Biodex Balance System

Original Editor - Heba El Saeid

Top Contributors - Heba El Saeid, Lucinda hampton and Angeliki Chorti  

Introduction[edit | edit source]

In recent years, the Biodex Balance System (BBS) has been used to evaluate postural balance. The BBS is a multiaxial device that objectively measures and records an individual’s ability to stabilize the involved joint under dynamic stress. It uses a circular platform that is free to move in the anterior-posterior and medial-lateral axes simultaneously. it can also be used for the purpose of balance training.[1]

Method of Use[edit | edit source]

The BBS allows up to 20° of foot platform tilt, which permits the ankle joint mechanoreceptors to be stimulated maximally. The BBS measures, in degrees, the tilt about each axis during dynamic conditions and calculates a medial-lateral stability index (MLSI), anterior-posterior stability index (APSI), and an overall stability index (OSI). These indexes represent fluctuations around a zero point established prior to testing when the platform is stable. For example, an OSI of 5° would be interpreted to mean that on average, the displacement from the center is 5°. A high score in the for example, OSI, indicates poor balance. The OSI score is believed to be the best indicator of the overall ability of the patient to balance the platform. The stability of the platform can be varied by adjusting the level of resistance given by the springs under the platform. The platform stability ranges from 1–8, with 1 representing the greatest instability. The lower the resistance level the less stable the platform. The system is equipped with a screen with adjustable height to be suitable for each patient. on the screen there is a cruser that represents the patient's position and performance while trying to stand still and maintain balance. [2]

To start assessing balance using the Biodex balance system you should:

  1. measure the patient's height and weight as this data is required by the system before starting the test
  2. enter the patient's age and determine the type of test (dynamic/static), determine the testing conditions under which the test is going to be performed.
  3. ask your patient to remove their footwear, explain in detail how the test is going to be performed and asking them to step on the device with the platform locked;
  4. unlock the platform and determine the zero point of your patient (feet coordinates)
  5. start performing a familiarity trial to minimize the effect of learning.

Interpretation of Results[edit | edit source]

The Biodex balance system measures three indices

  1. medio-lateral stability index (MLSI) represents fluctuations from the horizontal around the mediolateral axis
  2. anterior-posterior stability index (APSI) represents fluctuations from the horizontal around the anteroposterior axis
  3. overall stability index (OSI) a composite of MLSI and APSI so it is sensitive to changes in both directions

These indices are standard deviations assessing fluctuations around the zero point from the horizontal rather than around the group mean. higher values indicate more deviations and poor balance control.[3]

Psychometric Properties[edit | edit source]

The Biodex balance measures have been found to be reliable. Biodex Balance may be useful for the measurement of the risk of falls and for demonstrating the progress patients in exercise programs oriented to the improve of balance for falls prevention.[4]

References[edit | edit source]

  1. Arifin N, Osman NA, Wan Abas WA. Intrarater test-retest reliability of static and dynamic stability indexes measurement using the Biodex Stability System during unilateral stance. Journal of applied biomechanics. 2014 Apr 1;30(2). BibTeXEndNoteRefManRefWorks
  2. Karimi N, Ebrahimi I, Kahrizi S, Torkaman G. Evaluation of postural balance using the biodex balance system in subjects with and without low back pain. Pakistan Journal of Medical Sciences. 2008;24(3):372-7.
  3. Arnold BL, Schmitz RJ. Examination of balance measures produced by the biodex stability system. Journal of athletic training. 1998 Oct;33(4):323. BibTeXEndNoteRefManRefWorks
  4. Cachupe WJ, Shifflett B, Kahanov L, Wughalter EH. Reliability of biodex balance system measures. Measurement in physical education and exercise science. 2001 Jun 1;5(2):97-108. BibTeXEndNoteRefManRefWorks