Transcript Ankle - Iambiomed

GAIT ANALYSIS
 WALKING: depends upon the repeated performance
by the lower limbs of a sequence of motions which
advance the body along a desired line of progression
while also maintaining a stable weight bearing
posture.
 The effectiveness of walking will depend upon free
joint mobility and muscle action.
Gait Cycle
 Each sequence of limb action is called a gait cycle
which involves a period of weight bearing (stance) and
a period of self advancement i.e. swing.(i.e. the action
of our limbs is reciprocal action ,when one leg is in
stance the other leg is in swing)
 Approximately 60% of time is spend in stance & 40%
in swing.
 The reciprocal action of the limbs is timed to trade
their weight bearing responsibility during a period of
double stance
Gait Parameter Definitions:
Base of Support is the distance between parallel lines intersecting the midpoint
of each heel print
 Line of Progression is a line located approximately at the center point
between both feet along the walker’s path of progression
 Foot Angle is the angle formed by the intersection of the line of progression
and a second line, which is drawn through the midpoint of the heel and the
space between the second and third tarsal
Gait Parmeter Definitions
 Step Length =Distance between corresponding successive points of
heel contact of the opposite feet
 Rt step length = Lt step length (in normal gait)
 Stride Length =Distance between successive points of heel contact of
the same foot
 Double the step length (in normal gait)
 Cadence =Number of steps per unit time
 Normal: 100 – 115 steps/min
 Velocity = Distance covered by the body in unit time
 Usually measured in m/s
 Instantaneous velocity varies during the gait cycle
 Average velocity (m/min) = step length (m) x cadence (steps/min)
 Comfortable Walking Speed (CWS) =Least energy consumption per unit
distance
 Average= 80 m/min (~ 5 km/h , ~ 3 mph)
Functional Elements
 Three are three components or functional elements of
walking:
 Progression
 Standing Stability
 Energy Conservation
Functional Elements
 Progression: There are two main progressional forces:
1)The primary one is the forward fall of body weight as the ankle
dorsiflexes beyond neutral and accelerates with heel rise.
2)The second generated by the contra lateral swinging limb starts with
onset of single limb support The action is particularly important before
the body is aligned for a forward fall.
 The momentum generated by these two actions is preserved at the
onset of the next stance phase by floor contact with the heel.
 Thus throughout the stance the heel, forefoot and the ankle serve as a
rocker which advance the body over the supporting foot.
Functional Elements
 Standing Stability: Balance is challenged by two factors
1)body is top heavy & walking continuously alters the
segment alignment.
 During walking the body is divided into two functional
units: Passenger(head ,neck, trunk)as they are carried,
rather than contributing to the act the act of walking
Locomotor unit (limbs joint by intervening pelvis).
 Muscle action with the neck and the trunk is to maintain
neutral vertebral alignment
 Arm swing is a passive reaction to the momentum
generated during walking
Functional Elements
2)Weight bearing stability is maximum when it’s 3
components are vertically aligned.
 The skeletal architecture is designed for mobility, this
means some stabilizing mechanisms are needed
 Thus at the hip and knee joints ligaments and the
muscles in the limbs help to stabilize the joints
3)The ankle joint divides the foot in to a larger anterior
portion and a smaller posterior portion, thus the body
wt vector should pass through the anterior part of the
foot
Functional Elements
 Energy Conservation: efficiency is energy
expenditure per task performed. for walking it is
oxygen used per meter travelled
 Oxygen is consumed as the muscles contract during
walking. so the energy can be conserved by reducing
the amount of oxygen consumed i.e. by reducing
muscle activity
 The muscle activity can be reduced by 1) substituting
momentum in place of muscle action whenever
possible, displacement of body from the line of
progression is minimized .
Functional Elements
 Optimum use of momentum occurs during the persons natural
gait velocity which requires a least energy expenditure per meter
travelled
 Both slower and faster pace increase energy cost
 Minimization of body displacement from the line of progression
is accomplished by coordinating the pelvic, knee and ankle
motion to keep the relative limb length relatively constant
during stance. At the onset of double stance body height is the
lowest as the limbs are diagonal. The highest position is in
middle of the single stance when the limb is vertical
 To reduce these extremes normal gait cycle involves 3 pelvic
motions: lateral drop, transverse rotation and anterior tilt
Joint Motion
 The interplay of progression ,standing stability and
energy conservation result in complex and continually
changing relationship between the various limb
segments as the body advances over the supporting
foot and the toe is lifted to clear the ground.
 Each joint performs a repetitive pattern of motion
 There are three joints involved in walking:
1. Ankle
2. Knee
3. Hip
ANKLE JOINT
 The ankle joint is formed where the foot and the leg meet. The
ankle is a synovial hinge joint that connects the distal ends of the
tibia and fibula in the lower limb with the proximal end of the
talus bone in the foot.
 The bones of the ankle, called tarsal bones, consist of the talus,
calcaneus (heel), navicular, cuboid, medial or internal
cuneiform, middle cuneiform, and lateral or external cuneiform
 The ankle joint is bound by the strong deltoid ligament and
three lateral ligaments: the anterior talofibular ligament, the
posterior talofibular ligament, and the calcaneofibular ligament
 The ankle joint permits planter flexion ,dorsiflexion ,inversion
eversion (foot)
Motion At Ankle
 Two periods of planter flexion and dorsiflexion are





experienced in each gait cycle.
At onset of stance ankle has 90 degree position w.r.t
foot(neutral)
As heel is loaded ankle drops into 10 degrees of PF
Then action is reversed and reaches 1o degrees of
dorsiflexion.
The PF is resumed reaching 20 degrees by the end of
stance(double stance)
With toe-off foot is raised to neutral dorsiflexion and is
maintained in this position throughout the swing phase
Motion At Ankle
KNEE JOINT
 The knee is essentially made up of four bones. The femur, which
is the large bone in your thigh, attaches by ligaments and a
capsule to your tibia. Just below and next to the tibia is the
fibula, which runs parallel to the tibia. The patella, or what we
call the knee cap, rides on the knee joint as the knee bends.
 When the knee moves, it does not just bend and straighten, or,
as it is medically termed, flex and extend. There is also a slight
rotational component in this motion. The knee muscles which
go across the knee joint are the quadriceps and the hamstrings.
The quadriceps muscles are on the front of the knee, and the
hamstrings are on the back of the knee. The ligaments are
equally important in the knee joint because they hold the joint
together. the bones support the knee and provide the rigid
structure of the joint, the muscles move the joint, and the
ligaments stabilize the joint.
Motion At Knee
 Two phases of flexion and extension
 Beginning in full extension(flexed 5 degrees). It rapidly flexes to 15
degrees.
 Then it progressively begins to extend .
 Within onset of double stance it again begins to flex.
 The action continues in swing till it reaches 60 degrees before
extension is resumed
Motion At Knee
HIP JOINT
 The hip joint is the joint between the femur and
acetabulum of the pelvis and its primary function is to
support the weight of the body in both static (e.g.
standing) and dynamic (e.g. walking or running) postures.
 The hip joint is reinforced by five ligaments, of which four
are extracapsular and one intracapsular
 The hip muscles act on three mutually perpendicular main
axes, all of which pass through the center of the femoral
head, resulting in 3 movements: Flexion and extension
around a transverse axis (left-right); lateral rotation and
medial rotation around a longitudinal axis (along the
thigh); and abduction and adduction around a sagittal axis
(forward-backward) and circumduction
Motion At Hip
 Only a single arc of hip extension and flexion occurs




fro each gait cycle.
As the foot strikes the ground the hip is in 30° of
flexion.
Throughout the stance there is progressive extension
into 10° of hyperextension.
Then flexion begins in terminal double stance and
continues in most of the swing.
When the 30° posture is reached it is maintained until
stance resumed
Motion At Hip
Gait Cycle
 Stance Phase: To allow progression while maintaining
weight bearing stability the limb performs the distinct
tasks that define the phases of stance.
 The stance phase is further divided into five stages
1. Initial contact
2. Loading response
3. Mid Stance
4. Terminal Stance
5. Pre swing
Initial Stance
 Of primary concern is the way the foot strikes the floor
 Heel will strike the floor at an angle of 25°
 The ankle is in neutral position(PF 3°)
 Knee is extended between o to 5 °of flexion
 Hip is flexed 30°
 The body weight vector passes through the heel
which is anterior to both knee and hip.
 Three torques are generated: ankle PF, Knee extension,
hip flexion
Initial Stance
 Control of both knee and ankle is critical to have a
normal heel strike
 The ankle motion is dependent on the free joint
mobility and the pretibial muscles
 Knee extension is accomplished by the quadriceps
action
 Hip does not influence mode of floor contact but
determines the angle between foot and floor
Initial Stance
stance
wt vector
Loading response
 Acceptance of body weight in such a manner that assures
limb stability and still perform progression is the goal of
this stage. The action at the ankle precedes and contributes
to the knee action.
 Ankle: After floor contact by the heel the foot drops into 10
of PF in a controlled manner. The action is initiated when
the body weight is applied at the talus and the floor
contact is still at the calcaneus (heel bone).An unstable
lever will result from difference in length between these
two points. Strong action by the pretibial muscles retards
the terminal arc of ankle planter flexion so forefoot contact
is gradual .thus heel strike is heard but no foot slap
Loading response
 Knee: flexion of knee is to 15 is initiated by heel rocker
action. As the pretibial muscles contract to restrain
ankle PF it also draws tibia forward this is rapid action
and it advances the knee much faster than the thigh
and trunk can follow. As result the body weight shifts
posterior to the knee and a flexion torque is induced.
 Two types of muscle actions result –increased
quadriceps activity to restrain rate of knee flexion
 No hamstring muscles are needed for knee
hyperextension.
Loading response
 Hip: little change in the body position occurs during
the loading response.
stance
Mid Stance
 Advancement of body and
limb over a stationary foot is
the functional objective of
this gait phase
 As the other foot is lifted
from ground a period of
single limb support begins,
maximum stability is gained
by having the foot stationary
and in total contact with the
floor
 As the body weight advances
the base of the weight vector
moves from heel to forefoot
stance
stance
Mid Stance
 Ankle: At onset of single stance ankle is slightly PF by
5°
 From this position there is gradual dorsiflexion, the
basic arc is from -5° to 5° with 10° of DF being attained
just as the heel rises to initiate terminal stance
 The body vector moves anterior to the ankle
Mid Stance
 Knee: knee flexion introduced during response increases to 18° just as
single limb support is initiated
 In the middle of mid-stance body wt vector moves anterior to the joint
center so the need for active muscular control is terminated.
 Quadriceps action is maximum at the onset of mid stance ,it then
progressively declines as knee extends over vertical tibia
 Once the vector becomes anterior to the knee axis ,extension stability is
provided passively and the quadriceps relaxes.
Mid Stance
 Hip :Progressive decline of hip flexion and entry in to
extension allow trunk to remain erect while limb
becomes more vertical
Mid Stance
 Lifting the opposite limb removes support from that
side of the body .The unsupported pelvis falls creating
hip adduction in the stance limb. This is rapidly
limited to 4 degrees and reduced by active abduction
 Hip abductor muscle activity is intense throughout the
mid stance while extensors are quiet.
Terminal Stance
 Primary objective of TS is
forward fall to generate a
propulsive force.
 Heel rise signifies on state
of second phase of single
stance.
 Now forefoot serves as the
rocker with the body
falling forward of it’s area
of support .
 This creates a primary
propulsive force for
walking
Terminal Stance
 Ankle: At onset of heel rise the ankle drops in to maximum





dorsiflexion (10°) occurring in stance
Motion then reverses to 5° of PF by end of single limb support
Stability is accomplished by the triceps surae
With heel rise body vector is concentrated at the forefoot
The distance between the vector and ankle joint generates a maximum
dorsiflexion torque
Both soleus and gastrocnemius respond vigorously to maintain ankle in
neutral position and ceases as the weight is transferred to the other
foot.
Terminal Stance
 Knee: maximum extension of knee between o to -5
 At the end of the terminal stance the knee begins to
flex .Body weight is rapidly falling towards the other
limb
 There is no quadriceps action for knee extension
 Stability is gained from the body vector being anterior
to the knee axis
Terminal Stance
 Hip: Passive extension of the hip jt continues as the
body wt advances over the supporting foot and the
trunk remains erect by the end of stance there is 10
degrees of hyperextension
 There is no hip extensor activity during terminal
stance
 As the body wt begins to fall forward the other limb
the hip abductors terminate their action ,for passive
abduction is induced.
Terminal Stance
Preswing
 Preparation of the limb for swing is the purpose of
action that occur during the preswing phase.
 Floor contact by the other foot initiates this interval of
terminal double support
 Rapid transfer of body wt to the limb allows the
desired action to follow.
 The critical area of response is the knee
Preswing
 Ankle: there is rapid ankle
PF to a 20 position
 Knee: There is rapid
passive flexion to 45 which
occurs because the body wt
is rolled so far forward of
the forefoot rocker that the
tibia is no longer stable.
 Hip: flexion of hip jt is
initiated with recovery
from hyperextension to
neutral that occurs during
this phase.
stance
stance
stance
stance
stance
swing
 Lifting the foot from the ground and limb
advancement followed by preparation for stance are
the objectives of three phases of swing
Initial Swing
 Recovery of the trailing position is the task that is
accomplished
 This involves two critical actions flexion of both hip
and the knee.
Initial Swing
 Ankle : DF of the ankle is initiated but only half of the





20 PF present at toe off is recovered at this time
Thus toe clearance is not dependent on the ankle
dorsiflexion during initial phase of the swing.
The muscles contract quickly to lift the foot.
Knee: the flexion increases to 60
No dominant flexion force
Hip: from the neutral position at toe-off the hip
rapidly flexes to 20
Mid Swing
 As the limb advancement continues the changes in the
tibial alignment make foot control critical for floor
clearance
Mid Swing
 Hip: maximum flexion to 30 is reached by iliacus
action
 Knee: relaxation of the flexor muscles allows the knee
to extend passively ,which accelerates advancement of
leg and foot
 By the end of mid swing knee flexion equals that of
hip flexion
 Ankle: Dorsiflexion to neutral is accomplished and
maintained.
Terminal Swing
 Advancement is terminated and the leg is prepared for
stance.
 Knee extension is the critical event.
Terminal Swing
 Ankle: continued neutral dorsiflexion is the basic
posture, but the foot may drop in to slight PF (3° to 5°)
at the end of the phase.
 Knee: The extension of the knee to neutral
continues(0° t 5°).The quadriceps provide the
necessary extensor force
 Hip: The 30° of flexion attained in flexion is
maintained .For this purpose iliacus continues to
support limb weight while hamstrings prevent further
motion.
Joint angles Ankle
Joint
Knee Joint
Hip Joint
Weight Vector
Initial
Stance
neutral
5 degree flextion
30 degree flexion Passes through
heel,anterior to
knee and hip
Loading
Response
10 degree
PF
15 degree PF
Almost same
Heel,posterior to
knee,hip
Mid Stance
10 degree
DF
18 degree flex
Entry into
extension
Heel and then
through forefoot
Terminal
Stance
5 degree
DF
0-5 degree
extension
10 degree
hyperextension
forefoot
Pre Swing
20 degree
PF
45 degree flex
Entry into flex
Passes through the
Tip of forefoot
Initial swing
10 degree
PF
60 degree flex
20 degree flex
-
Mid swing
neutral
30 degree flex
30 degree flex
-
Terminal
swing
0-5 degree 5 degree flex
30 degree flex
-
Gait cycle summery
Gait cycle summery
Determinants of Gait :

(1) Pelvic rotation:



Forward rotation of the pelvis in the horizontal plane approx. 8o on
the swing-phase side
Reduces the angle of hip flexion & extension
Enables a slightly longer step-length w/o further lowering of CG
Determinants of Gait :

(2) Pelvic tilt:
5o dip of the swinging side (i.e. hip adduction)
 In standing, this dip is a positive Trendelenberg sign
 Reduces the height of the apex of the curve of CG
