Range of motion (ROM) of the knee is the range in degrees through which the knee can bend and straighten (flex and extend).

range of motion plastic goniometer for measuring range of motion goniometer measuring knee range of motion

Normal ROM is usually minus 5 to 143 degrees in women and minus 6 to 140 degrees in men.

A plastic goniometer with longer arms is usually used to measure range of motion.

The scale part of the goniometer is placed on the joint line.


Measuring range of motion in the knee

Knee range of motion is usually measured with a simple plastic device called a 'goniometer', although more sophisticated electronic devices are available.


Range of Motion

Video explaining the terminology of flexion and extension of the knee.

Range-of-motion is a key concept in knee rehabilitation. This paper discusses how it is measured.

Assisted passive extensions

Exercise to increase range of movement.

CPM - continuous passive motion

Passive gentle machine-assisted exercise to maintain range of motion.

Assisted flexion

Video of an Assisted Flexion exercise to help to re-build range of motion.

The knee - range of motion

Part 2 of a course by Dr Frank Noyes on Arthrofibrosis

An 'interpretation' of a medical article from 2001 detailing the various causes of diminished range of motion in the knee after ligament injuries.



Increasing Knee Range of Motion Using a Unique Sustained Method. Shah N. N Am J Sports Phys Ther. 2008 May; 3(2): 110–113.

Smartphone-based accelerometry is a valid tool for measuring dynamic changes in knee extension range of motion. Støve MP, Palsson TS, Hirata RP. Knee. 2018 Jan;25(1):66-72.

See also:

and ROM exercises:

and ROM devices:

eBook of knee rehabilitation exercises

Cornerstones of Early Knee Rehabilitation - ebook

eBook on objectives of knee rehab

Objectives of Knee Rehabilitation - ebook