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Table 2 Median value of Likert scale data and agreement level for all statements from Round 3

From: A consensus approach toward the standardization of spinal stiffness measurement using a loaded rolling wheel device: results of a Delphi study

Domain

Consensus statement

Median (Range)

Percentage of respondents rating each statement

Agree (%)

Neutral (%)

Disagree (%)

Inclusion criteria

The ability to tolerate a load of at least 40 N.

1 (1–3)

95.0a

5.0

0.0

BMI under 40 for ease of palpation.

1 (1–3)

85.0a

15.0

0.0

18 years or older.

3 (1–4)

30.0

55.0

15.0

Chronic back pain.

3 (1–5)

25.0

45.0

30.0

Exclusion criteria

Pregnancy.

1 (1–2)

100.0a

0.0

0.0

Skin lesion, infection, or open wounds over the back region.

1 (1–1)

100.0a

0.0

0.0

Unable to lie in the prone position (e.g., severe deformities to spine or limbs, static tremor, uncontrolled epilepsy).

1 (1–1)

100.0a

0.0

0.0

Serious spinal pathology (e.g., spinal tumor, fracture, infectious disorder, osteoporosis, or other bone demineralizing condition).

1 (1–2)

100.0a

0.0

0.0

Unable to maintain their breathing cycle in passive expiration (functional residual capacity) for at least 10 s.

1 (1–2)

100.0a

0.0

0.0

Unable to follow instructions (e.g., those with dementia or children (age under 18) who may move during the test.

1 (1–3)

95.0a

0.5

0.0

A head, neck, or thoracoabdominal surgery within the last 6 months.

1 (1–3)

90.0a

10.0

0.0

Unstable spondylolisthesis.

1 (1–5)

85.0a

10.0

5.0

Unstable and/or acute disc herniation or injury.

1.5 (1–4)

75.0a

20.0

5.0

People who do not feel comfortable with the VerteTrack procedure.

1 (1–4)

75.0a

20.0

5.0

Unstable heart condition.

2 (1–4)

70.0a

15.0

15.0

Claustrophobia (a fear of being in closed or small spaces).

2 (1–5)

65.0

15.0

20.0

Acute pain in the test area (depends on whether a participant can tolerate the loading and how long the aggravated pain will subside).

2 (1–5)

60.0

20.0

20.0

Obesity using BMI (e.g., BMI > 30).

2 (1–4)

55.0

15.0

30.0

Hyperalgesia (an abnormally increased sensitivity to pain).

 

55.0

25.0

20.0

Obesity using waist circumference (e.g., waist circumference more than 35 in. in women).

2.5 (1–5)

50.0

15.0

35.0

Previously sacrum trauma/sensitive sacrum.

3 (1–5)

45.0

25.0

30.0

Spinal canal stenosis.

3 (1–5)

35.0

25.0

40.0

Participants with exaggerated spinal curves e.g., thoracic hyper-kyphosis.

3 (1–5)

30.0

25.0

45.0

People with asthma, colds, or breathing disorders.

4 (1–5)

25.0

20.0

55.0

History of spine surgery (depends on whether a participant can tolerate the loading and how long the aggravated pain will subside).

3.5 (1–5)

25.0

25.0

50.0

Scoliosis.

3.5 (1–5)

20.0

30.0

50.0

Tenderness in the test area (depends on whether a participant can tolerate the loading and how long the aggravated pain will subside).

4 (1–5)

15.0

20.0

65.0

Pregnancy

A pregnant woman should not participate at any stage of pregnancy.

3 (1–5)

45.0

30.0

25.0

From the first day of pregnancy to 3 months postpartum.

3 (1–5)

45.0

35.0

20.0

Excluded from the second trimester.

3 (1–5)

40.0

35.0

25.0

From confirmation of pregnancy till 6 weeks postpartum.

3 (1–5)

35.0

30.0

35.0

From the first day of pregnancy till 1 month postpartum.

3 (1–5)

30.0

40.0

30.0

From the first day of pregnancy to the day following the delivery.

3 (1–5)

25.0

35.0

40.0

From confirmation of pregnancy to 12 months postpartum.

4 (1–5)

15.0

30.0

55.0

Participants’ familiarization procedures

Remind the participants once again some points to note e.g., hold breath during the measurement.

1 (1–2)

100.0a

0.0

0.0

Make sure participants have understood the procedure and don’t have any questions.

1 (1–2)

100.0a

0.0

0.0

Practice breathing protocol with the participant before beginning the measurements.

1 (1–2)

100.0a

0.0

0.0

Some reassurance that while they may feel pressure on the spine, the device will not cause any harm.

1 (1–2)

100.0a

0.0

0.0

Explain that there is an emergency stop.

1 (1–2)

100.0a

0.0

0.0

Explain in detail the duration of the experiment and the set of data that needed to be collected.

1 (1–2)

100.0a

0.0

0.0

Show participants the orientation video.

2 (1–4)

75.0a

20.0

5.0

Show the device to the participant in person, pointing out the different parts and what their function is to help them further understand the process.

2 (1–4)

70.0a

25.0

5.0

Orientation to the texture and feel of the rolling device.

2 (1–5)

65.0

30.0

5.0

Allow an upper limit of 5 unloaded practice rounds and always note in the protocol how many practice rounds were completed.

2 (1–5)

65.0

20.0

15.0

A sensory perception (load on hand).

3 (1–5)

35.0

35.0

30.0

Watch someone else have the measures done (if this is not in the orientation video).

3 (2–5)

30.0

25.0

45.0

Instructions for participants before the assessment

You should wear clothes that can be moved to expose your waistline. A gown or shorts might be needed.

1 (1–2)

100.0a

0.0

0.0

You have to empty your front and back pockets including coins, keys, cellphones.

1 (1–2)

100.0a

0.0

0.0

You should remove your glasses.

1 (1–2)

100.0a

0.0

0.0

You should go to the restroom before testing.

1 (1–2)

100.0a

0.0

0.0

Explain and practice breathing protocol.

1 (1–2)

100.0a

0.0

0.0

You should disrobe/change as necessary to expose the test area sufficiently.

1 (1–2)

100.0a

0.0

0.0

You should wear comfortable clothing.

1 (1–2)

100.0a

0.0

0.0

Explain some circumstances where the participant might want to press the emergency stop. E.g., if they have radicular pain, and they experience pain in their leg.

1 (1–4)

95.0a

0.0

5.0

Explain how the device works to increase participant comfort.

1 (1–3)

95.0a

0.0

5.0

Explain how to lay down.

2 (1–4)

80.0a

5.0

15.0

Cell phones should be allowed to stay on for emergency calls etc. but the participant should be instructed that we don’t want them looking at their phones during the protocol.

2 (1–5)

65.0

15.0

20.0

Identifying the Spinous processes

Use a standardized palpation procedure based on anatomical landmarks (count up from the sacral base and down from T12/ribs) and confirm with diagnostic ultrasound.

1 (1–4)

95.0a

0.0

5.0

Ultrasound if available.

2 (1–3)

95.0a

5.0

0.0

Palpation in a prone position in combination with ultrasound for verification.

2 (1–4)

85.0a

10.0

5.0

Palpation of the spinous processes.

1.5 (1–4)

85.0a

10.0

5.0

Place hands on iliac crests, identify the L4 spinous process, place a mark on the skin, go down towards the sacrum, identify the L5 spinous process, go up towards the thoracic vertebrae, identify each spinous process.

1 (1–4)

80.0a

10.0

10.0

Having someone with sufficient experience landmarking spinous process perform the markings.

2.5 (1–5)

50.0

25.0

25.0

Palpation, and confirmation by a healthcare professional.

3 (1–5)

40.0

20.0

40.0

Check by palpation done by two people.

3 (1–5)

45.0

20.0

35.0

Identify L5 via location 1st sacral tubercle (landing point). Then L5-S1 interspinous up to L1.

3 (1–5)

45.0

30.0

25.0

L2 spinous process is at the level of the line joining the inferior borders of the 10th ribs. The intercostal line is at the level of the L3/4 interspinous space or L3 spinous process.

3 (1–4)

35.0

40.0

25.0

It depends on the protocol, the type of study, and the research questions being asked if accurate palpation is needed.

3.5 (1–5)

35.0

15.0

50.0

Placing the wheels over the test area

Make sure that the wheels are aligned on the skin before running each trial.

1 (1–2)

100.0a

0.0

0.0

Make sure there is enough vertical travel in the roller to test the most posterior part of the participants’ back.

1 (1–2)

100.0a

0.0

0.0

Without changing the table height or moving the frame, move the roller wheels to the landing site by positioning the laser over the center of the “X” axis.

1 (1–2)

100.0a

0.0

0.0

Jog wheel down onto participant and add enough cable slack (approximately 5 extra jogs down).

1 (1–2)

100.0a

0.0

0.0

Move the roller wheels above the highest point of the test area.

1 (1–3)

95.0a

5.0

0.0

Raise the plinth until the highest point on the participant is 3 cm from the wheels.

1 (1–3)

95.0a

5.0

0.0

Some participants with hyper-lordosis may require more than 5 extra jogs down.

1 (1–4)

90.0a

5.0

5.0

Wheels starting position

Look at the laser from the same angle to ensure it is lined up perfectly before each trial.

1 (1–2)

100.0a

0.0

0.0

Check the laser goes back to the reference point prior to subsequent runs.

1 (1–2)

100.0a

0.0

0.0

Make sure the participant is not moving between the trials.

1 (1–2)

100.0a

0.0

0.0

Mark the starting position with an “x”.

1 (1–4)

95.0a

0.0

5.0

Photos of the back should be taken.

3 (1–5)

35.0

35.0

30.0

Measure the length of the trajectory by a tape measure.

3 (1–5)

20.0

45.0

35.0

Instructions for participants during the assessment

You should relax your back and abdominals.

1 (1–2)

100.0a

0.0

0.0

Let us know if you wish to stop the measurements at any time or if you have any concerns (e.g., discomfort).

1 (1–2)

100.0a

0.0

0.0

You should remain still for the duration of the test (~ 15 min) even when you answer a question in between the trials.

1 (1–2)

100.0a

0.0

0.0

You will be asked to hold your breath at various times during the procedure for approximately 10 s each time.

1 (1–2)

100.0a

0.0

0.0

You should wait for my instructions before you move away from the table.

1 (1–2)

100.0a

0.0

0.0

You should keep your arm position the same for the duration of the test.

1 (1–3)

95.0a

5.0

0.0

You should not talk during the procedure.

1 (1–4)

90.0a

5.0

5.0

The operator should check the participant’s readiness for each trial.

1 (1–4)

90.0a

5.0

5.0

You’ll be instructed when you can start breathing again.

1 (1–4)

90.0a

5.0

5.0

You should not endure discomfort at any time especially when adding weight plates during testing.

2 (1–4)

65.0

10.0

25.0

You should give us a sign to indicate that you have exhaled the air and ready to be tested before each trial.

2.5 (1–5)

50.0

20.0

30.0

Instructions for participants after the assessment

You should contact us if you experience any discomfort in the next few hours or days.

1 (1–2)

100.0a

0.0

0.0

Let us know if you feel discomfort after the session or any skin irritation. These two conditions might be expected, but they will eventually disappear.

1 (1–2)

100.0a

0.0

0.0

Wait to get up until the device is removed from above you.

1 (1–2)

100.0a

0.0

0.0

You may experience some mild, short-term pain and discomfort in the area that has been tested.

1 (1–4)

90.0a

5.0

5.0

You may experience some dizziness. If so, sit for a few minutes before standing up.

1 (1–4)

90.0a

5.0

5.0

It is normal to feel slightly stiff after the measurements.

1 (1–4)

85.0a

10.0

5.0

Slowly get up and watch your head.

1 (1–4)

85.0a

5.0

10.0

You might feel sore in the next 48 h, this is normal but if the pain does not subside after that time or you feel worried do not hesitate to contact the principal investigator.

2 (1–5)

75.0a

15.0

10.0

No residue pain or discomfort should remain after the measurements. Any discomfort or problems should be reported to the staff at any time.

3 (1–5)

45.0

25.0

30.0

You should walk on a level surface (low-level exercise) for a few minutes after the test procedure.

3.5 (1–5)

15.0

35.0

50.0

No need for specific instructions after testing. Unless there is interest in the perception of stiffness or mobility in a given study.

4 (1–5)

10.0

15.0

75.0a

A good/bad trial definition

A good trial is a trial where the wheels follow the curvature of the spine without deviating sideways, and which does not cause discomfort to the participant.

1 (1–2)

100.0a

0.0

0.0

A good trial is one in which the participant is relaxed, does not move, and holds his/her breath out for the entire trial.

1 (1–2)

100.0a

0.0

0.0

A bad trial is the one with irregular change in the trajectory line.

1 (1–3)

90.0a

10.0

0.0

A good trial is consistent data collected towards a single participant.

1.5 (1–4)

85.0a

10.0

5.0

If the wheels did not move smoothly and they are not continuously pointed forward, it is a bad trial.

2 (1–4)

70.0a

20.0

10.0

If the displacement decreased at a higher load, it’s a bad trial.

4 (2–5)

40.0

20.0

40.0

In a good trial, the participant gets an appreciation of how the testing will feel.

4 (2–5)

10.0

30.0

60.0

A good or bad trial would be defined based on patient reports and visual inspection.

4 (2–5)

10.0

25.0

65.0

A good trial is when the same value is collected for all segments.

4 (2–5)

10.0

10.0

80.0a

This is typically up to the participant whether the trial is good or bad.

5 (3–5)

0.0

10.0

90.0a

Instructions for the operator to ensure a good trial

I will monitor the wheels by enough cable slack and will align the wheels.

1 (1–2)

100.0a

0.0

0.0

I will properly communicate with the participant what I expect from them and give them regular feedback.

1 (1–2)

100.0a

0.0

0.0

I look for movement, breathing, and tonicity.

1 (1–2)

100.0a

0.0

0.0

I will focus on the graphic trend.

1 (1–3)

95.0a

5.0

0.0

I will double-check the data collected before letting the participants leave, repeat if failed.

1 (1–3)

95.0a

5.0

0.0

I look at the graphics in the software after a few trials to make sure that the graphics look appropriate.

2 (1–5)

90.0a

5.0

5.0

I will make sure that the graph output after each trial matches the general graph expected.

2 (1–5)

90.0a

5.0

5.0

I’ll check the values.

2 (1–5)

85.0a

5.0

10.0

If I noticed something different with the process, I would mark it as a bad trial.

2 (1–3)

80.0a

20.0

0.0

It is necessary that the table on which the patient is positioned has armrests to rest the arms in prone position.

2 (1–5)

75.0a

15.0

10.0

Instructions for participants for between the measurement sessions

Use the restroom.

1 (1–2)

100.0a

0.0

0.0

Maintain your normal routine.

1 (1–2)

100.0a

0.0

0.0

Depending on what is being investigated, researchers might need to control for exercise, food intake, hydration levels (e.g., abdominal contents, gas, delayed onset muscle soreness, etc).

1 (1–3)

95.0a

5.0

0.0

Activities between days depending on the research question.

1 (1–3)

90.0a

10.0

0.0

Go for a walk.

1 (1–4)

80.0a

10.0

10.0

You must not have any treatment on the spine between sessions unless this treatment is the subject of experimentation.

2 (1–4)

80.0a

15.0

5.0

Recommendations to be more or less active than usual could be a confounding factor to results.

2 (1–4)

75.0a

15.0

10.0

Do not begin new physically intensive activities between measurement sessions.

1 (1–3)

75.0a

25.0

0.0

Do not do heavy weightlifting/training in between same-day sessions.

2 (1–4)

70.0a

25.0

5.0

If you take medication like muscle relaxants or pain killers, take the medication after the assessment.

2 (1–5)

70.0a

15.0

15.0

No strenuous exercise should be done in between sessions.

2 (1–4)

60.0

30.0

10.0

Come back at the same time of the day.

2 (1–4)

60.0

15.0

25.0

Don’t do any vigorous back exercises two days before the test.

2 (1–5)

55.0

25.0

20.0

No additional care between sessions.

2.5 (1–4)

50.0

35.0

15.0

Don’t undergo any physically demanding activity involving the back.

2.5 (1–5)

50.0

15.0

35.0

Sleep well.

3 (1–4)

40.0

45.0

15.0

Avoid big meals in between sessions.

3 (1–4)

35.0

50.0

15.0

Avoid swimming and scrubbing your back.

3.5 (1–5)

15.0

35.0

50.0

Wear the same clothes for the next session.

4 (2–5)

15.0

10.0

75.0a

Instructions for the same position over multiple measurement sessions

Use a permanent marker (particularly for S1) to ensure the starting position of the measurement is the same.

1 (1–2)

100.0a

0.0

0.0

Keep the reference points intact.

1 (1–2)

100.0a

0.0

0.0

Have a standardized examination table with markings that could be used to align participants in a reproducible manner.

1 (1–3)

95.0a

5.0

0.0

Take a photo with the consent of the participant.

1 (1–4)

90.0a

5.0

5.0

Put a band-aid/ adhesive tape on top of the marked “x” spot so you don’t lose it for the next visit.

1 (1–3)

85.0a

15.0

0.0

Measure the trajectory distance.

2 (1–4)

70.0a

25.0

5.0

Participants should feel just as comfortable as before.

2.5 (1–5)

50.0

20.0

30.0

Since the testing plinth has a hole, the participant will always align at approximately the same distance from the cephalic end of the plinth.

3 (1–5)

45.0

40.0

15.0

Take notes on the position of the patient (head, arms, legs).

3 (1–4)

40.0

40.0

20.0

Tape on the table and the floor to ensure the same position of equipment and person on the table.

3 (1–5)

35.0

35.0

30.0

Software program crashes

I will stop the software and restart software.

1 (1–2)

100.0a

0.0

0.0

I will inform the participant of the situation and will ask to lie still for the issue to be fixed.

1 (1–2)

100.0a

0.0

0.0

I will ask the participant’s permission to start over.

1 (1–2)

100.0a

0.0

0.0

I will ask participants if they would like a rest before starting over.

1 (1–2)

100.0a

0.0

0.0

I will re-calibrate the device.

1 (1–3)

95.0a

5.0

0.0

I will remove all the weights.

1 (1–3)

95.0a

5.0

0.0

Make sure the participant is safely out of the device.

1 (1–3)

95.0a

5.0

0.0

I will remove the device from the above participant and start over.

1 (1–5)

85.0a

10.0

5.0

My actions depend on the severity of the crash. For example, if I have to recalibrate the trajectory, I will have to recollect all trials.

1.5 (1–4)

75.0a

15.0

10.0

I will re-do the problematic trial and resume the measurements.

2 (1–4)

70.0a

15.0

15.0

I will re-do the measurements from 0 N.

2 (1–4)

65.0

25.0

10.0

Software program crashes are less likely to be related to the control box issue. Therefore, turning off the computer or control box will be my last resort.

2 (1–4)

65.0

25.0

10.0

I will close the software and restart the computer.

2 (1–5)

55.0

30.0

15.0

I will turn off the control box and restart the whole system.

2 (1–5)

55.0

15.0

30.0

I will re-schedule the participant.

4 (1–5)

15.0

15.0

70.0a

I will press the emergency stop button.

4 (1–5)

10.0

30.0

60.0

Participants’ Safety

The safety stop button should immediately elevate the load and return the rolling arm to a position away from the patient - so that the patient can exit if needed.

1 (1–2)

100.0a

0.0

0.0

Clear instructions to participants with expectations explained.

1 (1–2)

100.0a

0.0

0.0

The participants should not get up before the frame is off them.

1 (1–1)

100.0a

0.0

0.0

Make sure the device is properly operational (or locked in place) when loading weights.

1 (1–2)

100.0a

0.0

0.0

Make sure all the 1 kg weights are removed from the device before and after assessment by the VerteTrack.

1 (1–1)

100.0a

0.0

0.0

Familiarize yourself with the location of the hardware emergency stop (E-stop) before assessment by the VerteTrack.

1 (1–2)

100.0a

0.0

0.0

Follow the suggested pre-test protocol to make sure all “detectors” are functioning properly.

1 (1–1)

100.0a

0.0

0.0

Procedures explained to participants for emergency stop.

1 (1–2)

100.0a

0.0

0.0

Continuing to check in with the patient throughout the process to make sure that they are feeling okay.

1 (1–2)

100.0a

0.0

0.0

Disinfect the wheels/bench/equipment prior to each participant.

1 (1–1)

100.0a

0.0

0.0

Make sure to remove the weights one by one at the end of the measurement.

1 (1–4)

95.0a

0.0

5.0

Have an easy reading format for clients with disabilities before assessment by the VerteTrack.

1 (1–4)

90.0a

5.0

5.0

Make sure to depress the emergency stop and then disengage it to ensure it is working before assessment by the VerteTrack.

1 (1–4)

85.0a

5.0

10.0

I will raise the plinth when not testing to make sure it will not drop if it malfunctions.

3 (1–5)

45.0

35.0

20.0

Have a mirror to be able to see the client’s face.

3 (1–5)

10.0

50.0

40.0

  1. Note: Scores are on a scale from 1 to 5, where 1 = strongly agree, 2 = agree, 3 = neither agree or disagree, 4 = disagree, and 5 = strongly disagree
  2. Consensus was achieved when at least 70% of participants strongly agreed/agreed or strongly disagreed/ disagreed with a statement
  3. aConsensus reached