Introduction: Goniometer for Joint Range of Motion Measurement
Make a low-cost version of this clinical joint angle measuring tool and begin assessing your Range of Motion!
Step 1: Print Paper Copy of Real Goniometer
If you had a real gonimeter, you would not need to build a homemade one! However, I include this step, as you may wish to make multiple goniometers for others to use, and will then need multiple copies! I have also included a pre-made copy to use as a pattern (the PDF file is: Goniometer Pattern is found in this step).
If you make your copy directly on heavy weight card-stock, that's all you need. If you print or copy onto regular print paper, in the next step you will need to tape or glue your goniometer pattern onto some stiffer material.
Step 2: Cut Out the Goniometer Pattern
If you have printed the goniometer template directly on card stock, just cut that out. If you printed on regular printer paper, find some stiffer material to which to affix the pattern. Here I show Card Stock, Paper Board (such as from a cereal box), and thin cardboard. I chose the paperboard because it was easy to cut, but has a good degree of stiffness.
Holding the paperboard behind my pattern, I cut out both sides of the goniometer template. Notice that the larger (darker) dial was cut out completely round, but the smaller (lighter) dial was cut with a little notch in the tab extending from the dial (see the last three images). Unlike the 'store-bought' kind, our goniometer is not transparent, so the notch will let you read the dial when taking an angle measurement.
Finally, affix your goniometer sides to their backing with tape or glue. A glue stick would work great, but I chose to use clear tape and covered pretty much the whole template, which will help when I spill my coffee on it down the road.
Step 3: Attach the Goniometer Sides
Your next step is to find a suitable 'axis' with which to attach the goniometer arms to each other, and around which the goniometer will rotate. As the back of the tool may be placed up against a joint of the body when taking measurements, things cannot protrude much. I found a number of possibilities laying around. I first tried a flat pin with a pin back that holds fairly tight. That worked pretty good, but it stuck out a bit too much on the front for my liking. So I decided to go with an innovative piece of modern technology called a 'paper clip'. Notice how I bent the section on the back so it would not pull through, then after pinning the sides together through the middle of the dials I bent the front part down to keep things together. Worked great! Be sure to have the smaller dial on the front, so you can see the degree readings on the larger dial.
Step 4: Learn to Read Your Goniometer.
You now have a fully functional Goniometer! One minor difference from the real thing that is important to note is that when the real goniometer is extended fully, it can be read as 180 degrees (the true angle between the goniometer arms) or as 0 degrees (for instances when you want to measure how far the joint moves from a fully extended position). Notice in the angled position, you can read either how far the goniometer has moved from fully extended (50 deg. in the example), or you can read the true angle between the arms (130 degrees). On our homemade one, we can only see the 50 deg reading - but you would just have to subtract that from 180 to get the 130 degree reading.
Step 5: Take Some Joint Angle Measurements!
The basic thing to remember in order to take clinically accurate measurements using your goniometer is that the Goniometer Arms essentially serve as a model for the segments of the body forming the joint of interest. In the Wrist Joint example, the goniometer axis is placed over the rotational axis of the joint (where the bones of the hand meet the bones of the arm forming the wrist joint). As the hand moves, one goniometer arm is always kept aligned with the arm, and the other goniometer arm is allowed to move with the hand. In the position shown, it looks like the Wrist is extended approx. 50 deg. from a starting point with the hand and arm aligned (the Anatomical Position for this joint). If I wanted the true angle between the arm and hand, I would subtract from 180 to get 130 degrees, the angle formed between the arm and hand on the back side (the direction of extension).
In the Elbow Joint Example on my skinny friend, the goniometer axis is placed over the rotational center of the elbow joint, with the goniometer arms aligned with the upper arm (humerus), and lower arm (radius/ulna). In the fully flexed position shown, it looks like my friend achieved an elbow angle of about 25 degrees, or 165 degrees of flexion from the Anatomical Position.
4 years ago
Nice. I always love seeing people making DIY science equipment.