Goniometry: Introduction

Introduction to Goniometry

by Brent Brookbush DPT, PT, COMT, MS, PES, CES, CSCS, ACSM H/FS

Definition:

Goniometry - "…refers to the measurement of angles, in particular the measurement of angles created at human joints by the bones of the body (1)."

Why Goniometry? In rehab, fitness and sports performance settings, goniometry is most often used to refine exercise/intervention selection. Relevant goniometric assessments highlight hypo-mobility in osteokinematic range of motion, implying which release, flexibility and mobility techniques may be appropriate. In essence, goniometry will assist the human movement professional in building a more refined flexibility/mobility routine. Less often, goniometry will highlight hyper-mobility implying the need for activation and stabilization techniques .

What's in a name?

• -gon - word-forming element meaning "angle, corner," from Greek gonia "corner, angle," from PIE root *genu- (1) "knee; angle" (see knee (n.)). (Etymology Online )
• -meter - word-forming element meaning "device or instrument for measuring;" commonly -ometer, occasionally -imeter; from French -mètre, from Greek metron "a measure" (see meter (n.2)). (Etymology Online )
  • A device for measuring angles

Parts of a Goniometer:

• Body (Fulcrum) - The body of a goniometer is the centerpiece, usually circular or semicircular, with a protractor printed on its face and the fulcrum of the movement arm at its center.
  • Generally, the fulcrum of the goniometer is placed over the center of a joint during measurement.
• Stationary Arm (Stabilization Arm) - The arm that is affixed to the body of the goniometer in such away that it's relative position does not change.
  • Generally, the stationary arm is aligned with a reference line that does not move during measurement.
• Moving Arm (Movement Arm) - The arm that is affixed to the face of the goniometer at it's fulcrum; and is free to move the full range of degrees printed on the face of the goniometer.
  • Generally, the movement arm follows the moving bone during measurement.

Parts of a Goniometer - http://www.scranton.edu/faculty/kosmahl/courses/gonio/intro/images/stdgonio.jpg

What are We Measuring?

Summary: Goniometry measures osteokinematic range of motion in degrees (not muscle length or arthrokinematic motion), most often as a means of tracking changes in hypo-mobility.

Arthrokinematic Motion versus Osteokinematic Motion:

• Osteokinematics (Movement of bones) - Movement of bones around a joint; described by the terms flexion, extension, abduction, adduction, etc. You may think of this in terms of movement of the shafts of bones relative to one another.
• Arthrokinematics (Movement of joint surfaces) - Small amplitude movements occurring between joint surfaces, described by the terms, roll, glide, spin, compression and distraction. Arthrokinematics and osteokinematics must occur simultaneously.
  • Goniometry is a measurement of osteokinematic motion. Although we may be able to hypothesize that a decrease in osteokinematic range of motion is due, in-part to altered arthrokinematics, goniometry is not a direct measure of arthrokinematic motion. Goniometry measures the amount of osteokinematic motion available at a joint in total number of degrees.

Unit of Measurement:

As most bones pivot in an arc around a fulcrum, or fixed point (a joint), goniometry is measured in degrees. That is, the angle created between a bone and reference line. That reference line is most often related to "anatomical position " of a bone.

• A degree (in full, a degree of arc, arc degree, or arcdegree), usually denoted by ° (the degree symbol ), is a measurement of plane angle , representing 1⁄360 of a full rotation (Wikipedia ).

A goniometer is nothing more than a protractor (just like you used in geometry class), affixed to two rulers. The method used to determine joint angles is no different than the method used to find the angle between two lines. Some helpful angles to remember:

• 360º - A full circle; or one rotation that resulted in ending with the original angle
• 180º - Half a circle; a straight line dividing a circle in half.
• 90º - A right angle; a perfect "L" shape
• 45º- Half a right angle

Hyper-mobility versus hypo-mobility:

• Hyper-mobility - the range of motion achieved by the patient/client is greater than normal values.
• Hypo-mobility - the range of motion achieved by the patient/client is less than normal values

Normal values are established via research on joint motion across various demographics; this research is well-cited and discussed in Measurement of Joint Motion: A Guide to Goniometry, 3rd Edition. (1).

Note: Both hyper-mobility and hypo-mobility may adversely affect motion and may lead to deleterious affects on joints and soft tissue over time. There is no evidence to suggest that their is a benefit to flexibility beyond normal, or having tightness in tissues that are responsible for force production.

**Range of Motion and End Feels:

**

Range of motion:

• Passive (PROM) - The amount of motion achieved by the practitioner without assistance from the client/patient (the client/patient is passive).
• Active (AROM)- The amount of motion achieved by the patient without assistance from the practitioner (the client or patient is active).
• Active Assisted (AAROM) - The amount of motion achieved when the practitioner applies additional force to a range of motion achieved by the client/patient (active range of motion with over-pressure).

End Feels (1 - 3)

• Soft - A normal end feel when tissue approximation is the limiting factor to joint range of motion.
  • An example of a normal soft end feel is the end of elbow flexion, in which the flexor mass of the forearm meets the biceps brachii.
• Firm - A normal end feel when muscles, ligaments and/or the joint capsule are the limiting factor to joint range of motion. This end feel has been described as "the way it feels to pull a leather strap to its end range."
  • An example of a normal firm end feel is the end of dorsiflexion or shoulder internal rotation.
• Hard - A normal end feel when bone on bone contact is the limiting factor to joint range of motion
  • An example of a normal hard end feel is the end of elbow extension.
• Empty - This end feel is never normal, and signifies that a "true" end range could not be achieved due to pain and muscle guarding by the patient/client.
  • An example of an empty end feel can be seen in the individual who "threw their back out" and will not bend forward due to pain and spasm.

Notes:

• Soft, firm and/or hard end-feels can be normal or abnormal depending on the joint. For example, a soft end feel at the limit of elbow extension may indicate effusion (swelling), where as a firm end feel, short of terminal extension may indicate adaptive shortening of the joint capsule, ligaments and other soft tissues.
• Other terms have been used to describe end feels in an attempt to further clarify or describe abnormal end feels (boggy, spasm, capsular, ligamentous, muscular, etc.,). Until considerable practice and experience is achieved, having compared the various abnormal end feels associated with pathology to the assessment of other colleagues and diagnosis by physicians, it is likely prudent to only use and document the 4 well defined terms above, and note any further description/hypothesis as a parenthetical (e.g. Firm (capsular)).

Necessary Prior Knowledge:

• Know Your Functional Anatomy - Using goniometry to refine exercise/intervention selection is not complicated; however, a sound knowledge of anatomy is necessary. The more anatomy you understand the more information you will gain from each goniometric assessment.
• Start with a Dynamic Postural Assessment - It is the recommendation of the Brookbush Institute that a gross dynamic movement assessment, such as the Overhead Squat Assessment , is used to highlight which body segments and ranges should be assessed further using goniometry. This will result in a more efficient assessment, and more relevant data acquired from goniometry.
• Experience with Corrective Exercise - Some experience with corrective/therapeutic exercise (and the Overhead Squat Assessment ) is also recommended prior to adding goniometry to your assessment/evaluation process. This will result in goniometry adding to a foundation of exercise selection based on the most commonly implicated structures.

Why Assess?

• Assessment - is the act of assessing, i.e. determining the importance, size, or value of -

In most cases, the results of an assessment are compared to normative data. If the individual exhibits values that are within normal parameters than, it may be assumed that the aspect of health or motion assessed is not contributing to the patient's complaint or movement impairment. If the results fall outside of normal parameters, it may indicate that the aspect of health or motion assessed is contributing to, or being affected by the patient's complaint or movement impairment. In some cases, the results of an assessment are compared to an "ideal model." In this case, deviations from the ideal are noted as potential issues. For example, deviations noted in the Overhead Squat Assessment are compared to an "ideal model" of posture and movement. Assessments used by human movement professionals can be divided into three broad categories:

• "Clear" the Patient/Client for Intervention - These are tests, assessments and evaluations used to determine if a patient/client's issue may improve given the assessing professional's scope, skills, abilities and willingness to treat that individual.
  • For example, many of the special tests used in orthopedic medicine assist in determining the level of pathology or likelihood of a particular diagnosis. Certain issues and diagnoses are beyond the scope of the human movement professionals, and some issues are not optimally treated by the interventions within our scope (physicians, podiatrists, surgeons, etc.). The Ottowa Foot/Ankle Signs are an example of a test in which a cluster of positive signs indicates that imaging is needed to determine whether a fracture is present.
• Highlight Contraindications - Tests, assessments and evaluations used to stratify risk or preclude a professional from addressing certain tissues, motions or using a particular technique.
  • For example, the Vertebral Artery Test (VBI) is often used to determine if high velocity thrust mobilizations (manipulations) are safe for a patient with cervical dysfunction.
• Refine Exercise/Intervention Selection: Tests, assessments and evaluations used to assist the professional in determining which techniques, modalities and exercises will best address a patient/client's complaints or desired goals.
  • Most movement assessments fall into this category. For example, a positive Ely Test may indicate a need to release and/or lengthen the rectus femoris .

Note: An assessment, or a particular assessment result, may fall into more than one category. For example, although goniometry is an assessment most often used to Refine Exercise/Intervention Selection, if a particular range of motion is significantly altered, with an abnormal end-feel, and/or causes the patient or client/pain, the individual may need to be referred to a physician for further testing and Clearance to resume rehab activities. Further, that same patient may return to the human movement professional with a list of Contraindicated Activities from the physician. - "When in doubt, refer out!"

The Difference Between a Good Test and a Bad Test:

Good tests, assessments and evaluations are valid, reliable and relevant -

Validity - refers to how well a test measures what it is purported to measure. Specifically, "face validity" refers to whether a test measures what it appears to measure; that it is possible.

• Goniometry is valid as long as it is used to measure the range of motion (ROM) of a joint, and not used to infer the length of a structure crossing that joint (7).

Reliability - the overall consistency of a measure.

• General guidelines for enhancing the reliability of Goniometry:
  • Assessment parameters are carefully followed (example, landmarks defined and identified) (1, 6, 10)
  • Extremity assessments are generally more reliable than assessments of the spine (23 - 27) (except, lateral flexion of the cervical spine is reliable (25))
  • Large joint assessments are generally more reliable than small joint assessments (elbow more reliable than wrist) (28)
  • Stable positions are generally more reliable than unstable positions (supine versus sitting for upper extremity) (12, 13, 21)
  • At least 5 degrees difference denotes a change in range of motion (this accounts for a margin of error) (8, 9)

Relevance - closely connected or appropriate to the matter at hand.

• Will the test you are using enhance the service you are offering? In my humble opinion, the actual impact an assessment has on application is not given enough credit. If the results of an assessment do not impact how you will proceed, that assessment is not relevant, and it should be discarded. Each test, assessment and evaluation used by the human movement professional should be chosen because the data from that assessment has a direct impact on practice.
• Relevance of Goniometry:
  • In fitness and sports medicine, goniometry is most often used to refine exercise/intervention selection. Most often, reliable and relevant goniometric assessments highlight hypo-mobility in osteokinematic range of motion, implying which release, flexibility and mobility techniques may be appropriate. In essence, goniometry will assist the human movement professional in building a more refined flexibility/mobility routine. Less often, goniometry will highlight hyper-mobility implying the need for activation and stabilization techniques .

How to use Goniometry:

Now that you have read the definitions and descriptions above the initial paragraph titled "Why Goniometry" should make more sense:

• In fitness and sports medicine, goniometry is most often used to refine exercise/intervention selection. Most often, reliable and relevant goniometric assessments highlight hypo-mobility in osteokinematic range of motion, implying which release, flexibility and mobility techniques may be appropriate, and add objective, ordinal data for assessment of continued progress. In essence, goniometry will assist the human movement professional in building a more refined flexibility/mobility routine. Less often, goniometry will highlight hyper-mobility implying the need for activation and stabilization techniques .

Once a gross movement assessment is used (e.g. Overhead Squat Assessment ) to determine the segments that exhibit compensatory motion, and the pattern of compensation, goniometry may be used as an "objective measure" the available range of motion at each joint associated with those segments. Where as gross movement assessment can only implicate all structures at a joint that has adopted compensatory changes in length, extensibility and activity - goniometry may assess individual joint motions. Although this may seem to imply that goniometry is superior to gross movement assessment, the results of goniometry have to be considered relative to how the individual compensates during functional movement patterns. Generally, comparing goniometry to gross movement assessment results in one of 3 types of changes to a corrective exercise/intervention plan.

• Reduces Potential Structures - Example, an individual exhibits "knees bow in" during an overhead squat assessment, but hip range of motion is normal. This individual may not need release, mobility and lengthening techniques for the commonly short/over-active structures at the hip (for this compensation pattern), and further reasoning may imply that more attention should be given to compensation and a loss of range of motion at the ankle.
• Highlights Additional Structures - Example, an individual exhibits excessive forward lean during an overhead squat assessment, and exhibits restricted knee flexion during goniometric assessment. This may imply that in addition to a loss of extensibility in those structures that restrict dorsiflexion and over-activity of muscles that flex the hip - additional techniques should be added to address extensibility of knee extensors.
• Confirms Findings of Gross Movement Assessment - Example, an individual exhibits "arms fall" during an overhead squat assessment, also exhibits a loss of shoulder flexion and external rotation. Although this does not add or reduce the potential limiting structures, it does add an objective measure to the compensation noted.

Goniometric assessment may also be used to add objective, ordinal data to a group of movement assessments. For example, the Overhead Squat Assessment can be used to determine whether a compensation is apparent or not apparent (binary), it cannot be reliably used to place a value on the "amount of compensation", or the amount of improvement made in a single session (unless the improvement is absolute). For example, if the "Feet Turn Out " during the Overhead Squat Assessment , to say that "less Feet Turn Out" was noted in session two is not reliable. However, goniometry may be reliably used to track the amount of dorsiflexion range of motion gained in each session (ordinal data), or after a set of interventions.

Additional Articles on Goniometric Assessment:

• Upper Body Goniometry
• Lower Body Goniometry

Bibliography:

1. Cynthia C. Norkin, D. Joyce White. Measurement of Joint Motion: A Guide to Goniometry 3rd Edition. Copyright (C) 2003 by F.A. Davis Company
2. Dr. Mike Clark & Scott Lucette, “NASM Essentials of Corrective Exercise Training” © 2011 Lippincott Williams & Wilkins
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   • Both Upper and Lower
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    • Lower Body
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    • Extremities more reliable than spine
23. Burdett, R. G., Brown, K. E., & Fall, M. P. (1986). Reliability and validity of four instruments for measuring lumbar spine and pelvic positions. Physical therapy, 66(5), 677-684.
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    • Small Joint Reliability
28. Hellebrandt, F. A., Duvall, E. N., & Moore, M. L. (1949). The measurement of joint motion. Part III: Reliability of goniometry. Phys Ther Rev, 29(6), 302-7.

© 2017 Brent Brookbush

Questions, comments and critiques are welcome and encouraged.