How to use an inclinometer to measure the spine’s range of motion

Pronunciation: /ˌinkləˈnämitər

The inclinometer is a tool used to determine angles of motion—particularly when measuring the spine.

Besides being fun to say, an inclinometer is nothing more than a fancy level with a protractor on it.

How to use an inclinometer

Because the spine has motion at both the top and lower segments its necessary that two inclinometers be employed simultaneously for recording the dynamic motion. One inclinometer is placed at the top of the measured spine segment, and the other at the lower spine location. The measurement value of the lower spine is subtracted from the upper spine value. This result is known as the “true angle”.

Types of inclinometers

There are two types of inclinometers: manual and digital.

The manual inclinometer, sometimes referred to as a “bubble inclinometer” has a fluid filled face in a circle. The fluid is a combination of a colored fluid and a clear fluid. The fluid interface moves with gravity, and the movement of the interface is used to read the measurement off a rotating 360 degree face dial.

Manual inclinometers

Measuring spine motion with the manual inclinometer requires a bit of practiced talent. The patient is instructed to stand in the upright position and the dial faces are set to the 0 degree position. The user must then hold the two inclinometers at once on the spine while movement is measured. It sounds easy, but in practice for the first several exams, it is difficult. The user must coordinate the physical control of the inclinometer while also performing the calculations and documenting the findings. When using the dual manual inclinometers for the first time, it is like trying to catch a falling snake. Patience is a virtue and persistence is necessary to capture accurate and consistent measurements.  The upside of the manual inclinometer is that they are relatively inexpensive ($50 each on Amazon as of the writing of this article), and no batteries are necessary. The down side is they do take some practice and can be difficult to read due to the small print face. A good pair of reading glasses are recommended.

Digital inclinometers

Digital inclinometers have been gaining some popularity because of ease of use and automatic calculation of the true angle. Digital inclinometers are two electronic gravity sensors which have ability to standardize a zero measuring reference with the click of a button. They are approximately the size of a pocket-watch and are typically connected by an electronic cord. One end is the measurement reading end (typically referred to as the “master”) placed at the top of the spine. The other device is placed at the lower segment of the spine section (typically referred to as the “slave”). The upside of the digital inclinometer is the ease of use during exam, and it automatically calculates the true angle. The downside is the device may not have an auto off feature.  This means it is easy to leave on, and may be found dead for the next exam. Additionally, digital inclinometers are expensive and can range into the hundreds of dollars.


Regardless of the style of inclinometer used, understanding the inclinometer and its function is essential for accurate and well supported impairment report (PR-4 Report) conclusions. The time invested in becoming familiar with the inclinometer will result in faster and more accurate report for patients, workers’ compensation insurance carriers, employers, and administrators.

Update! September 4th, 2015

The RateFast Dual Inclinometer mobile app is now in app stores! Turn your phone into a dual inclinometer for less than $5.

Read more about the RateFast Dual Inclinometer app here.
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