disk but you already have a file named "test" listed on your Main Menu. The program will

import the data from the floppy and assign the new name "test1."

7.1.1 Options: Located within the Main Menu is the "Options" button. This allows the user to

change certain settings within the program.

7.1.2 "Switch X-Y Axis in Analysis" By selecting this option the user determines whether "Force"

or "Displacement" measures will be displayed on the X or Y axes (see Figures 33 and 34). The

20

program typically defaults to having "Force," the independent variable, located on the X-axis. The

option to switch X and Y axes is also available within the Analysis program. There is an

arrow box located on the top right of the graph which, when activated, will switch the

axes.

7.1.3 "Number of Measures" Typically it is recommended that the user obtain the average of 3 to

5 measurements for each condition (i.e. you press the probe onto the muscle 5 times to get the

measurement of muscle tone during relaxation and 5 times during contraction). But, this number can

be changed by the user.

7.1.4 "Units" Clicking the right arrow key allows the user to select the unit of measurement to be

used during Force measurements.

7.1.5 "Port" The Communication Port to be used is typically detected automatically during setup. If

subsequent changes are made to the computer configuration it might be necessary to manually

change the ComPort.

7.1.6 "Use external printing program" This option is selected if the user wants data sent to a

graphics editor installed on their computer (MS Paint, Imaging, PhotoShop, Corel Draw, MS Word or

any other using .BMP file structures). Click "external printing program" box and use "Browse" to

select appropriate path to your graphics editor.

7.1.7 Please note that you must exit out of the program and re-enter before any of your

"Options" selected will become effective.

21

8.1 Main Window Options/Procedures:.

8.1.1 If you are taking measurements from a patient for which the muscle list has already been

established and saved all you need to do is highlight the patient's name in the Main Window and

click "Measure." The "Client" window will appear with the information about the patient and with

the list of previously listed muscles and conditions.

8.1.2 The "Edit" button allows the user to change the list of muscles by using "Add" or "Delete."

The window will cue the user regarding whether your intention is to make a permanent file change,

or just a change for this particular measurement session (Fig.18).

You can also delete muscles to be measured from your list by clicking on the small square window

with the sign to the left of the name of the muscle. After completing the editing process, select "OK".

Again the "Measure" button will be activatedclick on it and the "Measure" window will appear

(Fig.17).

Fig.33

Fig.32

22

Sample Protocol for Testing of Muscle Injury or Muscle Imbalance

The following protocol describes a procedure for assessing the muscle health of the kneeextensors during or following anterior cruciate ligament (ACL) surgery rehabilitation.

Resting Muscle Tone: The athlete is positioned in a supine position with legs extended or flexedover the edge of the treatment table. Myotonometric measurements are then taken of the desiredmuscles for each leg (legs must be positioned similarly). The Myotonometer probe is pressed ontothe muscle perpendicularly until an audible tone is heard. The probe is then lifted off the muscle andre-positioned to take the next measurement. Five probe measurements are suggested. This requiresless than one minute for data acquisition. For knee extensors the rectus femoris, vastus lateralis andvastus medialis can be measured separately. The athlete can then be asked to move into a proneposition with legs extended and the biceps femoris tested if desired.

Muscle Strength: Muscle strength is assessed using a maximal voluntary isometric contraction. Theathlete does not have to be in the same position during assessment of muscle strength as they werefor resting muscle tone. For instance, the athlete can be sitting at the edge of the treatment tablewith knees flexed or they can be positioned in isokinetic dynamometer equipment. The athlete isasked to maximally contract against an immovable force (e.g. cable attached to treatment table,examiners resistance etc.). The examiner asks the athlete to maximally contract the muscle to betested. While the athlete contracts the muscle, the examiner presses the Myotonometer probeperpendicularly onto the muscle. A hand-held or computerized dynamometer can be used to ensureconsistency of effort between trials if this is an issue. Dynamometry will measure total joint torqueproduction but not provide information about individual muscles. Myotonometric measurements willprovide information about individual muscle contribution to torque output.

Analysis: Several types of analyses are possible following the above outlined testing protocol.Resting muscle tone of the various muscles can be compared between the right and left legs. Theresting tone should be the same. Stiffness of different muscles of the same leg should not beexpected to be identical. Muscle stiffness during muscle contraction should show a significantdifference from resting tone. In addition, muscle stiffness during contraction should be symmetricalbetween both legs. If myotonometric measurements were taken pre-injury or pre-surgery, they canbe used to assess the rehabilitation and progress of specific muscles.

The graph on the following page was generated by Myotonometer computational software anddepicts data collected from the vastus medialis of an athlete three years following ACL surgery. Theathlete tested normal during computerized isokinetic testing.

23

Myotonometer measurements of vastus medialis (VMO) of an athlete who had ACL surgery threeyears prior. Red line shows resting muscle tone. The green line shows the stiffness obtained fromthe non-surgical leg during a maximal voluntary contraction. The blue line shows the stiffness of thesurgical leg during a maximal voluntary contraction.

The small difference between stiffness of the surgical VMO during contraction (blue line) from restingstiffness indicates weakness of this muscle (despite the fact that computerized isokineticdynamometry indicated equal strength of both legs). This assessment of weakness is further verifiedby the inability of the surgical VMO to generate as much stiffness during contraction as thenonsurgical VMO (green line).

(Note that the legend [generated from the computers clock] indicates that all data were acquired inless than two minutes).

VMO Weakness s/p ACL Surgery

24

Sample Protocol for Testing Muscle Tone, Paresis and Level of Severity of Spastic Paresis

Biceps Brachii Testing

Tone measurements are taken while the subjects muscles are relaxed and during a

maximal voluntary contraction (MVC). It is recommended that at least 3 trials of 5

measurements each be taken (required testing time is less than 1 minute).

The area over the flexor surface of the arm is tested with the subject in a sitting or

supine position. The elbow is extended with the forearm supinated (putting muscle at end

range). The area of application of the Myotonometer probe for the biceps is located (e.g.

equidistant between the lateral aspect of the acromion process and the most inferior part of

the olecranon). This point is marked with an ink pen. Measurements are then be taken with

the muscle relaxed.

For the contraction phase, subjects are instructed to perform a maximal isometric

contraction (MVC) of the elbow flexors. To ensure limited movement of the extremity, a

strap can be placed at the wrist for resistance. A hand-held force dynamometer, placed

at the distal aspect of the forearm, should be used to gauge the force of the isometric

contraction of the upper extremity. For this protocol, subjects should reproduce

similar force output for each trial during MVC testing.

Myotonometer Measurement Procedures

The Myotonometer contains a linear array of transducers that measure: 1) the amount

of displacement of a probe as it is pushed onto the skin overlying the tested muscle and 2)

the amount of force required per millimeter of tissue displacement. Measurements are taken

25

every .25 kg of force up to 2.0 kg. Computational software generates force/displacement

curves for each condition (relaxed; contracted). The percent difference at each .25 kg

of force between the relaxed and contracted conditions can be computed. The

smaller the difference in measurements between the two conditions, the more

severe the spastic condition (figs 1-3). Percent difference scores correlate with the

modified Ashworth scale but Myotonometer measurements are more sensitive to smaller

changes. In addition, this protocol will enable the clinician and researcher to determine the

extent to which changes in muscle tone or paretic changes within a muscle contribute to a

disability.

Fig. 1

GROUP 1: CONTROLSBICEPS BRACHII

0

2

4

6

8

10

12

0 0.25 0.5 0.75 1 1.25 1.5 1.75 2

Force (kg)

Dis

plac

emen

t(m

m)

Rest

Contracted

26

Fig. 2

GROUP 2: INVOLVED EXTREMITYBICEPS BRACHII

0

2

4

6

8

10

12

0 0.25 0.5 0.75 1 1.25 1.5 1.75 2Force (kg)

Dis

plac

emen

t(m

m)

Rest

Contracted

Fig. 3

GROUP 3: UNINVOLVED EXTREMITYBICEPS BRACHII

0

2

4

6

8

10

12

0 0.25 0.5 0.75 1 1.25 1.5 1.75 2

Force (kg)

Dis

plac

emen

t(m

m)

Contracted

Rest

27

Myotonometer Reference List

Aarrestad DD, Williams MD, Fehrer S, Mikhailenok E, Leonard CT (2004). Intra- and inter-raterreliabilities of the Myotonometer for assessing the spastic condition of children with cerebralpalsy. Child Neurology (In press).

Aarrestad DD, Williams MD, Fehrer S, Mikhailenok E, Leonard CT (2003). Intra- and inter-raterreliabilities of the Myotonometer for assessing the spastic condition of children with cerebralpalsy. Electronic publication: ptjournal.org/abstracts/pt2003.

Ashina M, Bendtsen L, Jensen R, Sakai F, Olesen J (1999). Muscle hardness in patients with chronictension-type headache: relation to actual headache state. Pain 1999; 79:201-205.

Bizzini M, and Mannion AF. (2003) Reliability of a new, hand-held device for assessing skeletal musclestiffness. Clinical Biomechanics, 459-461.

Coon, T., Ikeda, E., Lamb, J., & Sebastian, D. (2002). The effects of strain-counterstrain on musclehardness and tenderness in subjects with neck pain. Journal of Orthopedic and SportsPhysical Therapy, 32(1), A29.

Day M, Spafford N, Kitzman, P, Queen S. (2004) The effect of position on muscle tone in post strokepatients. In press: Electronic publication: ptjournal.org/abstracts/pt2004.

Ditto, K., Fischer, M., Fehrer, S., & Leonard, C. (2002). Myotonometer assessment of changes in thetriceps surae musculotendinous unit following a stretch intervention. Journal of Orthopedicand Sports Physical Therapy, 32(1), A33.

Horikawa, M., Ebihara, S., Sakai, F., & Akiyama, M. (1993). Non-invasive measurement method forhardness in muscular tissues. Med Biol Eng Comput, 31, 623-627.

Horikawa M. (2001). Effect of visual display terminal height on the trapezius muscle hardness:quantitative evaluation by a newly developed muscle hardness meter. Applied Ergonomics,32:473-478.

Kaplan, S, Chernyavasky G, Holland K, Palgi K, Pancholi C, Smith T, & Warley N. (2001)Myotonometer: A reliability study. APTA-New Jersey State Conference Poster Presentation.

Kato G, Andrew PD, Sato H. (2004) Reliability and validity of a device to measure muscle hardness.Journal of Mechanics in Medicine and Biology, 4(2): 213-225.

Leonard, C., Brown, J., & Price, T., Queen SA, Mikhailenok EL. (2004). Comparison of surfaceelectromyography and myotonometric measurements during isometric contractions. Journalof Electromyography and Kinesiology. 14(6):709-714.

Leonard, C., Deshner, W., Romo, J., Suoja, E., Fehrer, S., & Mikhailenok, E. (2003). Myotonometerintra and inter-rater reliabilities. Arch Phys Med Rehabil, 84, 928-932.

Leonard, C., Brown, J., & Price, T. (2002). Comparison of surface electromyography andmyotonometric measurements during isometric contractions. Archives Phys Med and Rehabil,83:1683.

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Leonard, C. (2001). Examination and management of spasticity and weakness. Neurology Report,25(3), 106-112.

Leonard, C., Stephens, J., & Stroppel, S. (2001). Assessing the spastic condition of individuals withupper motoneuron involvement: Validity of the Myotonometer. Arch Phys Med Rehabil, 82,1416-1420.

Leonard, C., & Mikhailenok, E. (2000). The Myotonometer: A computerized electronic device thatquantifies muscle tone/compliance, paresis and spasticity (Abstract) Physical Therapy, 80,S18.

Leonard, C., Mikhailenok, E., Stephens, J., & Stroppel, S. (2000). The Myotonometer: Validity of thedevice and protocol to quantify muscle tone/compliance and other aspects of the spasticcondition. Neurology Report, 24(5), 187.

Mayston, MJ. (2003) Strength training for children with cerebral palsy. Poster presentation andabstract. Chartered Society of Physiotherapy Congress 2003.

Murayama, M., Nosaka, K., Yoneda, T., & Minamitani, K. (2000). Changes in hardness of the humanelbow flexor muscles after eccentric exercise. European Journal of Applied Physiology andOccupational Physiology, 82, 361-367.

Nansel D, Waldorf T, Cooperstein R. (1993). Effect of cervical spinal adjustments on lumbarparaspinal muscle tone: Evidence for facilitation of intersegmental tonic neck reflexes. Journalof Manipulative and Physiological Therapeutics, 16:91-95.

Rydahl SJ, & Brouwer BJ. (2004). Ankle stiffness and tissue compliance in stroke survivors: Avalidation of Myotonometer measurements. Archives of Physical Medicine and Rehabilitation(In press).

Shchurova EN, Shchurov VA, Grebenyuk LA. (2004). Age-related changes in contractile capacity oflower extremity muscles caused by inadequate blood supply. Human Physiology, 30(2): 209-215.

Sakai, F., Ebihara, S., Akiyama, M., & Horikawa, M. (1995). Pericranial muscle hardness in tension-type headache: A non-invasive measurement method and its clinical application. Brain, 118,523-531.

Steinberg, B., & Gelberman, R. (1994). Evaluation of limb compartments with suspected increasedinterstitial pressure. Clinical Orthopaedics and related Research, 300, 248-253.

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References Establishing Relationship Between Muscle Stiffness, Muscle Activation andTorque Production During Contraction

Bizzini M, and Mannion AF. (2003). Reliability of a new, hand-held device for assessing skeletalmuscle stiffness. Clinical Biomechanics, 459-461.

Cannon, S, & Zahalak, G. (1982). The mechanical behavior of active human skeletal muscle in smalloscillations. J Biomech, 15: 111-121.

Carter, R, Crago, P, & Gorman, P. (1993). Nonlinear stretch reflex interaction during co contraction.J Neurophysiol, 69: 943-952.

Horikawa, M, Ebihara, S, Sakai, F, & Akiyama, M. (1993). Non-invasive measurement method forhardness in muscular tissues. Med Biol Eng Comput 31: 623-627.

Kato G, Andrew PD, Sato H. (2004) Reliability and validity of a device to measure muscle hardness.Journal of Mechanics in Medicine and Biology, 4(2): 213-225.

Kearney RE, & Hunter IW. (1990). System identification of human joint dynamics. CRC Crit RevBiomed Eng 18: 55-87.

Lan, N, & Crago, P. (1994). Optimal control of antagonistic muscle stiffness during voluntarymovements. Biological Cybernetics 71: 123-135.

Leonard, C., Brown, J., & Price, T., Queen SA, Mikhailenok EL. (2004). Comparison of surfaceelectromyography and myotonometric measurements during isometric contractions. Journalof Electromyography and Kinesiology. 14(6):709-714.

Leonard, C., Brown, J., & Price, T. (2002). Comparison of surface electromyography andmyotonometric measurements during isometric contractions. Archives Phys Med and Rehabil,83: 1683.

Walsh, E. (1992). Muscles, Masses and Motion. The Physiology of Normality, Hypotonicity, Spasticityand Rigidity. London: MacKeith Press.

Woledge, R, Curtin, N, & Homsher, E. (1985). Energetic Aspects of Muscle Contraction. London:Academic Press.

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Sport-related Myotonometer References

Bizzini M, and Mannion AF. (2003) Reliability of a new, hand-held device for assessing skeletal musclestiffness. Clinical Biomechanics, 459-461.

Coon, T., Ikeda, E., Lamb, J., & Sebastian, D. (2002). The effects of strain-counterstrain on musclehardness and tenderness in subjects with neck pain. Journal of Orthopedic and SportsPhysical Therapy, 32(1), A29.

Ditto, K., Fischer, M., Fehrer, S., & Leonard, C. (2002). Myotonometer assessment of changes in thetriceps surae musculotendinous unit following a stretch intervention. Journal of Orthopedicand Sports Physical Therapy, 32(1), A33.

Kato G, Andrew PD, Sato H. (2004) Reliability and validity of a device to measure muscle hardness.Journal of Mechanics in Medicine and Biology, 4(2): 213-225.

Leonard, C., Brown, J., & Price, T., Queen SA, Mikhailenok EL. (2004). Comparison of surfaceelectromyography and myotonometric measurements during isometric contractions. Journalof Electromyography and Kinesiology. (In press).

Leonard, C., Deshner, W., Romo, J., Suoja, E., Fehrer, S., & Mikhailenok, E. (2003). Myotonometerintra and inter-rater reliabilities. Arch Phys Med Rehabil, 84, 928-932.

Leonard, C., Brown, J., & Price, T. (2004). Comparison of surface electromyography andmyotonometric measurements during isometric contractions. EMG and Kinesiology,14(6):709-714.

Murayama, M., Nosaka, K., Yoneda, T., & Minamitani, K. (2000). Changes in hardness of the humanelbow flexor muscles after eccentric exercise. European Journal of Applied Physiology andOccupational Physiology, 82, 361-367.

Shchurova EN, Shchurov VA, Grebenyuk LA. (2004). Age-related changes in contractilecapacity of lower extremity muscles caused by inadequate blood supply. HumanPhysiology, 30(2): 209-215.