Biodex Balance System
Original Editor - Heba El Saeid
Top Contributors - Sonal Joshi, Heba El Saeid, Angeliki Chorti and Lucinda hampton
Purpose
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 stabilise 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]
Technique
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:
- measure the patient's height and weight as this data is required by the system before starting the test
- 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.
- 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;
- unlock the platform and determine the zero point of your patient (feet coordinates)
- start performing a familiarity trial to minimize the effect of learning.
Interpretation of Results
The Biodex balance system measures three indices:
- medio-lateral stability index (MLSI) represents fluctuations from the horizontal around the mediolateral axis
- anterior-posterior stability index (APSI) represents fluctuations from the horizontal around the anteroposterior axis
- 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]
Evidence
Reliability & Validity
- BBS and Healthy adults
Study was conducted in 20 healthy male & females to measure an overall stability index (OSI), an anterior-posterior stability index (APSI), and a medial-lateral stability index (MLSI). The researchers found BBS showing good reliability as indicated by R = .94 (OSI), R = .95 (APSI), and R = .93 (MLSI). [4]
- BBS and Patients with Chronic Low Back Pain
A study in 2013 evaluated reliability of Biodex Balance System in chronic low back pain patients. It was found to be a reliable measure of postural control in the patients especially in difficult positions such as with eyes closed. [5]
- BBS and Older Active People, Test-Retest Reliability
The BBS shows good reliability of balance measurement. It was also shown to be useful for measuring risk of fall and monitoring programme for fall risk reduction. [6]
Resources
https://biodexrehab.com/products/balance-system-sd/
References
- ↑ 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. J Applied Biomech. 2014 Apr 1;30(2): 300-4.
- ↑ 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. Pak J Med Sci 2008;24(3):372-7.
- ↑ Arnold BL, Schmitz RJ. Examination of balance measures produced by the biodex stability system. J Athl Train. 1998 Oct;33(4):323-7.
- ↑ Cachupe WJ, Shifflett B, Kahanov L, Wughalter EH. Reliability of biodex balance system measures. Meas Phys Educ Exerc Sci. 2001 Jun 1;5(2):97-108.
- ↑ Sherafat S, Salavati M, Takamjani IE, Akhbari B, Mohammadirad S, Mazaheri M, Negahban H. Intrasession and intersession reliability of postural control in participants with and without nonspecific low back pain using the Biodex Balance System. J Manipulative & Physiol Ther. 2013 Feb 1;36(2):111-8.
- ↑ Parraca JA, Olivares Sánchez-Toledo PR, Carbonell Baeza A, Aparicio García-Molina VA, Adsuar Sala JC, Gusi Fuertes N. Test-Retest reliability of Biodex Balance SD on physically active old people. J Human Sport Exercise. 2011; 6(2): 444-51.