bio mechanics of gait

Mark David S. Basco, PTRPFacultyDepartment of Physical TherapyCollege of Allied Medical ProfessionsUniversity of the Philippines Manila

At the end of the session, you should be able to:

Explain the importance of studying gait in PT and OT

Identify fundamental requirements of normal gait

Define the phases and sub-phases of gait and tasks accomplished by these

At the end of the session, you should be able to:

Describe gait in terms of kinematic and kinetic variables

Explain the “determinants” of gait Describe changes in aging Describe effects of common pathological

conditions on gait

Appreciation of our own locomotor ability Knowledge of gait is important in

understanding human function Knowledge of gait can aid in identifying

abnormalities and, thus, care needs of patients in PT and OT

Equilibrium and Locomotion

Others◦ Intact musculoskeletal system◦ Normal muscle tone◦ Intact sensory system

Tasks accomplished by gait Gait cycle:

◦ Phases◦ Sub-phases

Time and distance parameters of gait Relationships among gait variables

Tasks accomplished by gait Weight acceptance Single limb support Limb advancement

Gait cycle phases Gait cycle, stride, step Stance

◦ Single limb support (SLS)◦ Double limb support (DLS)

Swing

Gait cycle sub-phases (STANCE) Initial contact Loading response Midstance Terminal stance Preswing

Initial contact

Loading response

Midstance

Terminal stance

Preswing

Gait cycle sub-phases (SWING) Initial swing Midswing Terminal swing

Initial swing

Midswing

Terminal swing

Traditional terminology◦ Heel strike (HS)◦ Foot flat (FF)◦ Midstance (MSt)◦ Heel off (HO)◦ Toe off (TO)

Traditional terminology◦ Acceleration (Acc)◦ Midswing (MSw)◦ Deceleration (Dec)

Time and distance gait variables Stride length and stride time Step length and step time Stance time and swing time SLS time and DLS time Base / step width

Time and distance gait variables Foot angle Gait velocity: free, fast, slow Cadence Period of “double float”

Relationships among some variables Gait velocity and cadence Gait velocity and step length Gait velocity and SLS time Gait velocity and DLS time

The equivalent of heel strike in the Rancho Los Amigos terminogy is:

A. Initial contact

B. Loading response

C. Preswing

D. Initial swing

This sub-phase of stance occurs from the time the contralateral foot gets into contact with the ground until the reference foot lifts off the ground:

A. Terminal stance

B. Preswing

C. Loading response

D. None of the above

With an increase in gait velocity, the following will increase logically, EXCEPT:

A. Cadence

B. Step length

C. DLS time


Description of joint motions that occur during gait

Ideally, description should encompass all three planes of motion

Often, sagittal motions are described (simplistically)

HS – FF 0 – 15 deg p/flex

FF – MSt 15 deg p/flex – 10 deg d/flex

MSt – HO 10 – 15 deg d/flex

HO – TO 15 deg d/flex –20 deg p/flex

O’ Sullivan, S.B., & Schmitz, T.J. (2001). Physical rehabilitation: Assessment & treatment. Philadelphia; F.A. Davis.

Acc – MSw d/flex - neutral

MSw – Dec neutral


HS – FF 0 – 15 deg flex

FF – MSt 15 deg flex – 5 deg flex

MSt – HO 5 deg flex - neutral

HO – TO 0 – 40 deg flex


Acc – MSw 40 – 60 flex

MSw 60 deg flex – 30 deg flex

Dec 30 deg flex - neutral


HS – FF 30 deg flex

FF – MSt 30 – 5 deg flex

MSt – HO-TO 5 deg flex - 10 deg ext

Acc - MSw 20 – 30 deg flex

MSw – Dec 30 deg flex


At the moment of HS, the ankle is normally in this many degrees of dorsiflexion:

A. 20

B. 10

C. 5


Using traditional terminology, the highest amount of knee flexion during normal (comfortable) gait is observed in:

A. Toe off

B. Acceleration

C. Midswing

D. Deceleration

Normally, the hip must extend to at least this many degrees during HO – TO to aid limb advancement:

A. 10

B. 20

C. 30

Ground reaction forces

Electromyographic activity

Ankle dorsiflexors Just after initial contact

Swing phase

Ankle plantarflexors Loading response

Preswing

Knee extensors Loading response

Preswing (slight)◦ Rectus femoris

Knee flexors Terminal swing to initial contact

Initial swing

Hip extensors Terminal swing to initial contact

Hip flexors Initial swing

Hip abductors Loading response through midstance

Hip adductors Preswing ; Initial swing

Back extensors At initial contact (both sides)

Peak activity of the knee extensors occur in:

A. Loading response

B. Midstance

C. Terminal stance

D. Preswing

At initial contact, the erector spinae on both sides are active to check:

A. Trunk flexion

B. Trunk lateral flexion

C. Hip flexion


Intuitively, peak activity of the ankle plantarflexors should occur in:

A. Initial contact

B. Loading response

C. Terminal stance

D. Preswing

Reduce maximum COM height of the body during midstance

Increase minimum COM height of the body at heel-strike and toe-off

Pelvic rotation Pelvic obliquity or “list” Knee flexion in the stance phase Ankle rockers Transverse rotation Genu valgum

Pelvic rotation

Pelvic obliquity or “list”

Knee flexion in the stance phase

Ankle rockers

Transverse rotation (1)

Transverse rotation (2)

Genu valgum

Gender; age Sensory conditions Demands / purpose of the task Environmental constraints Mood / psychological state

Dimensions of mobility (Patla & Shumway-Cook 1999)

Post-OTPT102 exam: which one represents you?

Physiological decline of multiple systems in the body

Effects of chronic conditions

Effects of acute conditions

Common observable changes* Decreased:

◦ GAIT velocity◦ STEP length◦ Arm swing◦ PELVIC rotation◦ ANKLE motions

Common observable changes* Increased:

◦ Cadence◦ DLS time◦ Postural sway

The COM of the body normally translates a total of ____ cm in the coronal plane:

A. 2

B. 4

C. 6


Gait changes observed in aging is / are considered to be primarily a function of:

A. Acute health conditions

B. Chronic health conditions

C. Normal decline of physiological functions

D. All of the above

Common causes of abnormal gait Pain Muscle weakness Soft tissue or contracture Abnormal muscle tone

Common causes of abnormal gait Lower limb length discrepancy Impaired proprioception / kinesthesia Impaired balance or motor control

Some patterns of abnormal gait Antalgic gait Equinus gait Stiff knee gait Waddling gait

Some patterns of abnormal gait Hemiplegic gait Parkinsonian gait Scissors gait Ataxic gait

This abnormal gait pattern typically results when there is generalized muscle weakness in one side of the body:

A. Antalgic

B. Hemiplegic

C. Equinus


In an antalgic gait pattern, the following would be expected to decrease, EXCEPT:

A. SLS time – affected limb

B. DLS time

C. Preswing – affected limb


Generalized reflex hyperactivity of the lower limb muscles, the hip adductors in particular, often result in this abnormal gait pattern:

A. Equinus

B. Parkinsonian

C. Ataxic


EACH GROUP must bring: Kinesiology attire 2 – 3 ink markers Masking tape Measuring tape Stopwatch 1m x 6m walkway Pair of sunglasses Piece of wood Small pebble

Gait is a complicated subject to learn and study. It is strongly encouraged that you do extra reading. For references that you

could use, do not hesitate to seek consult.

I would like to acknowledge Prof. EJ Gorgon, MPhysio, PTRP for the powerpoint slides used in this

presentation.

The depth and quality of learning that you would get from this college does not entirely depend on the faculty and the instructional materials used...

Most of it depends...

On the passion that you put into learning and your perseverance to rise up against the challenges and difficulties you would encounter.

bio mechanics of gait

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