1. Gait Errors Ankle and foot: 1)Inappropriate initial contact
Low heel strike
Flat foot contact
Forefoot contact
2)Excessive planter flexion
3)Excessive dorsiflexion
4)Varus(inversion)
5)Valgus (eversion)

2. Gait Errors Knee: Inadequate extension Limited flexion, no flexion
Hyperextension
Varus
Valgus
Hip:
Inadequate flexion
Adduction-abduction

3. Gait Phase Abnormalities
Initial contact : loss of normal heel strike can occur because of three reasons-
1)A low heel strike, results due to loss of ankle dorsiflexion to the neutral, floor contact is made by the heel so that the foot is nearly parallel to the ground
2)Flat foot contact can occur when the knee is flexed even though the ankle is at neutral
3)Forefoot contact often called as toe strike will indicate combined ankle planter flexion and knee flexion

4. Gait Phase Abnormalities
Loading response: Attempting to bear weight on a flexed knee in the presence of weak quadriceps leads to a total limb collapse
Midstance: Excessive ankle planter flexion prevents the body from moving forward
Terminal Stance: Inadequate ankle PF is the critical problem, thus there is excessive ankle dorsiflexion
Heel rise is lost and body advancement usually provided by the forefoot is lacking
Preswing: loss of passive knee flexion

5. Gait Phase Abnormalities
Initial swing : Inability to flex the hip deprives the patient of limb advancement
Mid Swing: Excessive ankle planter flexion causes toe drag
Terminal swing: Inability to extend the knee fully leaves the limb in an undesirable position for stance

6. Instruments used for gait analysis
During walking major displacement of various body segments occur. these are synchronized to reduce the work involved in walking
The hip,knee,ankle describe complicated motions during a complete gait cycle
Characterization of these motions provides specific information regarding abnormalities in gait
E.g. A reduced single limb support could be due to no of phenomenon: hip or knee pain, decreased hip or knee motion, weak musculature etc
Motion analysis can help to find the abnormality, but the motion occurs to fast to be discerned by a human eye
Thus measurement using recording instruments is necessary to permit observation at a lower speed

7. Picture Video
One of the simplest pieces of gait instrumentation is the picture video
A picture video helps to measure a persons gait prior to applying any instrumentation, that might alter gait pattern
It provides a visual documentation of what happened during instrumented test and is the only way of resolving differences when the recorded footswitches or motion data do not correspond to clinicians visual image of a subject

8. Picture Video
A basic video system consist of a VCR,one or two video cameras ,a character generator ,a video mixer and a TV monitor
The video mixer combines images from 2 cameras so that the lateral and anterior /posterior view can be observed simultaneously
The character generator enables to overlay text(e.g. name and date)on the video image
The clinician can use it as a stand-alone device or with another system

9. Temporal Gait Measurement
Temporal gait measurements help to find the timings of critical events in gait measurement
Cadence, gait cycle duration, stance and swing times, single limb support ,initial & terminal double limb support can be measured
By making the measurements over a definite walking distance the persons velocity and stride length can be defined ,which can reveal a great deal about the persons ability to walk
E.g. If a person gets weaker has painful joints or feels unstable ,velocity will decrease and the person will spend less time in single limb support on the affected side

10. Footswitches
Footswitches are a convenient and inexpensive way of obtaining temporal gait measurement
There are 2 basic types of foot switches:
1)Compression closing footswitches
2)Force sensitive resistor switches(FSR)

11. Compression closing footswitches
Compression closing switches consist of sandwich of thin pieces of brass shim stock separated by a compressible (non conducting) foam rubber insole
In contact areas conductive rubber cylinders are inserted into holes in the insole
When pressure is applied the insole compresses and the conductive rubber cylinder contact the pieces of brass on each side of the insole ,closing an electrical circuit
The sandwich is held together with duct tape and is typically about 4 mm thick

12. Force Sensitive Resistor footswitches
The FSR switches consist of 2 thin layers of flexible plastic with printed circuits on the inner surfaces separated by a thin layer of double sided adhesive
Holes in the adhesive create contact areas
As pressure is applied carbon on one surface contact a metal pattern on the other surface creating a resistive electrical circuit
As more pressure is applied the resistance drops
The associated circuitry triggers at a predefined resistance value indicating a switch closure

13. Footswitches
Footswitches have typical contact areas in the 1st and the 5rd metatarsal, heel and great toe areas
In most footswitch systems, a pair of light beams is positioned along the line of walking progression. The light beams are arranged at a known distance from one another. As the walking subject passes each beam, a signal is received in the recording device. Thus, data about distance travelled and time are acquired.
Footswitch and light beam signals can be transmitted and recorded in 3 different ways.
The simplest method is to connect the switches to recording devices by cable. Cables can be made lightweight and flexible. They are relatively simple, reliable and expensive. subject must drag the cable along the walkway or some provision must be made for movement of the cable with the subject.

15. Gait mats
Gait mats are relatively new systems that provide temporal and spatial measurements
These mats consist of a long strip of walking surface such as a carpet into which is embedded an array of switches running across and along the length of the mat
As the person walks along the mat the switches close under the feet due to foot pressure enabling the computer to calculate the timing of each switch closure and thus the floor/foot contact pattern
Since the geometry of the mat is known the special parameters of gait can be calculated
Besides step length measurements advantages of these system are elimination of gait encumbering attachments ,low cost and portability

16. Gait mats
Gaitrite: This is a portable instrumented carpet that can be used in either a laboratory or field setting.
The walkway is 4m long x 0.6m wide x 6mm high and contains 13,824 sensors. Up to forty-one basic gait measures such as walking speed and step length are immediately available upon the completion of a walk across the mat.
Assessment using this system takes about half an hour.
The Gait Scan is a noninvasive method whereby a computerized pressure mat is utilized to record pressures on the bottom of the foot as a patient walks over the mat. Pressure distribution is directly related to the overall posture and stability of the foot. It is this data that the doctor then analyzes to precisely determine abnormalities and develop an appropriate treatment regimen for the patient.

18. Gait mats Gait Mat II:The dimensions of a GaitMat II mat are
12'8" long x 32" wide x 1-1/4" high (walking surface is 23.6" (0.6m) x 12.6' (3.84m)).
The GaitMat II mat weighs approximately 100 pounds.
The GaitMat II mat uses pressure sensitive switches arranged in 38 rows of 256 switches each. The switches are on 15 mm centers, thus, 15 mm is the spatial resolution of the system.
The GaitMat II interface uses either USB or DMA to transfer data from the mat to the computer's memory.

23. Goniometers
These are the instruments used to measure different joint angles
They are available in various sizes 6 inch,8 inch ,12 inch and are also used to measure 180° and 360° angles
The 180 ° and 360° are used to measure range of motion of finger and wrist & ROM of large joints respectively

24. Goniometers
Jamar Plastic Goniometers opaque white background behind degree markings for easy, accurate readings. Inch and centimeter linear measurements.
12 ½" Goniometer: Scale reads 0° to 180° and 0° to 360° in 1° increments.
8" Goniometer: Scale reads 0° to 180° in opposite directions in 1° increments.
6" Goniometer: Scale reads 0° to 180° in opposite directions in 1° increments.
6 ¾" Goniometer: Scale reads 0° to 180° in 5° increments. Ideal for small joints.

25. Goniometers Stainless Steel Goniometers
clearly marked degree increments and easy-to-read inch and centimeter linear measurements.
360° Goniometer: Features one 360° and two 180° scales that read in opposite directions. 14" long. Scales marked in 1° increments. Locking arm.
180° Goniometer: Has two 180° scales that read in opposite directions. 14" long. Scales marked in 10 increments. Non-locking friction arm.
8" Goniometer: Has two 180° scales in opposite directions marked in 1°increments. Turn the knurled knob to vary amount of tension on the arms or to fully lock them.
180° "Robinson" Pocket Goniometer: Scale is marked in 5° increments. Ideal for measuring small joints of the hand. 7" long.

26. Goniometers
Biplane Goniometer : Hand held, transparent goinometer standardizes the clinical assessment of ankle dorsiflexion.
Structure allows examiner to control entire forefoot, subtalar joint and ankle joint, preventing unacceptable pronation during measurement.

27. Goniometers Extendable Goniometer
Versatility, Reliability, Accuracy and Portability . Its arms can extend to 22.25" to measure large joints and retract to 6.875" to measure all but the smallest joints.
The dual scale of 0º - 180º and 180º - 0º is magnified four times, improving the accuracy of the reading, thus, reducing the chance for error.,
Its lightweight ,ABS plastic construction long lasting , affordable

28. Goniometers Finger Goniometer- Stainless Steel
For ROM measurements of metacarpal, phalangeal and interphalangeal joints. Linear inch and centimeter markings on both sides of protractor in opposite directions. Protractor measures 0° to 150° in 5" increments

29. Finger Circumference Gauge
Measures as a direct readout of the circumference of a finger joint or digit. Ruler is transparent.

30. Goniometers
Electronic goniometers: these are electromechanical devices that span a joint to be measured with attachments to proximal and distal limb segments
These devices provide an output voltage proportional to the angular changes between the two attachment surfaces
They move on assumption that the attachment surfaces move with midline of the limb segment onto which they are attached and thereby measure actual angular change of joint
The 2 major advantages of these device are low cost and ease of use

31. How to use a goniometer

32. How to use a goniometer

35. Force Plate
A force plate is a device that measures the ground reaction forces exerted by a subject as they step on it during gait. they consist of a Top plate & a bottom plate separated by Force transducers at each corner
Any force exerted on the top surface is transmitted through force transducers
The force plates are of 2 Types:
1. Piezoelectric: Utilize quartz transducers that produce an electric charge when stressed. No power supply needed
2. Strain Gauge: Utilize strain gauges in specially machined aluminum transducer bodies referred to as load cells to measure stress

36. The forces can be applied in three directions Fx,Fy,Fz and can be measured by using a force plate

37. As the person steps on the gait mat The force applied in a vertical direction is measured, as force is applied the graph increases ,as the person steps off the gait mat the graph decreases

39. Pressure Insoles Pressure Insoles
Pressure insoles were designed to provide the same kind of data available from pressure mats, with the added advantage of in-shoe measurement and multiple cycles.
Dynamic measurement of footwear and orthoses is possible with these insoles . One can quickly and easily compare the plantar pressure distribution with different shoe inserts and/or orthoses
With special care, barefoot data can also be obtained by lightly taping the transducer to the bottom of the foot .
The insole must be protected from possible damage and the clinician must insure that the floor/insole interface does not create a slipping hazard for the wearer

40. Electromyography
EMG is an instrument used for recording electrical activity of the muscles(action potential of muscles) to determine whether the muscle is contracting or not,
Time course of muscle contraction
Contraction force
Coordination of several muscles in a movement sequence
These parameters are derived from the amplitude, frequency, and change of these over time of the EMG signal

41. Electromyography
EMG signals are also imp for myoelectic control of prosthetic devices.
This involves picking up EMG signals from the muscles at terminated nerve endings of remaining limb and using a the signal to activate a mechanical arm
EMG is usually recorded by using surface electrodes or by using needle electrodes

43. Electromyography
Needle Electrodes: are used in clinical electromyography for investigation of muscle tissue under the skin and in the deeper tissues
The material used for needle electrode is stainless steel, because of its solidity and low price
They should be sterilized before used
Monopolar needle electrode consist of a Teflon coated stainless steel wire which is bare only at the tip
After the needle has used for several times the Teflon coating recede, increasing the tip area
The needle must be discarded when this occurs

44. Electromyography
Surface Electrodes: are used to measure electrical activity from a group of muscles
Surface electrodes can be easily and quickly attached and are generally comfortable to wear over long periods
These usually consist of square or circular metal plates with leadoff wires attached, they are held in place by straps and adhesive tapes
To reduce electrical resistance between skin and electrode surface a small amount of electrode gel is used
Disposable adhesive type of tapes are also used

45. Electromyography
A preamplifier (preamp) is an electronic amplifier that prepares a small electrical signal for further amplification or processing

46. Electromyography
EMG contains a varying negative, positive alternative current (AC) signal
Rectified = all negative values converted to positive values (absolute value)

47. Electromyography
Case Study: The EMG electrodes were fixed to the Gastrocnemius and Soleus muscles of both the legs of the subject using medical grade both sided tapes
To prevent the electrodes from being displaced from their fixed locations during the course of the experiment tapes were used
The ground strap of the EMG setup was worn on the left leg. The leads of all the four pre amplifiers were fed to the base-unit of the EMG acquisition system which acted as an interface to the PC.
The subject was instructed to walk a few rounds before actual data acquisition to get familiar walking with the setup intact.
Three sets of data were acquired, with the subject walking at self
selected speed for fast and slow walking. The collected data was stored and analyzed offline using Biometrics Management Software

48. Electromyography

49. Electromyography

50. Electromyography

51. Video Motion
One or more video cameras can be used in a video system in order to track the bright markers that are placed on the subject along specific locations.
Passive Marker System–solid shapes with retroreflective tape
Active Marker System–infrared (IR) light-emitting diodes (LEDs).
The system keeps track of the horizontal and vertical coordinates of each marker from each camera
In Three –Dimensional (3D) System 2 or more video cameras are used,Computer software program calculates 3D coordinates for each marker using the 2D data obtained from the cameras.
In Two –Dimensional (2D) System a single video camera is used, assuming all of the motion is occurring on a single plane perpendicular to camera axis.It is Not recommended for use in gait analysis.

52. Video Motion
Active marker systems have LED markers that are pulsed sequentially ,so the system knows the identification of each marker
These systems require more equipment to be placed on the user- battery back, pulsing circutry,markers,cables attached to and carried by the userFor a long duration heat generated by the LED’s can be a problem
These markers are used in CODA system which uses a specially designed camera with a array of photodiodes
When the LED flashes the signal is detected by the sensor array
The data is transmitted to the computer which calculates the 3D coordinates

53. Video Motion
Passive Marker system: these use light weight reflective markers without the need of electrical cable or batteries on the user
IR LED’s send out pulses of IR radiation that are reflected back into the lenses from the marker
As the subject walks the markers are detected and later a computer software is used to calculate 3D data

54. Vicon
Vicon 3-D Motion Analysis System (6 240Hz cameras) for quantitative analysis of human motion.  3-D models are generated to calculate joint range of motion as well at the translation of a subject through the cameras’ capture field. This data may be used in collaboration with force plate data to calculate variables such as joint moments, power, and work.

55. Vicon
The eight camera Vicon System seen below allows for sophisticated measurement of gait parameters and joint angles.

56. Cerebral palsy
Cerebral palsy (CP) is an encompassing a group of non-progressive non-contagious motor conditions that cause physical disability in human development, chiefly in the various areas of body movement.
These affect the gait cycle and the various joint angles

57. Parkinson’s Disease
In Parkinson's disease the person has a stooped posture
Head forward
Hips and knees bent
Walking on the front of feet