- Email: [email protected]
Utilization of a lower extremity ambulatory feedback system to reduce gait asymmetry in transtibial amputation gait
Gait & Posture 36 (2012) 631–634
Contents lists available at SciVerse ScienceDirect
Gait & Posture journal homepage: www.elsevier.com/locate/gaitpost
Short communication
Utilization of a lower extremity ambulatory feedback system to reduce gait asymmetry in transtibial amputation gait L. Yang, P.S. Dyer, R.J. Carson, J.B. Webster, K. Bo Foreman, S.J.M. Bamberg * University of Utah, Salt Lake, United States, UT
A R T I C L E I N F O
A B S T R A C T
Article history: Received 5 November 2010 Received in revised form 15 September 2011 Accepted 5 April 2012
The goal of our research is to augment gait rehabilitation for persons with gait asymmetry through a realtime feedback system that can be used independently by patients in the community. Our wireless, wearable, real-time gait asymmetry detection system called the lower extremity ambulatory feedback system (LEAFS) is a low-cost, in-shoe gait detection device that provides real-time auditory feedback based on the stance time symmetry ratio between the right and left limbs. This study evaluated the performance of the LEAFS in three study subjects with gait asymmetry secondary to unilateral transtibial amputation. Study subjects used the LEAFS for six 30-min training sessions under the supervision of a physical therapist. Two subjects demonstrated improved gait symmetry, with one subject reducing trunk sway by 85.5%, and the other subject reducing trunk sway by 16.0% and increasing symmetry ratio toward unity by 26.5%, as measured by a clinical motion analysis lab. The third subject did not demonstrate any objective improvements in gait symmetry or trunk sway. While testing with a larger number of subjects is necessary, this initial study using LEAFS with persons with transtibial amputations suggests that it can assist in improving gait symmetry in this population. ß 2012 Elsevier B.V. All rights reserved.
Keywords: Gait asymmetry Amputee gait Insole sensors Feedback Wireless
1. Introduction Gait asymmetry is considered an indication of gait pathology and occurs in many populations including persons with lowerlimb amputations [1]. Individuals with lower-limb amputations may experience changes in stance time, force, and joint moments that can lead to poor balance, higher metabolic costs, osteoarthritis, and back pain [1–5]. Additional co-morbidities such as diabetes (over half of all lower-limb amputations occur in people with diabetes [6]) are particularly impacted by these increased metabolic costs. Furthermore, the number of persons living with limb loss in the United States is projected to rise from 1.6 million in 2005 to 3.6 million in 2050 [7]. An abundance of commercial clinical devices (camera-based laboratories, instrumented treadmills, floor mats, insole sensor devices) are capable of detecting gait asymmetry. These systems are generally expensive, lab-based, and provide results after data collection rather than in real-time. Thus, these devices are generally ill-suited for use clinically. Existing interventions for gait asymmetry in the clinic are scarce and often rely on subjective observations [8–11]. A commercial option intended for clinical use is the Andante SmartStep, which uses an insole and ankle box for
* Corresponding author at: 50 S. Central Campus Dr., MEB Room 2110, Salt Lake City, UT 84112, United States. Tel.: +1 801 585 9081; fax: +1 801 581 9826. E-mail address: [email protected] (S.J.M. Bamberg). 0966-6362/$ – see front matter ß 2012 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.gaitpost.2012.04.004
wireless feedback about gait asymmetry, but retails over $5000 (including a laptop to provide feedback), an excessive cost for a typical consumer. Because the standard treatment in the amputee population is typically limited to symptom relief and treatment of conditions once they occur [12], our goal is to extend rehabilitation by providing patients with an inexpensive gait asymmetry feedback tool that can be used independently by patients in the community. This would provide patients with the opportunity to improve their gait and balance between therapy visits. LEAFS is designed to be inexpensive and provide feedback of a person’s gait in real-time and in any environment [13–15]. Our hypothesis is that providing real-time external feedback will assist amputees to achieve a symmetric gait pattern. 2. Methods 2.1. Subjects The University of Utah Institutional Review Board approved the research protocol (#36494). Inclusion criteria included unilateral transtibial amputation, asymmetric gait pattern with symmetry ratio <0.95 and trunk sway >100 mm (measured in a clinical motion lab and defined below), and stable from a rehabilitation standpoint (no interventions took place during this study). Subjects were recruited from the University of Utah Rehabilitation Program.
L. Yang et al. / Gait & Posture 36 (2012) 631–634
632
2.2. Test procedures Each subject completed a pre-test, six 30 min training sessions using the LEAFS during the span of three weeks, and a post-test. The pre- and post-tests were performed in a clinical motion analysis lab one week before and after training. Training was moderated by a physical therapist familiar with each subject’s case. The physical therapist set the feedback threshold and trial duration, for multiple individual trials lasting from 30 to 240 s followed by a similar length break. 2.3. Lower extremity ambulatory feedback system (LEAFS) LEAFS, shown in Fig. 1, measures ground-reaction forces generated by the feet in real-time and provides feedback to improve gait symmetry. Stance time measurements with the LEAFS have been previously validated [13]. The data from the force sensitive resistors is transmitted wirelessly to a netbook; the entire system costs less than $500 (including the netbook). Data is transmitted from each sensor at 114 Hz, and a single AA battery powers each insole system for 10 h. A custom program in MATLAB1 operates in real-time to analyze the force data. This program determines the times of initial contact (tic) and final contact (tfc), and calculates stance time (ST) from the difference: Stance Time ¼ t ic t fc
(1)
Subsequently, following successive strides by the intact and then the affected limb, the symmetry ratio (SR) is calculated from the stance times: Symmetry Ratio ¼
STaffected 100% STintact
(2)
Perfect symmetry occurs when SR = 1. Persons with unilateral amputations and asymmetric gait are expected to have SR < 1 because stance time on the amputated limb is typically decreased. If the SR is below the feedback threshold (set before each trial), a
1.2
Fig. 1. An insole containing force sensitive resistors and conditioning circuitry and its ankle box containing a microcontroller, wireless transceiver, and a single AA battery. The insole is split into two pieces to accommodate different foot sizes, ranging from men’s size 5 to 11, by placing the heel piece and toe piece in the posterior and anterior portions of the shoe, respectively.
loud beep is heard, while the system is silent if the SR is equal to or above the feedback threshold. 2.4. Motion analysis Pre- and post-testing occurred in a clinical motion analysis lab equipped with an eight-camera Vicon motion analysis system and two AMTI OR-6 series multi-axis force platforms. Subjects were fitted with a standard marker set, and walked until a minimum of three complete footstrikes from the amputated limb were captured on a force plate. Vicon BodyBuilder1 and Polygon1 were used to determine the two outcome measures, symmetry ratio (as in Eq. (2)) and trunk sway. Trunk sway was calculated using the difference in the coronal plane between the C7 vertebrae marker and a point halfway between the hip joint centers.
Patient A
1.0 0.8
Symmetry Ratio (SR)
1
1.2
2
3
4
5
6
2
3
4
5
6
2
3
4
5
6
Patient B
1.0 0.8 1
1.2
Patient C
1.0 0.8 1
Training Session Fig. 2. Mean symmetry ratios (SR) for the three study subjects during each subject’s six training sessions using the LEAFS. Error bars are the standard error of the mean. A movement of SR toward 1.0 corresponds to improved gait asymmetry (perfect symmetry occurs when SR = 1). The six training sessions were moderated by a physical therapist and each lasted 30 min (inclusive of rest time) and all six training sessions were completed within two weeks.
L. Yang et al. / Gait & Posture 36 (2012) 631–634
633
Table 1 Pre- and post-test measures of symmetry ratio (SR) and trunk sway for the three study subjects, as measured by the motion analysis lab (MAL). Percent change was calculated by subtracting the pre-test value from the post-test value and dividing by the pre-test value. ID
A B C
Demographic information
Gait asymmetry measures
Sex
Age (years)
Height (cm)
Mass (kg)
Shoe size
Amputation (limb, reason, time)
Symmetry ratio (SR) Pre
Post
% Change
Pre
Post
% Change
M F F
65 62 22
187.96 157.48 160.02
116.2 57.6 63.5
M 12 W 7.5 W 7.5
Left, infection, 7 months Left, embolism, 1.5 years Left, infection, 5.5 yearsa
0.92 0.04 0.84 0.05 0.83 0.02
0.95 0.06 0.84 0.04 1.05 0.02
3.3 0.0 26.5
126 9 163 8 164 13
18 6 161 8 137 8
85.5 1.4 16.0
0.86 0.05
0.95 0.11
151 21
105 76
34.3 44.9
Overall: a
Trunk sway (mm)
9.9 14.5
Subject C received a new prosthetis 2.5 years prior to the study.
3. Results For the three study subjects (two female and one male, 49.7 19.6 years, 168.5 13.8 cm, 79.1 26.3 kg), the pre-test and post-test results from the motion analysis are presented in Table 1. The mean symmetry ratios during all training sessions for each of the three study subjects are shown in Fig. 2.
of the three subjects suggest that this technique can contribute to improved gait symmetry in this population. Funding This project was supported in part by a University of Utah Center for Contemporary Rehabilitation Research Seed Grant and a University of Utah Technology Commercialization Proposal.
4. Discussion Two of the three study subjects demonstrated a marked improvement in at least one of the outcome measures of gait asymmetry determined by the motion analysis lab. Subjects A and C had amputations due to infection, and their intact limbs may have been better able to respond to changes in gait than subject B, whose progress may have been hindered by the numbness remaining in her intact limb. Subject A received his prosthesis relatively recently prior to testing, which may have enabled him to more readily adapt his gait. Though subject C’s trunk sway did not change as dramatically as A, she had the largest change in SR. This may have been a function of her young age or her prosthesis, which transferred the load above the knee. Our current work has resulted in a feedback system using a mobile phone instead of the netbook, and it has also allowed the incorporation of other types of feedback [15]. This will enable us to study the use of our system in the home environment and to extend the training sessions beyond six short sessions over three weeks. Future studies will include additional post-tests to investigate how long changes in gait persist. This initial small study was limited to unilateral transtibial amputees to ensure a cohesive population, but it was difficult to find patients in this group with asymmetric gait, particularly among the population treated at the University of Utah hospital. In the future, we plan to recruit subjects in the broader community and expand our subject population to include transfemoral amputees. We are also interested in investigating differences in subjects with amputations due to a change only in one limb (e.g. infection, trauma) versus those due to changes that affect both limbs (e.g. bilateral emboli, diabetes). 5. Conclusion LEAFS has been designed to provide a low cost and long-term feedback strategy away from the clinic for reducing gait asymmetry. Symmetric gait improves the cosmetic appearance of gait, reduces metabolic costs and decreases the risks of conditions such as osteoarthritis. Although further testing is required with a larger number of subjects and with post-tests to examine persistence of the effects, use of LEAFS in persons with transtibial amputations appears feasible. The considerable improvements in trunk sway and symmetry ratio noted in two
Acknowledgments This work was supported in part by a University of Utah Center for Contemporary Rehabilitation Research Seed Grant and a University of Utah Technology Commercialization Proposal. We are especially grateful to all the study subjects for their enthusiasm and participation and to Crystal Chrastil and Esther Smith for assisting with the analysis of the motion laboratory data. Conflict of interest Stacy J. Morris Bamberg, Randy J. Carson, Joseph B. Webster, Dante Bertelli, ‘‘Lower Extremity Feedback System (LEFS),’’ University of Utah. U.S. non-provisional patent application filed March 20, 2009 (20090240171). References [1] Sadeghi H, Allard P, Prince F, Labelle H. Symmetry and limb dominance in ablebodied gait: a review. Gait and Posture 2000;12:34–45. [2] Platts MM, Rafferty D, Paul L. Metabolic cost of overground gait in younger stroke patients and healthy controls. Medicine and Science in Sports and Exercise 2006;38:1041–6. [3] Nolan L, Wit A, Dudzinski K, Lees A, Lake M, Wychowanski M. Adjustments in gait symmetry with walking speed in transfemoral and trans-tibial amputees. Gait and Posture 2003;17:142–51. [4] Norvell DC, Czerniecki JM, Reiber GE, Maynard C, Pecoraro JA, Weiss NS. The prevalence of knee pain and symptomatic knee osteoarthritis among veteran traumatic amputees and nonamputees. Archives of Physical Medicine and Rehabilitation 2005;86:487–93. [5] Kulkarni J, Gaine WJ, Buckley JG, Rankine JJ, Adams J. Chronic low back pain in traumatic lower limb amputees. Clinical Rehabilitation 2005;19:81. [6] National Limb Loss Information Center. Diabetes and lower extremity amputations. ACA fact sheet 2008. http://www.amputee-coalition.org/fact_sheets/ diabetes_leamp.pdf [accessed 16.08.08]. [7] Ziegler-Graham K, MacKenzie EJ, Ephraim PL, Travison TG, Brookmeyer R. Estimating the prevalence of limb loss in the United States: 2005–2050. Archives of Physical Medicine and Rehabilitation 2008;89(3):422–9. [8] Davis BL, Ortolano M, Richards K, Redhed J, Kuznicki J, Sahgal V. Realtime visual feedback diminishes energy consumption of amputee subjects during treadmill locomotion. Journal of Prosthetics and Orthotics 2004;16:49–54. [9] Dingwell JB, Davis BL, Frazier DM. Use of an instrumented treadmill for realtime gait symmetry evaluation and feedback in normal and trans-tibial amputee subjects. Prosthetics and Orthotics International 1996;20:101–10. [10] Draper ER. A treadmill-based system for measuring symmetry of gait. Medical Engineering and Physics 2000;22:215–22. [11] Lee MY, Lin CF, Soon KS. Balance control enhancement using sub-sensory stimulation and visual–auditory biofeedback strategies for amputee subjects. Prosthetics and Orthotics International 2007;31(4):342–52.
634
L. Yang et al. / Gait & Posture 36 (2012) 631–634
[12] Pasquina PF, Bryant PR, Huang ME, Roberts TL, Nelson VS, Flood KM. Advances in amputee care. Archives of Physical Medicine and Rehabilitation 2006;87(3 Suppl. 1):S34–43 [quiz S44–5]. [13] Bamberg SJM, Carson RJ, Stoddard G, Dyer PS, Webster JB. The lower extremity ambulation feedback system (LEAFS) for analysis of gait asymmetries: preliminary design and validation results. Journal of Prosthetics and Orthotics 2010;22(1):31–6.
[14] Redd C, Bamberg SJM. A wireless sensory feedback system for realtime gait modification. In: Proceedings of the 33rd annual international conference of the IEEE engineering in medicine and biology society; 2011 [paper WeB23.3]. [15] Redd CB, Bamberg SJM. A wireless sensory feedback device for real-time gait feedback and training. IEEE/ASME Transactions on Mechatronics 2012;17(3):425–33, http://dx.doi.org/10.1109/TMECH.2012.2189014.
Contents lists available at SciVerse ScienceDirect
Gait & Posture journal homepage: www.elsevier.com/locate/gaitpost
Short communication
Utilization of a lower extremity ambulatory feedback system to reduce gait asymmetry in transtibial amputation gait L. Yang, P.S. Dyer, R.J. Carson, J.B. Webster, K. Bo Foreman, S.J.M. Bamberg * University of Utah, Salt Lake, United States, UT
A R T I C L E I N F O
A B S T R A C T
Article history: Received 5 November 2010 Received in revised form 15 September 2011 Accepted 5 April 2012
The goal of our research is to augment gait rehabilitation for persons with gait asymmetry through a realtime feedback system that can be used independently by patients in the community. Our wireless, wearable, real-time gait asymmetry detection system called the lower extremity ambulatory feedback system (LEAFS) is a low-cost, in-shoe gait detection device that provides real-time auditory feedback based on the stance time symmetry ratio between the right and left limbs. This study evaluated the performance of the LEAFS in three study subjects with gait asymmetry secondary to unilateral transtibial amputation. Study subjects used the LEAFS for six 30-min training sessions under the supervision of a physical therapist. Two subjects demonstrated improved gait symmetry, with one subject reducing trunk sway by 85.5%, and the other subject reducing trunk sway by 16.0% and increasing symmetry ratio toward unity by 26.5%, as measured by a clinical motion analysis lab. The third subject did not demonstrate any objective improvements in gait symmetry or trunk sway. While testing with a larger number of subjects is necessary, this initial study using LEAFS with persons with transtibial amputations suggests that it can assist in improving gait symmetry in this population. ß 2012 Elsevier B.V. All rights reserved.
Keywords: Gait asymmetry Amputee gait Insole sensors Feedback Wireless
1. Introduction Gait asymmetry is considered an indication of gait pathology and occurs in many populations including persons with lowerlimb amputations [1]. Individuals with lower-limb amputations may experience changes in stance time, force, and joint moments that can lead to poor balance, higher metabolic costs, osteoarthritis, and back pain [1–5]. Additional co-morbidities such as diabetes (over half of all lower-limb amputations occur in people with diabetes [6]) are particularly impacted by these increased metabolic costs. Furthermore, the number of persons living with limb loss in the United States is projected to rise from 1.6 million in 2005 to 3.6 million in 2050 [7]. An abundance of commercial clinical devices (camera-based laboratories, instrumented treadmills, floor mats, insole sensor devices) are capable of detecting gait asymmetry. These systems are generally expensive, lab-based, and provide results after data collection rather than in real-time. Thus, these devices are generally ill-suited for use clinically. Existing interventions for gait asymmetry in the clinic are scarce and often rely on subjective observations [8–11]. A commercial option intended for clinical use is the Andante SmartStep, which uses an insole and ankle box for
* Corresponding author at: 50 S. Central Campus Dr., MEB Room 2110, Salt Lake City, UT 84112, United States. Tel.: +1 801 585 9081; fax: +1 801 581 9826. E-mail address: [email protected] (S.J.M. Bamberg). 0966-6362/$ – see front matter ß 2012 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.gaitpost.2012.04.004
wireless feedback about gait asymmetry, but retails over $5000 (including a laptop to provide feedback), an excessive cost for a typical consumer. Because the standard treatment in the amputee population is typically limited to symptom relief and treatment of conditions once they occur [12], our goal is to extend rehabilitation by providing patients with an inexpensive gait asymmetry feedback tool that can be used independently by patients in the community. This would provide patients with the opportunity to improve their gait and balance between therapy visits. LEAFS is designed to be inexpensive and provide feedback of a person’s gait in real-time and in any environment [13–15]. Our hypothesis is that providing real-time external feedback will assist amputees to achieve a symmetric gait pattern. 2. Methods 2.1. Subjects The University of Utah Institutional Review Board approved the research protocol (#36494). Inclusion criteria included unilateral transtibial amputation, asymmetric gait pattern with symmetry ratio <0.95 and trunk sway >100 mm (measured in a clinical motion lab and defined below), and stable from a rehabilitation standpoint (no interventions took place during this study). Subjects were recruited from the University of Utah Rehabilitation Program.
L. Yang et al. / Gait & Posture 36 (2012) 631–634
632
2.2. Test procedures Each subject completed a pre-test, six 30 min training sessions using the LEAFS during the span of three weeks, and a post-test. The pre- and post-tests were performed in a clinical motion analysis lab one week before and after training. Training was moderated by a physical therapist familiar with each subject’s case. The physical therapist set the feedback threshold and trial duration, for multiple individual trials lasting from 30 to 240 s followed by a similar length break. 2.3. Lower extremity ambulatory feedback system (LEAFS) LEAFS, shown in Fig. 1, measures ground-reaction forces generated by the feet in real-time and provides feedback to improve gait symmetry. Stance time measurements with the LEAFS have been previously validated [13]. The data from the force sensitive resistors is transmitted wirelessly to a netbook; the entire system costs less than $500 (including the netbook). Data is transmitted from each sensor at 114 Hz, and a single AA battery powers each insole system for 10 h. A custom program in MATLAB1 operates in real-time to analyze the force data. This program determines the times of initial contact (tic) and final contact (tfc), and calculates stance time (ST) from the difference: Stance Time ¼ t ic t fc
(1)
Subsequently, following successive strides by the intact and then the affected limb, the symmetry ratio (SR) is calculated from the stance times: Symmetry Ratio ¼
STaffected 100% STintact
(2)
Perfect symmetry occurs when SR = 1. Persons with unilateral amputations and asymmetric gait are expected to have SR < 1 because stance time on the amputated limb is typically decreased. If the SR is below the feedback threshold (set before each trial), a
1.2
Fig. 1. An insole containing force sensitive resistors and conditioning circuitry and its ankle box containing a microcontroller, wireless transceiver, and a single AA battery. The insole is split into two pieces to accommodate different foot sizes, ranging from men’s size 5 to 11, by placing the heel piece and toe piece in the posterior and anterior portions of the shoe, respectively.
loud beep is heard, while the system is silent if the SR is equal to or above the feedback threshold. 2.4. Motion analysis Pre- and post-testing occurred in a clinical motion analysis lab equipped with an eight-camera Vicon motion analysis system and two AMTI OR-6 series multi-axis force platforms. Subjects were fitted with a standard marker set, and walked until a minimum of three complete footstrikes from the amputated limb were captured on a force plate. Vicon BodyBuilder1 and Polygon1 were used to determine the two outcome measures, symmetry ratio (as in Eq. (2)) and trunk sway. Trunk sway was calculated using the difference in the coronal plane between the C7 vertebrae marker and a point halfway between the hip joint centers.
Patient A
1.0 0.8
Symmetry Ratio (SR)
1
1.2
2
3
4
5
6
2
3
4
5
6
2
3
4
5
6
Patient B
1.0 0.8 1
1.2
Patient C
1.0 0.8 1
Training Session Fig. 2. Mean symmetry ratios (SR) for the three study subjects during each subject’s six training sessions using the LEAFS. Error bars are the standard error of the mean. A movement of SR toward 1.0 corresponds to improved gait asymmetry (perfect symmetry occurs when SR = 1). The six training sessions were moderated by a physical therapist and each lasted 30 min (inclusive of rest time) and all six training sessions were completed within two weeks.
L. Yang et al. / Gait & Posture 36 (2012) 631–634
633
Table 1 Pre- and post-test measures of symmetry ratio (SR) and trunk sway for the three study subjects, as measured by the motion analysis lab (MAL). Percent change was calculated by subtracting the pre-test value from the post-test value and dividing by the pre-test value. ID
A B C
Demographic information
Gait asymmetry measures
Sex
Age (years)
Height (cm)
Mass (kg)
Shoe size
Amputation (limb, reason, time)
Symmetry ratio (SR) Pre
Post
% Change
Pre
Post
% Change
M F F
65 62 22
187.96 157.48 160.02
116.2 57.6 63.5
M 12 W 7.5 W 7.5
Left, infection, 7 months Left, embolism, 1.5 years Left, infection, 5.5 yearsa
0.92 0.04 0.84 0.05 0.83 0.02
0.95 0.06 0.84 0.04 1.05 0.02
3.3 0.0 26.5
126 9 163 8 164 13
18 6 161 8 137 8
85.5 1.4 16.0
0.86 0.05
0.95 0.11
151 21
105 76
34.3 44.9
Overall: a
Trunk sway (mm)
9.9 14.5
Subject C received a new prosthetis 2.5 years prior to the study.
3. Results For the three study subjects (two female and one male, 49.7 19.6 years, 168.5 13.8 cm, 79.1 26.3 kg), the pre-test and post-test results from the motion analysis are presented in Table 1. The mean symmetry ratios during all training sessions for each of the three study subjects are shown in Fig. 2.
of the three subjects suggest that this technique can contribute to improved gait symmetry in this population. Funding This project was supported in part by a University of Utah Center for Contemporary Rehabilitation Research Seed Grant and a University of Utah Technology Commercialization Proposal.
4. Discussion Two of the three study subjects demonstrated a marked improvement in at least one of the outcome measures of gait asymmetry determined by the motion analysis lab. Subjects A and C had amputations due to infection, and their intact limbs may have been better able to respond to changes in gait than subject B, whose progress may have been hindered by the numbness remaining in her intact limb. Subject A received his prosthesis relatively recently prior to testing, which may have enabled him to more readily adapt his gait. Though subject C’s trunk sway did not change as dramatically as A, she had the largest change in SR. This may have been a function of her young age or her prosthesis, which transferred the load above the knee. Our current work has resulted in a feedback system using a mobile phone instead of the netbook, and it has also allowed the incorporation of other types of feedback [15]. This will enable us to study the use of our system in the home environment and to extend the training sessions beyond six short sessions over three weeks. Future studies will include additional post-tests to investigate how long changes in gait persist. This initial small study was limited to unilateral transtibial amputees to ensure a cohesive population, but it was difficult to find patients in this group with asymmetric gait, particularly among the population treated at the University of Utah hospital. In the future, we plan to recruit subjects in the broader community and expand our subject population to include transfemoral amputees. We are also interested in investigating differences in subjects with amputations due to a change only in one limb (e.g. infection, trauma) versus those due to changes that affect both limbs (e.g. bilateral emboli, diabetes). 5. Conclusion LEAFS has been designed to provide a low cost and long-term feedback strategy away from the clinic for reducing gait asymmetry. Symmetric gait improves the cosmetic appearance of gait, reduces metabolic costs and decreases the risks of conditions such as osteoarthritis. Although further testing is required with a larger number of subjects and with post-tests to examine persistence of the effects, use of LEAFS in persons with transtibial amputations appears feasible. The considerable improvements in trunk sway and symmetry ratio noted in two
Acknowledgments This work was supported in part by a University of Utah Center for Contemporary Rehabilitation Research Seed Grant and a University of Utah Technology Commercialization Proposal. We are especially grateful to all the study subjects for their enthusiasm and participation and to Crystal Chrastil and Esther Smith for assisting with the analysis of the motion laboratory data. Conflict of interest Stacy J. Morris Bamberg, Randy J. Carson, Joseph B. Webster, Dante Bertelli, ‘‘Lower Extremity Feedback System (LEFS),’’ University of Utah. U.S. non-provisional patent application filed March 20, 2009 (20090240171). References [1] Sadeghi H, Allard P, Prince F, Labelle H. Symmetry and limb dominance in ablebodied gait: a review. Gait and Posture 2000;12:34–45. [2] Platts MM, Rafferty D, Paul L. Metabolic cost of overground gait in younger stroke patients and healthy controls. Medicine and Science in Sports and Exercise 2006;38:1041–6. [3] Nolan L, Wit A, Dudzinski K, Lees A, Lake M, Wychowanski M. Adjustments in gait symmetry with walking speed in transfemoral and trans-tibial amputees. Gait and Posture 2003;17:142–51. [4] Norvell DC, Czerniecki JM, Reiber GE, Maynard C, Pecoraro JA, Weiss NS. The prevalence of knee pain and symptomatic knee osteoarthritis among veteran traumatic amputees and nonamputees. Archives of Physical Medicine and Rehabilitation 2005;86:487–93. [5] Kulkarni J, Gaine WJ, Buckley JG, Rankine JJ, Adams J. Chronic low back pain in traumatic lower limb amputees. Clinical Rehabilitation 2005;19:81. [6] National Limb Loss Information Center. Diabetes and lower extremity amputations. ACA fact sheet 2008. http://www.amputee-coalition.org/fact_sheets/ diabetes_leamp.pdf [accessed 16.08.08]. [7] Ziegler-Graham K, MacKenzie EJ, Ephraim PL, Travison TG, Brookmeyer R. Estimating the prevalence of limb loss in the United States: 2005–2050. Archives of Physical Medicine and Rehabilitation 2008;89(3):422–9. [8] Davis BL, Ortolano M, Richards K, Redhed J, Kuznicki J, Sahgal V. Realtime visual feedback diminishes energy consumption of amputee subjects during treadmill locomotion. Journal of Prosthetics and Orthotics 2004;16:49–54. [9] Dingwell JB, Davis BL, Frazier DM. Use of an instrumented treadmill for realtime gait symmetry evaluation and feedback in normal and trans-tibial amputee subjects. Prosthetics and Orthotics International 1996;20:101–10. [10] Draper ER. A treadmill-based system for measuring symmetry of gait. Medical Engineering and Physics 2000;22:215–22. [11] Lee MY, Lin CF, Soon KS. Balance control enhancement using sub-sensory stimulation and visual–auditory biofeedback strategies for amputee subjects. Prosthetics and Orthotics International 2007;31(4):342–52.
634
L. Yang et al. / Gait & Posture 36 (2012) 631–634
[12] Pasquina PF, Bryant PR, Huang ME, Roberts TL, Nelson VS, Flood KM. Advances in amputee care. Archives of Physical Medicine and Rehabilitation 2006;87(3 Suppl. 1):S34–43 [quiz S44–5]. [13] Bamberg SJM, Carson RJ, Stoddard G, Dyer PS, Webster JB. The lower extremity ambulation feedback system (LEAFS) for analysis of gait asymmetries: preliminary design and validation results. Journal of Prosthetics and Orthotics 2010;22(1):31–6.
[14] Redd C, Bamberg SJM. A wireless sensory feedback system for realtime gait modification. In: Proceedings of the 33rd annual international conference of the IEEE engineering in medicine and biology society; 2011 [paper WeB23.3]. [15] Redd CB, Bamberg SJM. A wireless sensory feedback device for real-time gait feedback and training. IEEE/ASME Transactions on Mechatronics 2012;17(3):425–33, http://dx.doi.org/10.1109/TMECH.2012.2189014.