ELECTRONIC GONIOMETER pptx....pptx

basic description of electronic goniometers, its components, types, uses, advantages and disadvantages.

1. ELECTRONIC GONIOMETER PRESENTED BY – GROUP 3

2. Introduction Electrogoniometry is one of the methods of kinematic measurements to objectively measure the human motion. Electrogoniometers are the electronic devices which uses angle sensors to measure dynamic movement of the joint. Components These devices have two arms , similar to those of the universal goniometer , which are attached to the proximal and distal segments of the joint being measured. A potentiometer is connected to the two arms.

3. Working of Electrogoniometer POSITIONING The arms of the electrogoniometer are strapped to the body segments, such that the axis of rotation of the goniometer is approximately aligned with the joint’s axis of rotation. WORKING Rotation of a calibrated potentiometer measures the angular position of the joint. The angle of the joint is converted to voltage which is sampled continuously and again converted to an angle using manufactured supplied scale factor. The related output voltage is typically measured by a computer data acquisition system (analog to digital data) which display the joint angle in real time. The position data obtained from the electrogoniometer combined with the time data can be mathematically converted to angular velocity and acceleration.

4. TYPES OF ELECTOGONIOMETER 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. Optoelectronic systems offer good precision But their collaboration procedures and data analysis are time-consuming.

5. 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’s movement. The instrument’s precision can also be compromised due to inability to follow any changes in the joint’s axis of rotation. .

6. Strain gauges – Also known as flexible goniometers, a strain gauge is 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 block’s longitudinal axis. Strain gauges are light weight, portable, easily applied do not restrict movements not interfere in patient’s activities and adapt well to different body segments. These are currently the most popular electrogoniometers.

7. ADVANTAGES Ease of use Cost effective than other methods of measuring dynamic movements Determine precise joint angles which is extremely important in rehabilitation. Angle data is essential for determining abnormal patterns, characterizing disability, impairments, handicap

8. Disadvantages They are less accurate than other systems used to record movement. In addition, both designs i.e. potentiometers and strain gauge require placement over the joint, which may interfere with the natural kinematics because of cumbersome cabling and method of attachment. Another drawback of these devices is that while they provide a relative measure of joint angular position The computation of which requires knowledge of the absolute positions of the body.

9. RELIABILITY OF ELECTROGONIOMETER The electrogoniometer evaluated has a very high precision when range of motion measurements are made. A systematic review of measurement tools (standard goniometers , fluid- and gravity-based inclinometers, photographs, and motion analysis systems) used to quantify knee joint motion found that for dynamic measurements, electrogoniometers and 3D motion analysis systems were the most reliable and had low measurement error. There is a reliability study on the use of universal goniometer and electro goniometer in measuring knee range of motion which concludes that Universal goniometer in clinical evaluation (as they are easy to be employed) and electro goniometers in laboratory studies ( as they are more accurate) are reliable.

10. References : Donald A Neumann, Kinesiology of Musculoskeletal System: Foundations for rehabilitation.3 rd edition.Elsevier ,Inc.;2010 Leonardo Mangiapelo , Implementing an electrogoniometer;2008