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Robotic Stretching + Active Movement

Deborah Gaebler-Spira, MD

XIII International ORITEL Conference

Foundational and First General Assembly

of the Latin American Academy on Child

Development and Disability

Objectives

Review of muscle

Evidence for stretching

Discuss Intelligent stretching device development and use as a research tool

Skeletal muscle – anatomy review• Muscle > fascicles > fibers > myofibrils > sarcomeres

Fibers can be white (Type I, fast twitch) or red (Type II, slow twitch)

Fiber packing (pennation angle) can have an effect on line of force production, and therefore torque about a joint

Exciting muscles for movement

• neuromuscular junction: electrical signal stimulates the flow of calcium, causes thick and thin myofilaments to slide across one another

• sarcomere shortens, generates force

• many sarcomeres working together = muscle fiber contraction

• more muscle fibers are recruited as they are needed (small large fibers)

Musculoskeletal changes in CP

(Oberhofer et al., 2010)

Typically developing child Child with cerebral palsy

Pediatric considerations

• Collagen turnover rates: 300 days in adults vs 80 days in children (Gorter, 2007)

• Growth in general, periods of growth spurts-put children at risk for deformity

• Access to therapist and compliance with home programs may differ during critical periods of development

Short muscles in CP: depends on what you measure• Passive range of motion often decreased,

• Fascicle length reduction (Mohagheghi et al, 2007 & 2008, Gao et al 2009) or the same (Shortland, 2002)

• Measured using ultrasound, Use of normalizing factor matters.

• Variability in fiber size is higher in CP, increased odd fiber shapes and extracellular space (Ponten 2005; Lieber, 2010)

• Increased sarcomere length in medial hamstrings (Smith, 2011), FCU (Lieber, 2004)

Muscle- as a Simple Spring

Model of a muscle

(Lieber, 2010 pg 278)

Neural reflex

Passive muscle

Active muscle contraction

contractile Series elastic

Parallel elastic

Typical stretch reflex-Excitation of a stretched muscle, reciprocal inhibition of antagonist

• Sensory information

– static component persists as long as the muscle is being stretched: nuclear chain fibers

– dynamic component lasts for only a moment, with sudden change in muscle length: nuclear bag fibers

• Motor output

– Short latency– spinal reflex loop

– Long latency – brain stem

– Volitional – cortical awareness and response

Short muscles in CP: spasticity? [neural components]

• Measured as speed dependent increased resistance to passive stretch, but difficult to manually differentiate source of tightness (De Grongen, 2013)

Golgi apparatus(afferrent)

• Increased neural activation increases resistance to stretch

• Prolonged stretch dampen the effect on the motor neuronal discharges, thereby causing relaxation of the muscle–tendon unit, which would in turn reset its resting length.

• Second, Pacinian corpuscles serve as pressure sensors to modulate pain

• Acute versus chronic outcome

Model of a muscle

(Lieber, 2010 pg 278)

Neural reflex

Passive muscle

Active muscle contraction

contractile Series elastic

Parallel elastic

Short muscles in CP: cellular changes?[passive components]

• extracellular matrix between mm fibers shows decreased quality and stiffness. Collagen concentration is increased in spastic mm, but the type distribution is unknown. (Foran, 2005)

• Individual mm fibers and titan were not stiff but that muscle bundles and extracellular matrices were (Smith, 2011)

• By 3 years of age, passive properties of the muscle cause changes between CP and typically developing (Willerslev-Olsen,

2013)

Cellular Changes

Lieber et al 2004

•Spastic muscle (B) has higher density of glycolytic (type Iib) muscle fibers

•Increased variability

•Change in morphology

CP-Satellite Cell-deficiency

Decrease with age

Essential for repair

Mechanical stretch activates

Model of a muscle

(Lieber, 2010 pg 278)

Neural reflex

Passive muscle

Active muscle contraction

contractile Series elastic

Parallel elastic

Short muscles in CP: motor problem? [active components]

• Decreased selective motor control

– Abnormal synergies, distal more impaired than proximal (Fowler, 2010)

• Muscle weakness and disuse

– Muscle atrophy (Shortland et al, 2004)

– voluntary torque generation is less than what can be maximally stimulated. (Rose, 2005)

Stretching as an intervention

• Cochrane review found little or no effect on passive stretch on preventing contracture in people with neurological disorders (Katalinic, 2010)

– Only 5/35 trials included children, so extrapolation should be cautioned (Wallen, 2012)

• limited effects of passive stretching on ROM/spasticity, but recommend 30 min daily (Pin,

2006)

• More work must be done on dosage, modality-hard to find agreed upon stretching paradigm

Self Passive Stretching vs Therapist or parent delivered stretching

• Encourage Self management

• Hard to motivate at certain ages

• Hard to reinforce

• begins with the sarcomere, overlap decreases

• some fibers lengthen, but others may remain at rest

• Once the muscle fiber is at its maximum resting length (all the sarcomeres are fully stretched), additional stretching places force on the surrounding connective tissue

• during high speed stretch with active muscle, tendon may take much of the stretch

Stretching typical muscle

Treatment flow chart

• Risk of abandoning stretching is ROM regression (Franki, 2012)

• should be used as part of an overall treatment plan (Gorter, 2007)

Treatment flow chart con’t

(Gorter, 2007)

Robots as an evaluation tool

• Instrumentation can be used to quantify what we might feel during manual exam (Wu, 2011; Zhao, 2011; De Gooijer,

2013; Ross, 2011)

• Motors – move the joint at an exact speed over a specific range of motion

• Position sensors – what is the joint position

• Torque sensors – how hard is it to move the joint

• EMG – monitor muscle activity

• Apply models to the torque/angle curves

(De Gooijer, 2013)

(Ross, 2011)

Robots as a treatment tool• Continuous passive motion at constant velocity

effects last up to 3 days (knee) (Cheng et al, 2013)

• Robotics can be utilized to give repeatable/quantifiable stretch, and assistance as needed for motor training (Zhang et al, 2013)

• Biodex-type motorized dynamometers allow strengthening isometrically or isokinetically(Engsberg et al, 2006)

• Haptic feedback and gaming can be used to increase motivation (Wu et al, 2011; Cioi et al, 2011; Burdea et

al, 2013)

Rutgers Ankle (Cioi, 2011; Burdea, 2013)

• Hypothesis

– Combining passive stretching and active movement

training using the rehab-robot along with biofeedback

game play improves lower-limb motor function in

children with CP and improve the patient experience of

stretching

• Objectives

– Develop the therapeutic robot and the training

protocol to offer a more engaged and playful approach

– Examine the effectiveness of the robotic intervention

Robotic Rehabilitation

Passive Stretching under Intelligent Control

• Knows how fast to move;

• How hard to stretch;

• How long to hold at the extreme

IntelliStretch

• Positional parameter in real time as visual feedback for motor learning

• Device detects the movement of participant’s foot and provides the assisted

Assisted Active Movement Training

AR

OMP

RO

M

Resisted-active

training within

AROM

Assisted-active

training within

PROM

• Resisted active

– Extra torque loaded for strengthening the dorsiflexors/plantarflexors

• Combined feedback

– Sensory

– Motor

– Visual

Resisted Active Movement Training

AR

OMP

RO

M

Resisted-active

training within

AROM

Assisted-active

training within

PROM

Passive stretching Assisted-active movementTo increase AROM

Resisted-active movementStrengthening within AROM

Training Paradigm

Passive StretchingWarm up stretching

(~ 20 mins)

Active MovementAssisted-active (~ 15 mins)

Resisted (~ 15 mins)

Passive StretchingAfter exercise stretching

(~ 10 mins)

40 deg/sec max

AR

OMP

RO

M

Resisted-active

training within

AROM

Assisted-active

training within

PROM

Robot detects the movement of participant’s foot and provides the

assistance

Lab-Based Rehab

Experimental setup• Subject sat comfortably with the

knee extended• A portable rehab robot

• Strenuous and safe stretching under

intelligent control

• Voluntary movement training with

robot assistance or resistance.

• Motivating games

Home-Based Rehab

• User-friendly interface

• Passive stretching with intelligent control

• Active movement training

• Audio-visual interface

• Tele-interactions

Protocol • 3 sessions/week for 6 weeks

• 45 minutes per session

Passive stretching Active movement training

Passive stretching range:

> passive ROM

Active Moving Range:

In passive ROM (robot assistance)

In active ROM (robot resistance)A

RO

MPR

OM

Resisted-active

training within

AROM

Assisted-active

training within

PROM

Evaluation Measures and Time Points

3 sessions/wk of home or lab based robotic

therapy for 6 weeks6 weeks with no robotic therapy

Pre-evaluation Post-evaluation Follow-up

• Clinical measures

– Modified Ashworth Scale (MAS)

– Selective Control Assessment of

the Lower Extremity (SCALE)

– Pediatric balance scale (PBS)

– 6-Min Walk Test (6MWT)

– Timed Up-and-Go (TUG)

– 10m walk test

• Biomechanical measures

– Passive ROM (PROM)

– Active range of motion (AROM)

– Muscle strength (dorsiflexor and

plantarflexor)

Changes of Clinical ScalesHome-based & Lab-based

Changes of Clinical Scalesin Home-based & Lab-based

Biomechanical ChangesHome-based & Lab-based

0

2

4

6

8

10

12

14

Pre PostCO

F T

raje

cto

ry D

ista

nce (

cm

)

Results — COF Trajectory

Pre- Post-

*

Discussion & Conclusion

• User-friendly, portable, suitable for home setting

• No adverse events reported-no pain

• Strength training did not increase spasticity

• Passive stretching and active movement training is effective in improving functional and biomechanical measures of motor function in both lab &home settings.

– Better control after muscles became less stiff

– Biofeedback game-playing and large # of repetitions

– Closed-chain training (sensory input)

• Improvement of selective motor control also seen in other joints

• Home-based training more convenient, comparable improvements as lab-based

Argument for stretching

• Repeated stretching reduces passive tension and allows greater elongation through small changes in the viscoelastic properties of the muscle–tendon unit (Ryan et al., 2008).

Repeated Stretchingmay provide the necessary

stimulus for the muscle's adaptive

process

exact mechanism for sarcomere

addition and longitudinal growth

in the muscle is unknown,

previous research has indicated

that muscle stretching is a very

powerful stimulant (Williams,

1990).

• Use of the device is feasible in clinical practice and can be used in home or for more precise quantitative research

• Can be used for bouts of therapy or as part of ongoing therapy

• Utilized to provide elongation to the most adaptable tissues in the BODY

World Health OrganizationInternational Classification of Function

Activities• Gross Motor Skills• Mobility• Basic functional skills

Impairment• ROM limitations• spasticity• Weakness• Reduced selective motor control

ParticipationInvolvement in daily activities at home, school, community with family/peers

Cerebral Palsy

Personal Factors• Response to BoNT-A & PT • Motivation• Priorities and goals• Maturation/age• Safety concerns

Interactions between components of the ICF

Environmental Factors• Accessibility• Opportunity/Availability• Support• Season• Teacher/Peer attitudes

Translation of research to the clinic

New focuses• Position Changes, Different Joints, Multiple Joints

Make it FUN and ENGAGING

• Home program great option

• Don’t give up on stretching-theoretically promotes satellite cell proliferation

• Strengthening and active control key concepts

ADIOS