Gait Cycle Analysis

High-yield overview

The repeating sequence of limb movements from one foot's initial contact to the next contact of the same foot

60% / 40%stance / swing

20%double support

~1.3 m/sadult walking speed

Gait Phases

Stance (60%)

PatternInitial contact, loading response, midstance, terminal stance, pre-swing

TreatmentWeight acceptance and single-limb support

Swing (40%)

PatternInitial swing, mid-swing, terminal swing

TreatmentLimb advancement and clearance

Critical Must-Knows

Definition: One complete gait cycle runs from initial contact of one foot to the next contact of the same foot, divided into stance (60%) and swing (40%)
Double vs single support: Double support occupies 20% total (10% at the start and 10% at the end of stance) and disappears at running speeds; single support equals the contralateral swing time
Key kinetics: Vertical ground reaction force is an M-shaped double hump (first peak ~110% body weight at loading, valley ~80% at midstance, second peak ~110-120% at terminal stance)
Clinical use: Phase-by-phase muscle and joint analysis localises pathology (Trendelenburg, antalgic, steppage, equinus) and guides surgical and rehabilitation planning

Clinical Pearls

"
Quadriceps fire eccentrically at loading response (shock absorption); gastrocnemius-soleus fire concentrically at terminal stance (push-off)
"
Trendelenburg gait reflects weakness on the STANCE limb (gluteus medius), not the dropping side
"
Three ankle rockers (heel, ankle, forefoot) smooth centre-of-mass progression; losing them after ankle fusion raises walking energy cost

Clinical Imaging

Imaging Gallery

High Yield Exam Points

Stance vs Swing Ratio

Stance phase: 60% of gait cycle. Swing phase: 40%. Double support: 20% (10% at beginning and end of stance). Single support: 40%. These percentages are exam favorites.

Muscle Activation Sequence

Initial contact: ankle dorsiflexors eccentric. Loading response: quadriceps eccentric. Terminal stance: gastrocnemius-soleus plantarflexion. Pre-swing: hip flexors initiate swing. Know the timing.

Ground Reaction Forces

Vertical GRF shows double-hump pattern: first peak at loading response (110% body weight), second peak at terminal stance (120% body weight). Anterior-posterior force shows braking then propulsion.

Pathological Gait Patterns

Trendelenburg: weak hip abductors (gluteus medius). Antalgic: shortened stance on painful limb. Steppage: foot drop (weak dorsiflexors). Equinus: tight gastrocnemius. Know the underlying causes.

At a Glance

The gait cycle is the repeating sequence of limb movements from heel strike to next heel strike, divided into stance phase (60%) and swing phase (40%). Double support occurs for 20% of the cycle (10% at beginning and end of stance). Critical muscle activations include eccentric dorsiflexors at initial contact, eccentric quadriceps during loading, and gastrocnemius-soleus push-off at terminal stance. Recognise pathological patterns: Trendelenburg (weak hip abductors), antalgic (shortened stance on painful side), steppage (foot drop from weak dorsiflexors), and equinus (tight gastrocnemius).

Mnemonic

I Love My Two PillowsPhases of Stance Phase

I	I - Initial contact (heel strike)
L	L - Loading response (foot flat)
M	M - Midstance (single limb support)
T	T - Terminal stance (heel off)
P	P - Pre-swing (toe off)

I	I - Initial contact (heel strike)	T	T - Terminal stance (heel off)
L	L - Loading response (foot flat)	P	P - Pre-swing (toe off)
M	M - Midstance (single limb support)

Hook:Think of resting on pillows through the stance phase from heel to toe

Mnemonic

I Must TryPhases of Swing Phase

I	I - Initial swing (acceleration)
M	M - Mid-swing (foot clearance)
T	T - Terminal swing (deceleration)

I	I - Initial swing (acceleration)
M	M - Mid-swing (foot clearance)
T	T - Terminal swing (deceleration)

Hook:Like swinging a baseball bat: accelerate, maintain arc, decelerate

Mnemonic

PELVIC KneeGait Determinants of Perry

P	P - Pelvic rotation (4 degrees forward on swing side)	I	I - Initial contact knee flexion (15 degrees)
E	E - Elevation of pelvis (pelvic tilt on swing side)	C	C - Controlled knee flexion during stance (reduces vertical displacement)
L	L - Lateral displacement of pelvis (4-5 cm side to side)	K	Knee - Knee and ankle interactions minimize energy expenditure
V	V - Vertical displacement of center of mass (5 cm rise and fall)

P	P - Pelvic rotation (4 degrees forward on swing side)	V	V - Vertical displacement of center of mass (5 cm rise and fall)	K	Knee - Knee and ankle interactions minimize energy expenditure
E	E - Elevation of pelvis (pelvic tilt on swing side)	I	I - Initial contact knee flexion (15 degrees)
L	L - Lateral displacement of pelvis (4-5 cm side to side)	C	C - Controlled knee flexion during stance (reduces vertical displacement)

Hook:Perry's PELVIC movements plus Knee mechanics reduce energy cost of walking

Overview

Definition

The gait cycle represents one complete sequence of walking from the initial ground contact of one foot to the subsequent ground contact of the same foot. [1] Normal human gait is characterized by alternating periods of single and double limb support, with each limb progressing through a repeating sequence of stance and swing phases that enable efficient forward progression while maintaining balance and minimizing energy expenditure. [2]

Temporal Parameters

Gait Cycle Division:

Stance Phase: 60% of the gait cycle (from initial contact to toe-off)
Swing Phase: 40% of the gait cycle (from toe-off to next initial contact)
Double Support: 20% of the cycle (10% at beginning and 10% at end of stance)
Single Support: 40% of the cycle (when contralateral limb is in swing)

The stance-to-swing ratio changes with walking speed, with faster speeds showing decreased stance time and increased swing time. [1,2]

Speed-Dependent Variables:

Cadence: 90-120 steps per minute (normal adult walking)
Stride length: 1.2-1.5 meters (distance between successive contacts of same foot)
Step length: 0.6-0.8 meters (distance between contacts of opposite feet)
Walking velocity: 1.2-1.4 meters per second (average adult)

These parameters vary with age, gender, height, and pathology. [3]

Epidemiology and Clinical Relevance

Gait analysis is fundamental to orthopaedic assessment:

Diagnosis: Identifies specific gait abnormalities indicating underlying pathology
Treatment planning: Guides surgical interventions (lengthening, osteotomy, fusion)
Outcome assessment: Objective measurement of intervention effectiveness
Rehabilitation: Informs physical therapy protocols and assistive device prescription

Three-dimensional gait analysis is the gold standard for quantifying gait deviations in cerebral palsy, neuromuscular disorders, and complex deformities. [4,5]

Gait Cycle Phases and Characteristics

Stance Phase (60% of Cycle)

Stance Phase Subdivisions

1. Initial Contact (0-2% of cycle)

Biomechanics:

First moment when foot touches ground (historically termed "heel strike")
Hip: 30 degrees flexion
Knee: Near full extension (0-5 degrees flexion)
Ankle: Neutral position (0 degrees)
Foot: Supinated position preparing for contact

Muscle Activity:

Tibialis anterior: Maximum activity (eccentric) to control plantarflexion
Quadriceps: Beginning activation to prepare for loading
Hamstrings: Active to decelerate forward swing of leg
Gluteus maximus: Active to control hip flexion

Ground Reaction Force:

Vertical force begins to rise from zero
Posterior force component (braking) begins
Center of pressure at heel contact point [1,6]

2. Loading Response (0-10% of cycle)

Biomechanics:

Period from initial contact to contralateral toe-off
Represents first period of double support
Hip: 30 degrees flexion maintained
Knee: Flexes to 15-20 degrees (shock absorption)
Ankle: Plantarflexes 10-15 degrees (controlled by dorsiflexors)
Foot: Progresses from supination to pronation

Muscle Activity:

Quadriceps: Eccentric contraction (critical for controlled knee flexion)
Tibialis anterior: Eccentric contraction (controls foot slap)
Hip abductors (gluteus medius/minimus): Activate to stabilize pelvis
Hip extensors: Continue activity from initial contact

Ground Reaction Force:

Vertical force rapidly increases to first peak (110% body weight)
Braking force reaches maximum
Lateral force shows small lateral component
This phase is critical for shock absorption and weight acceptance [1,6,7]

3. Midstance (10-30% of cycle)

Biomechanics:

Single limb support phase begins
Body weight passes over supporting foot
Hip: Extends from 30 to 0 degrees
Knee: Extends from 15-20 degrees to 5 degrees
Ankle: Dorsiflexes from 10 degrees plantarflexion to 5 degrees dorsiflexion
Foot: Pronated and flattened (shock absorption)

Muscle Activity:

Ankle plantarflexors (gastrocnemius-soleus): Begin activity to control tibial advancement
Hip abductors: Maximum activity (single limb support stability)
Quadriceps: Decreasing activity as knee extends
Intrinsic foot muscles: Active for arch support

Ground Reaction Force:

Vertical force decreases from first peak to valley (80-90% body weight)
Braking force transitions to propulsive force
Center of pressure moves anteriorly along foot [1,6,7]

4. Terminal Stance (30-50% of cycle)

Biomechanics:

From heel rise to contralateral initial contact
Hip: Continues extension to 10-20 degrees hyperextension
Knee: Remains near full extension (0-5 degrees flexion)
Ankle: Dorsiflexes to maximum (10 degrees) as tibia advances over foot
Foot: Heel rises, weight transfers to forefoot

Muscle Activity:

Gastrocnemius-soleus: Maximum activity (concentric plantarflexion for push-off)
Hip extensors: Continue activity
Intrinsic foot muscles: Maximum activity for rigid lever formation
Tibialis posterior: Active for supination and arch support

Ground Reaction Force:

Vertical force increases to second peak (120% body weight)
Propulsive force reaches maximum
Center of pressure at metatarsal heads
This phase generates forward propulsion [1,6,7]

5. Pre-swing (50-60% of cycle)

Biomechanics:

From contralateral initial contact to toe-off
Second period of double support
Hip: Neutral to slight flexion
Knee: Rapidly flexes to 40 degrees
Ankle: Plantarflexes to 20 degrees (passive)
Foot: Final push-off from hallux

Muscle Activity:

Hip flexors (iliopsoas, rectus femoris): Begin activation for swing initiation
Ankle dorsiflexors: Begin activation preparing for swing
Gastrocnemius-soleus: Decreasing activity
Adductor longus: Active for limb advancement

Ground Reaction Force:

Vertical force rapidly decreases to zero
Propulsive force decreases
Center of pressure at toe [1,6,7]

Swing Phase (40% of Cycle)

Swing Phase Subdivisions

6. Initial Swing (60-73% of cycle)

Biomechanics:

From toe-off to feet adjacent
Acceleration phase of swing
Hip: Rapidly flexes to 20 degrees
Knee: Flexes to maximum (60 degrees) for toe clearance
Ankle: Dorsiflexes from plantarflexion toward neutral
Foot: Clears ground by approximately 1 cm

Muscle Activity:

Hip flexors (iliopsoas): Concentric contraction for limb advancement
Tibialis anterior: Active to achieve foot clearance
Short head of biceps femoris: Assists hip flexion
Rectus femoris: Active for both hip flexion and knee extension initiation

Ground Reaction Force:

No ground contact (zero force on swinging limb)
Contralateral limb in single support [1,8]

7. Mid-swing (73-87% of cycle)

Biomechanics:

From feet adjacent to tibia vertical
Hip: Continues flexion to 30 degrees
Knee: Begins extension from 60 to 30 degrees (passive pendular motion)
Ankle: Achieves neutral position (0 degrees)
Foot: Maintains clearance

Muscle Activity:

Tibialis anterior: Maintains dorsiflexion for clearance
Hip flexors: Continue activity
Quadriceps: Begin activity to extend knee
Hamstrings: Begin activity to decelerate knee extension

Ground Reaction Force:

No ground contact
Minimum muscle activity during this phase (most efficient part of gait) [1,8]

8. Terminal Swing (87-100% of cycle)

Biomechanics:

From tibia vertical to next initial contact
Deceleration phase
Hip: Maintains 30 degrees flexion
Knee: Extends to near full extension (0-5 degrees flexion)
Ankle: Maintains neutral dorsiflexion
Foot: Prepares for initial contact

Muscle Activity:

Hamstrings: Maximum activity (eccentric) to decelerate knee extension
Tibialis anterior: Maintains ankle dorsiflexion
Quadriceps: Active to achieve full knee extension
Gluteus maximus: Begins activation for upcoming stance

Ground Reaction Force:

No ground contact until next initial contact [1,8]

Principles of Joint Kinematics and Range of Motion

Each lower-limb joint follows a characteristic, repeatable angle-versus-cycle curve. The core principle is that motion is task-specific: the hip and ankle drive progression and power, while the knee provides two flexion waves - one for shock absorption in stance and one for toe clearance in swing. Deviations from these normative curves localise pathology to a joint, plane and phase.

Joint Motion During Gait

Hip Joint Motion

Sagittal Plane (Flexion-Extension):

Maximum flexion: 30 degrees (at initial contact and terminal swing)
Neutral: 0 degrees (at midstance)
Maximum extension: 10-20 degrees (at terminal stance)
Total range of motion: 40-50 degrees

Coronal Plane (Abduction-Adduction):

Small amplitude motion (5-7 degrees total)
Slight abduction during single limb support
Returns to neutral during double support

Transverse Plane (Internal-External Rotation):

Internal rotation during loading response (5 degrees)
External rotation during terminal stance (5 degrees)
Total rotation: approximately 10 degrees

The hip joint serves as the primary controller of limb advancement and body progression. [9]

Knee Joint Motion

Sagittal Plane (Flexion-Extension):

Initial contact: 0-5 degrees flexion
Loading response: 15-20 degrees flexion (shock absorption)
Midstance: 5 degrees flexion
Terminal stance: 0-5 degrees flexion
Pre-swing: 40 degrees flexion
Initial swing: Maximum flexion 60 degrees
Terminal swing: Returns to 0-5 degrees

Two Flexion Waves:

First wave: Loading response flexion (shock absorption)
Second wave: Swing phase flexion (toe clearance)

The knee demonstrates the largest range of motion of any lower extremity joint during gait (0-60 degrees). [9,10]

Ankle Joint Motion

Sagittal Plane (Dorsiflexion-Plantarflexion):

Initial contact: Neutral (0 degrees)
Loading response: 10-15 degrees plantarflexion (controlled)
Midstance to terminal stance: Progressive dorsiflexion to 10 degrees
Pre-swing: Rapid plantarflexion to 20 degrees
Swing phase: Return to neutral dorsiflexion

Critical Functions:

Controlled plantarflexion prevents foot slap
Dorsiflexion accommodates forward tibial progression
Plantarflexion generates propulsive power
Neutral position enables toe clearance [9,10]

Foot and Subtalar Motion

Pronation-Supination Sequence:

Initial contact: Supinated (rigid structure for heel contact)
Loading response to midstance: Pronation (shock absorption, adaptation)
Terminal stance: Resupination (rigid lever for push-off)

This pronation-supination cycle is essential for:

Shock absorption during loading
Adaptation to uneven terrain
Conversion to rigid lever for propulsion [11]

Muscle Activation Patterns

Neuromuscular Control

Ankle Dorsiflexors (Tibialis Anterior)

Activation Timing:

Terminal swing to initial contact: Concentrically activate to achieve neutral ankle position
Loading response: Eccentrically contract (maximum activity) to control plantarflexion and prevent foot slap
Swing phase: Active throughout to maintain toe clearance

Clinical Significance:

Weakness produces foot drop and steppage gait
Excessive activity seen in spastic gait patterns [6,12]

Ankle Plantarflexors (Gastrocnemius-Soleus)

Activation Timing:

Midstance to terminal stance: Progressive increase in activity
Terminal stance: Maximum concentric contraction for push-off (second rocker)
Pre-swing: Rapidly decreasing activity

Power Generation:

Gastrocnemius-soleus complex generates majority of propulsive power
Contributes to forward acceleration of center of mass
Critical for normal walking speed and efficiency [6,12]

Quadriceps Muscle Group

Activation Timing:

Terminal swing: Begins activation to extend knee
Initial contact to loading response: Maximum eccentric activity to control knee flexion (critical for shock absorption)
Midstance: Decreasing activity as knee extends

Clinical Significance:

Weakness produces instability during loading response
May cause knee hyperextension or flexed knee gait as compensation [12]

Hamstring Muscle Group

Activation Timing:

Terminal swing: Maximum eccentric activity to decelerate knee extension and control hip flexion
Initial contact: Continue activity for hip extension
Loading response to midstance: Decreasing activity

Dual Function:

Decelerate lower leg during terminal swing
Assist hip extension during early stance [12]

Hip Abductors (Gluteus Medius and Minimus)

Activation Timing:

Loading response through midstance: Maximum activity during single limb support
Terminal stance: Decreasing activity

Critical Function:

Stabilize pelvis in coronal plane during single limb support
Prevent contralateral pelvic drop (Trendelenburg sign)
Weakness produces characteristic Trendelenburg gait [12,13]

Hip Flexors (Iliopsoas)

Activation Timing:

Pre-swing: Begin activation to initiate swing
Initial swing to mid-swing: Continue activity for limb advancement
Terminal swing: Decreasing activity

Function:

Primary driver of swing phase initiation
Advance limb forward during swing [12]

Ground Reaction Forces

Kinetic Analysis

Vertical Ground Reaction Force

Characteristic Pattern:

Loading response: Rapid rise to first peak (110% body weight)
Midstance: Decrease to valley (80-90% body weight)
Terminal stance: Increase to second peak (120% body weight)
Pre-swing: Rapid decrease to zero

Double-Hump Pattern:

First peak: Weight acceptance and impact absorption
Valley: Single limb support with body passing over foot
Second peak: Push-off and propulsion
Shape varies with walking speed and pathology [7,14]

Anterior-Posterior Ground Reaction Force

Braking and Propulsion:

Loading response to midstance: Posterior (braking) force reaches maximum (15-20% body weight)
Midstance: Transition from braking to propulsion
Terminal stance: Anterior (propulsive) force reaches maximum (20-25% body weight)

Net Effect:

Braking force decelerates forward progression
Propulsive force accelerates body forward
Forces approximately equal in normal gait (net zero horizontal acceleration) [7,14]

Mediolateral Ground Reaction Force

Lateral Stability:

Small amplitude forces (5% body weight)
Medially directed during loading response
Laterally directed during terminal stance
Maintains mediolateral stability [7,14]

Center of Pressure Progression

Path During Stance:

Initial contact: Lateral heel
Loading response to midstance: Progresses along lateral border of foot
Terminal stance: Moves medially toward metatarsal heads
Pre-swing: Terminates at hallux

This progression reflects the foot's rocker mechanism and weight transfer pattern. [11,14]

Gait Determinants and Energy Conservation

Perry's Six Determinants of Gait

Saunders, Inman, and Eberhart described six major determinants that minimize energy expenditure during normal gait by reducing vertical and lateral displacement of the center of mass. [15]

1. Pelvic Rotation

Mechanism: Pelvis rotates approximately 4 degrees forward on the swing side
Effect: Effectively lengthens the limb during initial contact and terminal swing
Energy saving: Reduces amplitude of vertical displacement of center of mass

2. Pelvic Tilt

Mechanism: Pelvis drops approximately 5 degrees on the swing side (contralateral hip adduction)
Effect: Lowers the peak of vertical displacement during single limb support
Energy saving: Flattens the sinusoidal curve of center of mass trajectory

3. Knee Flexion During Stance

Mechanism: Knee flexes 15-20 degrees during loading response
Effect: Lowers the body during what would otherwise be highest point
Energy saving: Reduces vertical displacement amplitude

4. Foot and Ankle Motion

Mechanism: Foot serves as rocker in three phases (heel, ankle, forefoot)
Effect: Smooths the forward progression of center of mass
Energy saving: Prevents abrupt changes in velocity

5. Knee Mechanism

Mechanism: Coordinated knee flexion-extension pattern throughout stance
Effect: Works with ankle motion to smooth progression
Energy saving: Reduces energy required for limb advancement

6. Lateral Pelvic Displacement

Mechanism: Pelvis shifts laterally approximately 4-5 cm from side to side
Effect: Keeps center of mass closer to supporting limb
Energy saving: Reduces need for excessive hip abductor force

Clinical Application: Loss of any determinant (e.g., fused knee, ankle arthrodesis) increases energy cost of walking by requiring greater muscular effort and increased vertical displacement. [15,16]

Pathological Gait Patterns

Differential Diagnosis of Common Gait Patterns

Pattern recognition is the highest-yield exam skill: match the visible deviation to the underlying lesion.

Gait Pattern	Key Visible Feature	Phase Affected	Underlying Lesion / Cause
Antalgic	Shortened stance on painful limb	Stance	Pain (arthritis, fracture, infection) in any lower-limb joint
Trendelenburg (abductor lurch)	Contralateral pelvic drop / trunk lean over stance leg	Single-limb stance	Hip abductor weakness - gluteus medius, superior gluteal nerve, hip OA/DDH
Steppage (high-stepping)	Exaggerated hip/knee flexion, foot slap	Swing and initial contact	Foot drop - common peroneal palsy, L5 radiculopathy, peripheral neuropathy
Equinus / toe-walking	Forefoot initial contact, no heel strike	Stance	Gastrocnemius-soleus contracture, spastic CP, idiopathic toe-walking
Circumduction	Swing limb traces a lateral semicircle	Swing	Functional limb lengthening - stiff/fused knee or ankle, hip flexor weakness, spasticity
Vaulting	Rises onto stance-side toes to clear the swing limb	Swing	Inadequate swing-limb clearance (long leg, knee/ankle stiffness, prosthesis)
Spastic (hemiplegic)	Stiff extended limb, circumduction, equinovarus foot	Whole cycle	Upper motor neurone lesion - stroke, TBI, hemiplegic CP
Parkinsonian (festinating)	Shuffling short steps, reduced arm swing, stooped posture	Whole cycle	Basal ganglia dysfunction - Parkinson disease, parkinsonism
Ataxic	Wide base, irregular step length, instability	Whole cycle	Cerebellar disease or sensory (proprioceptive) ataxia
Short-leg (uncompensated)	Pelvic drop and trunk dip to short side each step	Stance	True or apparent limb-length discrepancy

Common Gait Abnormalities

Antalgic Gait

Characteristics:

Shortened stance phase on painful limb
Rapid transfer of weight to opposite limb
Decreased vertical ground reaction force on affected side
May show decreased hip and knee motion

Causes:

Arthritis (hip, knee, ankle)
Fracture or stress fracture
Muscle strain or tendinopathy
Any painful lower extremity condition [17]

Trendelenburg Gait

Characteristics:

Contralateral pelvic drop during stance on affected limb
Trunk lean toward affected side (compensated Trendelenburg)
Decreased stance time on affected side

Causes:

Gluteus medius weakness or paralysis
Hip joint pathology (arthritis, developmental dysplasia)
L5 radiculopathy (superior gluteal nerve)
Post-hip surgery (nerve injury) [13,17]

Steppage Gait (Foot Drop)

Characteristics:

Exaggerated hip and knee flexion during swing phase
Foot slap at initial contact
Dragging toe if compensation inadequate

Causes:

Common peroneal nerve palsy
L5 radiculopathy
Anterior compartment syndrome
Peripheral neuropathy
Sciatic nerve injury [17]

Equinus Gait (Toe Walking)

Characteristics:

Initial contact with forefoot instead of heel
Excessive plantarflexion throughout stance
Shortened stride length
May show knee hyperextension (compensation)

Causes:

Gastrocnemius-soleus contracture
Achilles tendon shortening
Cerebral palsy (spastic)
Clubfoot (residual or recurrent)
Idiopathic toe walking (children) [17]

Vaulting Gait

Characteristics:

Excessive plantarflexion on stance limb
Rising up on toes to clear opposite limb
Seen during swing phase of affected limb

Causes:

Functional leg length discrepancy
Inability to flex knee or dorsiflex ankle on swing side
Compensation for inadequate limb clearance [17]

Circumduction Gait

Characteristics:

Swing limb traces semicircular path
Hip abduction and external rotation during swing
Increased energy expenditure

Causes:

Limb length discrepancy
Knee or ankle fusion/stiffness
Hip flexor weakness
Spasticity (stroke, cerebral palsy) [17]

Spastic Gait (Hemiplegic)

Characteristics:

Affected limb held in extension
Circumduction during swing phase
Equinovarus foot position
Decreased knee flexion during swing

Causes:

Stroke (cerebrovascular accident)
Traumatic brain injury
Cerebral palsy (hemiplegic type) [17]

Parkinsonian Gait

Characteristics:

Shuffling steps with reduced stride length
Decreased arm swing
Flexed posture (trunk, hips, knees)
Festinating gait (rapid small steps)
Difficulty initiating movement

Causes:

Parkinson disease
Parkinsonism (drug-induced, vascular) [17]

Clinical Gait Assessment

Observational Gait Analysis

Systematic Visual Assessment

Lateral View:

Initial contact: Heel strike, knee extended, ankle neutral
Loading response: Knee flexion, controlled plantarflexion
Midstance: Tibia advances over foot, knee extends
Terminal stance: Heel rise, ankle dorsiflexion
Pre-swing: Toe-off, rapid knee flexion
Swing phase: Knee flexion peak, ankle dorsiflexion

Anterior/Posterior View:

Pelvic stability during single limb support
Hip abduction-adduction
Knee varus-valgus alignment
Foot progression angle (internal/external rotation)
Base width (normal: 5-10 cm)

Common Deviations to Identify:

Decreased stance time (antalgic)
Excessive pelvic drop (Trendelenburg)
Knee hyperextension (quadriceps weakness, knee instability)
Foot slap (dorsiflexor weakness)
Toe walking (equinus contracture) [17,18]

Instrumented Gait Analysis

Three-Dimensional Motion Analysis:

Gold standard for quantifying gait deviations
Uses multiple cameras and reflective markers
Measures joint angles in three planes
Calculates joint moments and powers
Essential for complex deformity assessment (cerebral palsy) [4,5]

Force Plate Analysis:

Measures ground reaction forces in three directions
Calculates center of pressure trajectory
Determines temporal parameters
Assesses asymmetry between limbs [14]

Electromyography (EMG):

Records muscle activation timing and amplitude
Identifies abnormal muscle firing patterns
Guides treatment (e.g., selective dorsal rhizotomy, botulinum toxin) [12]

Evidence Base and Key Studies

The Major Determinants in Normal and Pathological Gait (Foundational Theory)

Saunders JBdeCM, Inman VT, Eberhart HD • J Bone Joint Surg Am (1953)

Key Findings:

Described six kinematic determinants that flatten the sinusoidal path of the body centre of mass and so reduce the energy cost of walking
The six determinants: pelvic rotation, pelvic tilt (list), knee flexion in stance, foot-ankle interaction (rockers), knee-ankle interaction, and lateral pelvic displacement
Argued that loss of any determinant (e.g. a fused joint) forces compensatory motion and raises metabolic demand

Clinical Implication: Provides the conceptual framework still used to explain why stiffening or fusing a lower-limb joint increases walking energy cost and why surgical planning aims to preserve sagittal motion.

Limitation: Later dynamic-walking and inverted-pendulum modelling challenged the relative importance of several determinants (notably pelvic rotation and tilt); treat the list as a teaching framework rather than a quantitatively exact energy model.

Verify on PubMed (PMID 13069544)

The Development of Mature Gait - Landmark EMG/Kinematic Series

Sutherland DH, Olshen R, Cooper L, Woo SL • J Bone Joint Surg Am (1980)

Key Findings:

Combined cinematography, force-plate and EMG data to define normal and maturing gait in children
Identified five maturity determinants and showed adult-pattern gait is essentially established by about age 7
Documented the phasic timing of muscle activity (e.g. quadriceps at loading response, gastrocnemius-soleus at terminal stance) that underpins modern gait interpretation

Clinical Implication: Establishes the normative paediatric dataset against which pathological (especially cerebral palsy) gait is compared and the age at which gait is mature enough for reliable analysis and surgical decision-making.

Limitation: Observational instrumented series in typically developing children; normative bands have modest spread and instrumentation has since advanced to 3D optoelectronic systems.

Verify on PubMed (PMID 7364807)

Energy Generation and Absorption at the Ankle and Knee (Joint Power Analysis)

Winter DA • Clin Orthop Relat Res (1983)

Key Findings:

Biomechanical analysis of 15 normal adults at slow, natural and fast cadences
The ankle has two power phases: negative work (absorption) during weight acceptance then a dominant positive-work burst at push-off, identifying the plantarflexors as the prime movers of forward propulsion
The dominant plantarflexor push-off burst falls as walking speed decreases; the knee shows four distinct power phases

Clinical Implication: Confirms that gastrocnemius-soleus push-off generates most of the propulsive power in gait, explaining the marked functional loss with calf weakness, ankle fusion or below-knee amputation.

Limitation: Small cadence-controlled laboratory cohort; absolute power values vary with body mass, marker model and walking speed.

Verify on PubMed (PMID 6839580)

Measurement of Lower Extremity Kinematics During Level Walking (3D Marker Model)

Kadaba MP, Ramakrishnan HK, Wootten ME • J Orthop Res (1990)

Key Findings:

Developed and validated an external marker set and Euler-angle algorithms (the basis of the Helen Hayes / Plug-in-Gait model) on a VICON system
Gait analysis repeated on 40 normal young adults across three separate test days produced repeatable hip, knee, ankle and pelvis angle curves
Quantified the effect of marker-placement and embedded-axis uncertainty on joint-angle error

Clinical Implication: Underpins the marker-based 3D gait laboratory still used worldwide for clinical kinematic analysis and provides the repeatability/error context needed to interpret patient data.

Limitation: Validated only in healthy young adults; soft-tissue artefact and transverse/coronal-plane error remain larger than sagittal-plane error.

Verify on PubMed (PMID 2324857)

Energy Expenditure of Normal and Pathologic Gait (Comprehensive Review)

Waters RL, Mulroy S • Gait Posture (1999)

Key Findings:

Synthesised oxygen-consumption data across neurological and orthopaedic conditions, using the rate of energy expenditure and energy cost per metre as the key metrics
Pathological gait raises energy cost broadly in proportion to the level and severity of disability, with patients typically self-selecting a slower speed to keep the rate of expenditure near normal
Hemiplegic, paraplegic and high-level amputation gaits carry the largest penalties; more proximal amputation and greater neurological involvement cost more

Clinical Implication: Justifies energy-conservation as an outcome measure and explains why patients walk slower after major lower-limb pathology - they trade speed to keep metabolic rate tolerable.

Limitation: Narrative review aggregating heterogeneous small studies; absolute figures vary with methodology, and the often-quoted single-value energy costs should be read as approximate.

Verify on PubMed (PMID 10575082)

Comfortable and Maximum Walking Speed - Reference Values (Age 20-79)

Bohannon RW • Age Ageing (1997)

Key Findings:

230 healthy adults timed over a 7.62 m walkway, generating decade- and sex-specific reference speeds
Comfortable speed ranged from ~127 cm/s (women in their 70s) to ~146 cm/s (men in their 40s); maximum speed up to ~253 cm/s in young men
Walking speed correlated with age, height and lower-limb muscle strength and was highly reliable (coefficients greater than 0.9)

Clinical Implication: Supplies the normative speed bands used clinically as a vital sign of mobility and to interpret a patient's spatiotemporal gait report against age-matched controls.

Limitation: Single healthy convenience sample over a short walkway; population-specific norms differ and very old / frail individuals are under-represented.

Verify on PubMed (PMID 9143432)

The Significance of the Trendelenburg Test (Standardisation Study)

Hardcastle P, Nade S • J Bone Joint Surg Br (1985)

Key Findings:

Examined 50 normal subjects and 103 patients with spine or hip disorders to standardise single-leg stance testing
Defined the test as an assessment of hip abductor function and specified a standard performance method
Catalogued the main false-positive (pain, poor cooperation, rib-iliac impingement) and false-negative (trunk/pelvic compensation) pitfalls

Clinical Implication: Provides the validated method and pitfalls for the Trendelenburg test, the bedside correlate of the Trendelenburg (abductor-lurch) gait seen in single-limb stance.

Limitation: Older clinical series predating instrumented analysis; inter-observer reliability of the bedside test remains operator-dependent.

Verify on PubMed (PMID 4055873)

The Gait Deviation Index (GDI) - Comprehensive Index of Gait Pathology

Schwartz MH, Rozumalski A • Gait Posture (2008)

Key Findings:

Derived a multivariate, single-number index of overall gait pathology from 15 independent kinematic gait features
GDI is scaled so 100 represents the mean of typically developing children and every 10 points below 100 is one standard deviation of pathology
Validated against the Gillette Gait Index and functional walking scales and shown to track severity across cerebral palsy topographical types

Clinical Implication: Gives a reproducible summary score for tracking gait severity and treatment response in cerebral palsy and other conditions, complementing phase-by-phase visual analysis.

Limitation: Derived in a paediatric (largely cerebral palsy) population; a global index can mask which specific joint or plane is abnormal, so it supplements rather than replaces full curve interpretation.

Verify on PubMed (PMID 18565753)

Distal Rectus Femoris Transfer in Multilevel Surgery - Randomized Trial

Dreher T, Gotze M, Wolf SI, et al. • Gait Posture (2012)

Key Findings:

32 children with spastic diplegia indicated for distal rectus femoris transfer (DRFT) randomised to single-event multilevel surgery with or without DRFT, with 3D gait analysis at baseline and 1 year
Peak knee flexion in swing was preserved in the DRFT group but fell in the non-DRFT group; benefit was confined to patients with a pre-operative knee-flexion deficit (stiff-knee gait)
Around one third of DRFT patients did not benefit and roughly half of non-DRFT patients avoided an unnecessary procedure, so DRFT is not recommended as a prophylactic add-on for severe flexed-knee gait

Clinical Implication: Demonstrates how instrumented 3D gait analysis can individualise (and de-escalate) surgical decisions in cerebral palsy, restricting DRFT to true stiff-knee gait rather than applying it routinely.

Limitation: Small single-centre randomised trial with 1-year follow-up; outcomes were kinematic rather than long-term functional or patient-reported.

Verify on PubMed (PMID 22425637)

Exam Viva Scenarios

Use these scenarios to practise clinical reasoning and management decisions

CLINICAL SCENARIOStandard

Scenario 1: Normal Gait Cycle Fundamentals

CLINICAL PROMPT

"An examiner asks you to describe the phases of the gait cycle and their relative durations. They then ask about the muscle activity patterns during these phases."

PRACTICAL APPROACH

The gait cycle is divided into stance phase, comprising 60% of the cycle, and swing phase, comprising 40%. Stance phase is further subdivided into five functional phases: initial contact, loading response at 0-10% where the first period of double support occurs, midstance from 10-30% representing single limb support, terminal stance from 30-50% ending at contralateral initial contact, and pre-swing from 50-60% which is the second period of double support. Swing phase has three subdivisions: initial swing, mid-swing, and terminal swing. During loading response, the quadriceps contract eccentrically to control knee flexion for shock absorption, while tibialis anterior controls foot plantarflexion eccentrically to prevent foot slap. During terminal stance, the gastrocnemius-soleus complex generates maximum concentric force for push-off and propulsion. The hip abductors, particularly gluteus medius, are maximally active during midstance to stabilize the pelvis during single limb support. Understanding these phases and muscle activation patterns is essential for identifying pathological gait and planning treatment interventions.

KEY CLINICAL POINTS

Stance 60%, swing 40%, double support 20% total

Five stance subdivisions, three swing subdivisions

Quadriceps eccentric in loading response (shock absorption)

Gastrocnemius-soleus concentric in terminal stance (propulsion)

Hip abductors active midstance (pelvic stability)

COMMON PITFALLS

Confusing percentages of stance vs swing phases

Forgetting that double support occurs twice (10% at start and 10% at end of stance)

Not knowing muscle contraction types (eccentric vs concentric)

Missing the clinical relevance of each phase

FURTHER QUESTIONS

"What happens to stance-swing ratio with increased walking speed?"

"Describe the ground reaction force pattern during stance phase"

"How would quadriceps weakness affect the gait cycle?"

CLINICAL SCENARIOStandard

Scenario 2: Pathological Gait Patterns

CLINICAL PROMPT

"A 65-year-old patient presents with a noticeable limp. On observation, you note that the pelvis drops on the right side when standing on the left leg. The examiner asks you to explain this finding and its underlying causes."

PRACTICAL APPROACH

This patient is demonstrating a Trendelenburg gait pattern. The Trendelenburg sign occurs when the pelvis drops toward the unsupported side during single limb stance, indicating weakness or dysfunction of the hip abductor muscles, primarily gluteus medius and minimus, on the stance limb. Normally, these muscles contract forcefully during the single limb support phase of stance to stabilize the pelvis and prevent contralateral drop. When the patient stands on the affected left leg, the weakened left hip abductors cannot adequately stabilize the pelvis, resulting in the right-sided pelvic drop. Possible causes include hip abductor muscle weakness from superior gluteal nerve injury, L5 radiculopathy, direct muscle injury, or hip joint pathology such as osteoarthritis or developmental dysplasia that mechanically disadvantages the abductors. Some patients compensate by leaning their trunk toward the affected side during stance, which is termed a compensated Trendelenburg gait, as this shifts the center of mass closer to the hip joint and reduces the abductor moment arm requirement. Treatment depends on the underlying cause and may include physical therapy for strengthening, gait aids to reduce abductor demand, or surgical intervention for structural hip problems. This gait pattern significantly increases energy expenditure and can lead to secondary problems including low back pain and contralateral hip overload.

KEY CLINICAL POINTS

Trendelenburg sign: pelvic drop on unsupported side during stance

Caused by hip abductor weakness (gluteus medius/minimus)

Common causes: nerve injury, radiculopathy, hip joint pathology

Compensated form: trunk lean toward affected side

Increases energy expenditure significantly

COMMON PITFALLS

Confusing which side is weak (stance side, not dropped side)

Forgetting to mention superior gluteal nerve

Not discussing compensatory mechanisms

Missing the functional impact on energy expenditure

FURTHER QUESTIONS

"How would you test for hip abductor weakness on examination?"

"What is the difference between compensated and uncompensated Trendelenburg?"

"Describe the biomechanics of why the abductors are so important"

CLINICAL SCENARIOStandard

Scenario 3: Energy Conservation Mechanisms

CLINICAL PROMPT

"The examiner presents a patient with bilateral ankle arthrodesis who complains of fatigue with walking. They ask you to explain why ankle fusion increases the energy cost of gait."

PRACTICAL APPROACH

Ankle arthrodesis eliminates the normal ankle joint motion that is critical for energy-efficient gait. Perry and colleagues described six gait determinants that minimize energy expenditure by reducing vertical and lateral displacement of the center of mass. The ankle contributes to several of these determinants. First, the normal ankle functions as three rockers during stance: the heel rocker at initial contact, the ankle rocker during midstance as the tibia advances over the fixed foot, and the forefoot rocker during terminal stance push-off. These rockers smooth the forward progression of the center of mass and prevent abrupt velocity changes. With ankle fusion, the patient loses the ankle rocker function, forcing compensation through increased hip and knee motion, which requires greater muscular effort. Second, normal ankle plantarflexion-dorsiflexion motion works in coordination with knee flexion during stance to minimize vertical displacement of the center of mass. Loss of this coordination increases the amplitude of vertical rise and fall, increasing potential and kinetic energy requirements. Third, the ankle's contribution to push-off power is lost or reduced, requiring compensation from the hip flexors and contralateral limb for forward propulsion. Studies have shown that bilateral ankle arthrodesis can increase the metabolic cost of walking by 20-30% compared to normal gait. Additionally, the loss of normal foot and ankle motion eliminates the shock absorption function during loading response, transmitting greater forces to proximal joints. To minimize fatigue, patients may benefit from rocker-bottom shoes to partially restore the rocker mechanism, physical therapy to optimize compensatory strategies, and energy conservation techniques.

KEY CLINICAL POINTS

Ankle provides three rockers: heel, ankle, forefoot

Rockers smooth center of mass progression and reduce velocity changes

Ankle-knee coordination minimizes vertical displacement

Loss of push-off power requires compensation

Bilateral fusion increases metabolic cost 20-30%

COMMON PITFALLS

Not knowing Perry's six gait determinants

Failing to explain the rocker mechanism specifically

Missing the quantitative increase in energy cost

Not offering practical solutions (rocker shoes)

FURTHER QUESTIONS

"List all six of Perry's gait determinants"

"How does knee fusion differ from ankle fusion in terms of energy cost?"

"What is the role of the gastrocnemius-soleus in power generation?"

High-Yield MCQ Topics

Temporal Parameters

Stance phase = 60% of gait cycle
Swing phase = 40% of gait cycle
Double support = 20% total (10% at beginning and end of stance)
Single support = 40% of cycle
As walking speed increases, stance time decreases and swing time increases

Ground Reaction Forces

First peak: 110% body weight (loading response)
Valley: 80-90% body weight (midstance)
Second peak: 120% body weight (terminal stance)
Braking force maximum: 15-20% body weight
Propulsive force maximum: 20-25% body weight

Joint Range of Motion

Hip: 30 degrees flexion to 20 degrees extension (total 50 degrees)
Knee: 0-60 degrees flexion (maximum at initial swing)
Ankle: 10 degrees dorsiflexion to 20 degrees plantarflexion (total 30 degrees)

Muscle Activation

Loading response: quadriceps eccentric (shock absorption)
Terminal stance: gastrocnemius-soleus concentric (propulsion)
Midstance: hip abductors maximum (pelvic stability)
Terminal swing: hamstrings eccentric (knee deceleration)

Pathological Gait Recognition

Trendelenburg = hip abductor weakness (gluteus medius)
Steppage = foot drop (tibialis anterior weakness)
Antalgic = shortened stance on painful side
Equinus = toe walking (gastrocnemius contracture)

Controversies and Areas of Uncertainty

Gait analysis is mature science, but several issues remain genuinely debated and are favourite "higher-order" viva topics.

Validity of the six determinants of gait. The Saunders/Inman/Eberhart model remains the standard teaching framework, yet dynamic-walking and inverted-pendulum studies (e.g. Gard and colleagues) showed that pelvic rotation and pelvic list contribute little to flattening the centre-of-mass trajectory. The determinants are now best taught as a conceptual scaffold rather than a quantitatively exact energy model.
Clinical impact of instrumented 3D gait analysis. It is the reference standard for quantifying deviations, but high-level evidence that it changes hard outcomes is limited. It demonstrably alters and often de-escalates surgical recommendations in cerebral palsy, yet routine 3D analysis before all multilevel surgery is not universally funded or adopted, and reliability depends on marker placement and modelling.
Single global indices vs full curve interpretation. Summary scores such as the Gait Deviation Index and Gait Profile Score give reproducible severity tracking, but a single number can mask which joint or plane is abnormal; experts disagree on how far they should replace expert reading of kinematic curves.
Terminology and normative ranges. "Heel strike" versus "initial contact", differing phase percentage boundaries between texts, and laboratory-specific normative bands mean reported joint angles and force values are approximate and method-dependent rather than fixed constants.
Markerless and wearable gait analysis. Inertial-sensor and video/AI markerless systems are rapidly emerging as cheaper, clinic-friendly alternatives, but their agreement with gold-standard optoelectronic systems and their role in surgical decision-making are still being established.

Guidelines, Registries & Global Practice

Global Epidemiology and Clinical Drivers

Gait disorders are common and rise steeply with age: a frequently cited US community study (Verghese and colleagues) found abnormal gait in roughly one-third of adults over 70, with neurological and multifactorial causes predominating.
Cerebral palsy, the single largest indication for instrumented gait analysis, has a global prevalence of approximately 2 per 1000 live births, higher in preterm and low-birth-weight infants and in lower-resource perinatal settings.
Reduced walking speed is an established marker of frailty and predicts falls, hospitalisation and mortality, making spatiotemporal gait a low-cost global health metric.

Guideline and Society Positions (Side by Side)

Body / Region	Position on Gait Analysis
AACPDM (international, paediatric)	Supports 3D instrumented gait analysis to inform single-event multilevel surgery and to evaluate outcomes in cerebral palsy
NICE (UK)	Cerebral palsy guidance recommends specialist assessment, with instrumented gait analysis used in tertiary centres before complex multilevel surgery
AAOS / US paediatric centres	Routine use of motion-analysis laboratories for surgical planning and outcome measurement in CP and complex deformity
EFORT / European centres	Endorse 3D gait laboratories as the reference standard for quantifying gait deviation and guiding orthopaedic intervention

The common thread worldwide: observational analysis is universal and free; instrumented 3D analysis is reserved for complex (mainly neuromuscular) cases and for pre-/post-surgical assessment, with concentration in tertiary referral laboratories.

Standardisation and Outcome Measures

There is no implant/arthroplasty-style registry for gait; instead, standardisation comes from shared marker models (Helen Hayes / Plug-in-Gait, derived from Kadaba's work) and validated summary scores - the Gait Deviation Index (GDI) and the Gait Profile Score (GPS) - which enable comparison across laboratories.
Movement-analysis societies (e.g. ESMAC in Europe, GCMAS in North America) publish laboratory accreditation and good-practice standards to improve cross-centre comparability.

High- vs Limited-Resource Practice Variation

High-resource settings: dedicated optoelectronic gait laboratories with force plates, dynamic EMG and, increasingly, markerless/wearable systems; routine pre-operative analysis for cerebral palsy multilevel surgery.
Limited-resource settings: reliance on structured observational gait analysis (Edinburgh Visual Gait Score, Physician Rating Scale), smartphone video and timed walk tests (10-metre and 6-minute walk), which are validated, portable and inexpensive substitutes that capture most clinically actionable information.

MCQ Practice Points

Clinical Pearl

Q: What are the phases of the gait cycle and their relative durations?

A: Stance phase: 60% of cycle (heel strike to toe-off). Swing phase: 40% of cycle (toe-off to heel strike). Stance subdivided: initial contact (0-2%), loading response (2-12%), mid-stance (12-31%), terminal stance (31-50%), pre-swing (50-60%). Double limb support occurs at 0-12% and 50-60%.

Clinical Pearl

Q: What are the six determinants of gait described by Saunders?

A: 1) Pelvic rotation (4° each direction), 2) Pelvic tilt (5° drop on swing side), 3) Knee flexion in stance (15-20°), 4) Foot mechanisms (ankle plantarflexion/dorsiflexion), 5) Knee mechanisms, 6) Lateral displacement of pelvis. These minimize vertical and lateral center of mass displacement, reducing energy expenditure.

Clinical Pearl

Q: What muscle activity occurs during loading response phase of gait?

A: Tibialis anterior: Eccentric contraction controlling plantarflexion (foot slap prevention). Quadriceps: Eccentric contraction controlling knee flexion. Gluteus maximus/medius: Hip stabilization. This phase absorbs impact forces as body weight transfers onto the limb. Peak ground reaction force occurs here.

Clinical Pearl

Q: What causes Trendelenburg gait?

A: Weakness of hip abductors (gluteus medius/minimus) on stance side causes contralateral pelvis to drop during single-limb support. Patient compensates with trunk lean toward affected side (compensated Trendelenburg). Causes: L5 radiculopathy, superior gluteal nerve injury, hip pathology, abductor mechanism failure post-THA.

Clinical Pearl

Q: What is the center of mass displacement during normal gait?

A: Normal gait has approximately 5cm vertical displacement (sinusoidal pattern, lowest at double support, highest at mid-stance) and 4cm lateral displacement (side to side with each step). The determinants of gait minimize these excursions. Greater displacement = increased energy expenditure.

Management Algorithm