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Biomechanics II > Chapter 1 > Flashcards

Chapter 1 Flashcards

1
Q

Factors to Consider in gait

A

Gait is efficient (100 calories/mile) when biomechanically sound

Complicated process a) 100 bones, 200 muscles involved

Significant involvement of pelvis and lumbar spine

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2
Q

Pronation

A

Eversion, dorsiflexion

In gait, it usually refers to movement of the calcaneus, which produces motion in the subtalar joint.

This is different than the way we use the term in posture analysis where it refers to a position of the foot.

In gait, it’s a dynamic movement. In posture, it’s a static position.

Importance in gait
A normal amount of pronation happens during gait.
An excessive amount can lead to problems.

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3
Q

Supination

A

Inversion, plantarflexion

In gait, it also usually refers to movement of the calcaneus, which produces motion in the subtalar joint.

Again, this is different than the way we use the term in posture analysis where it refers to a position of the foot.

In gait, it’s a dynamic movement. In posture, it’s a static position.

Importance in gait
A normal amount occurs during gait, but if excessive, can also lead to problems.

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4
Q

Phases of Gait

A

stance phase - weight bearing, approximately 60% of gait cycle

swing phase - toe-off to heel strike, approximately 40% of gait cycle

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5
Q

stance phase

A

heel strike

midstance

propulsive period

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6
Q

heel strike

A

(contact period)

Toe-off opposite foot

Knee extended

Foot dorsiflexed

Leg decelerating

Subtalar joint pronating throughout

Note that even though the subtalar joint is pronating (calcaneus rocking laterally), the foot itself is in a supinated position.

27% of stance phase

Major function: transfer weight and shock absorption

Note to remember:
At any given moment during the stance phase, the subtalar joint is doing the opposite of the position of the foot itself (pronation or supination).
o For example, if the foot is in a supinated position (e.g., heel strike), the subtalar joint is pronating.

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7
Q

midstance

A

Weight-bearing period between foot flat and heel lift

Toe-off completed for opposite foot

Foot in full contact with floor

40% of stance phase

Subtalar joint supinating

Note that even though the subtalar joint is supinating (calcaneus rocking medially), the foot itself is moving toward a pronated position.

Major functions:
bearing weight
convert foot from adaptive shock absorber to rigid lever for propulsion

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8
Q

Propulsive period

A

Period between heel lift and toe-off (push-off)

33% of stance phase

Subtalar supination continued and completed

Note once again that even though the subtalar joint continues to supinate (calcaneus rocking medially), the foot itself is in a pronated position.

major functions:

  • transfer weight from lateral to medial side of foot, and to ball and toes for even propulsion
  • shifting weight of body to other foot
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9
Q

Swing phase

A

toe-off to heel strike, approximately 40% of gait cycle

Acceleration phase

midswing

deceleration

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10
Q

Gait Determinants

A

Efficient gait has minimal vertical oscillations; additional energy is used for these vertical displacements.

Determinants are biomechanical properties which decrease vertical oscillations and allow for more efficient motion.

Normal oscillation pattern
High point: midstance (either foot)
Low point: double weight bearing (toe-off/heel strike)

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11
Q

Six classical determinants

A

Pelvic rotation

Pelvic tilt

Pelvis shift

Knee flexion

Knee-ankle relationship

Hip flexion

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12
Q

Pelvic rotation

A

Rotation of the entire pelvis away from the side of the forward leg

I.e., when the right leg is forward, the pelvis is rotated to the left.

4° to each side

Axis of rotation in the opposite hip

Result is decreased angle between leg and floor, and between hip and leg (i.e., decreased hip flexion)

Vertical displacement decreased by 3/8 “

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13
Q

Pelvic tilt

A

Pelvis dips inferiorly on the swing side (4-6°)

Opposite hip adducts (weight bearing hip)

Gluteus medius is important to prevent excessive adduction of weight bearing hip (Trendelenburg test)

Decreases vertical displacement 1/8”

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14
Q

Pelvis shift

A

Pelvis shifts toward stance side (approximately 1”)

Hip adduction on stance side

Smoothes pelvic motion, helps maintain balance

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15
Q

Knee flexion

A

Stance leg knee goes from full extension (heel strike) to 15° flexion; knee re-extends as toe-off approaches

Important shock absorber

Decreases vertical displacement 1/8”

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16
Q

Knee-ankle relationship

A

Similar to knee flexion determinant

Ankle 90° at heel strike, plantar flexion follows, then dorsiflexion as toe-off approaches

As heel raises during toe-off, vertical lift smoothed out by knee flexion

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17
Q

Hip flexion

A

Acceleration stage of swing phase

Moves foot forward with minimal vertical undulation

Would have to raise pelvis without hip flexion

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18
Q

Which are the prime movers of gait?

A

Prime movers

(1) hip flexors/extensors

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19
Q

Major muscles of gait

A

Gluteus maximus and medius

Hamstrings

Gastrocnemius and soleus

Tibialis anterior

Quadriceps

Iliopsoas

TFL

20
Q

Muscle activity during Heel Strike of stance phase

A

heel strike

(deceleration and
stabilization)
(a) Hamstring activity decreases
(b) Quads - extend knee
(c) Gluteus medius - stabilizes
pelvis, abducts hip
(d) Paraspinal muscles - keep
pelvis from dipping excessively
(e) Tibialis anterior - dorsiflexes
foot, eccentric contraction as foot makes contact
21
Q

muscle activity during acceleration of swing phase

A

Acceleration

(a) Hip flexors (iliopsoas and quads) flex hip and accelerate forward
(b) Tibialis anterior contracts so toes clear floor

22
Q

Concentric Contraction

A

the force generated is sufficient to overcome the

resistance, and the muscle shortens as it contracts.

23
Q

Eccentric Contraction

A

the force generated is insufficient to overcome the resistance and the muscle lengthens as it contracts.

24
Q

Muscle activity during midstance of stance phase

A

Midstance

(a) Body weight being pulled over
foot by the body's momentum
(b) Gastroc., soleus, and TFL
braking and controlling
(3) Toe-off
(a) Propel body weight forward (i.e.,
upward and toward other foot)
(b) Gastroc and soleus contraction
25
Q

Muscle activity during Propulsion of stance phase

A

Toe-off

(a) Propel body weight forward (i.e.,
upward and toward other foot)
(b) Gastroc and soleus contraction

26
Q

Which are the stabilizers of gait?

A

Stabilizers

(1) hip abductors/adductors

27
Q

Which are the decelerators of gait?

A

Decelerators

(1) hamstrings and gluteus maximus to slow down swing

28
Q

muscle activity during decelleration of swing phase

A

Deceleration

(a) Contraction of gluteus maximus and hamstrings decelerates and prepares limb for heel strike

29
Q

What are the important aspects of physical examination of gait?

A

(1) Nervous system integrity
(2) Coordination and integration of movements
(3) Muscle strength and health
(4) Biomechanical integrity and stability of involved joints

30
Q

What are the methods of evaluting gait?

A

a) Complex and difficult process to assess
b) Begin with general observation and overview
c) Break down into component parts

31
Q

What are the difference causes of stance phase abnormality?

A

Muscle weakness
Instability
Pain

32
Q

What is a gluteus medius lurch?

A

(i) Weak or paralyzed gluteus medius (hip abductor)
(ii) Can’t abduct hip during stance phase
(iii) Must lean toward weak involved side to center gravity over stance leg
(iv) Or may let opposite side hip sag excessively during swing phase (a) Trendelenburg Gait

33
Q

What is a gluteus maximus lurch?

A

(i) Weak gluteus maximus (hip extensor)

(ii) Must shift pelvis anterior and thorax posterior to maintain hip extension

34
Q

What is a waddling gait?

A

(i) Proximal lower extremity (hip, etc.) muscle atrophy, dystrophy (ii) Example: bilateral gluteus medius lurch
(iii) Feet are wide apart; walk resembles that of a duck

35
Q

What is do weak quadriceps do in gait?

A

(i) May cause knee to buckle into flexion

36
Q

What is ataxic gait look like?

A

(i) Characterized by staggering and unsteadiness

37
Q

What does propulsive gait or festination look like?

A

(i) Walks on toes as though being pushed, small steps
(ii) Starts slowly, then gets faster; may need to grab something to stop
(iii) Typical of Parkinson’s disease

38
Q

What is the gait presentation cerebellar instability?

A

(i) Cerebellum controls coordination
(ii) Reeling gait
(iii) May wander off to one side or the other

39
Q

What is the presentation of gait with joint injury?

A

(i) Meniscal and cruciate ligament tears which lead to instability

40
Q

What presentation in gait can pain cause?

A

Limping or antalgia

41
Q

What are the two types of trauma?

A

Macro

Micro

42
Q

What is limping gait? (include examples)

A

(i) Pain while weight bearing for whatever reason

(ii) Examples: Low back pain, gout, heel spurs, ingrown toenails, etc.

43
Q

What is antalgia?

A

(i) Antalgia = anti-pain, or away from pain
(ii) Protective gait
(iii) Could be from pain anywhere in the body

44
Q

What are some causes of swing phase abnormality?

A

Weak dorsiflexors
Hypomobile joint
Spastic paraplegia

45
Q

What is the presentation of weak dorsiflexors?

A

Footdrop
(i) drags toes on floor when swinging the leg forward
Steppage
(i) lifts leg higher than normal so foot will clear floor

46
Q

What is the presentation of a hypomobile joint (ie: hip or knee)

A

(a) May need to swing leg out to the side so foot will clear the floor (circumduction gait)
(b) May need to raise swinging hip higher than normal so foot will clear the floor (hip hike gait)

47
Q

What is the presentation of spastic paraplegia (scissors gait)

A

(a) Legs cross the midline
(b) Bilateral contractural changes (adductors)
(c) Partial paralysis - must swing leg out in front without muscular assistance

Biomechanics II (6 decks)

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