Software Application for Balance Assessment

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Original Editors - Aya Alhindi

Top Contributors - Shrouk Ashraf Rekaby, Kim Jackson, Shahd Mohammed Abdelhafeez Hamed, Adham Abdelhady, Mohamed A Hassanin, Mariam Eldaly, Aya Alhindi and Esraa Elsaeed Mohamed  

Introduction

Balance is the ability to evenly distribute body weight in static positions e.g. standing or during movement so person doesn’t fall or can recover from any external disturbances to this state and it is closely related to the position of body’s center of gravity. Due to its dependence on neuromusculoskeletal system, Balance deficits can occur due to many disorders or diseases in your body. Imbalance symptoms like dizziness and vertigo are common in world-wide community (dizziness 17 - 30%, and for vertigo 3 - 10%). That’s why Physiotherapists and other health care professions pay special attention to balance deficits among patients they deal with.

The three-level nervous system deficits model based on the level of neuronal processing involved:

Level 1: Low level deficits depict gait disorders due to peripheral sensory (peripheral neuropathy, vestibular, hearing or visual dysfunction) or peripheral motor impairment (myopathy, focal muscle weakness e.g. peroneus paresis). Low level impairments can be compensated, if central nervous functions are intact.

Level 2: Intermediate level deficits are caused by dysfunction of postural or motor responses, and sensory and motor modulation as in spastic hemiplegia, spastic paraplegia, extrapyramidal (e.g. Parkinsonian) gait disorders, and cerebellar movement disorders.

Level 3: Higher level disorders are characterized by cognition deficits in planning, intention, and executive functions, as well as gait apraxia. As in dementia and depression.

Patients with diseases of other body systems can complain from imbalance like patients with chronic obstructive pulmonary disease, Obesity, Hip arthroplasties (Surgical and post-operative risk factors)and knee osteoarthritis.

Types of Balance

1. Static balance: can be defined as the maintenance of a steady position on a fixed ,firm stable support base . Static balance can be also defined as the ability to maintain support with minimum movement of one or both legs.
2. Dynamic balance: it is the ability to perform activities while maintaining a stable position.

Software Application Assessment

Control of balance is complex and involves maintaining postures, facilitating movement, and recovering equilibrium. Balance control consists of controlling the body center of mass over its limits of stability. Clinical balance assessment can help assess fall risk and/or determine the underlying reasons for balance disorders.

Most of the traditional ways to assist balance are merely subjective, that's why more research, effort and time were put into the investigation of more accurate ways, and many ways were proven effective and easier for both parts.

There are many forms of evaluating body movements and balance, including observational assessments performed by experts, self-reporting of fall history, measurements collected from sensors and devices, and machine learning applications. Such sensor-based methods include laboratory force plates, accelerometers worn on the body, and, more recently, 3D motion capture devices and RGB-D sensors.

An RGB-D sensor-based instrument for sitting balance assessment

Sitting balance is an important aspect of overall motor control, particularly for individuals who are not able to stand. Typical clinical assessment methods for sitting balance rely on human observation, making them subjective, imprecise, and sometimes time-consuming.

Sitting balance is assessed almost entirely by observational methods with potentially imprecise and/or subjective mechanisms, particularly in the fields of physical and occupational therapy.

Sensor-based methods of balance assessment have multiple advantages over methods that rely on human observation, including that they are based on objective data, they avoid the problem of bias associated with inter-operator variability, and participants may act more naturally than they would while under human observation. Another advantage offered by sensor-based methods is their ability to capture data from multiple parts of the body at once. A human observer is only able to direct attention to one area of the subject’s body at a time, meaning the subject will need to perform multiple tasks which isolate different areas of the body in order to receive a comprehensive assessment. 3D motion capture devices are more precise, objective, and capable of assessing multiple parts of the subject’s body simultaneously, which can significantly reduce data collection times.

Red-Green-Blue-Depth (RGB-D) sensors have been widely used in many applications including rehabilitation, evaluation of patients with Parkinson’s disease, assessments of workplace ergonomics, and assessments of balance and postural control.

Microsoft Kinect™ to assess standing balance.

Many researchers have used inexpensive RGB-D sensors like the Microsoft Kinect™ to assess standing balance during clinical tests of postural control. The Kinect device incorporates a color video camera and a depth camera to create a 3D map of the area in front of the sensor and uses a randomized decision forest algorithm in close to real time to determine the location of the subject’s body joints. The sensor can recognize 25 body joints representing the positions of the major joints of the human body and estimations of the positions of the major limbs.

The Kinect offers some advantages over other 3D camera body tracking systems in that it is both portable and affordable, and minimally intrusive, as it does not require the subject to wear markers on the body. In their review of Kinect-based applications to elderly care and stroke rehabilitation, authors Webster & Celik acknowledged the Kinect’s potential as a component of financially accessible and medically beneficial therapy and alert systems. However, they also identified the following limitations: difficulty in capturing fine movements, fixed location and limited range of capture, lack of biomechanical accuracy in the shoulder joint, and limitations in fall risk reduction methodologies. A number of studies have evaluated the efficacy of using the Kinect for postural assessment in comparison to more expensive 3D motion capture devices, and have concluded that although slightly less accurate, the data collected with the Kinect was reliable enough to use for the assessment of body movements and postural control during common clinical tests .

The Kinect was more spatially accurate for large body movements than small body movements and suggested that it could be valuable for tracking relative changes in body movements over time.

The Kinect was found to be slightly less accurate in identifying sitting body movements than standing body movements.

Wearable Inertial Sensors.

A wearable inertial sensing unit typically includes accelerometers, gyroscopes, and magnetometers. A triaxial accelerometer measures the proper linear acceleration of movements in a sensor-fixed three-dimensional (3D) frame; measured data include both motion and gravity components.

From the beginning of the new millennium, technology advances in the field of motion measurement techniques allowed to measure kinematics of body segments without the need of camera-based systems using wearable inertial sensors. Some of the potential benefits of using wearable inertial devices to assess movements in clinical settings include the low cost, small dimensions and light weight of these devices, and the absence of any limitation of the testing environment to a laboratory.

The most common and promising areas of application of IMUs are gait analysis, instrumented clinical tests; daily-life activities, and tremor. Gait analysis performed by using IMUs may allow for suitably assessing upright gait stability.

One of the most important advantages of wearable IMU is the possibility of collecting data without laboratory restrictions: it allows for a continuous and objective assessment of activities of daily living. IMUs also allow the possibility of a quantitative assessment of tremor in terms of amplitude and frequency. The interest for wearable inertial systems will probably even increase in the next years, becoming a common tool for clinical motor assessment. In the next future, these devices will also be combined with other machines, for example embedded in video-game based therapy and in neuro-robots for rehabilitation.

Mobile phone applications

There is a need for portable, valid, and reliable methods to facilitate the easy collection of real-world data, as mobile phones.

There are many attempts for several mobile phone applications to assess balance, including MyAnkle, Sway, sensor kinetics pro and many others.

The number of smartphone apps for self-managed or professional health assessment is rapidly developing. Furthermore, the use of mobile devices for mHealth continues growing in all groups of population. Thus, due to the situation described, apps targeted to assess the body balance need to be validated in order to offer an adequate service. The assessment accuracy of these kind of apps will support an adequate training program, through the same app or leads by a therapist, so the app reports are useful. However, the apps development in relation to health assessment or promotion needs to be regulated. There are several commercial software developers that offer mHealth solutions without evidence in their results. As it is reflected in the scientific literature, the risks to patient safety and professional reputation are real, and some considerations should be taken into account.

MyAnkle application

"MyAnkle” is a smartphone application that was developed to assess standing balance in healthy volunteers. This application was validated against subjective experts’ rating rather than using objective methods.

“MyAnkle” smartphone application is an alternative to the BBS in assessing overall balance among patients and healthy volunteers when the eyes are closed, regardless of limb dominance. However, there is no evidence to support application’s validity in assessing balance when the eyes are opened, regardless of limb side and participants’ grouping.

Reliability

Functional Reach Test

Functional Reach Test is a reliable and valid measure of balance that is also sensitive to clinically significant changes.

• The ordinal level tests (supported sitting and standing balance and static tandem standing tests) showed 100% agreement in all aspects of reliability.
• Intra-class correlations for the other tests ranged from 0.93 to 0.99. All the tests showed significant correlations with the appropriate comparator tests (r=0.32-0.74 p≤0.05)
• Test-retest reliability r = 0.89
• Inter-rater agreement on reach measurement = 0.98.

Berg balance scale:

• A total of 33 articles were included. The BBS was found to have excellent reliability and validity. The scores were predictive of factors contributing to patient function and performance. Fall risk was unable to be strongly predicted from scores.
• Studies of various elderly populations (N = 31–101, 60–90 + years of age) have shown high intra-rater and inter-rater reliability (ICC =.98,14,15 ratio of variability among subjects to total = .96–1.0,16 rs =.8817). Test-retest reliability in 22 people with hemiparesis is also high (ICC [2,1]=.98).

Fullerton Test:

• Excellent test-retest reliability (ICC=0.98).
• Older Adults: Excellent test re-test reliability (r = 0.96) for total score.
• Older adults: Excellent internal consistency (H coefficients >0.75) for all 10 items.
• Excellent internal consistency (Cronbach’s alpha=0.805).

The BESTest

The BESTest showed excellent inter- reliability of the total score with inter-class correlation (ICC) of 0.91 and subsection ICC ranged from 0.79 to 0.95:

• Bio-mechanical constraints: 0.80
• Stability limits/verticality: 0.79
• Anticipatory Postural Adjustments: 0.92
• Postural Reactions: 0.92
• Sensory Orientation: 0.96
• Stability of Gait: 0.88

Four stage balance test:

Interclass (Pearson) correlations, with time between test and re-test of 3-4 months, 187 subjects from the community) is reported as moderate (0.66).

Functional Gait Assessment Test:

Eight studies have shown that The FGA has a high inter-rater reliability across the patient populations studied.

• Intrarater reliability of the total FGA: ICC = 0.83
• Interrater reliability of the total FGA: ICC = 0.84
• ⁠Internal Consistency: Cronbach alpha value 0.79 across both trials
• The FGA has been found to maintain reliability when translated into different languages and from standard to metric scale.

Biodex Balance System (BBS):

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.

Microsoft Kinect™:

A number of studies have evaluated the efficacy of using the Kinect for postural assessment in comparison to 3D motion analysis system have concluded that although slightly less accurate, the data collected with the Kinect was reliable enough to use for the assessment of body movements and postural control during common clinical tests.

In a study by Clark et al. (2015) comparing the inter-trial reliability and concurrent validity of the Microsoft Kinect™ and 3D motion analysis systems; The Microsoft Kinect™ and 3D motion analysis systems had comparable inter-trial reliability (ICC difference = 0.06 ± 0.05; range, 0.00–0.16) and excellent concurrent validity, with Pearson's r-values >0.90 for the majority of measurements (r = 0.96 ± 0.04; range, 0.84–0.99) .

Microsoft Kinect™ system provides comparable data to a video-based 3D motion analysis system when assessing step length and less accurate but still clinically acceptable for step times during balance recovery when balance is lost and fall is initiated.

In assessing standing balance Microsoft Kinect™ may reliably and validly evaluate standing balance when its measured COM parameters are calibrated by linear equations.

Slight body movements may not be detected accurately by the Kinect, which would result in an unchanged COM.

MyAnkle software application

The application showed a significant poor to good inter-session correlations for all the measured variables in the two groups (ICC:0.34-0.81, p < 0.05), except for healthy volunteers' tested during dominant limb standing while eyes were opened in the D6 level

Validity

Functional reach test:

functional reach test has been proven to be a valid method for balance assessment, but clinicians should consider other factors that can affect the results, such as decreased trunk mobility, decreased calf muscle flexibility, trunk rotation, and center of pressure displacement. So, it is recommended that clinicians use multiple assessment tools for balance assessment, as no one test can measure all factors affecting balance.

Berg Balance Scale (BBS) and Balance Evaluation Systems Test (BESTest):

The validity of (BBS, BESTest, Mini-BESTest, and brief BESTest) was studied in several studies and it was found that all four tests have almost the same validity in balance with slightly increased accuracy in mini-BESTest when compared only with BBS and suggestions for usage of brief BESTest due to its simplicity and quickness in usage.

Fullerton Advanced Balance Scale (FAB):

Schlenstedt et al., tested the validity of FAB scale in postural control assessment in Parkinson's disease and Özbaş et al., also tested the validity of the same test in patients with multiple sclerosis. Both studies revealed that FAB scale is a valid method, does not need an experienced physiotherapist, and suitable for online use.

The Functional Gait Assessment (FGA):

The convergent validity of FGA was compared with 10 minutes walk test (10MWT), Walking Index for Spinal Cord Injury II (WISCI-II), and Spinal Cord Injury Functional Ambulation Profile (SCI-FAP). This comparison resulted in the FGA is an excellent valid method for assessing balance in spinal cord injury population as the other tests have limitation in clinical application.

Biodex Balance System (BBS):

Dawson et al., examined the validity of commonly used assessment tools to measure balance (i.e., four‐square step test, timed‐up‐and‐go test, and Biodex balance system) and found that all these tools have poor construct validity, and each of them is focused on a particular aspect of balance factors.

Microsoft Kinect™:

Several studies assessed the validity of using Microsoft Kinect™ for standing balance assessment using positional variability of center of mass (COM) and revealed that it is a valid method for this assessment.

MyAnkle software application:

Abdo et al., tested the validity of MyAnkle smartphone application using BBS as a gold standard and supported usage of MyAnkle for balance assessment while closing eyes but the validity of the application to evaluate balance with eyes open is unsupported by any evidence, irrespective of the participant's grouping or limb side. Also, the application failed to discriminate between patients and healthy people so clinicians should be cautious while using this application in follow-up.