Electrogoniometer

1. E lectrogoniometer Done BY : Areej alorini

2. Presentation Outline background Definition Uses of electrogoniometer Type of electrogoniometer advantages and disadvantages Reliability  of electrogoniometer

3. Background Electronic goniometers Continuously measure joint angle Compatible goniometers are cost prohibitive Affordable goniometers use a separate software clock

4. Background The subthalamic nucleus (STN) is a common target in deep brain stimulation (DBS) procedures for movement disorders. Ascertaining the somatotopic map of the STN requires: Microelectrode recordings Electrode position Joint velocity

5. Electrogoniometers are devices that convert joint angle to a voltage. The voltage can be sampled continuously, making electrogoniometers ideal for measuring dynamic movement. There are basically two designs, both of which fall under the category of resistive transducers. These devices, namely potentiometers and strain gauges, output a voltage related to the angular position of the joint. The voltage is converted to an angle by using a manufacturer supplied scale factor specific to each transducer. The joint angle can be displayed in real time and/or stored on a computer equipped with an analog-to-digital data acquisition card. Definition

6. Uses of electrogoniometer Rehabilitation engineering is the systematic application of engineering sciences to design, develop, adapt, test, evaluate, apply and distribute technological solutions to problems confronted by individuals with disabilities. Determining precise joint angles is extremely important to rehabilitation and biomedical engineers as well as physiotherapists and ergonomics specialists. The angle data is essential for identifying abnormal patterns and characterizing impairments, disabilities and handicaps.

7. Cont.. Disabled patients, such as those suffering from hemiplegia (half the body is paralyzed) or hemiparesis (half the body is weakened but not paralyzed), may experience limited speed and amplitude in some body movements. For such cases, an electrogoniometer is a useful tool for measuring joint angles, such as those for elbows or knees, to determine the extent of the disability. The electrogoniometer is an electronic device that uses angle sensors, such as potentiometers, strain gauges and, more recently, accelerometers to record such measurements.

8. Type of electrogoniometer

9. Optoelectronic systems: These are video systems that use one or more video cameras to track bright markers placed at various locations on the patient's body. These markers are either infrared (IR), light emitting diodes (LEDs) or solid shapes of reflective tape. The system keeps track of the vertical and horizontal coordinates of each marker, and computer software processes this information to determine the angle on the body segments of interest. Although optoelectronic systems offer good precision, their calibration procedures and data analysis are time-consuming.

10. Potentiometers: A potentiometric element is attached to a joint's rotation point. The potentiometer's electrical resistance can be used to determine the angle between the joints. These types of electrogoniometers are somewhat bulky and restrict patient movement. The instrument's precision can also be compromised due to its inability to follow any changes in the joint's axis of rotation.

11. Strain gauges: Also known as flexible electrogoniometers , a strain gauge is a flexible spring with plastic end blocks on each end. The strain gauge mechanism is housed inside the spring, which changes its electrical resistance proportionally to the change in angle between the plastic end blocks' longitudinal axes. Strain gauges are lightweight, portable, easily applied, do not restrict movements nor interfere in patient activities and adapt well to different body segments. These are currently the most popular electrogoniometers .

12. advantages and disadvantages There are advantages and disadvantages associated with the use of electrogoniometers . In their favor are ease of use and cost. On the other hand, they are less accurate than other systems used to record movement. In addition, both designs (i.e., potentiometer and strain gauge) require placement over the joint, which may interfere with the natural kinematics because of cumbersome cabling and/ or method of attachment. Another drawback of these devices is that while they provide a relative measure of joint angular position, the data do not lend themselves to an inverse dynamics analysis in which joint reaction forces and moments are of interest, the computation of which requires knowledge of the absolute positions of the body segments.

13. Reliability  of electrogoniometer .  The electrogoniometer evaluated has a very high precision when range of motion measurements are made. However, the accuracy of the device is less than acceptable.