A goniometer is a device used to measure the range of motion in a joint. It is mostly used in the fields of ergonomics, physiotherapy, and orthopedics. We explain the procedure to use this device appropriately. Take a look!
Before testing joint movements, it’s ideal to do some warmup exercises as this increases extensibility of the tissues around the joints.
A goniometer, in its most basic sense, is a circular protractor designed to be used on the human body. Goniometers are mostly used by physiotherapists or orthopedic doctors to detect irregular joint movement. Ergonomists use this scale to measure a specific joint angle associated with a certain task. This helps them design equipment more precisely, such that it suits the posture of the person using it.
Joint flexibility is indicated by the range of motion or the Movement allowed at the joint. Increasing joint flexibility is known to help prevent injuries. In human anatomy, there are several terms used to denote different motions of a joint. For instance, ‘flexion’ refers to the reduction of angle between the joint and the moving bone (when we sit on a chair, our knees are flexed). ‘Extension’ refers to an increase in the angle between the joint and the moving bone (when we stand, knees are extended).
Similarly, there are other types of motions which include, pronation, supination, deviation, abduction, adduction, and rotation. These motions can be easily measured by a goniometer, provided you know the correct way to use it.
How to Use a Goniometer
A goniometer is a circular protractor with two extended arms. The stationary arm is fixed at 0°, whereas the rotational arm can move from 0° to 360°.
When using a goniometer to measure the range of motion in a joint, line the fulcrum (the center) of the goniometer with the fulcrum of the joint.
Next, line the stationary arm of the goniometer with the stationary or fixed segment of the joint. This varies with different joints. For instance, when measuring flexion, extension, or deviation in the wrist, the fixed segment would be the forearm. Make sure that the stationary arm is perfectly aligned with this part, and hold it steady before proceeding.
Once you’ve appropriately aligned the stationary arm and held it firmly in place, you’ll need to align the moving arm with the moving segment. To achieve this, hold the moving segment of the body in its neutral (at rest) position. Then, align the moving arm to this position.
Now that the goniometer is set to use, ask the subject to move the said segment. For instance, if you’re attempting to measure flexion of the wrist, ask the subject to move his/her hand downwards, while you have goniometer aligned to the side of the wrist joint. For the most precise measurement, the subject should move the said segment to the maximum he can. Once the subject has flexed or extended his hand completely, move the goniometer’s arm to align it with the moved segment.
Now that the goniometer is perfectly aligned with the moved segment, take the reading on the protractor, and note it down. In this way you can measure any joint of the body using a goniometer. In case you still need some more clarification, refer to the example given below.
How to Use a Goniometer to Measure Knee Angle
From the above figure, you can clearly understand the way to hold the goniometer. The physiotherapist has correctly aligned the fulcrum of the goniometer with that of the knee joint. He is firmly holding the stationary arm which is aligned with the upper leg, while measuring the angle of flexion using the mobile arm.
When measuring, the lower leg is flexed to its fullest, whereas the upper leg is kept as steady as possible. The knee joint, in most cases, only supports flexion; hyperextension is rarely possible, and can range from 10 to 20 degrees.
Normal Range of Motion Chart
When using a goniometer, compare your readings to this chart in order to check normal range of motion in all joints.