Goniometer, what is it and how to buy it?

November 2, 2021

goniometer is a laboratory instrument whose function is to measure an angle or allow an object to rotate according to a precise angular position. The term as such of goniometer is derived from Greek words, which is gonia, which means angle, and metron, whose meaning is close to measure. The earliest description we have of the goniometer derives from the astrolabe, apparently dated 1538.

By aligning the axis of rotation of the instrument, with the central axis of the joint, and each leg of the goniometer along the joint segments, visual inspection of the tool will show the angle desired by the user.

This instrument was particularly used in the study of crystals in laboratories around the world. Nicolaus Steno, in 1669, was able to determine the interfacial angles of quartz crystals by cutting perpendicular sections of the edges. The first known instrument to be used to measure angles was the goniometer created by Anould Carangeot in 1783. So he could easily be credited with the invention.

There are different types of goniometer , each with its own peculiarities and specifications. However, the one most used by scientists is a universal goniometer, known as such because it can be used for all the functions for which it was invented. It is made with plastic tools, but can also be found in metal. This laboratory instrument consists of an arm that is stationary, one that does move, and a point of support for greater precision.

If you want to know more about this particular material, known as a goniometer, and which is similar to others such as ammeter or speedometer , you have to stay with us. Join us in the next article where we will break it down in detail!

What is a goniometer?

In general terms, we can define the goniometer as a tool capable of measuring the range of motion of a joint while it is available. If a client, or in any case a patient, suffers a decreased range of motion in a joint of the body, the therapist using the goniometer can assess the range of motion in the initial evaluation. Later, after making sure that the intervention is working, using the goniometer of course, it will be used in later sessions.

This is essentially a conveyor with two arms detaching from it. As mentioned above, to measure the range of motion of a joint. It is frequently used in physical therapy to track the progress of movement. So, more than in a laboratory, you will see it used by a health professional. This is not limited to a single joint, but there are many that you can measure with the goniometer. Be it the knee, hip, shoulder and wrist. It is important that I aligned it well to the center, along the joint, and using the arms to correctly track how far a limb can bend or extend.

This is mega necessary for therapies, since it is not known how much pain or flexibility a person may have. Remember that each body is a world, and some will not necessarily have the same angle as the other. This is where the importance of this laboratory material lies.

Where is the goniometer used?

It is generally used in medical rehabilitation settings , where physical conditioning or athletic performance persists. The goniometer is most often used to moderate and adjust the selection of exercise a person is performing. Or also to carry out an intervention. The evaluations carried out by the goniometer are quite relevant since they highlight the hypo-mobility in the range of movement called ‘osteokinematic’. Which implies, right off the bat, that flexibility and mobility techniques may be appropriate for this instrument.

In conclusion, the goniometer will help a professional or physiotherapy to build an adequate routine based on the flexibility and mobility of a person to the point that it is refined. Less frequently, but not least, it is also often used to highlight hypermobility. This implies that there is a need to perform activation and stabilization techniques for the parts or joints of the body.

Parts of a goniometer

The goniometer includes some parts that you need to know, including:

  • Body . Also known as the fulcrum, it is the body of the goniometer. What would be considered the centerpiece and what makes it work. It is generally circular or semi-circular in shape, with a protractor printed on the face and the fulcrum of the movement arm in the center.
  • Stationary arm . Known as a stabilization arm, it is the one that is fixed to the body of the instrument in such a way that its relative position never changes. Hence its name.
  • Mobile arm . Unlike the one mentioned above, this arm can be moved according to the user’s specifications. It does not need to be aligned with a reference, as it will constantly move with the joint measurement.

Types of goniometer

There is a wide variety of these useful tools, which we will detail below. Each one with a wide variety of similarities, but they tend to do a different job. Among them we find:

Contact goniometer

This type of goniometer, known as a contact, consists of two metal rulers that are turned, but together, in the center of a graduated semicircle . The instrument is placed with its plane perpendicular to an edge between two glass faces to be measured. Meanwhile, the rules get in touch with the faces. The angle between the rulers gives the angle between the two faces. The rules in general are grooved, this so that they can be shortened and applied partially embedded to the matrix.

Reflective Goniometer

The reflective goniometer is a material that is often used for its greater precision in the angles when small crystals with a smooth face are available. Such faces reflect well-defined images of a shiny object. By rotating the glass of the goniometer about an axis parallel to the edge between two faces, the image that is reflected from a second face can be placed in the same position that the reflected image previously occupied.

Different forms of instruments have been invented depending on the principle mentioned above. The first type consisted of a vertically graduated circle that read degrees and minutes, while rotating on a horizontal axis. A great improvement of the goniometer was achieved when a graduated circle was placed in a horizontal position.

Other types of horizontal circle goniometer have also been built, which are used in telescopes and collimators. This in the construction of essentially the same spectrometer. With the addition of the arrangements for adjusting and centering the glass is a stage in the horizontal circle.

Goniometer Applications

In topography

Before the theodolite was invented, the goniometer was used for surveying functions . The application of triangulation to geodesy was described in several books dating to the year 1533.

For communications

While the Second World War was going on, a type of radio direction finder was created that was used by soldiers. This type of goniometer used signals from two crossed antennas, and even four individual antennas, which simulated two crossed ones to recreate the radio signal. All this in a small area between two cable loops. The operator could measure the angle of the radio source by doing a direction search within the area.

In crystallography

For crystallography , the goniometer was used so that it could measure the angles between glass faces. It was also used in X-ray diffraction to rotate samples.

In light measurement

Gonphotometers are instruments known for measuring the distribution of spatial light that is visible to the human eye at a specific angular position used by the user.

In medicine

The goniometer is used in medicine to document the initial and subsequent range of motion of visits by injured persons . These are used by disability evaluating physicians in order to determine the permanent disability of an injury or joint.

It serves fully to evaluate progress, also for legal medical purposes. Another common use of the goniometer within the medical world is that it is used to evaluate the signs of Waddell, which is an important finding to indicate the increase of the symptoms of this disease.

How to use the goniometer

First of all, before using the goniometer as a professional, you must know it in detail to the point that you become familiar with it. Remember that it has two arms, one that is attached to the circle with the degrees of angle and another mobile arm that measures what is to be examined. Of course, make sure you understand how the swing arm points to angle degrees for the best movement precision.

Second, align the center of the instrument to get the center of the joint. The center of the goniometer, also called the fulcrum, has to be positioned right in the middle of the joint you are examining or measuring. The center is that round section that is attached to the stationary arm.

Third, hold the stationary arm of the goniometer along the limb. Once the tool is at the center, align the stationary arm with the limb so that it stays fixed in place for the best possible results.

Finally, instruct the patient or client to stretch the range of motion joint. This while holding the goniometer and stationary limb in place.

Dr. Loony Davis5
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Born and raised in Brussels in an English family, I have always lived in a multicultural environment. After several work experiences in marketing and communication, I came to Smart Water Magazine, which I describe as the most exciting challenge of my career.
I am a person with great restlessness and curiosity to learn, discover what I do not know, as well as reinvent myself daily, someone who is curious about life and wants to know. I enjoy sharing knowledge.
This is my personal project but I also collaborate in other blogs, it is the case, the most important web on water currently exists in the US, if you are interested you can read my articles here.

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