Inclinometer And Physical Therapy

The role of a physical therapist is to help people to regain their function and allow them to return to their life of work, recreation, and other daily activities. A key element of this role is determining whether people have the appropriate range of motion (ROM) available to accomplish their daily activities without pain.

Physical therapists, until today, used a device known as a goniometer to measure this range of motion at the joints. Recently, physical therapists measure range of motion in a different way. This change of motion was brought about by studies showing range of motion measurements made using a new tool, known as an inclinometer, are more accurate, precise, and reproducible than measurements made using goniometers. According to the Guides of American Medical Association to the Evaluation of Permanent Impairment, the inclinometer has been adopted to measure spinal range of motion. According to the physical therapists, the inclinometers are easier to use, and provide new and more useful information.

A goniometer is much similar to a protractor people may have used to measure angles in geometry class, but with arms, like the type of compass used for drawing circles. The arms of a goniometer interconnected at a single axis or pin. To measure the range of motion at a joint with a goniometer, the patient moves his or her body part to the position directed by the physical therapist. The physical therapist aligns the arms of the goniometer with the bones surrounding the particular joint and aligns the pin with the joint axis. Because the physical therapist cannot hold the goniometer directly against the bones, bone and joint axis positions must be estimated. The angle of the joint indicated by the goniometer is recorded. Goniometer measurements typically require the joints to be moved from the opening of its range to the end of its range of motion. For instance, in the knee, a measurement of range of motion is taken when the joint is fully bent and then again when it is fully straightened.

Because the positions of the bones and their axis points must be estimated, each reading of the device made with a goniometer introduces error into the measurement. Normal joint mechanics introduce another source of error into the device measurements, unlike a door hinge rotating around a cylindrical pin; a joint rotates around the ends of the bones, which are not perfectly round. Therefore the joint axis of the bone itself moves, making the estimation of the axis position more difficult.

No such estimates or alignments of the bone axis are necessary with an inclinometer. Inclinometer device has dials or digital readouts that display the angle at which the inclinometer is situated relative to the line of gravity. To use an inclinometer device, the physical therapist holds the instrument on the patient, who begins in a standard starting position. The physical therapist zeroes-out the inclinometer and then directs the patient to bend the joint through its range of motion. The final reading of the inclinometer is the measurement of the range of motion. The inclinometer device never leaves contact with the patient and the axis does not need to be identified.