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By Betty | 12 October 2022 | 0 Comments

How to Use a Goniometer

A goniometer is essentially a protractor with two arms, used to measure a joint's range of motion. They're most often used in physical therapy to track the progress of a joint's movement. There are many goniometers made in different shapes and there is a classic one. You can use the goniometer to measure many joints, such as the shoulder, wrist, hip, knee, and even finger, etc. 

General Steps to Use a Goniometer

Step 1: Preparation

Before using the goniometer, please align and familiarize it. 

A goniometer has two arms. One is attached to the circle with the angle degrees on it. The other movable arm does measuring. Understand how the moving arm points to the angle degrees so that you can accurately measure the range of motion. 

Step 2: Align the center of the goniometer with the center of the measuring joint. 

It is important to align the center of the goniometer along the center of the joint you prepare to measure. So that you can track how far a limb can bend or extend using the two arms and get an accurate measurement.

The center of the goniometer also called the fulcrum of the goniometer, should be placed right on the fulcrum of the joint you are measuring. The center is the round section attached to the stationary arm. 

Step 3: Hold the goniometer's stationary arm along the limb being measured.

Align the stationary arm (the arm attached to the circle) with the limb that's going to remain in place. This is the limb that you hold steady. If it helps, imagine you are aligning the arms of the goniometer with the bones in your body.

Step 4: Stretch the joint throughout the entire range of motion.

Be careful not to move any other part of the body except the limb being measured. Stretch the joint as safely as possible, then hold the limb.

Step 5: Move the moving arm of the goniometer to align with the moving limb.

Once you've stretched your limb as far as possible, slide the goniometer's moving arm so that it aligns with the stretched limb. You should now have the fixed arm of the goniometer aligned with the fixed limb and the moving arm of the goniometer aligned with the moving limb.

Step 6: Record the angle to find out the range of motion.

Look at the reading on the goniometer before removing it from the person’s body in case the goniometer’s arms move once it’s removed. Write down which joint you measured, what type of movement was done, and the range of motion in degrees.

Example: how to use a goniometer to measure knee angle

To measure the hyperextension of the knee, have the person lay flat on their back on a stable surface with the leg extended as straight as possible. 

Step 1: Hold the goniometer to the side of the knee joint and align the arms on either side, with the moving arm aligned with the moving leg.

The average knee extension should be 0 degrees (when your leg is in a straight line), while the average flexion is roughly 135 degrees.

Step 2: To align the goniometer's arms correctly, imagine your lining up the goniometer’s arms along the bones of the leg.

Step 3: Keep the body stable and unmoving while the leg is bending.

Step 4: Record the angle and get the flexion of the knee.


Only trained doctors, physical therapists, occupational therapists, or other personnel with prior training should perform evaluations using goniometers.

The skilled person must know how to:

  • Correctly position and stabilize the joint.
  • Move body parts with an appropriate range of motion (ROM).
  • Determine the end and end feel of the joint's range of motion.
  • Palpate the appropriate bony landmarks.
  • Align the goniometer with the landmark.
  • Read the measuring instrument correctly.
  • Record measurements correctly.

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