Goniometer Use in Physical Therapy

Diagnostic Measurements Provide a Baseline and Encourage Improvementgoniometry personalized care

The goniometer, or “goni,” is a tool used in physical therapy that measures a joint’s range of motion. The therapist measures the joint passively (the patient relaxes) or actively (effort made by the patient) so that they may establish a baseline and set goals for improvement. The therapist visualizes the angles of the body, adapts to the certain joints they are inspecting, and places the goniometer in a way that may measure those angles.

Depending on whether the joint is going into flexion, extension, abduction, etc., there are different angles that the therapist must be aware of and careful to consider when dealing with an injury that may restrict or require limited movement during the range of motion assessment. In case of an arthroplasty, for example, or knee replacement, the therapist, will continuously monitor and provide the measurements for the patient in hopes of gaining the range of motion that will provide functionality and ease. 

A therapist keeps in mind that for the patient to safely and comfortably navigate stairs, they will want to achieve approximately:

  • 120 degrees of flexion, as well as strength and control through that flexion.

If that patient wants to return to bicycle riding, they would have to have approximately:

  • 110 degrees of flexion to appropriately bring their legs through the cycling movement. These are just some of the things considered by the therapist when evaluating and treating a wide spectrum of injuries and post-operative joints.

Above, Kelsey measures Ashley’s flexion and practices for her future career as a Physical Therapist Assistant. She is aware of the joint’s possible movements (the knee is a hinge joint and has two methods of movement: flexion and extension) and documents the total range of motion.


In an article in the Journal of Rural Medicine, a study aimed to elucidate the target range of motions for a knee post-arthroplasty during rehabilitation. This study utilized goniometry to establish a quantitative progression for improvement, which ultimately personalized the patient’s plan of care. For example, if a patient had only 90 degrees of flexion in the first measurement, and after three successive visits, the flexion improved to 110 degrees of flexion, the goniometer successfully provided a measurable and objective way to classify personal advancement. Studies like this and real-world implementation help create boundaries and guidelines for rehabilitation in the physical therapy setting. The use of the goniometer acts as an essential tool in these guidelines and helps further personalize rehabilitation.




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