5/7/2014
Disclosure
Understanding and Writing the
Lower Limb Orthotic Prescription
• Mr. Jennings is currently employed by Hanger Clinic, a for-profit
orthotic and prosthetic company. He is currently practicing as an
Orthotist/Prosthetist and is the Area Clinic Manager in Houston, TX.
Jason M Jennings, CPO
Area Clinic Manager, Hanger Clinic, Houston, TX
Carolyn P Da Silva, PT, DSc, NCS
Associate Professor, Texas Woman’s University, Houston, TX
Basic Biomechanics
for Orthotic Intervention
Learning Objectives
The learner will:
•
•
•
•
•
•
1. Understand basic biomechanics of normal and
pathological gait.
2. Understand principles of orthotic intervention to
improve gait and function of patients/clients
with neurological conditions.
3. Utilize gait and orthotic knowledge to formulate
descriptive lower limb orthotic prescriptions.
Review of Terminology
Basic Biomechanical Principles
Normal Gait
Pathological Gait
Pathological Gait Assessment
Goals of Orthotic Treatment
Review of Terminology
• Biomechanics
– The branch of science that studies the structure and function of
the body
• Ground Reaction Force (GRF)
– A force exerted by the ground that is equal and opposite in
direction to the force being exerted on it by an object
• Ground Reaction Vector
– The result of two or more GRFs. We need to start looking at
these forces in 3 dimensions, as a combination of forces from
the sagittal, coronal, and transverse planes
• Sagittal plane – Anterior/posterior axis
• Coronal plane – Medial/lateral axis
• Transverse plane – Vertical axis
REVIEW OF TERMINOLOGY
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6
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Review of Terminology
Review of Terminology: ROM
• Passive ROM
• Vertical Alignment Line
– The angular movement applied to a joint by another person
– The alignment of two random points in a plane by a vertical or
plumb line
• Functional ROM
• Shank to Vertical Angle
– The angular movement of a joint caused by the subjects’ applied
muscle force
– It may be limited due to weakness, spasticity, contracture or
bony abnormality.
– The angle of the shank as it relates to the vertical
• Anterior crest of the tibia Owen
• Common practice in US to use midline of the leg
• What standard should we use?
• Tardieu Scale
• Initial end range or first catch (functional range during activity)
– Patterning of the limb during weight bearing
– R2 ROM
• Secondary Patterning
– Patterning of the limb during swing
Haugh 2006
– R1 ROM
• Primary Patterning
• Maximum passive end range with torque applied
7
Review of Terminology: AFO Footwear
Combination (AFOFC)
• Heel sole differential
– Difference in thickness
between the heel height
and sole height
• Casting block height
– The amount of block or
wedge necessary to
accommodate the heel sole
differential, angle of
contracture at the ankle,
and/or knee to place the
shank in the desired
amount of inclination or
reclination
Basic Biomechanical
Principles - Kinetics
• Kinetic Chain
– Combination of several joints uniting
successive limb segments
– Open: Distal segment of the chain moves
in space (Swing Phase)
– Closed: Distal segment is fixed, with
proximal parts moving over it (Stance
Phase)
BASIC BIOMECHANICAL
PRINCIPLES
Importance of Kinetics in
Orthotic Design
• The assessment of the point in stance or swing
phase that a problem occurs will influence your
choice of orthotic design.
• Open kinetic chain problems require much less
rigid devices.
• Closed kinetic chain problems must be able to
resist the tri-planar forces that occur thru the
subtalar joint under full weight bearing.
Steindler, 1955
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Normal Gait
• Each limb blends the patterns of motion, passive force, and
muscle control into a sequence of activity (called a gait cycle
or a stride), which is repeated until the desired destination is
reached. The head, neck, trunk and pelvis are self contained
passengers riding on the limb’s locomotor system.
Perry J, et. al.. Gait Analysis, Slack 1992
NORMAL GAIT
Normal Gait
• Four Basic Functions are Necessary for
Normal Gait
– Weight Bearing Stability
– Stance Limb Progression
– Shock Absorption
– Energy Conservation
Perry 1992
Normal Gait
• Weight Bearing
Stability
– Muscles around hip, knee and
ankle sequentially stabilize these
joints as body weight is
transferred to the stance limb.
– The pattern of muscle control is
dictated by the changing
alignment of the body weight line
(vector) to the individual joint.
– As the vector moves away from
the joint center, a rotational force
or moment develops that must
be controlled by opposing
muscles to preserve postural
stability.
Perry 1992
Normal Gait
• Stance Limb
Progression
– To advance the weight
bearing limb over the
supporting foot, three
rockers are used. A
fourth rocker initiates
swing limb
advancement
– This can be useful in
visualizing the impact
an orthosis will have
on the patient during
stance phase.
Perry 1992
Normal Gait
• Shock Absorption
– The rapid transfer of
body weight to the
limb is dissipated by
knee flexion
redirecting the force to
the quadriceps and is
initiated at heel rocker
Perry 1992
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Normal Gait
• Energy
Conservation
– The selective
relaxation of muscles
when momentum and
passive positioning
can substitute;
conserves energy
– Co-contraction of
antagonists is rare.
PATHOLOGIC GAIT
Perry 1992
Pathological Gait
• Many types of disease and injury impair a
patient’s ability to walk.
• Patients develop compensations or
substitutions.
• This results in an increase in the energy cost of
walking.
• When physiologic effort or pain exceed
tolerance, the disability becomes visible.
Pathological Gait
• As we look at pathological gait, we must
remember that we are looking at a
combination of cause and effect.
Perry 1992
Pathological Gait
• Pathological Patterns/Functional
Categories:
– Brain Injury
– Central Control Dysfunction
– Motor Unit Insufficiency
– Peripheral Sensory and Motor Impairment
– Structural Impairment
Pathological Gait
• Brain injury can interfere with gait in
several ways causing:
– Primary effects
– Secondary effects
– Tertiary effects
Pathological gait is a mixture of primary,
secondary and tertiary abnormalities.
Gage JR, Schwartz M
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Pathological Gait
Pathological Gait
• Secondary Effect
• Primary Effect
– Occurs as a direct result of a brain injury
– Examples in periventricular leukomalacia
(PVL) might be:
• Loss of selective muscle control
• Balance difficulties
• Abnormal muscle tone
Gage JR, Schwartz M
– Because the primary effects of brain injury
impose abnormal forces on the skeleton,
neither bone nor muscle grow normally.
– These changes are not immediate.
– Muscles and bones grow slowly over time,
and these skeletal deformities emerge slowly
and in direct proportion to the rate of skeletal
growth.
Gage JR, Schwartz M
Pathological Gait
Pathological Gait
• Central Control Dysfunction
• Tertiary Effects
– The primary and secondary effects of the
brain injury burden the patient/child with
structural and dynamic abnormalities that
make walking difficult.
– The patient/child will develop “coping or
compensatory mechanisms” to walk which
increases energy consumption.
– These coping mechanisms represent the
tertiary effects of brain injury.
– Upper motor neuron pathways
control the anterior horn cells,
determining which muscles are
activated.
• Brain lesions such as stroke,
acquired brain injury or cerebral
palsy are common causes.
• Cervical and thoracic spinal
cord injuries are others.
• Spasticity is a universal
characteristic.
• Patients differ considerably due
to variability in loss of selective
control and emergence of
primitive control mechanisms.
Gage JR, Schwartz M
Gage JR, Schwartz M
Pathological Gait
Pathological Gait
• Motor Unit Insufficiency
• Motor Unit Insufficiency
– Muscle weakness is the clinical penalty of
having fewer motor units available to generate
the forces needed for walking.
Perry 1967
– Muscle weakness • Lower Motor Neuron
Disorders
– Poliomyelitis, GuillainBarré Syndrome
• Muscular Pathology
– Muscular Dystrophy
• Patients can substitute for
local weakness since
sensation and central
control have been
maintained.
Perry 1967
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Pathological Gait
Pathological Gait
• Peripheral Sensory
and Motor Impairment:
– Examples:
• Peripheral Sensory and Motor Impairment
– The addition of a sensory loss to muscle
paralysis reduces the patient’s ability to
Perry
substitute.
Pathological Gait
• Structural Impairment
– Although some lesions can cause hypermobility,
restricted passive motion and malalignment are more
common problems
– Contributing pathologies are:
• Contractures
• Skeletal Deformity
• Cauda Equina Spinal
Cord Injury
• Spina Bifida
• Acute Trauma
– Impaired Sensation
delays awareness of
floor contact.
– Walking ability
decreases with each
higher level of spinal
cord impairment.
Perry 1967
Pathological Gait
• Structural Impairment
– Contracture: Freedom to move is impaired by
fibrous connective tissue stiffness
• Plantarflexion
• Knee Flexion
• Hip Flexion
– Congenital
– Traumatic
• Musculoskeletal Pain
Perry 1967
Pathological Gait
Perry 1967
Pathological Gait
• Structural Impairment
• Structural
Impairment
– Contracture:
Plantarflexion
• A 15° contracture
can significantly
impair stance
limb progression.
– Contracture: Knee
Flexion
• Threatens stance
stability
• A 15° knee flexion
contracture
requires 20% of
max quad effort
• At 30°, a force
equal to 50% of
max is required.
Perry 1967
Perry 1967
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Pathological Gait
Pathological Gait
• Structural Impairment
– Contracture: Hip
Flexion
• Threatens stance
stability and
forward progression
• Structural Impairment: Skeletal Malalignment
– Can lead to motion errors or abnormal movement
during gait
– Deformed joint surfaces or supporting shafts can be
further impaired by continued weight bearing.
• Wolf Law, 1882: Weight bearing pattern alters
bony architecture.
– Children – susceptible to developing deformed and
asymmetric skeletal structures
– Adults – lack growing tissue; therefore, develop
degenerative changes that lead to pain and loss of
function
Perry 1967
Pathological Gait
• Structural Impairment
– Musculoskeletal Pain
• Protective
response leads to
shortened stance
limb period
• Trauma or
inflammation can
result in swelling
which reduces
ROM and causes
patient to assume
position of least
discomfort
Pathologic Gait Assessment
• Clinical Assessment (Clues)
– ROM
– MMT
• Observational Gait Analysis
– Primary Patterning (weight bearing)
– Secondary Patterning (swing phase)
– Compensatory patterning
• Patient’s Profile
Perry 1967
Pathological Gait Assessment
• ROM: R1, R2 Values
• Help to define the functional
and passive profile of the
patient.
• Help to define a difference
between a stiff or spastic
muscle
• Give clues as to what to look
for in the observational gait
analysis
• Start to define the angular
parameters of the initial
orthotic design.
Pathological Gait Assessment
• MMT
• Helps to define the
patient’s physical
profile
• Gives clues as to what
to look for in the
observational gait
analysis
• Starts to help define
the necessary
mechanical forces that
the orthotic design
should re-establish
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Observational Gait Analysis
• Foot and Ankle
Observational Gait Analysis
• Knee
– Attitude of foot at end of
swing
– Part of foot contacting
ground at initial contact
– Foot progression angle
in stance & swing in
reference to line of
progression & plane of
the knee (ext rot 5o)
– Is the foot plantargrade
in stance?
– Does foot go through
normal rockers?
– Attitude of the knee at
terminal swing (nearly full
extension)
– Does knee fully extend or
hyperextend at any point?
– To what degree does knee
flex during swing (normal
swing phase knee motion –
60o)?
– What is knee progression
angle in swing and stance?
Perry 1967
Perry 1967
Observational Gait Analysis
• Trunk, Pelvis and Hip
– Adduction deformity at
hip in swing
– Persistent flexion of
the hip
– Sagittal plane hip
motion (normal ~ 45o)
– Is pelvic motion
excessive in sagittal,
coronal or transverse
plane?
– Position of the upper
trunk with reference to
the base of support
Pathological Gait Assessment
• Patient’s Profile
– Goals
– Expectations
– Needs
• Orthotic Design
–
–
–
–
Correct or Accommodate
Assist/Resist Motion
Stability/Balance
Function
Perry 1967
Overview
• ~3% of US population use some type of
an orthosis.
• Majority are prescribed by PM&R and
Orthopedics.
GOALS OF ORTHOTIC
TREATMENT
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Overview
• A broad range of individuals with varied
diagnoses, impairments, and activity
limitations may benefit from the use of
an orthosis
–
–
–
–
–
Muscle weakness
Spasticity
Uncoordinated muscle movement
Skeletal deformity or weakness
Trauma or congenital defect
Overview
Overview
A good Orthotic
Evaluation should include
assessment of:
• Diagnosis
• Treating diagnosis
• Impact of other diagnoses
•
•
•
•
Strength
Range of Motion
Skeletal Alignment
Observational Gait
Analysis
A good Orthotic
Prescription should
include:
• Motor Control
• Coordination
• Posture
• Sensation
• Balance
• Primary: weight bearing
patterns
• Secondary: swing phase
patterns
• Compensatory patterns
Goals of Orthotic Treatment
• Prevent deformity
• Orthosis design must:
– Control the bony segments of the lower
extremity
– Meet musculotendinous objectives
– Meet motor control objectives
– Meet functional objectives
Prevention of Deformity
• Provide optimal skeletal alignment
– Understand normal alignment
– Appreciate what is attainable for that patient
– Consider its impact on orthotic design and on
the patient’s function
– Provide optimal skeletal alignment
• Provide stability
– Block aberrant motion
– Assist or resist joint motion
• Facilitate function
– Harness GRFs to optimize movement thru
swing and stance
Facilitation of Function
• Harness ground reaction forces
– Appreciate how GRF affects the limb during
stance
– Understand how external moments generated
affect each joint
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Design Criteria Necessary to
Achieve These Goals
• Accurate impression - optimizing alignment
• Application of appropriate three point force
systems
• Application of appropriate materials and
componentry
• Height appropriate to control joints as indicated
• Total contact fit/pressure distribution
Application of Appropriate
Three Point Force Systems
• Perform static and dynamic analysis
• Separate swing and stance phase
problems
• Attempt to identify segment deviations.
• Organize force systems
Define Trimlines
• These must be appropriate to
accommodate force systems defined
above
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Height Appropriate to Control
Joints as Indicated
• Relate to Perry’s three rocker concept.
• Consider orthoses’ affect on GRFs and
their impact on the external moments
created on the more proximal joints.
• Define height.
Fitting and Tuning Orthosis
The shank to vertical angle (SVA) is
different from the angle of the ankle (AA)
• Assess the shank to vertical angle
– Assess angle of ankle in the orthosis
– Heel sole differential
• Assess additional footwear characteristics
such as stiffness and profile of heel and
sole
AA
– Heel Rocker
– Toe Rocker
– Flexibility of the toe of the orthosis
SVA
Owen 2004
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Writing the Lower Limb Orthotic
Prescription
Purposes of the Prescription
• Communication
• Billing
• Legal/regulatory issues
Who Best Knows the Patient
Time of Initial Orthotist’s
Examination?
Why Written Communication?
• Constraints of therapists & orthotists
– Time
– Geography
– Rarely have PT/CO/MD/patient in same room
at same time
• Clarity
– Reduce risk of miscommunication
– Provide contact information
Who Best Knows the Patient at Time of
Initial Orthotist’s Examination?
• Communication critical if patient has
fluctuations in:
Communication with Patient
• Informed consent process
• Orthotic trial ideal
– Impairments:
•
•
•
•
Tone
Edema
Muscle &/or general fatigue
Behavior
– Level of function/activity
• Assist level
• Endurance
– Opens door for communication
•
•
•
•
•
Goals/expectations
What orthosis can/cannot do
Cosmesis
Weight
Issues related to clothing, toileting, etc
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Essential Parts of Prescription
•
•
•
•
Patient information
Contact information of referring providers
Contact information of recommended orthotist
All diagnoses
– Include precautions
• Orthosis &/or shoe modifications
– Side
– Type
– Components & features suggestions/requests
Medical Necessity
• Why is orthosis needed?
• What issues are you trying to
control/support or assist during:
– Gait
– Standing
– Transfers
– Bed or wheelchair positioning
Case Examples
Good, Bad, or Ugly?
AFO?
Good, Bad, or Ugly?
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Thank you!
Questions?
14
ABC NEURO CLINIC
1333 SMITH ST
HOUSTON, TX 77030
EQUIPMENT PRESCRIPTION
LETTER OF MEDICAL NECESSITY
DATE: 5/7/14
PATIENT NAME: Bubba Jones
DIAGNOSIS: Paralysis
ITEMS AND SPECIFICATIONS:
• Orthotic
MEDICAL NECESSITY:
PHYSICIAN’S SIGNATURE:_____________________________ DATE:_________________
PHYSICIAN’S NAME:
(unreadable signature of Dr. Knowitall)
713-797-xxxx (phone number no longer working)
ALMOST GOOD NEURO CLINIC
1333 SMITH ST
HOUSTON, TX 77030
EQUIPMENT PRESCRIPTION
LETTER OF MEDICAL NECESSITY
DATE: 5/7/14
PATIENT NAME: Donnita Brace
DIAGNOSIS: Post-polio syndrome; progressive neuromuscular atrophy
PHYSICAL THERAPIST: Carolyn Da Silva, PT, DSc, NCS (713-794-2087)
VENDOR:
LENGTH OF NEED: 99 months
ITEMS AND SPECIFICATIONS:
L AFO
MEDICAL NECESSITY:
Walking difficulty, high fall risk
PHYSICIAN’S SIGNATURE:_____________________________ DATE:_________________
PHYSICIAN’S NAME:
Dr. E. Strangelove
1333 Smith St
Houston, TX 77030
713-797-xxxx
fax 713-797-xxxx
STRIVING FOR EXCELLENCE NEURO CLINIC
1333 SMITH ST
HOUSTON, TX 77030
EQUIPMENT PRESCRIPTION
LETTER OF MEDICAL NECESSITY
DATE: 5/9/14
PATIENT NAME: Anita Brace
DIAGNOSIS: Post-polio syndrome; progressive neuromuscular atrophy; leg length discrepancy;
s/p partial arthrodesis L ankle; degenerative joint changes L ankle; L sacroiliac pain
PHYSICAL THERAPIST: Carolyn Da Silva, PT, DSc, NCS (713-794-2087)
VENDOR: Hanger Orthotics, Jason Jennings, CPO 713-747-4171
LENGTH OF NEED: 99 months
ITEMS AND SPECIFICATIONS:
L AFO
• As lightweight as possible, evaluate for plastic design
• Rear entry/ground reaction design
• Articulating ankle
o Dorsiflexion stop prior to onset of pain in stance
o Dorsiflexion assist
Shoe modifications
• Heel lift on L
• Rocker soles on B shoes
MEDICAL NECESSITY:
Mrs. Brace is a 58 year old female with history of polio and post-polio syndrome. She has B
lower extremity weakness, with the L side being weaker than the R. She has been walking fulltime without assistive devices or orthosis since healing from her childhood arthrodesis (joint
fusion). Currently, she has severe pain in the anterior part of her ankle during stance phase, as
she progresses through midstance into terminal stance and preswing subphases. Her pain
intensifies as she walks longer distances. As she becomes more painful, she compensates in ways
to try to minimize the pain, causing excessive wear and tear on other joints, including her L
sacroiliac joint.
She requires an AFO that is lightweight to avoid over-fatiguing her already weak muscles. It
needs to rigidly block her painful dorsiflexion in stance phase as described above. However, it
also needs a jointed ankle to allow the plantarflexion that should occur from initial contact into
loading response to allow as smooth weight acceptance into stance as possible for joint
protection, pain management, and energy efficiency.
Mrs. Brace also requires shoe modifications to minimize (not necessarily correct) her structural
leg length discrepancy. The heel lift will also reduce the amount of dorsiflexion required during
stance phase, thereby helping to reduce her pain. The rocker bottom soles are required to allow a
more efficient transition from terminal stance into preswing, since the rigidity of the AFO will
hinder her mechanical 3rd/toe rocker.
PHYSICIAN’S SIGNATURE:_____________________________ DATE:_________________
PHYSICIAN’S NAME:
Dr. Wonderful
1333 Smith St
Houston, TX 77030
713-797-xxxx
fax 713-797-xxxx
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