Plain English Summary
Background and study aims
Cerebral Palsy (CP) is a general term that describes a number of neurological conditions that affect movement and coordination. CP can be caused by complications during pregnancy or birth that then causes brain damage. People with CP often develop spasticity. Spasticity is an increased resistance with exaggerated muscle activity when the muscle is stretched (reflex mediated stiffness). Spasticity is caused by a reflex and is controlled by the brain. Another symptom of patients with CP is increased stiffness when a joint is moved due to changes in the muscle. These two symptoms need different treatments; however it is hard to differentiate between them. The standard way to assess spasticity is usually based on a subjective score where the therapist ranks the resistance felt when moving the joint. With this method, it is difficult to separate the resistance coming from muscle spasticity from the resistance related to changes in muscles, tendons or connective tissue. There are now hand-held devices that can be used to as an objective method to measure joint stiffness and reflect mediated stiffness (spasticity). This device combines dynamometer (measures force), electromyography (EMG) (records electrical activity of the muscles), accelerometer (measures the speed of the body movement) and gyroscope (measures the angle of the movement). The aim of this study is to investigate the validity and reliability of a hand-held device.
Who can participate?
Healthy adults (age 18 or over) with no history of neurological disease and adults (age 18 or over) with cerebral palsy (CP), who did not receive anti-spastic treatment 12 months before the study.
What does the study involve?
Participants are allocated to one of two groups. The first group consists of participants with CP. They attend one 30 minute test session where a portable device is attached to the participant’s foot. A clinician then performs five slow stretches of the ankle joint and five fast stretches, while the device measures acceleration (speed), angle, muscle activity and force during the movement. Those in the second group undergo six test sessions (all in one day) using the hand-held device. First, participants wear either the hand-held device or a stationary dynamometer and perform slow and fast stretches. Participants are then seated in a stationary dynamometer, which automatically stretches the ankle joint at a slow speed. This is done to compare the measurements from the hand-held device with the standard measurements from the stationary dynamometer. To see if the hand-held device is capable of measuring stretch reflexes, participants are also assessed with the hand-held device before and during ischemia (blocking nerve impulses). This involves placing a blood pressure cuff above the knee and inflating it to around 240 mmHg. The total duration of the test sessions for the healthy participants is around three hours.
What are the possible benefits and risks of participating?
There are no notable benefits or risks with participating.
Where is the study run from?
Elsass Institute (Denmark)
When is the study starting and how long is it expected to run for?
January 2011 to July 2014
Who is funding the study?
1. Elsass Foundation (Denmark)
2. Association of Danish Physiotherapists (Denmark)
Who is the main contact?
Miss Mathilde Kofoed-Hansen
Distinguishing passive and reflex-mediated ankle joint stiffness in adults with cerebral palsy using a portable device
The hand-held device may be able to adequately distinguish passive and reflex mediated ankle joint stiffness in an objective manner and this method is both valid and reliable.
Ethics Committee of Copenhagen Denmark, 06/06/2011, ref: H-4-2012-107
Observational cross-sectional case-control reliability study
Primary study design
Secondary study design
Patient information sheet
Not available in web format, please use contact details to request a participant information sheet.
Cerebral Palsy (CP)
Both healthy adults and adults with Cerebral Palsy (CP) are included in this study. Participants are allocated to one of two groups.
Group 1 Participants with CP:
Participants in this group attend one test session. The total duration of this session is 30 minutes. The test session consists of measuring passive and reflex mediated stiffness in the ankle joint plantar flexors by a hand-held device attached under the foot. The device contains a dynamometer, electromyography, accelerometer and a gyroscope. An experienced clinician performs slow stretches of the ankle joint from a plantar flexed position. Afterwards, fast stretches above the stretch reflex threshold are applied. One test session consists of five slow stretches and five fast stretches of each ankle joint. The purpose of this test session is to evaluate whether the hand-held device could evaluate and differentiate the passive ankle joint stiffness in subjects with CP compared to the population of healthy subjects.
Group 2 Healthy Participants:
Those in group two are allocated to a reliability study to investigate the reliability and reproducibility of the hand-held device. Each participant undergoes six test sessions with the hand-held device. Three different clinicians (raters) complete two test sessions each on the same participant. This is done for evaluation of both inter-rater and intra-rater reliability of the hand-held device.
After this, those in group two are seated in a stationary dynamometer where ten stretches of the ankle joint are automatically applied at a slow velocity. The purpose of this session is to investigate the validity of the measurements of passive joint torque obtained with the hand-held device compared to golden standard measurements of passive joint torque obtained using a stationary dynamometer.
To evaluate the validity of measuring reflex mediated joint stiffness (stretch reflex) with the hand-held device, five of the healthy participants are furthermore assessed both before and during ischemia. Ischemic nerve blockade of the tibial nerve has previously shown to abolish the stretch reflex. Ischemia of the lower leg is induced by placing a blood pressure cuff above the knee and inflating it to around 240 mmHg.
For those in group two, the total duration of the test sessions is approximately 3 hours. All test sessions are performed on the same day for each participant.
Primary outcome measure
1. Intra- and inter-rater reliability of slow and fast stretches are measured using the hand-held device at baseline
2. Validity of passive ankle joint stiffness is measured comparing the hand-held device compared to the golden standard stationary dynamometer at baseline
3. Differentiation of passive ankle joint stiffness between healthy subjects and subjects with CP is measured using the hand-held device at baseline
Secondary outcome measures
Velocity dependent contribution to passive stiffness is assessed using the hand-held device before and during ischemic nerve block
Overall trial start date
Overall trial end date
Reason abandoned (if study stopped)
Participant inclusion criteria
Aged 18 or older
1. Diagnosed with CP
2. Aged 18 or older
Target number of participants
Participant exclusion criteria
1. History of a neurological disease
2. Fracture in lower limbs
3. Treatment with anti-spastic medication within 12 months prior to the inclusion of the study
Recruitment start date
Recruitment end date
Countries of recruitment
Trial participating centre
Funding Body Type
Funding Body Subtype
Association of Danish Physiotherapists
Funding Body Type
private sector organisation
Funding Body Subtype
Associations and societies (private and public)
Results and Publications
Publication and dissemination plan
Planned publication in a high-impact peer reviewed journal.
IPD sharing plan:
The datasets generated during and/or analysed during the current study will be stored in a non-publicly available repository at the research site Elsass Institute. The data is expected to be made available after publication.
Intention to publish date
Participant level data
Stored in repository
Basic results (scientific)