A full spectrum of technologies that assess and measure gait and balance power up the latest strategies to return patients to their feet.

by Judith M. Burnfield, PT, PhD, and Amy Goldman, PT, DPT

online art_iCare

This integrated body weight support system is built to secure a person’s weight up to 500 pounds with 80% support. This design can enable most people to enjoy the cardiovascular benefits of exercise, regardless of mobility limitations.

 

 Gait and balance deficits limit the independence and quality of life of many individuals living with neurologic disorders. Physical movements once performed effortlessly and without conscious thought become laborious due to limitations in strength, sensation, coordination, and endurance. One of the central purposes of rehabilitation is to help patients achieve their highest level of function given their specific limitations. Using principles emerging from the neurosciences to guide treatment interventions, clinicians integrate their knowledge of each patient’s impairments with the training opportunities afforded across different technologies to promote recovery and independence. The focus of this article is to address the therapeutic application of a wide array of gait and balance technologies in physical rehabilitation.

Gait Assessment Technology
Observational gait analysis is one of the more commonly used techniques to characterize gait deficits in the clinical setting as it requires no equipment except, perhaps, a pen and paper to document the deviations.1 Instrumented approaches to gait assessment are not uncommon, but their usage varies widely across settings. Special mats and foot switches quantify stride characteristics and plantar pressures and require little training to operate. More complex systems integrate kinematic (motion), kinetic (force), and electromyographic (EMG, muscle activation) data recorded simultaneously to define not only joint-specific deviations, but also the possible causes. The following section briefly highlights different technological innovations for gait assessment.

Instrumented walkways provide a reliable, valid, and relatively affordable means for rapidly quantifying spatial and temporal gait parameters.2 Sensors embedded in the walkway record temporal (eg, speed) and spatial (eg, step length, stride length) characteristics as the patient walks the length of the mat. The data can be acquired rapidly as no sensors need to be applied to the patient. However, this type of technology cannot be used to assess gait characteristics on uneven terrains or stairs as the instrumented walkways do not accommodate these surfaces. An alternative approach is to place pressure-sensitive switches either on the patient’s feet or inside or outside of the shoes. The foot switches record foot-floor contact patterns (eg, heel contact, toe-off) and calculate variables such as stride length, velocity, cadence, cycle time, single and double limb support time, swing time, and stance time.3 These are relatively easy to apply and can be used to objectively document changes in gait characteristics across a variety of surfaces (eg, grass, stairs, ramps, level walkways).

Prolonged and repetitive exposure to elevated pressures on the plantar surface of the feet can lead to tissue injury in persons with diabetic neuropathies. Knowledge of how factors such as footwear, terrain, and physical activity impact plantar pressure patterns can guide patients in the selection of safer footwear and activities.4-6 Technology such as an in-shoe dynamic pressure measuring system can quantify the amplitude, anatomic location, and timing of high pressures. Colorful pictures can be used to guide patients’ understanding of the pressure patterns, particularly when sensory neuropathy prevents them from feeling the locations of elevated pressures.

For patients with complex walking disorders, gait labs are available that integrate a variety of sophisticated technology for documenting gait deficits.1 Motion capture systems quantify three dimensional motion of the lower limbs and trunk, creating a more complete understanding of gait deficits not just in the sagittal plane, but also in the frontal and transverse planes. The trajectories of markers, attached to the patient’s body over known anatomical locations, are tracked by special cameras as the patient walks. Computer software then integrates the data from multiple cameras and markers to generate the patient’s movement profile across each of the joints of interest. Force plates embedded within the walkway can be used to record the forces the patient generates while walking. This information helps infer the demands placed on muscles and potential sources of pathology. EMG sensors can be used to monitor muscle activation patterns and help determine the source of a gait deviation (eg, overactivity of a muscle, or failure to activate a key muscle at the correct time). The data collection and analysis associated with this type of comprehensive analysis requires a relatively high level of skill to ensure that data are acquired accurately and that the resulting interpretations are clinically meaningful.

Gait Rehabilitation Technology
Selecting the most effective means of helping a patient regain walking function is driven not only by the gait deficits that are identified, but also by the treatment options available in the therapeutic environment. Contemporary approaches to gait rehabilitation often extend beyond manual facilitation techniques to include some form of technology that helps physically support and/or move an individual as they relearn to walk. The scientific underpinnings for many of these innovations emerge, in part, from discoveries in the neurosciences that have helped shape therapists’ understanding of the optimal training parameters to promote recovery following an injury to the brain or spinal cord. For example, partial body weight support treadmill training (PBWSTT), robotic therapy, and motorized elliptical training each incorporates concepts of task specificity and mass practice (or repetition) to facilitate recovery of walking and induce cortical reorganization following neurologic injury.7,8 Physical assistance and guidance from either the clinician (PBWSTT) or device (robotic, motorized elliptical) encourages the lower limbs to move in a pattern that is kinematically similar to walking (task specificity). The external trunk support provided by the harness affords the patient an opportunity to load a portion of body weight onto weakened legs over and over again. This feat would not be accomplished easily if they have to rely solely on a clinician’s ability to safely support the full weight of a patient’s trunk, head, and arms early during the recovery process.

For more than two decades, PBWSTT has provided a means for increasing strength, endurance, and walking function, while minimizing the risk of overuse injuries to other parts of the patient’s body.9-15 Unfortunately, PBWSTT can be very labor-intensive16-19 and hence expensive for clinicians and facilities to implement, particularly when working with patients who are unable to independently lift and advance their legs. A leg weighs approximately 16% of body weight, which translates to ~32 pounds for a 200-pound patient. Repetitively lifting a patient’s leg through awkward postures even at relatively slow cadences is fatiguing for clinicians and has led to injury.16 Additionally, when profound weakness is present, as many as three clinicians may be needed to advance the legs and guide the pelvis and trunk. This staffing level is realistically not feasible for some facilities, particularly in an era emphasizing cost containment and productivity.16,20

Automated robotic gait systems notably reduce labor demands compared to PBWSTT21-24; however, the purchase price (some well over $300,000) inhibits use by many facilities. These systems often incorporate externally powered orthoses (braces) to guide each leg in a gait-like movement pattern while the patient walks on a treadmill with a portion of body weight supported. While the feasibility of using the devices has been established, the relative impact of robotic training on walking ability compared to other therapies is still being assessed.25 In addition, it has been suggested that the precisely controlled lower extremity joint trajectories imposed by some robotic devices may hinder recovery of the highly adaptable movements necessary for motor recovery of walking.26-29

Recently, a motor-assisted elliptical trainer was introduced to address the need for an affordable technology to help individuals with physical disabilities and chronic conditions improve their walking. Biomechanical testing identified an elliptical trainer that promoted joint motions and muscle demands that were similar to walking.30 Then, an auxiliary motor-drive system was integrated to help those with diminished strength/coordination to initiate and sustain pedal movement at training speeds up to 65 revolutions per minute.31-34 Stairs, ramps, support rails, pedal adaptations, a seat, and a body weight support system were added. Collectively, the modifications increased ease of access, safety, and usability of the elliptical by individuals with disabilities and chronic conditions31,35 while also reducing the labor demands of providing intensive locomotor training. The device has been used across a wide range of clinical settings including inpatient and outpatient physical rehabilitation and a medical fitness center.32,33,36

When weakness and control problems are isolated, functional electrical stimulation (FES) may provide an alternative approach to enable mass repetition of a desired movement pattern. One common deviation that emerges post-stroke is a drop foot (ie, excessive plantar flexion during swing).1 The deviation sometimes arises from difficulty voluntarily activating the pretibial muscles to lift the foot during swing. FES devices can be used to apply an electrical stimulus to the peroneal nerve to promote active dorsiflexion during the swing phase of each gait cycle, resulting in improved gait.37

Balance Assessment Technology
Impaired balance and postural control is another common problem affecting safety and mobility for patients with neurological disorders. Control of balance is a complex process involving maintaining postures, coordinating and facilitating movement, and recovering equilibrium. Clinical balance assessments assist with predicting fall risk and/or determining the underlying causes
for balance disorders in patients with neurological disorders. While commonly used clinical balance assessment tools do a good job at assessing fall risk and the need for rehabilitation, they do not necessarily identify the underlying cause of the balance deficit. This is unfortunate as this information assists clinicians to develop effective, targeted interventions.

Similar to the assessment of gait, there are a wide range of approaches for balance assessments including low tech approaches (eg, functional assessments, systems assessments, and quantitative assessments)38 and instrumented approaches. Functional balance assessments (eg, Berg Balance Scale, Tinetti Balance and Gait Test, Timed Up and Go, Activities of Balance Confidence, and Functional Reach) are primarily used to screen for balance problems and fall risk and assess changes as a result of intervention. A systems approach to assessing balance is helpful when the goal is to determine the underlying causes of a balance problem in order to direct treatments at the affected underlying systems. The recently developed Balance Evaluation Systems Test (BESTest)39 focuses on determining which balance systems are affected. BESTest consists of 36 items, grouped into six systems representing independent neural mechanisms affecting postural control and equilibrium responses involved in balance. It combines items from other commonly used clinical balance tests including the Berg Balance Scale, the Functional Reach Test,40 the Clinical Test of Sensory Integration for Balance (CTSIB),41 and the Get Up and Go test.42

During the past decade, quantitative assessments of balance have been made using computerized static and dynamic posturography. Center of pressure sway during unilateral and bilateral stance (eyes open and closed) provides insights into standing stability. Dynamic posturography, involving the use of external balance perturbations or alterations in the surface (eg, hard versus foam) and/or visual conditions, can be used to assess different neural systems involved in gait.43 External perturbations are made with a movable, computerized support surface (platform) used to induce disequilibrium through sudden horizontal plane or rotational movements. For example, a reactive balance system uses dynamic motion analysis to measure the individual’s center of mass movement and a computerized programmable, multidirectional, multispeed platform to provide both reactive and anticipatory training for individuals with balance and motor control impairments.44

Balance Rehabilitation Technology
In addition to impairments in postural control and balance, weight bearing asymmetry is common in patients with neurological conditions and is associated with increased postural instability and risk for falls. In a recent study by Lee et al,45 the feasibility and effects of balance training using a newly developed Balance Control Trainer (BCT) was investigated in chronic stroke patients. Unlike other functional walking and balance training methods like body weight unloading, robotics, and balance training systems, the BCT was designed to allow postural control training in both the horizontal and vertical planes in conjunction with video gaming and emphasis on lower extremity weight shifting and loading onto the affected side. Significant improvements on all balance and mobility measures were documented following the intervention including improvements on the Functional Ambulation Categories, 10-meter walk test, Timed Up and Go, and Berg Balance Scale.

Inexpensive commercially available balance boards also have been used for balance assessment and training; however, the validity and reliability of the scores requires further exploration. Foo et al46 demonstrated it was feasible to use two balance boards (peripheral devices designed to attach to a home video game console) and customized software to evaluate weight-bearing asymmetry during static and dynamic balance tasks in individuals with neurological disorders. The device also could be used to provide feedback to patients on weight-bearing asymmetry. Wikstrom,47 however, identified generally poor concurrent validity when comparing scores recorded during balance training activities conducted using a fitness program on a home video game console to standard measures of static (center of pressure excursion during single limb stance on a force plate) and dynamic balance (Star Excursion Balance Test) in individuals without known neurologic, vestibular, or balance deficits. Reliability between sessions also was poor.

As indicated earlier when discussing gait rehabilitation, principles of motor learning and recent advances in neuroscience emphasize the importance of incorporating treatments that provide feedback, are task specific, promote practice with multiple repetitions, and are motivating to patients. Recent studies examining the use of virtual reality and video-gaming to assist with improving cognition and motor skills in patients with acquired brain injuries have presented mixed results. Fritz et al48 evaluated the impact of either playing video games (in a standing position) 50-60 minutes per day, 4 days a week for 5 weeks, or engaging in standard balance activities in a cohort of 30 individuals with chronic hemiparesis following stroke.

No significant differences were noted between or within groups at the end of the study period or at 3 months. Another recent study by Cho and colleagues49 demonstrated a significant improvement in dynamic balance (Berg Balance Scale, Timed Up and Go test) following 6 weeks of virtual reality balance training (VRBT) with a balance board game system in a study of patients with chronic stroke. Pompeu et al50 concluded that the home video game console and balance board could be beneficial when used in conjunction with balance and mobility training and assist with motivating patients with Parkinson’s disease to adhere to a long-term exercise program and reduce the negative effects of immobility.

In summary, clinicians have a wide range of technological innovations to select from when addressing gait and balance disorders in individuals with neurologic disorders. Opportunities for task-specific and intensive training are abundant; however, affordability and work flow demands are factors that may influence device selection. RM

Judith M. Burnfield, PT, PhD, is Director of the Institute for Rehabilitation Science and Engineering, Director of the Movement and Neurosciences Center, and the Clifton Chair in Physical Therapy and Movement Sciences at Madonna Rehabilitation Hospital. She also serves as Director of the Nebraska Athletic Performance Laboratory at the University of Nebraska—Lincoln. Dr Burnfield earned her PhD in biokinesiology from the University of Southern California and completed her postdoctoral training at the Pathokinesiology Laboratory at Rancho Los Amigos National Rehabilitation Center. She holds adjunct faculty appointments at multiple universities where her teaching emphasis includes normal and pathologic gait and biomechanics.

Amy Goldman, PT, DPT, is the Stroke Program Manager and a physical therapist at Madonna Rehabilitation Hospital. She is trained in the Neuro-Developmental Treatment (NDT) Approach for treating adults with hemiplegia. Goldman received her Master of Physical Therapy degree from the University of Nebraska Medical Center in 2000, and transitional Doctor of Physical Therapy degree from the University of Nebraska Medical Center in 2005. She has served as co-investigator for stroke clinical research trials in the Institute for Rehabilitation Science and Engineering at Madonna Rehabilitation Hospital. For more information contact RehabEditor@allied360.com.

 

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