The Use of Specks in Gait Analysis

Smita Sasindran1, Jennifer Walsh2, Alison Richardson2, Jan Herman2, James Hollington2

1 School of Informatics, University of Edinburgh2 Anderson Gait Laboratory, SMART Centre, Astley Ainslie Hospital, Edinburgh

Gait Analysis • Brief observation to sophisticated measurement

• Patient population• 75% paediatric • Cerebral Palsy• Neurological Disorders• Prosthetics

• Treatment Planning

• Analysis of intervention

Clinical Gait Analysis• One of 2 centres in

Scotland providing clinical gait analysis

• Clinical Gait Analysis– 3D analysis

• Vicon 460

Biomechanical model

• Three markers per body segment

• Markers on joints define two adjacent segments

• Marker placement conducted by physiotherapist

• Markers placed on bony prominences and anatomical markers

Biomechanical model

• Modified Helen Hayes model 3D axis system for each segment

• Sagittal plane angles -Flexion/extension

• Coronal plane angles Abduction/adduction

• Transverse plane angles Internal/external rotation

Phases of Gait

Clinical Gait Analysis

Three-dimensional gait analysis

• Track images from two or more cameras

• Points used to reconstruct original 3D trajectories

Clinical Gait Analysis• Kinematics

• Angular displacements in 3 planes

• Kinetics• Forces, moments, powers

• Temporal Parameters• Walking speed (m/s)• Cadence (steps/min)• Double/Single support time (s)• Stride length (m)• Step length (m)• Step time (s)

Kinematics

Kinetics

Left Mean Barefoot (Mean Barefoot) Right Mean Barefoot (Mean Barefoot) Avg File 7 (Normals.gcd)

Hip Flexion Moment2.0

-1.0

Flex

Ext

Nm

Knee Flexion Moment2.0

-1.0

Flex

Ext

Nm

Ankle Flexion Moment3.0

-1.0

Dors

Plan

Nm

Fore/Aft Shear Force40

-40

N

Hip Ab/Adduction Moment1.0

-1.0

Add

Abd

Nm

Knee Ab/Adduction Moment1.0

-1.0

Var

Valg

Nm

Ankle Ab/Adduction Moment1.0

-1.0

Add

Abd

Nm

Medial/Lateral Shear Force30

-30

N

Hip Flexion/Extension Power3.0

-2.0

Gen

Abs

W

Knee Flexion/Extension Pow er2.0

-2.0

Gen

Abs

W

Ankle Flexion/Extension Pow er4.0

-2.0

Gen

Abs

W

Vertical Ground Reaction Force140

0

N

Limitations of current methods of Clinical Gait Analysis

• Modelling errors–Centre of knee rotation–Marker placement–Soft tissue movement–Foot modelling

Limitations of current methods of Clinical Gait Analysis

• Practical data collection constraints–Artificial capture environment–Snapshot analysis–Restricted activities–Specialist staff–Intrusive–Expensive

Specks

•

Potential benefits of Specks for CGA

• Address limitations of current optical motion capture methods

• Provide objective measure of functional ability in every day environments

• Provide ongoing monitoring• Increase national service capacity• Reduce assessment costs

Comparative Results

• Normal Data Collection

• Patient Data Collection

Graph from Specks Graph from Vicon

Pelvic Tilt30

-10

Ant

Post

deg

Comparative Results – Pelvic Tilt

Graph from Specks Graph from Vicon

Comparative Results – Hip FlexionHip Flexion60

-15

Flex

Ext

deg

Graph from Specks Graph from Vicon

Knee Flexion90

-15

Flex

Ext

deg

Comparative Results – Knee Flexion

Graph from Specks Graph from Vicon

Ankle Flexion30

-30

Dors

Plan

deg

Comparative Results – Ankle Flexion

Graph from Specks Graph from Vicon

Pelvic Obliquity15

-15

Up

Dow n

deg

Comparative Results – Pelvic Obliquity

Graph from Specks Graph from Vicon

Hip Adduction20

-15

Add

Abd

deg

Comparative Results – Hip Abduction

Graph from Specks Graph from Vicon

Pelvic Rotation30

-30

Int

Ext

deg

Comparative Results – Pelvic Rotation

Pelvic Tilt30

-10

deg

Patient Data

Knee Flexion90

-15

deg

Patient Data

Pelvic Obliquity15

-15

deg

Patient Data

Hip Adduction20

-15

deg

Patient Data

Pelvic Rotation30

-30

deg

Patient Data

Pelvic Tilt30

-10

deg

Patient Data

Hip Flexion60

-15

deg

Patient Data

Original Curves Zero Mean Adjusted

Original Curves Zero Mean Adjusted

Original Curves Zero Mean Adjusted

Analysis of The Use of Specks in Clinical Gait Analysis

• Format of result in line with Gait Analysis reports

• Integration cumulative error, reset at mid-stance

• Reset orientation of markers• Zero centred magnitudes

Future work

• Anterior/Posterior pelvic tilt • “Root” of calculations

• Position of foot marker

• Orientation of markers

Future Work• Design

–Size

• Transmitting Wire / Internal memory

• Battery life

• Transmission problems

• Segmentation automated for pathological gait

Summary of The Use of Specks in Gait Analysis

Kinematics• Angular displacements in 3 planes

• Kinetics• Forces, moments, powers• Force Transducers

• Temporal Parameters• Walking speed (m/s)• Cadence (steps/min)• Double/Single support time (s)• Stride length (m)• Step length (m)• Step time (s)

Thank you for your attention