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A goniometer is an instrument which measures the available range of motion at a joint. If a patient or client is suffering from decreased range of motion in a particular joint, the therapist can use a goniometer to assess what the range of motion is at the initial assessment, and then make sure the intervention is working by using the goniometer in subsequent sessions.

The term goniometry is derived from two Greek words, gonia, meaning "angle" and metron, meaning "measurement".

Medizinischer Goniometer.jpg
Goniometer have different types; the most use is the universal standard goniometer,which is either made with plastic or metal tool. It consists of a stationary arm, a movable arm and a fulcrum. Other types of goniometer use for joint range of motion measurement the telescopic-armed goniometer and some smart phone applications.

Validity and reliability

There is some question as to whether or not the use of a goniometer is a sufficiently valid and reliable instrument to determine whether an intervention has been effective[1] . Some research argues that the reliability of the measurement gotten from a goniometer depends on the type used[2][3] while some did not see any significant difference between some instruments[4][5]


  1. Goniometer. (2008, August 30). In Wikipedia, The Free Encyclopedia. Retrieved 11:12, September 14, 2008, from http://en.wikipedia.org/wiki/Goniometer.
  2. Milanese S et al. Reliability and concurrent validity of knee angle measurement: Smart phone app versus universal goniometer used by experienced and novice clinicians. Manual Therapy, 2014; 5: 1–6.
  3. Jones A, Sealey R, Crowe M, Gordon S. Concurrent validity and reliability of the simple goniometer iPhone app compared with the universal goniometer. Physiotherapy Theory and Practice. 2014;30 (7): 512–516.
  4. Mourcou Q, Fleury A, Diot B, Franco C, Vuillerme N. Mobile Phone-Based Joint Angle Measurement for Functional Assessment and Rehabilitation of Proprioception.Biomed Res Int. 2015; doi: 10.1155/2015/328142
  5. Ockendon M, Gilbert RE. Validation of a Novel Smartphone Accelerometer-Based Knee Goniometer. Journal of Knee Surg. 2012;25:341–346.