Accelerometers in Rehabilitation

Original Editor - Ananya Bunglae Sudindar

Top Contributors - Ananya Bunglae Sudindar  

Introduction

Wearable devices, also known as wearables, are instruments that have garnered significant attention for enabling non-invasive, real-time monitoring of physical and physiological parameters in smart care and digital medicine. These devices are worn on the body and provide physiological measures directly to smart devices, offering valuable insights into health metrics.

Accelerometers are wearable devices designed to measure the acceleration of the body segment to which they are attached. These devices play a crucial role in studying human movement across various applications, including activity detection, assessing postural balance, evaluating sports physical function, and investigating falls. They operate based on Newton’s law of motion wherein they measure linear acceleration which represents the change in an object’s speed over time.

Application in Rehabilitation

Gait Analysis

Gait analysis using accelerometers often involves placing sensors at various body segments in order to capture the spatiotemporal parameters of an individual's gait pattern. The collected data are then analyzed for clinical applications, disease-specific insights, and rehabilitation monitoring, providing valuable information for healthcare professionals and researchers.

Sensor Placement

• Accelerometers are strategically placed on different body parts, such as ears, thighs, pelvis, feet, and others, depending on the specific conditions and objectives of the evaluation.
• Multiple sensors may be used simultaneously to obtain comprehensive data about the entire body's movement.
• The accelerometers record the accelerations and decelerations of body segments during the gait cycle.
• Accelerometers such as triaxial accelerometers capture movement in three dimensions, providing detailed information about motion in the frontal, sagittal, and transverse planes
• The collected data are utilized to assess specific aspects of gait, such as symmetry, balance, stride length, step frequency, and temporal parameters.

Clinical Use

• Gait analysis using accelerometers is applied across various clinical conditions, including orthopaedic and neurological conditions.
• Gait analysis is tailored to the characteristics of specific diseases or conditions, such as Parkinson's disease, Huntington's disease, Cerebral Palsy, Orthopaedic injuries, and more.
• For example, in Parkinson's disease, gait analysis may focus on detecting freezing of gait (FoG) and other abnormalities.
• Accelerometers can be used to monitor the rehabilitation progress of patients by tracking the changes in gait patterns over time. It can also be used to assess the effectiveness of rehabilitation programmes.

Monitoring Physical Activity Levels

Physical activity (PA) plays a crucial role in maintaining the health and well-being of individuals. In recent years, accelerometers have emerged as essential tools for assessing PA. These devices are integral to clinical practice and contribute significantly to evaluating PA levels and monitoring treatment progress in individuals with chronic diseases.

Sensor Placement

The choice of accelerometer placement is subjective and depends on various factors such as the targeted activities and the consideration of participant burden. The most common sensor placements to measure physical activity include:

• Wrist: It is the most popular choice of location for placing accelerometers but has accuracy limitations across various activities.
• Hip: Hip placement is considered to be the most reliable location due to its high accuracy while evaluating different kinds of activities.
• Ankle: Placing the sensor at the ankle is often beneficial for faster activities but should be used with caution while evaluating slower activities.
• Thigh: Sensors placed on the thigh show good performance across various activities.

Clinical Use

• Accelerometers play an important role in monitoring the physical activity of high-risk populations with the aim of identifying sedentary behaviours that may result in various disease states, including but not limited to stroke and cancer.
• Accelerometers are used to oversee physical activity in the elderly demographic, contributing to the development and evaluation of interventions aimed at reducing prolonged sitting periods.
• Furthermore, this technology can be harnessed to monitor cardiometabolic health in individuals by means of tracking their physical activity.

Other Applications

• Postural evaluation
• Balance training
• Fall prevention

Advantages of Accelerometers

• Accelerometer-derived measures can be incorporated during patient assessments in situations where patients frequently struggle to complete standard questionnaire-based tools, administered on an intermittent basis.
• Accelerometers can be used for remote monitoring of patients which plays a significant role in improved patient outcomes and participation in research studies. It can be used to perform certain assessments such as the Timed Up and Go (TUG) which may allow clinicians to make decisions about treatment without necessarily seeing the patient in a clinic.
• Accelerometers can be used in telehealth to monitor patients physical activity level.

Challenges of Using Accelerometers in Rehabilitation

• Drift or change: Over time, the internal mechanical or electrical components of accelerometers may experience changes, resulting in bias or offset in the readings. This drift can affect the reliability of the measurements.
• Sensitivity of accelerometers: The sensitivity of accelerometers can lead to the amplification of microscopic mechanical motions, introducing noise into the readings. This noise can interfere with the precision of the accelerometer's measurements.
• Effects of gravity: The gravitational force of the earth is projected along the sensitivity axes, creating a confounding effect on movements along these axes. Understanding and accounting for this gravitational influence often poses a challenge in clinical practice.