Miller, Carol A. PT, PhD, GCS; Hayes, Dawn M. PT, PhD, GCS; Dye, Kelli SPT; Johnson, Courtney SPT; Meyers, Jennifer SPT
There are approximately 1.7 million persons living with limb loss in the United States,1 a number projected to increase to 3.6 million by the year 2050.2 The absolute number of older adults living with lower limb amputation is also expected to increase well into the 21st century, as a result of the aging of the US population and the increased incidence of diabetes and dysvascular disease.3–5 The most common causes of lower limb loss are due to dysvascular disease, trauma, cancer, and congenital limb deformity. Individuals who have an amputation secondary to vascular disease have a shorter life expectancy; however, for the individual who lost his/her limb secondary to a limb tumor or from trauma, the amputation has no bearing on life expectancy.1 Thus, the long-term impact of lower limb amputation specific to mobility across the lifespan is not well known.
Research illustrates that lower limb amputation impacts function and productivity and reduces quality of life.6,7 One study further revealed that fewer than 25% of transfemoral amputees older than 50 years achieved community mobility and around 50% achieved household mobility,8 whereas other studies note that persons with transfemoral amputation had an even greater level of mobility disability and increased energy expenditure than those with transtibial amputation.9,10 Rehabilitation potential in individuals with lower limb amputation depends on several factors including coexisting medical conditions, psychological adjustment, and level of amputation.11 Comorbidities, especially diabetes and peripheral vascular disease, and poor psychological adjustment negatively affect coping12,13 and physical functioning14 after lower limb amputation. Higher levels of amputation, such as transfemoral, creates greater physiologic deficits, which are noted as decreased balance, aerobic capacity, and altered gait.15
The increased risk for falls is apparent in people with amputation and is often attributed to altered balance and diminished gait patterns.16,17 Many people with lower limb amputation use assistive devices to allow independent ambulation and the literature shows that one of the strongest predictors of low balance confidence in persons with amputation is the use of an assistive device.18 Fear of falling may lead some individuals with amputation to assume a sedentary lifestyle and decrease active participation in the community. Miller and Deathe18 suggest that balance confidence is a better predictor of engagement in activity than skill or ability. Decreased balance confidence may lead to decreased participation and in turn cause deconditioning, increased symptoms of depression, further comorbidity, decreased independence, and self-restricted activity.16 Roberts et al11 suggest that addressing psychological concerns like balance confidence will improve many of these deficits. Although improving balance confidence levels does not guarantee success, this modifiable factor can and should be incorporated into rehabilitation.18
Individuals with transfemoral amputation lack essential proprioceptive feedback from both the ankle and knee joints and musculature to correct for balance perturbations in the amputated limb. Impaired balance responses, proprioception, and muscle weakness can further contribute to gait deviations during stance such as abduction and lateral trunk lean, which are particularly associated with use of a transfemoral prosthesis.17,19 When compared to gait of healthy participants, research has also found that individuals with transfemoral amputation have more asymmetrical gait patterns.19 Furthermore, there is strong evidence that persons with amputation have decreased velocity and abnormal patterns when compared to their able-bodied counterparts and that such gait patterns persist even 10 years after amputation.15
Gait alterations are also attributed to the changes caused by the prosthetic limb. Bae and colleagues20 report that persons with amputation feel so unstable during swing phase of the sound limb (during prosthetic stance) that excess muscle power was needed at the hip of the residual limb to overcome an increased flexion moment and maintain balance. Furthermore, decreased muscle activity of hamstrings and quadriceps and increased activity of the gastrocnemius and tibialis anterior of the sound limb was found when compared with healthy participants during level walking.20
Several studies have investigated the relationship between gait efficiency and energy expenditure among persons with lower limb amputation; and results have consistently shown that the higher the level of amputation, the higher energy expenditure required to ambulate compared to persons with intact lower extremities.21–24 Individuals with transfemoral amputation have decreased physical capacity because of many factors, including the loss of skeletal muscle mass that in turn diminishes systemic oxygen extraction and stroke volume, key determinants of aerobic capacity.25 The energy costs of using a prosthesis are substantially increased over normal bipedal locomotion, with estimates ranging from 90% to 120% VO2 max with unilateral transfemoral amputation.10,26,27
Economy of movement is another measure of metabolic efficiency measured by evaluation of steady rate of VO2 during exercise at a known power output or speed. Schenkman and colleagues28 define economy of movement as the rate of energy expenditure during any motor task, and specifically “walking economy” when referring to the energy expenditure rate during walking. Schenkman and colleagues28 revealed improvement in economy of movement in patients with Parkinson disease following endurance training with a treadmill. It is not known whether similar changes can be seen in persons with amputation; however, it is reasonable to posit that improvement in motor control and metabolic efficiency can improve economy of movement in those using a prosthesis as well.
A variety of physical therapy interventions have been used in traditional rehabilitation for people with lower limb amputation; these include limb strengthening, balance training, and weight shifting progressing to gait training.29 Many older adults who are several years status post transfemoral amputation are uncertain about how to begin an exercise program in later life; possible contributors to this uncertainty include limited physical abilities, fear of falling, and decreased motivation.30 To date, there is little, if any, research that investigates alternate exercise training for older individuals who acquired amputation many years ago or for those who desire to improve functional potential following prosthetic changes.
Virtual reality has been used as an intervention in rehabilitation because it provides users with interactive simulations, visual and auditory feedback, and motivates the user to participate in treatment.31 The Nintendo Wii Fit balance program (Nintendo of America, Inc, Redmond, Washington) provides an innovative adaptive option to traditional balance training modes of exercise, which is appealing to individuals of all ages. Research by Deutsch et al32 shows that training with Nintendo Wii Sports games led to improvements in postural control and stance stability. Recently, Nintendo introduced a new interactive platform game, Wii Fit, which was designed to provide multiple modes of exercise.
For the aerobic intervention, we introduced body weight support (BWS) gait training in an attempt to reduce the fear of falling while allowing for increased speed of walking. Body weight support has been traditionally used in neuromuscular rehabilitation; an approach used to stimulate recovery of walking after spinal cord injury.33 Body weight support can be adjusted as recovery progresses so that the individual is able to add more load to their lower extremities. Using a treadmill or walking on level surfaces as the contextual environment to stimulate practice stepping also provides opportunity for a person with amputation to correct gait deviations without the fear of losing their balance and falling.
To our knowledge, there has been no evaluation of the Nintendo Wii Fit balance board combined with BWS on balance and gait performance for individuals with lower extremity amputation. The purpose of this case report was to describe the effects of using the Nintendo Wii Fit balance gaming combined with BWS gait training to improve dynamic balance, aerobic capacity, and economy of movement during functional gait for individuals with transfemoral amputation. A secondary purpose was to describe concurrent effects on fear of falling and the potential for decreased use of assistive devices during functional gait.
Participant A was a 62-year-old man, who experienced a left traumatic above-knee amputation as the result of a motor vehicle accident approximately 32 months prior to this study. He reported his overall health as “good.” His past medical history included shoulder fracture (>15 years) of which he had functional range of motion and strength and no reported limitations in participation in sports such as Kayaking. He had no history of medical or cardiovascular disease and thus presented with no restrictions for participation in physical activities. He had mild to moderate residual limb pain secondary to extensive scarring in his hamstrings; he “tolerated the pain” and did not take medications for residual limb or phantom pain. The participant was well-fitted with an ischial containment transfemoral socket with semisuction lanyard suspension, Otto Bock C-leg microprocessor knee unit (Otto Bock Healthcare LP, Minneapolis, Minnesota), and a dynamic response Action foot. Participant A reported that he wore his prosthesis 12 to 14 hours per day and used his prosthesis almost all the time (more than 85%) to go about activities of daily living (ADLs). He reported using a single-point cane to ambulate in the community, and he also used a wheelchair only if needing to travel long distances or he was in a hurry.
Participant A's primary concerns included diminished confidence in balance, fear of falling, marked fatigue with community ambulation, and an increasingly sedentary lifestyle since amputation. His primary goal and desire was to walk without his crutch or cane to participate in his social roles. Yet, because of his fear of falling, the participant expressed reluctance to participate in community-based exercise outside the physical therapy setting.
Participant B was a 58-year-old man status post a right transfemoral amputation 9 years previously due to failed knee surgery with resultant tissue necrosis. He reported his overall health as “good.” His past medical history included chronic low back pain (>12 years) of which he had completed outpatient physical therapy with good results; however, his pain occasionally limited community ambulation and his lifting capacity. He had no history of medical or cardiovascular disease; he was being followed by a physician for anxiety disorder. He had mild to moderate residual limb pain secondary to an area of excess scar tissue on the posterolateral distal end of his limb; his physician prescribed gabapentin (Neurontin) for both the residual limb and phantom pain. Following amputation, the participant completed formal physical therapy (7 years before study) and was currently interested in improving his aerobic ability, balance, and community ambulation with exercise. Participant B had a well-fitted semisuction flexible socket, with an Otto Bock C-leg microprocessor knee unit and dynamic response foot; he did not use an assistive device at home or in the community when wearing his prosthesis for ambulation.
Both participants were referred from a local prosthetist and met criteria for this case report, which included (1) being 55 years of age or older, (2) lower limb amputation, either traumatic or nontraumatic (surgical), (3) properly fitted and aligned prosthesis, and (4) independent ambulation, with or without an assistive device. Neither participant had any exclusionary findings, such as uncontrolled medical conditions or complications that would prohibit gait training and balance activities (ie, chronic phantom pain or residual limb pain, unstable cardiac disease, etc) or were currently receiving physical therapy for prosthetic management. Both participants in this case study reported that they were not able to participate in community activities to their full potential and therefore would potentially benefit from BWS and Nintendo Wii Fit training. Each of the trials for this case study was approved by the institutional review board at North Georgia College & State University.
ASSESSMENT TOOLS AND PROCEDURES
The Biodex Balance System was used to measure dynamic balance and limits of stability (LOS). The Biodex allows clinicians to assess neuromuscular control through quantifying the ability to maintain dynamic bilateral and unilateral postural stability on a static or unstable surface.34 The platform can be adjusted in terms of stability ranging from level 8 (most stable) to level 2 (least stable). The platform level should be adjusted so that the individual can safely complete the test without upper extremity use, if possible. Postural stability includes an overall stability index (OSI), an anterior/posterior index, and a medial/lateral stability. Overall stability index represents the patient's ability to control their balance in all directions and is believed to be the best indicator of a patient's ability to balance on the platform.35 High values for each index represent the individual had difficulty and further assessment may be needed. Limits of stability is a timed test that measures the ability to maintain the base of support while leaning from a vertical position to the outermost range of an area. The ability to voluntarily move the center of gravity into positions within the LOS is fundamental to mobility tasks such as reaching for objects, balancing, and walking. Limits of stability is expressed as overall direction control (100% equaling perfection) and total time to complete the test (the quicker the better). Patients with reduced stability in the anterior-posterior direction tend to take smaller steps during gait, whereas laterally reduced limits can lead to broad-based gait.36 Although Biodex studies with individuals with amputation have not been conducted for dynamic balance or LOS, balance measures with the Biodex provide reliable measures of postural stability in the normal population.36
Participants' balance confidence was assessed with a self-administered subjective questionnaire called the Activities-specific Balance Confidence (ABC) scale. The ABC scale consists of 16 questions that reference balance confidence and fear of falling while performing various ambulatory activities.37 The items include such questions as “how confident are you when reaching into a cabinet?” and “how confident are you walking outdoors?” The overall score is the average sum of the individual items. According to Myers and colleagues, an averaged sum of 50% or less describes a low level of physical function, and averaged sum of 50% to 80% describes a moderate level of physical function, and an average score of 80% or higher describes a high level of physical function.38 ABC scale was found to have high test-retest reliability within a 4-week period (r = .91) in persons with unilateral transtibial and transfemoral amputation.39
GAITRite (GAITRite Gold, CIR Systems, PA), an electronic walkway approximately 8-meters long, was used to assess the spatial-temporal parameters of gait, including velocity, cadence, step length, step time, single limb support and to determine a functional ambulation profile (FAP) score. Using the GAITRite, vanUden and Besser40 examined test-retest reliability in spatial-temporal parameters of gait of 21 healthy participants free from lower extremity orthopedic pathology. The authors reported that at preferred walking speeds all gait measurements yielded ICC values above 0.92 except for base of support (ICC = 0.80). At fast walking speeds, all gait measurements had ICC values above 0.89 except base of support (ICC = 0.79).40 In a population of healthy adults, the FAP has an interrater reliability of ≲[GREEK UPSILON WITH ACUTE AND HOOK SYMBOL]τ∀0.99 and is considered a measure of functional ambulation in a variety of conditions.41
The GAITRite Functional Ambulation Profile (FAP) scoring system, which was developed by Nelson,42 integrates selected time and distance parameters to provide a single, numerical representation of gait in adults. The score provides a quantitative means of assessing gait without the subjective qualification that most rating scales require. The FAP score is composed of the linear relationship of step length/leg length ratio to step time when the velocity is “normalized” to leg length in healthy adults. The FAP score ranges from 95 to 100 points in the healthy adult population.42
Aerobic capacity has been measured in a number of ways including maximal VO2 tests, submaximal VO2 tests, economy of movement, and oxygen uptake efficiency slope (OUES).21,23,43,44 Oxygen uptake efficiency slope is applicable to all patient populations, as it is a submaximal exercise test that can be more easily tolerated than a maximal test, and the testing protocol does not depend upon intensity.45 It is an accurate prediction of energy cost that is highly correlated (r = 0.94) with VO2 max (mL/min).44 Economy of movement is an evaluation of the steady rate of VO2 during exercise at a set power output or speed.46 In effect, economy of movement examines the relationship between energy input and output while participants are walking.46 For the purpose of this study, OUES and economy of movement were assessed while participants underwent a progressive treadmill walking test without BWS at 4 speeds in 0.5-mph (0.22 m/s) increments. Participants were allowed to use upper extremity support on the handrails of the treadmill as needed. The maximum speed for testing was determined by the participants who, before baseline testing, ambulated on the treadmill at the maximum speed they perceived to be controlled and safe. Heart rate, blood pressure, and rating of perceived exertion were monitored during pre- and posttesting.
During treadmill testing, the participants walked for 3 minutes at each of the 4 speeds starting with the slowest speed first. Oxygen consumption (VO2) was measured using the VO2000 (MEDGRAPHICS, Medical Graphics Corporation, St Paul, Minnesota) metabolic system throughout the test. The treadmill used was a standard treadmill over which the clinician was able to control and adjust all parameters including speed, incline, and duration. From the data gathered by the VO2000, OUES was calculated to provide a measure of aerobic capacity. Oxygen uptake efficiency slope was determined by the relationship between VO2 response and total ventilation (VE in L/min), which examined how effectively oxygen was extracted per volume of air ventilated and used in the body. Studies have shown that the correlation between OUES and VO2 max is not greatly affected by the intensity of the exercise thus making it a reliable, objective measurement.44 Economy of movement was determined by calculating the average VO2 consumed each speed increment and compared with age-predicted values.
Each of the participants completed 2 measurement sessions: at baseline and following completion of 6 weeks of intervention. The baseline testing involved 1 visit in which the participant read and signed informed consent, completed the general demographic survey questions and activities-specific confidence balance survey. The participant then underwent a submaximal treadmill test while expiratory gasses were simultaneously recorded via the VO2000 metabolic cart. Heart rate and blood pressure were obtained and recorded before treadmill testing, during each stage of treadmill testing, and after treadmill testing.
Participants were given a 10-minute rest break followed by testing on the Biodex Balance System. Practice trials were performed before testing to determine the platform stability level. The platform level was decided when the participant could complete testing without the use of upper extremity support—a fall. Angle of toe in or toe out and stance width were recorded for consistent individual measurements throughout the study. The dynamic balance test involved 3 trials of 20 seconds; mean and standard deviation scores for the 3 trials were recorded. The LOS balance assessment was completed next; time to complete the test and percentage scores for multiple directions of control were recorded.
Spatial-temporal parameter measurements using the GAITRite took place at the start of the first treatment session to eliminate the effects of fatigue on test results at baseline. The participant was asked to walk without an assistive device over the 8-m walkway at a comfortable speed. Footsteps that did not fall entirely on the GAITRite mat were deleted during data review, according to the analysis program. Using the GAITRite software program, mean values for each of the gait parameters were calculated using 4 collapsed walking trials at baseline and for the outcome assessment. Participants wore the same pair of shoes for baseline and outcome assessments to ensure consistency with testing conditions.
Each intervention session lasted approximately 40 minutes, and consisted of 20 minutes of Nintendo Wii Fit balance gaming followed by 20 minutes of gait training using BWS—alternating treadmill and land walking. On the basis of clinical experience, it was felt that individuals with transfemoral amputation would be working at moderate to high intensity levels during gait training session as compared to able-bodied adults, therefore 20 minutes was deemed appropriate for the aerobic gait training program. For consistency of training both the Nintendo Wii Fit and gait training were kept at 20 minutes each. Blood pressure, heart rate, and rating of perceived exertion were monitored at beginning, following each bout, and after 5 minutes of recovery at end of session.
The Nintendo Wii Fit balance system includes a variety of training video games, including tilt table, skiing, tightrope walk, etc. The balance board was placed inside a set of adjusted parallel bars, so that the participant could use upper extremity support for safety as needed. The participant was encouraged at the outset of each session to use as little arm support as possible; no further cues were provided. Upon observation and trial, the Nintendo Wii Fit games appear to vary in complexity regarding the amount of lower extremity and trunk motion required to correctly perform each task. Participants were given verbal and tactile cues as needed for adjustments to playing the games. Currently there is no research to standardize Nintendo Wii balance games across any population; therefore, the balance games were selected on the basis of patient preference and consisted of 2 to 3 bouts of each game amounting to 20 total minutes of activity.
Body weight support for aerobic gait training was used in an attempt to encourage participants to ambulate beyond their comfort level as a form of overload stimulus to improve usual walking speed. The BWS served as a tool to reduce fear of falling during a progressively challenging gait training session in which assistive devices, if used, were removed. The BWS harness was used for security and not to unload the lower extremities, which is a modification of its traditional use. Thus, only the slack in the harness support lines was taken up during training. Both participants had ischial containment sockets, which dictated a second modification to the BWS harness placement to reduce pressure over the prosthetic socket and prevent undo changes in socket alignment during gait. Therefore, to secure the pelvis without hindering socket movement, the lower straps were loosened while the middle and upper straps were tightened more securely to maintain postural alignment.
On the basis of the results of the exercise capacity testing during the pretest session, BWS treadmill walking began with a 2- to 3-minute warm up followed by increments of increasing speed until 60% to 75% of the participants' maximum heart rate was achieved and a cool down period totaling 20 minutes of walking. The protocol typically included treadmill speed progressions beginning at 1.2 mph and ending at 2.5 mph prior to cool down. The participants were instructed to maintain the maximum speed for as long as they tolerated before initiating a cool down period. Level surface walking in the BWS consisted of walking at the fastest comfortable walking speed the participants could maintain until 60% to 75% of maximum heart rate was achieved followed by a cool down period. Tactile and verbal cues were provided during the training to encourage symmetry of gait patterns. The participants were informed that they should stop walking if shortness of breath or any discomfort while walking was experienced. Although neither participant stopped any intervention session for these reasons, Participant A often expressed greater fatigue and discomfort with the BWS land-walking.
Participant A attended all 12 intervention sessions over a 6-week period of time. Participant B attended 10 of 12 sessions over the 6-week period of time. The 2 missed sessions were due to scheduling conflicts with his family. He agreed to perform the intervention with the same parameters at home on the days he could not attend the study, as he recently purchased a Nintendo Wii Fit game console at home as well as a treadmill. The 2 sessions performed at the participant's home were unsupervised by the research team and he did not report doing any additional sessions while enrolled in the study. All outcome measure scores were calculated according to standards set by each given instrument.
Participant A improved his performance ability in all outcome tests except for OUES. Dynamic balance was tested at level 6 platform stability on the Biodex, with a 50% LOS test difficulty for both pre- and posttest measures. Marked improvements were noted in the OSI, anterior(posterior, and medial(lateral indexes. His overall score for LOS improved from 49% to 69% and the time to complete LOS test decreased from 90 seconds to 73 seconds (Table 1 and Table 2). In addition to improvement in dynamic balance, his confidence in balance improved by 17.5% as measured by the ABC scale (Figure 1). Higher scores were evident on all 16 items, including walking up and downstairs and reaching for objects on the floor; there was no change in confidence walking on icy sidewalks.
Participant A illustrated improvements in all spatial-temporal measurements including gait velocity, cadence, step time on left, step time on right, step length on left, step length on right, single support on left, single support on right, as measured by the GAITRite system (Table 3). Participant A's gait velocity markedly improved from 0.83 m/s to 1.02 m/s, which exceeded the minimal clinically important difference of 0.1 m/s. His functional ambulation profile score increased from 77 to 83, which remains lower than that of age-matched healthy norms. Following the intervention, however, participant A remarked that “he was much more confident in walking and was not afraid to ambulate without his cane outside.”
To illustrate how these 2 participants compare to an able-bodied individual, data on OUES, and economy of movement of a man who matched on age, height, and weight was used. The calculated OUES for participant A was recorded at pretest value of 1991.0 and the posttest value of 1444.5, whereas the control participant's OUES was recorded at 1878.6 (Figure 2). Despite the decrease noted in his OUES measure, participant A's economy of movement increased bringing him closer to an age-matched control (Figure 4). Therefore, he used less oxygen and was more economical or efficient walking during testing at all speeds on the treadmill.
Participant B was tested at level 6 platform stability to assess change in dynamic balance. He was not able to complete the test for LOS at platform level 6 without excess use of upper extremity support; therefore, he was tested at level 8 platform stability with a 50% LOS test difficulty for both pretest and posttest measures. All indexes of dynamic balance were improved and his overall score for LOS improved from 7% to 9%, with the time to complete LOS test decreasing from 243 seconds to 207 seconds (Table 1 and Table 2). Participant B's ABC scale score also changed by 2.5% (Figure 1). In review of specific items, he reported that he had less confidence in walking up and down stairs, standing on tiptoes, and reaching for something above the head. His fear of walking on icy sidewalks improved.
Participant B improved in all 10 spatial and temporal gait parameters evaluated on the GAITRite. Participant B entered the study with a functional ambulation profile score that fell within the range of normative data. Following intervention, his FAP score continued to improve as a result of his more normalized gait pattern and increased velocity (1.1 to 1.4 m/s (Table 3).
The same age-matched control (64-year-old healthy man) was used to compare results for OUES and economy of movement for participant B. The OUES value for participant B was recorded at pretest as a value of −457.49 and the posttest value improved to 1810.8 (Figure 3). The age-matched control's OUES was recorded at 1878.6. Participant B's economy of movement also improved, bringing him closer to an age-matched control (Figure 4).
The purpose of this case report was to describe the use of the Nintendo Wii Fit gaming and BWS for individuals with transfemoral amputation on balance responses, fear of falling, aerobic capacity, and economy of movement during prosthetic ambulation. The participants in this study completed traditional physical therapy; however, they did not continue these activities once discharged from physical therapy. The interventions chosen for this case study offered a controlled environment for training that addressed the participants' goals of reducing the need for assistive devices and fear of falling, and becoming more aerobically conditioned to meet the demands of community activity levels.
At study completion, both participants improved scores in all measures of dynamic balance and LOS. Age-matched range (54 to 71 years old) normative data for OSI falls between 1.5 and 3.5 in individuals with no physical impairments.34 Although participant A's baseline OSI (1.8 ± 0.5) already fell within normative data, his final OSI score (0.9 ± 0.2) dropped below the lower range of normal indicating a better-than-average score for someone of his age. Participant B initially tested 0.6 points above the normal range but improved at posttesting to be within normal range. Furthermore, overall LOS and total time to complete the LOS test improved in both participant A and participant B by 20% and 27 seconds and 2% and 36 seconds, respectively. These outcomes may suggest that balance training with Nintendo Wii Fit balance games can improve both dynamic balance and LOS in persons with transfemoral amputation. There are limitations and other factors that may account for these results; in addition, the clinimetric properties of the outcome measures have not been established to know whether their functional balance indeed had improved.
Considering the variety of balance games each participant completed during intervention, one may also theorize that certain games target either dynamic balance or LOS, which may explain greater gains seen in one aspect of balance over another. To date, there are no known published studies that classify and quantify balance games on the Nintendo Wii Fit in terms of dynamic balance or LOS. For example, the penguin, soccer ball, and ski slalom balance games require rapid, extreme medial/lateral, or anterior/posterior weight-shifting, which would correlate more appropriately with the LOS test. In addition, the table-tilt balance game requires more subtle, fine adjustments to advance to the next level, which seems to correlate more appropriately with the nature of the dynamic balance test. Each participant played the games for a total of 20 minutes; however, the researchers did not attempt to standardize the order or amount of time spent on each game. Further research is needed to determine whether certain balance games on the Nintendo Wii Fit foster a particular aspect of balance.
A number of clinical observations concerning balance responses were also made during intervention on the Nintendo Wii. For example, participant A had a tendency to balance with his fingertips on the parallel bars to more rapidly shift his weight and to achieve a better score, especially as the game became more challenging. Quite the opposite was noted in participant B during balance games as he did not reach out to the parallel bars as needed and instead, often fell out of his base of support. As a result, he had to temporarily step off the balance board. Perhaps the strategy for playing the games is related to confidence in balance. The technique of overusing the parallel bars with participant A may not only correlate with his competitiveness but his fear of falling because of the relative newness of his transfemoral amputation. Whereas participant B, whose amputation took place 9 years prior to this intervention, was not afraid to fall as was evident by his minimal use of the parallel bars.
Balance performance and functional mobility are strongly associated with balance confidence in community-dwelling older adults.47 Increased confidence in balance is more likely to contribute to an individual's willingness to participate in daily and leisure activities. At the beginning of the study, each participant's pretest score was below 80% indicating a moderate level of confidence in balance. At the end of this study, participant A's confidence exceeded 80% classifying him as a high physical functioning individual. Review of the individual items of the ABC scale illustrated that participant A reported increased balance confidence in daily activities such as walking up or down stairs, bending over and picking an object up, and standing on tiptoes to reach for an overhead object. Participant B's score only improved a small percentage from baseline to completion, ending at a 75% level of moderate physical functioning. Interestingly, during the posttesting session, participant B disclosed that in the previous 2 weeks he had fallen twice, with the more serious of the 2 falls being on the stairs. These falls may explain the decreased scores in balance confidence with going up and down stairs, and reaching overhead for objects on tiptoes, which also affected the outcome or total score. It appears that there might be carry over from training on the Wii Fit to the improvement noted in the participants Biodex balance responses and balance confidence.
As mentioned, BWS walking was primarily used to condition the aerobic system by allowing the participant a safe means of increasing his speed to increase his heart rate, while attempting to reduce fear of falling. As anticipated, each participant worked between 60% and 70% of his age predicted maximum heart rate. Overloading the aerobic system increases the body's ability to extract and use oxygen, making gait more efficient. By increasing the oxygen utilization in muscles recruited for ambulation, the participant is able to tolerate a longer duration of continuous submaximal activity such as used in community ambulation. The use of BWS as modified with these 2 participants, served as an innovative mode of exercise to facilitate work beyond their comfort level and achieve the overload stimulus necessary.
The BWS training was alternated between treadmill and over-ground surfaces. The treadmill allowed for a controlled elevation of intensity and also a constant walking speed at each level. The BWS on level walking surfaces is less controlled, but it more closely represents the participant's daily life. Although the harness was used to primarily reduce fear of falling, it was readily apparent after the first session that adjustment of the harness required further adaptation for both participants to increase walking speed while preventing hindrance of prosthetic socket motion.
To be considered a community ambulator, a walking speed of 1.2 to 1.4 m/sec (3 mph) is standard for healthy adults.48 During this study, without a set pace, as occurs in over-ground walking, the participant had to internalize his own speed while still maintaining a heart rate in the 60% to 70% range. Oxygen uptake efficiency slope was used to reflect changes in the individual's aerobic capacity after intervention. Aerobic capacity is determined by central factors (heart and lung function) and peripheral factors (ability to extract supplied oxygen by skeletal muscle). The higher the OUES value (steeper the slope) reflects a greater ability of the system to utilize the oxygen being supplied per ventilation volume. This capacity can be illustrated by an individual being better able to uptake and use oxygen for a longer period of time before an anaerobic threshold is reached.15 This increased ability to tolerate longer durations of continuous aerobic activities translates to an increased participation in ADLs and community life.
Participant A showed a decline in OUES, aerobic capacity, at posttest. The reason for this decline is not fully clear; however, we believe it was most likely due to lack of appropriate aerobic training stimulus and(or his cigar smoking habit. Perhaps, the improvement in his balance, gait control, and velocity allowed him to “work” less at the same given speeds during posttest. Although participant A admitted to “occasional” cigar smoking, the researchers did not monitor the amount of his smoking habit nor did we control for the time that he had last smoked before testing. Tobacco smoking does inhibit the body's ability oxygen carrying capacity and can reduce OUES.44,45
Participant B improved his aerobic capacity suggesting that the moderate intensity BWS walking intervention provided the necessary training stimulus to effect physiological adaptations directly influencing the aerobic system. Though he has been an amputee for 9 years and had excellent gait control, his oxygen uptake efficiency was lower. This observation may illustrate a preclinical disability state that is worth being identified in an individual with transfemoral amputation. Aerobic training proved to be challenging for him, represented by an increased heart rate in the first few minutes of each 20-minute BWS session. Participant B was able to reach 60% to 70% max heart, but he needed instruction to stay within this range. Participant B only completed 80% of the training sessions required for this 6-week study; however, when he could not attend at the clinic, he reported walking on his treadmill at home.
The importance of economy of movement begins with the body's ability to extract oxygen and use the oxygen. If an individual is consuming a high level of oxygen (above age-matched control), the energy expenditure is higher at the same work level leading to fatigue or early occurrence of anaerobic state. An increase in efficiency allows for more activity and a later occurrence of anaerobic state. For the participants, this means an increased tolerance to ADLs and ambulation with less expenditure of energy.28 Both participants were more economical in walking at posttest, and each participant's energy expenditure approached the walking efficiency of an age-matched control at the end of this study. Improvements noted in both participants' economy of walking may be explained by improved spatial temporal gait parameters, improved balance, and an improved perception of balance.15
It is well known that individuals with transfemoral amputation expend more energy over time than healthy counterparts and thus do not achieve the efficiency of an age-matched control.49 However, these 2 participants improved their economy of movement after the Nintendo Wii Fit balance gaming and BWS gait training. Another factor that may be related to improved efficiency during walking is increased motor control.28 Both participants improved balance abilities and gait skills through balance training, which may have contributed to improved economy of walking for these participants. In addition, there may be a carryover effect with balance, balance confidence, spatial temporal gait parameters, and aerobic capacity in an individual's economy of movement. To date, there are no known studies that discuss economy of movement in an amputee population. More research should be conducted to determine which of the aforementioned factors may contribute to the gains in economy of movement in individuals with lower limb amputation.
The GAITRite measurements for velocity are considered reliable across different methods of measurement, patient populations, and the presence of impairments that alter gait.40 Changes in spatial-temporal parameters improve gait efficiency, allowing a person to use less energy and work to perform the same task. Waters et al50 found normal or customary walking velocity for healthy men aged 20 to 60 years to be 1.4 m/sec, and cadence 110 steps/min. Gait velocity was measured for both participants, as it reflects both functional and physiological changes and can aid in prediction of fall risk and fear of falling.48 A change in velocity of 0.1 m/s is a meaningful clinical important difference for normal walking speed in older adults and is a useful predictor of higher levels of functional performance and well-being.48 Participants were encouraged to increase walking velocity during the intervention; however, less attention was given to improving the specific components of gait (cadence, equality of step time, length, and single limb support), which may explain while there was little change from left limb to right limb between the baseline and outcomes assessments.
Participant A showed improvement in velocity with gait parameters indicating he changed his gait strategy and achieved a more normalize gait speed. At study completion, he achieved a velocity of 1.02 m/s, which falls into the range demonstrative of a community ambulator, but is also slower than that of age-matched healthy norms.48 While participant A did not experience change in the amount of time spent on each limb during step time and single limb support (which should be nearly equal on both legs), he did decrease the time spent on each leg during step time. Therefore, he was able to cover the same distance in a shorter time by increasing both his cadence and his stride length.
Participant B also improved his gait strategy by increasing both cadence and stride length, and achieved a velocity comparable to healthy counterparts. At completion, he achieved a velocity of 1.4 m/s, consistent with normal walking—meaning sufficient speed to safely cross the street. Participant B also decreased his step time on both legs, which allowed him to cover the same distance in a reduced time. While there was no overall change in the difference (his step length was already fairly equal) in step length between legs, there was an increase in step length so he could potentially cover more distance in a shorter time. Similar to participant A, there was little change in single limb support time, with less time being spent on the prosthetic limb in both participants.
The GAITRite Functional Ambulation Profile (FAP) also revealed functional gait improvements for both participants. At the end of the current study, both participants had increased FAP scores, which reflected the participants' improved ability to ambulate under various conditions independently with the least amount of time. Higher scores also indicate lower fall risks in patients, with a score of 95 being a normative data score for adults.43
The 2 participants in this case study had the desire to improve balance and aerobic capacity for daily living and particularly found the Nintendo Wii Fit balance gaming to be “challenging and enjoyable.” Both participants reported greater confidence in increasing walking speed with BWS and thus were able to more effectively train on the treadmill and land without fear of falling. After 6 weeks of training, outcomes indicate that both of the participants benefited from the intervention.
Incorporating gait training with BWS on land and on a treadmill, and balance training using the Nintendo Wii Fit may be beneficial for individuals with limb loss even many years after amputation. Developing engaging wellness health maintenance programs through exercise will be especially important as people are now living longer with amputation in the United States. The results of this case study support the importance of conducting an experimental study with a larger sample size to further investigate the cause and effect relationships of the Nintendo Wii Fit balance gaming in combination with GAITRite BWS training on functional capacity variables in older adults with lower limb amputation.
The authors thank Nancy Kaselak, CPO at Hanger Prosthetics in Gainesville, for assistance with participant recruitment and fabrication and consultation with prosthetic fit.
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Amputation; Balance Confidence; Economy of Movement; Gait
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