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3 Orthopedics
C o n t e n t s
3.1 Biomechanics . . . . . . . . . . . . . . . . . . . . . . . . 50
by Justin Wernick, DPM
3.2 Common Orthopedic Pathologies of the
Foot and Ankle. . . . . . . . . . . . . . . . . . . . . . . 107
by Steve Levitz, DPM and
Justin Wernick, DPM
3.3 Neuromuscular Disease and Electrodiagnosis 119
by Ellen Sobel, DPM
3.4 Orthotics and Prosthetics . . . . . . . . . . . . . . 139
by Ellen Sobel, DPM and
Lauren Jones, DPM
3.5 Pathological Gait . . . . . . . . . . . . . . . . . . . . . 161
by Aaron Glockenberg, DPM
3.6 Pathomechanics . . . . . . . . . . . . . . . . . . . . . 169
by Justin Wernick, DPM
3.7 Physical Medicine . . . . . . . . . . . . . . . . . . . . 205
by Loretta Logan, DPM and
Carl Harris, DPM
3.8 Sports Medicine . . . . . . . . . . . . . . . . . . . . . 225
by Josh White, DPM and
Lauren Jones, DPM
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3.1 Biomechanics
Justin Wernick, D.P.M.
Introduction
Biomechanics is the study of the structure and function of the biological systems by means of the methods of
mechanics.
ASB,1975
Body Planes
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Dorsiflexion
A movement on the sagittal plane where the distal part of the foot or segments of the foot moves toward the
anterior of the leg.
Position
Dorsiflexed
Calcaneous
Plantarflexion
A movement on the sagittal plane where the distal part of the foot or segments of the foot moves away from the
anterior of the leg.
Position
Plantarflexed Equinus
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Closed Chain Sagittal Plane Movement of the Leg on the foot
Closed Chain Sagittal Plane Motion Dorsiflexion
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Closed Chain Sagittal Plane Motion Plantarflexion
Midline of the Foot
The body midline is used as the reference.
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Abduction
A movement on the transverse plane where the distal part of the foot or segments of the foot moves away from
the midline of the body.
Adduction
A movement on the transverse plane where the distal part of the foot or segments of the foot moves towards the
Position
Abducted
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Eversion
A movement on the frontal plane where the plantar surface of the foot or segments of the foot faces away from
the midline of the body.
Position
Everted
Valgus
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Inversion
A movement on the frontal plane where the plantar surface of the foot or segments of the foot faces toward the
midline of the body.
Position
Inverted
Varus
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Functional Definitions
Upper segment => Talus and the leg
Lower segment => Calcaneus and the foot
Rearfoot => Talus and the calcaneus
Forefoot => Distal to the MT joint
Hypermobility
Hypermobility implies instability and is defined as movement of a segment or part that should be fixed and
stable when stress is applied.
Abnormal Compensation
An abnormal change of structure, position, or function of one part in an attempt by the body to neutralize the
effects of a deviation of structure, position, or function of another part.
The results are pathological.
Daily Stress
Walking and standing on a hard, unforgiving surface + Number of steps taken each day + Average body
weight = The amount of force the feet and body are exposed to each day
Average number of steps taken each day(10,000) X Average body weight (150 lbs) = The amount of force the
feet and body are exposed to each day (1,500,000 lbs!)
Axis
The axis is an imaginary line passing through the center of a body about which a rotating body turns; synonymous
with an axle.
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Axis of Motion
The hinge around which motion takes place. The motion is always perpendicular to the plane or planes in
which the axis is placed.
The Foot is Predictable
The primary joints of the foot are hinge joints with one axis, and therefore will react in one direction or the
other!
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Triplane Motion
A motion-taking place, consisting of three components where the axis of the motion makes an angle to all
three-body planes.
Pronatory/Supinatory Axes
A pronatory/supinatory axis is directed from posterior, lateral, inferior to dorsal, medial, anterior.
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Triplane Motion
Components of the motion
Planal Dominance
The determination of a motion at a given joint based upon the orientation of the axis.
Planal dominance of the individual foot is important to the evaluation of the function of the foot. The direc-
tion in which an individual foot can compensate is important.
The primary plane of compensation and the amount of available range are important considerations when
evaluating foot function.
Green,D.,Carol,A., Planal Dominance, JAPA,Vol.74, #2
Planal Dominance of the Joints of the Foot
Deviations of the axis from the body planes will determine which component will be dominant at each joint.
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Even in our everyday attempts to control the variety of foot types seen in our offices, planal dominance can
play a major part in our success.
Green,D.,Carol,A., Planal Dominance, JAPA,Vol.74, #2
General Rules
After a thorough assessment of the patient, determine on which body plane(s) the pathologic influence is
taking place
Then determine which joints the pathological influence will select to compensate for the influence. It will be
the joints with the largest component in that body plane
Determine if there is an adequate range of motion in the joint(s) selected to fully compensate for
the influence
Open Chain Motion
A combination of several joints united successfully where the end segment is free! As during the swing phase
of gait.
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Open Chain Pronation
With the leg and talus held stable, the calcaneus and the foot will undergo eversion, abduction, and dorsiflexion.
Open Chain Supination
With the leg and talus held stable, the calcaneus and the foot will undergo inversion, adduction, and
plantarflexion.
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Closed Chain Motion
A combination of several joints united successfully where the end segment is not free! As during the stance
phase of gait.
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Subtalar Joint Closed Chain Pronation
Adduction and plantarflexion of the talus associated with internal rotation of the leg
Eversion of the calcaneus
Flexion of the knee
Anterior tilt of the pelvis
Subtalar Joint Closed Chain Supination
Abduction and dorsiflexion of the talus associated with external rotation of the leg
Inversion of the calcaneus
Knee extension
Posterior tilt of the pelvis
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Criteria for Normal Function of the Foot
A basis by which we measure to determine if a patient is functioning normally or abnormally
The appropriate functional alignment for the foot and leg during the stance phase of gait
Neutral Position of the Subtalar Joint
The neutral position is a position of the subtalar joint where the joint is congruent and a bisection of the lower
one-third of the leg creates an angle of zero to four degrees with the bisection of the posterior surface of the
calcaneus.
Forefoot/Rearfoot Relationship
The forefoot/rearfoot relationship is represented by the transverse plane of the lesser metatarsal heads (2-4)
being perpendicular to the calcaneal bisection when the subtalar joint is in neutral and the midtarsal joint is maxi-
mally pronated.
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Sagittal Plane Motion of the Ankle
Sagittal plane motion of the ankle is represented by approximately 10 degrees of dorsiflexion that is required at
the ankle joint with the subtalar joint neutral and the knee fully extended. Measured as a angle between the proxi-
mal heel and the lower one-third of the lateral surface of the leg.
Frontal Plane Function of the Leg
There shall be no deviation (+/- 2) of the leg above in the frontal plane as it enters the foot when the subtalar
joint is in neutral position.
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Sagittal Plane Function of the Leg.
There shall be no deviation (+\-2) of the leg in the sagittal plane as it enters the foot when the subtalar joint is
in neutral position.
Transverse Plane Function of the Leg
There shall be no deviation (+\-2) of the leg in the transverse plane as it enters the foot when the subtalar joint
is in neutral position.
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When the Foot hits the Ground, Everything Changes!
Muscle pull reverses itself and functions from its insertion to its origin
Range of motion of the joints will decrease from its off weight bearing position
Extrinsic factors play a dominant role in influencing foot function
Movement of the center of gravity is instrumental in stabilizing specific segments of the foot
Subtalar Joint
A pronatory/supinatory axis whose motion will appear clinically as:
Eversion/abduction of the rearfoot with pronation
Inversion/adduction of the rearfoot with supination
Planal Dominance of the Joints of the Foot
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High-Pitched Subtalar Joint Axis--Increase in Adduction-Abduction
Low-Pitched Subtalar Joint axisIncreased Inversion-Eversion
Conversion of Rotation at the HipRotation at the hip joint is converted to motion at the subtalar joint via a system similar to a universal joint.
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Rotation at the subtalar joint converts transverse plane motion to frontal plane motion via a mitered hinge
Effects of Leg Rotation on the Foot
Four degrees to six degrees of subtalar joint pronation is required to expedite internal rotation
Internal rotation of the leg results in pronation of the subtalar joint!
External rotation results in supination!
Effects of Friction
Friction enhances sagittal plane walking by converting internal and external rotation at the hip to pronation
and supination at the subtalar joint.
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Subtalar Joint
On closed chain, the motion will appear clinically as:
Eversion of the calcaneus with pronation
Inversion of the calcaneus with supination
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Subtalar Joint Pronation Closed Chain
Adduction and plantarflexion of the talus associated with internal rotation of the leg
Eversion of the calcaneus
Flexion of the knee
Anterior tilt of the pelvis
Subtalar Joint Closed Chain Pronation
Adduction and plantarflexion of the talus associated with internal rotation of the leg
Eversion of the calcaneus
Flexion of the knee
Anterior tilt of the pelvis
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Subtalar Joint Supination Closed Chain
Abduction and dorsiflexion of the talus associated with external rotation of the leg
Inversion of the calcaneus
Knee extension
Posterior tilt of the pelvis
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Subtalar Joint Closed Chain Supination
Abduction and dorsiflexion of the talus associated with external rotation of the leg
Inversion of the calcaneus
Knee extension
Posterior tilt of the pelvis
Effects of Subtalar Joint Motion on the Architecture of the Foot
The range of motion of the distal joints will increase with subtalar joint pronation and decrease with subtalar
joint supination.
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General Effects
The average range of motion of the subtalar joint has been found to be approximately 25 - 30. The ratio of
supination to pronation is usually 2:1 but may be 4:1.
Pronation
Supination
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Neutral Position
Definitions
A position of a joint from which maximum function may occur in any of the permissible directions.
A position where the joint is neither supinated nor pronated and the body of the talus is in line with the
body of the calcaneus.
Neutral Position Subtalar Joint Congruency
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Subtalar Neutral Position
Axis of the subtalar joint is a hinge that results in an arc like motion
Supination in one direction, pronation in the other
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The Ankle Joint
Planal Dominance of the Joints of the Foot
A pronatory / supinatory axis whose motion will appear clinically as:
Dorsiflexion and abduction with pronation
Plantarflexion and adduction with supination
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Ankle Joint Function
Expedites forward movement of the body over the foot
Compliments the pull of the swing limb with a push-off of the support limb
Adapts to situations where there is a limitation or lack of motion in the subtalar joint
Provides the sagittal plane component to the rearfoot
The Midtarsal Joints
Planal Dominance of the Joints of the Foot
Planal Dominance of the Longitudinal Midtarsal Joint Axis
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The Midtarsal Joint Longitudinal Axis
A pronatory/supinatory axis whose motion will appear clinically as:
Eversion of the forefoot with pronation
Inversion of the forefoot with supination
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On closed chain, the motion will appear clinically as:
Pronation of the rearfoot with supination of the forefoot
Supination of the rearfoot with pronation of the forefoot
Forefoot/Rearfoot Functional Relationships
Supination of the forefoot is: relative pronation of the rearfoot
Pronation of the forefoot is: relative supination of the rearfo
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Range of motion
The average range of Motion of the longitudinal MT Jt is 22. Pronation of the subtalar joint requires 4 - 6
of complimentary supination of the forefoot.
There is only supination available when the subtalar joint is neutral.
Effects of Rearfoot Function on the Midfoot
Subtalar Joint Pronation => Unlocks Midfoot => Longitudinal Axis MT Joint Supination
Subtalar Joint Supination => Locks Midfoot => Longitudinal Axis MT Joint Pronation
The Oblique Axis Midtarsal Joint
A pronatory/supinatory axis whose motion will appear clinically as:
Dorsiflexion/abduction of the forefoot with pronation
Plantarflexion/adduction of the forefoot with supinatio
Planal Dominance of the Joints of the Foot
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Planal Dominance of the Joints of the Foot
An increase in the pitch of the calcaneus will increase the transverse plane component.
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An increase in internal rotation of the leg will increase the sagittal plane component.
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Midtarsal Joint Oblique Axis
On closed chain, the motion will appear clinically as:
Dorsiflexion/abduction of the rearfoot with forefoot supination
Plantarflexion/adduction of the rearfoot with forefoot pronation
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Closed Chain Pronation
Apparent forefoot abductus
cuboid notch
Too many toes syndrome
Foot rolling out from under the leg
Apparent tibia varum
Planal Dominance of the Joints of the Foot
Forefoot
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Effects of Rearfoot Function on the Midfoot
Subtalar Joint Pronation => Unlocks Midfoot => Oblique Axis MTJt. Pronation
Subtalar Joint Supination => Locks Midfoot => Oblique Axis MTJt. Supination
Pillars of the foot
The medial pillar (column) is the adaptive or spring-like structure, and the lateral pillar (column) is the stabile
structure.
The 1st Ray
Axes of Motion
The axis of the 1st ray is deviated 45 from the sagittal and frontal planes. The major components of
the motion are: Plantarflexion with eversion
Dorsiflexion with inversion
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Joint Motions that Affect Arch Morphology
Joint involved Raise the arch Lower the arch
Subtalar Jt. No effect No effect
Long. MT Jt Pronation Supination
Oblique MT Jt. Supination Pronation
1st Ray Plantarflexion Dorsiflexion
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Components
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Planal Dominance of the Joints of the Foot
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Range of Motion
The 1st ray has a range of motion of 5 mm dorsally and 5 mm plantarly for a total range of 10 mm.
Stabilization of the 1st Ray
The peroneus longus muscle functions to:
Compress the tarsus in concert with the posterior tibial muscle
Stabilize the 1st ray both posterior and lateral
Resist the ground reaction forces from dorsiflecting the 1st ray
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Requirements for Proper Function of the 1st Ray
Subtalar joint supination
Stable midtarsal joint
Heel lift
Posterior movement of the 1st metatarsal head on the sesamoids
A second metatarsal that is longer then the first
Effect of Supination of the Subtalar Joint on the First Ray.
Effect of Pronation of the Subtalar Joint on the First Ray.
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The 1st MP Joint
Anatomy
Together they create a dynamic acetabulum.
Osseous structures
Head of the first metatarsal
Base of the proximal phalanx Medial and lateral sesamoids
Capsule
Muscle attachments
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Axes of Motion
IRolling motion
II, IIISliding motion associated with 1st ray plantarflexion
IVCompression
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Design and Function of the 1st Metatarsal Head
Since the design of the head is in the shape of a cam, rolling of the head and then sliding is expedited.
Demand for Dorsiflexion at the 1st MP Joint
The average range of motion is 55 to 85.
During the propulsive phase of gait, the demand for dorsiflexion at the MP joints is the result of :
Hip extension
Knee flexion
Ankle plantarflexion
As the 1st ray plantarflexes, it slides plantarly in relationship to the base of the proximal phalanx.
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Once the heel has lifted maximally, the 1st ray will fully compress against the base of the proximal phalanx.
The range of motion available at the 1st MP joint weight bearing is approximately 20 . This is consistent with
the rolling segment of the motion.
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Requirements for Essential Motion at the 1st MP Joint
1st ray plantarflexion
2nd metatarsal longer then the 1st
Normal intrinsic and extrinsic muscle function
Normal sesamoid function
Intact base of the proximal phalanx
Functional Hallux Limitus
A blockage of motion at the 1st metatarso-phalangeal joint during walking, resulting in the inability of the
proximal portion of the foot to pass over the toes
Limitation may occur in spite of a normal range of motion off-weight bearin
This will result in some form of compensation to occur in the foot , limb and/or back and neck
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Factors that Block Sagittal Plane Motion at the 1st MP Joint
Elevation of the 1st ray
Forefoot valgus/plantarflexed 1st ray
Rearfoot and forefoot instability Abnormal muscle function
Long 1st metatarsal
Degeneratve joint disease
Arthritides
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Elevatus of the 1st Ray Secondary to Pronation of the Rear Foot at Propulsion
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Compensations for sagittal plane blockade of the 1st MP joint
Intrinsic compensations
Dorsiflexion of the IP joint with medial roll-off
Inverted forefoot at propulsion. (Low gear) Abducted gait
S.A.R.P. (Secondary Active Retrograde Pronation)
Hallux abducto-valgus deformity
Extrinsic compensations
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Elevatus of the 1st Ray Secondary to a Long 1st Ray
Inverted Forefoot at Propulsion
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Secondary Active Retrograde Pronation (S.A.R.P.)
Compensations for Sagittal Plane Blockade of the 1st MP Joint
Extrinsic compensations
Flexion at the hip
Neck and shoulder flexion
Tempro -Mendibular Jt. complications
Flexion Contracture Compensation for Functional Hallux Limitus
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Examination for Functional Hallux Limitus
The range of motion available at the 1st MP joint on weight bearing is approximately 20 . This is consistent
with the rolling segment of the motion.
A lack of this motion is indicative of a functional hallux limitus.
Primary Passive Propulsive Phase Supination Windlass Mechanism
Heel lift with ankle plantarflexion will dorsiflex the MP joints
This will tighten the plantar fascia, raise the arch, and shorten the foot
Raising the arch will resist elongating the foot and assist in resupinating the subtalar joint
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Kinetic Wedge
Problem: Functional Hallux Limitus (FHL)
Dorsiflexion of the 1st ray at propulsion
Compensation causes foot symptoms
Compensation causes postural symptoms
Solution: Induce Plantarflexion-eversion of the 1st Ray
Dual angle cutout at the 1st MP joint
Parallels the 1st ray axisinduces plantarflexion and eversion of the 1st ray
Parallels the 1st MP joint axisassists hallux dorsiflexion and 1st ray plantarflexion
Bi-directional shell cutout to permit plantarflexion
Hallux extension to increase hallux purchase
Summary
The 1st ray is required to plantarflex and evert during the heel lift stage of walking
Motion at the 1st metatarso-phalangeal joint consists of rolling, sliding with compression at the end range
Factors that cause an elevatus of the 1st ray to occur will block motion and create a functional hallux limitus
Intrinsic and extrinsic compensations for this sagittal plane blockade will occur
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The 5th Ray
5th Ray Axis
A pronatory/supinatory axis whose motion will appear clinically as:
Dorsiflexion and eversion of the ray with pronation
Plantarflexion and inversion of the ray with supination
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Planal Dominance of the Joints of the Foot
On closed chain, the motion will appear clinically as:
Dorsiflexion/abduction of the 5th ray
Plantarflexion/adduction of the 5th ray
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GAIT
GENERAL CONCEPTS
2 periods of double support (25%)
2 periods of single support (75%)
0 - heel strike
7% - footflat 12% toe-off of opposite limb
15% full heel eversion occurs
34% heel rise
50% heel strike of opposite limb
62% toe-off (reswing)
Heel rise occurring before 34% = Gastroc spasticity
Footflat not occurring by 7% = Gastroc spasticity
Heel rise occurring later than 34% = Gastroc weakness
TERMINOLOGY NEW VERSUS THE OLD
Contact Phase
Heel strike ..................Initial contact
Footflat.......................Load response
Midstance...................Single leg stance
Propulsion
Heel-off .....................Terminal stance
Toe-off........................Preswing
GAIT CYCLE
STANCE PHASE
CONTACT (0-15%) HEEL STRIKE TO FOOTFLAT CALCANEUS everts (passively) maximum to 15%
Entire lower extremity internally rotates
ANKLE JOINT plantar flexes to ~20%
KNEE flexes 15-20o
HIP flexes
QUADRICEP (L2,3,4) contract eccentrically to stabilize knee and prevent buckling
GLUTEUS MAXIMUS acts as break preventing too much truck flexion
ANTERIOR LEG MUSCLES (L4) contract eccentrical slowing down ankle joint plantarflexion
MIDSTANCE (15-34%) FOOTFLAT TO HEEL OFF
CALCANEUS inverts
EXTERNAL ROTATION initiated by contralateral swing limb
ANKLE JOINT dorsiflexes to 20
KNEE extends
HIP extends
GLUTEUS MEDIUS (L5) holds pelvis down on stance side
ERECTOR SPINAE and HIP ADDUCTORS contract to hold swing leg up
CALF MUSCLES eccentrically contract to control ankle joint dorsiflexion
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PROPULSION (34-60%) HEEL-OFF TO TOE-OFF
CALCANEUS inverts
EXTERNAL ROTATION of stance limb continues
ANKLE JOINT plantarflexes ~20
KNEE flexes to 40
HIP flexes
CALF MUSCLES (S1, S2) concentrically plantarflex calf
SWING PHASE
INITIAL SWING (ACCELERATION)
CALCANEUS everts (STJ pronates)
Internal rotation of the leg
ANKLE JOINT dorsiflexes to clear ground
KNEE flexes to 60
HIP flexes
ILEOPSOAS initiates swing phase of gait
ANKLE DORSIFLEXORS concentrically contract for foot to clear ground
MIDSWING
Swing leg is adjacent to weight-bearing leg
Internal rotation of leg continues
KNEE flexes 60
HIP flexes
TERMINAL SWING (DECELERATION)
CALCANEUS inverts
INTERNAL ROTATION of leg continues
ANKLE JOINT remains dorsiflexed to 90
KNEE extends
HIP extends GLUTEUS MAXIMUS slows down swinging limb
HAMSTRINGS control hip flexion and also slow down swinging leg
QUADRICEPS control knee extension