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Effect of stump parameters on postural stability during stance modification in transtibial amputees
S96
ESMAC Abstracts 2015 / Gait & Posture 42S (2015) S1–S101
This work has demonstrated that it is possible to reduce stumbles and falls in individuals with transfemoral (TF) and transtibial (TT) amputations. Materials and methods: Twenty male service members (28 + 5 years) with unilateral TF (n = 5) or TT amputations (n = 15), who had been walking independently for 21 (range 2–115) months, were trained at a military treatment facility. Training consisted of six 30-minute training sessions over two weeks using a computerized treadmill (Active-Step, Simbex, Lebanon, NH) to deliver destabilizing perturbations giving subjects practice on recovering to avoid a fall. Treatment efficacy was evaluated in three ways. (1) An immersive virtual environment (CAREN, Motek Medical BV, Amsterdam) was used to create postural perturbations and assess trunk flexion angle and velocity following the perturbation. These are validated biomechanical metrics that have been associated with trip-related falls. Testing was done before and zero, three and six months after training. (2) Subjects were given a standardized perturbation (SP) task before and after training to determine training effectiveness. A subject passed the task if he avoided falling without assistance from the safety harness. (3) Patient questionnaires quantified balance confidence in the free-living environment. Results: Training significantly improved ability to avoid falling in both groups. Trunk flexion angle significantly improved after training for TF (p = 0.048) and TT (p = <0.001) and was unchanged (retained) at 3 and 6 months post-training for TF (p = 0.34) and TT (p = 0.19). Also, trunk flexion velocity significantly improved after training, TF (p = 0.17) and TT (p = <0.001) and was unchanged over time, TF (p = 0.06) and TT (p = 0.35). Prior to training, only 20% of TF and 7% of TT subjects avoided a fall following the SP. After training, 100% TF subjects successfully avoided falling, as did 87% of TT subjects. This training transferred to the free-living environment where 60% of the subjects reported a reduction in stumbles and 100% of the subjects avoided uncontrolled falls during the six month post-training period. Discussion: This research tested a novel training protocol to reduce falls in individuals with TF and TT amputations. Subjects had improved functional capabilities, increased reliance on their prosthesis during challenging conditions, and reduced fall-risk for at least six months post-training. The training protocol is effective, efficient, and can be easily implemented in rehabilitation clinics. Acknowledgements: DoD Grant No. W81XWH-11-2-0058 and Navy BUMED, Wounded Ill and Injured Program. Disclaimer: Views expressed are those of the authors and not of the DoD, or U.S. Government. http://dx.doi.org/10.1016/j.gaitpost.2015.06.175
Session OS20 Prosthetics Developing a set of norm data during activities of daily living – Comparison of the 3D kinematics of able-bodied and prosthesis users involving different artificial limbs A. Kranzl 1,∗ , B. Pobatschnig 2 , M. Schachinger 3 1
Orthopedic Hospital Speising, Vienna, Austria 2 Orthopädisches Spital Speising, Otto Bock Healthcare Group, Vienna, Austria 3 Otto Bock Healthcare Group, Vienna, Austria Research question: The aim of this work is to quantify the movement pattern in unilateral and bilateral activities (8 ADL) to
study the compensation movements in the use of hand prostheses with different number of degrees of freedom. Introduction: 3D upper extremities (UE) analysis is not commonly used due to the variety in degrees of freedom and complexity of UE [1,2]. As a result of variety of functional tasks for UE developing a standard protocol is very complex [2]. Therefore the aim of the study is to develop a set of norm data and to obtain information about the norm movement patterns during activities of daily living (ADL). In addition, norm data are compared to prosthesis users to understand their compensatory movements and to get a reference for evaluation of several artificial limbs. Materials and methods: 20 able-bodied subjects (26.3 years ±2.17) and two prosthesis users with different prostheses are being recorded via 3D motion capture system (biomechanical upper limb model [3]). 8 different ADL were recorded for each subject. Tasks are separated into different phases by means of proximity devices in order to interpolate angle progression in every phase and to make data more comparable. To check the validity of the standard data set for all ADL, the homogeneity of the individual movement patterns of the subjects and the homogeneity of the mean-values of all subjects was compared (ICC). In addition the Arm Profile Score (APS) was calculated to compare the outcome. Results: For all ADL we have found good values for ICC between 0.66 and 0.99 within the subjects and 0.5 and 0.99 over the subjects. Depending on the prosthetic devices differences can be detected concerning the APS values of the prosthetic users compared to the normal subjects. The device with the fixed wrist joint causes an increased average root means square errors in the elbow (sagittal, transverse) and shoulder (frontal, transverse). The device with the flexible wrist joint has increased values primarily in the shoulder (frontal, transverse) compared to the norm. Discussion: Despite the higher variations of the ICC of the normal subjects we were able to show that the kinematic set can be used for further analysis. Furthermore, we can confirm that compensation motion of the two prosthesis users were detected in comparison with the normal subjects and we able to quantify this compensation movements. Calculating the APS within the sub phases of each individual task may lead us to more detailed information about the compensation mechanism. References [1] Carey SL, Highsmith MJ, Maitland ME. Clin Biomech 2008;23:1128–35. [2] van Andel CJ, Nienke W, Doorenbosch C, et al. Gait Posture 2008;27:120–7. [3] Jaspers E, Feys H, Bruyninckx H, et al. Gait Posture 2011;33(4):568–75.
http://dx.doi.org/10.1016/j.gaitpost.2015.06.176
Session OS20 Prosthetics Effect of stump parameters on postural stability during stance modification in transtibial amputees K. Orechovska ∗ , Z. Svoboda, Z. Kovacikova, M. Janura Palacky University Olomouc, Faculty of Physical Culture, Olomouc, Czech Republic Research question: The aim of the study was to determine the effect of stump length and stump sensation on postural stability during modifications to stance in unilateral transtibial amputees. Introduction: Stance is an unstable position requiring coordination between intact proprioception, muscle activity and joint mobility, especially at the foot and ankle [1]. Any deficit here leads to deterioration in postural stability. Differences can occur in stability among amputees pursuant to varying stump length [1] and poor
ESMAC Abstracts 2015 / Gait & Posture 42S (2015) S1–S101
stance balance can be also associated with inadequate somatosensory perception in the residual limb [2]. Materials and methods: Sixteen patients with traumatic unilateral transtibial amputation (13 males, 3 females; age 42.8 ± 10.8 years, height 179.6 ± 11.1 cm, weight 88.6 ± 13.9 kg) participated in this study. The length of stump and stump sensation was assessed. For assessing the latter, the two-point discrimination was used. To determine the biomechanical parameters (COP sway and COP velocity movement) of postural stability during stance, the force plate Kistler9286AA was used. The stability was tested in modified situations: stance with eyes opened (EO), with eyes closed (EC), on a foam mat (EOM) and with eyes closed on a foam mat (ECM). For statistical comparison, the Spearmann correlation and the effect size (Cohen’s d) were used. Results: The results showed statistically significant correlation between stump length and COP sway in the anteroposterior direction – AP in EO (r = −0.526) and in EC (r = −0.506), and COP velocity movement in the mediolateral direction – ML (r = −0.597) in EC. In ECM, significant correlations were determined in all tested situations. The results between the group with hyposensitivity and the group with normal sensitivity in COP parameters showed the high effect of hyposensitivity on COP sway in AP (d = 1.04) in EOM, medium effect on COP sway in AP (d = 0.68) and ML (d = 0.51) in EO and in ML (d = 0.53) in EOM. Medium effect was found on COP velocity movement in AP in EO (d = 0.50) and in EC (d = 0.52). Discussion: The outputs indicate a significant correlation between stump length and COP parameters during stance modification, especially in the stance on foam mat with eyes closed. It shows that amputees with longer stump have better stability during stance [1]. Amputees with stump hyposensitivity had less stable stance than amputees with normal sensitivity. Further research encompassing a larger number of subjects would be appropriate to validate these results. References
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on discrete characteristics of trajectories, such as local minimum or maximum of a given joint angle. However, this only reflects a single point in time and therefore offers a limited picture of the physiological functionality within a gait cycle. Materials and methods: For the comparison of the two different approaches kinematic data (3d motion capturing, Vicon, plugin-gait modeling) of a group of n = 30 patients suffering from juvenile idiopathic arthritis (JIA; 13.1 ± 4.1 y; 42.6 ± 14.1 kg; 149.4 ± 13.5 cm) and n = 15 healthy controls (11.0 ± 2.0 y; 38.1 ± 9.9 kg; 147.0 ± 13.0 cm) were analyzed. For HMM modeling, gait cycles were divided into 16 equidistant states which together represent a compact model of the measured time series data (Fig. 1). We introduced a reference based index for the comparison of the pathologic gait and healthy controls using an effect size calculation for each state [2]. Results: The classical method identified for example a significant reduction in maximum hip extension of patients. In contrast, HMM approach not only found this reduction but additionally identified reduced hip extension angles throughout mid to terminal stance phase (7 states, effect size d > 0.7) (Fig. 2). Discussion: Using the HMM approach, information of the whole time series of kinematic data can be used to characterize the func-
[1] Lenka P, Tiberwala DN. Effect of stump length on postural steadiness during quiet stance in unilateral trans-tibial amputee. Al Ameen J Med Sci 2010;1:50–7. [2] Quai TM, Brauer SG, Nitz JC. Somatosensation, circulation and stance balance in elderly dysvascular transtibial amputees. Clin Rehabil 2005;19:668–76.
http://dx.doi.org/10.1016/j.gaitpost.2015.06.177
Session OS21 Methods and Models
Fig. 1. Time series generated by an explicit state duration HMM.
Continuous time series analysis using a Hidden Markov Model enhances informations about joint angle functionality of human gait F. Kreuzpointner 1,∗ , M. Karg 2 , M. Hartmann 3 , W. Seiberl 1 , J.-P. Haas 3 , A. Schwirtz 1 1 Department of Biomechanics in Sports, Technische Universität München, München, Germany 2 Department of Electrical and Computer Engineering, D. R. Cheriton School of Computer Science, Waterloo, ON, Canada 3 Deutsches Zentrum für Kinder- und Jugendrheumatologie, Garmisch-Partenkirchen, Germany
Research question: In order to evaluate possible shortcomings of a classical analysis using discrete parameters, we compared this method [1] with a new approach using the entire characteristic of a whole gait cycle by means of an explicit state duration Hidden Markov Model (HMM) [2]. Introduction: In many clinical laboratories and research articles description, analysis and interpretation of human gait is based
Fig. 2. Modeled hip joint angle and effect size between patients and healthy reference group (colored squares on top; green: small, yellow: medium, red: large effect). (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)
ESMAC Abstracts 2015 / Gait & Posture 42S (2015) S1–S101
This work has demonstrated that it is possible to reduce stumbles and falls in individuals with transfemoral (TF) and transtibial (TT) amputations. Materials and methods: Twenty male service members (28 + 5 years) with unilateral TF (n = 5) or TT amputations (n = 15), who had been walking independently for 21 (range 2–115) months, were trained at a military treatment facility. Training consisted of six 30-minute training sessions over two weeks using a computerized treadmill (Active-Step, Simbex, Lebanon, NH) to deliver destabilizing perturbations giving subjects practice on recovering to avoid a fall. Treatment efficacy was evaluated in three ways. (1) An immersive virtual environment (CAREN, Motek Medical BV, Amsterdam) was used to create postural perturbations and assess trunk flexion angle and velocity following the perturbation. These are validated biomechanical metrics that have been associated with trip-related falls. Testing was done before and zero, three and six months after training. (2) Subjects were given a standardized perturbation (SP) task before and after training to determine training effectiveness. A subject passed the task if he avoided falling without assistance from the safety harness. (3) Patient questionnaires quantified balance confidence in the free-living environment. Results: Training significantly improved ability to avoid falling in both groups. Trunk flexion angle significantly improved after training for TF (p = 0.048) and TT (p = <0.001) and was unchanged (retained) at 3 and 6 months post-training for TF (p = 0.34) and TT (p = 0.19). Also, trunk flexion velocity significantly improved after training, TF (p = 0.17) and TT (p = <0.001) and was unchanged over time, TF (p = 0.06) and TT (p = 0.35). Prior to training, only 20% of TF and 7% of TT subjects avoided a fall following the SP. After training, 100% TF subjects successfully avoided falling, as did 87% of TT subjects. This training transferred to the free-living environment where 60% of the subjects reported a reduction in stumbles and 100% of the subjects avoided uncontrolled falls during the six month post-training period. Discussion: This research tested a novel training protocol to reduce falls in individuals with TF and TT amputations. Subjects had improved functional capabilities, increased reliance on their prosthesis during challenging conditions, and reduced fall-risk for at least six months post-training. The training protocol is effective, efficient, and can be easily implemented in rehabilitation clinics. Acknowledgements: DoD Grant No. W81XWH-11-2-0058 and Navy BUMED, Wounded Ill and Injured Program. Disclaimer: Views expressed are those of the authors and not of the DoD, or U.S. Government. http://dx.doi.org/10.1016/j.gaitpost.2015.06.175
Session OS20 Prosthetics Developing a set of norm data during activities of daily living – Comparison of the 3D kinematics of able-bodied and prosthesis users involving different artificial limbs A. Kranzl 1,∗ , B. Pobatschnig 2 , M. Schachinger 3 1
Orthopedic Hospital Speising, Vienna, Austria 2 Orthopädisches Spital Speising, Otto Bock Healthcare Group, Vienna, Austria 3 Otto Bock Healthcare Group, Vienna, Austria Research question: The aim of this work is to quantify the movement pattern in unilateral and bilateral activities (8 ADL) to
study the compensation movements in the use of hand prostheses with different number of degrees of freedom. Introduction: 3D upper extremities (UE) analysis is not commonly used due to the variety in degrees of freedom and complexity of UE [1,2]. As a result of variety of functional tasks for UE developing a standard protocol is very complex [2]. Therefore the aim of the study is to develop a set of norm data and to obtain information about the norm movement patterns during activities of daily living (ADL). In addition, norm data are compared to prosthesis users to understand their compensatory movements and to get a reference for evaluation of several artificial limbs. Materials and methods: 20 able-bodied subjects (26.3 years ±2.17) and two prosthesis users with different prostheses are being recorded via 3D motion capture system (biomechanical upper limb model [3]). 8 different ADL were recorded for each subject. Tasks are separated into different phases by means of proximity devices in order to interpolate angle progression in every phase and to make data more comparable. To check the validity of the standard data set for all ADL, the homogeneity of the individual movement patterns of the subjects and the homogeneity of the mean-values of all subjects was compared (ICC). In addition the Arm Profile Score (APS) was calculated to compare the outcome. Results: For all ADL we have found good values for ICC between 0.66 and 0.99 within the subjects and 0.5 and 0.99 over the subjects. Depending on the prosthetic devices differences can be detected concerning the APS values of the prosthetic users compared to the normal subjects. The device with the fixed wrist joint causes an increased average root means square errors in the elbow (sagittal, transverse) and shoulder (frontal, transverse). The device with the flexible wrist joint has increased values primarily in the shoulder (frontal, transverse) compared to the norm. Discussion: Despite the higher variations of the ICC of the normal subjects we were able to show that the kinematic set can be used for further analysis. Furthermore, we can confirm that compensation motion of the two prosthesis users were detected in comparison with the normal subjects and we able to quantify this compensation movements. Calculating the APS within the sub phases of each individual task may lead us to more detailed information about the compensation mechanism. References [1] Carey SL, Highsmith MJ, Maitland ME. Clin Biomech 2008;23:1128–35. [2] van Andel CJ, Nienke W, Doorenbosch C, et al. Gait Posture 2008;27:120–7. [3] Jaspers E, Feys H, Bruyninckx H, et al. Gait Posture 2011;33(4):568–75.
http://dx.doi.org/10.1016/j.gaitpost.2015.06.176
Session OS20 Prosthetics Effect of stump parameters on postural stability during stance modification in transtibial amputees K. Orechovska ∗ , Z. Svoboda, Z. Kovacikova, M. Janura Palacky University Olomouc, Faculty of Physical Culture, Olomouc, Czech Republic Research question: The aim of the study was to determine the effect of stump length and stump sensation on postural stability during modifications to stance in unilateral transtibial amputees. Introduction: Stance is an unstable position requiring coordination between intact proprioception, muscle activity and joint mobility, especially at the foot and ankle [1]. Any deficit here leads to deterioration in postural stability. Differences can occur in stability among amputees pursuant to varying stump length [1] and poor
ESMAC Abstracts 2015 / Gait & Posture 42S (2015) S1–S101
stance balance can be also associated with inadequate somatosensory perception in the residual limb [2]. Materials and methods: Sixteen patients with traumatic unilateral transtibial amputation (13 males, 3 females; age 42.8 ± 10.8 years, height 179.6 ± 11.1 cm, weight 88.6 ± 13.9 kg) participated in this study. The length of stump and stump sensation was assessed. For assessing the latter, the two-point discrimination was used. To determine the biomechanical parameters (COP sway and COP velocity movement) of postural stability during stance, the force plate Kistler9286AA was used. The stability was tested in modified situations: stance with eyes opened (EO), with eyes closed (EC), on a foam mat (EOM) and with eyes closed on a foam mat (ECM). For statistical comparison, the Spearmann correlation and the effect size (Cohen’s d) were used. Results: The results showed statistically significant correlation between stump length and COP sway in the anteroposterior direction – AP in EO (r = −0.526) and in EC (r = −0.506), and COP velocity movement in the mediolateral direction – ML (r = −0.597) in EC. In ECM, significant correlations were determined in all tested situations. The results between the group with hyposensitivity and the group with normal sensitivity in COP parameters showed the high effect of hyposensitivity on COP sway in AP (d = 1.04) in EOM, medium effect on COP sway in AP (d = 0.68) and ML (d = 0.51) in EO and in ML (d = 0.53) in EOM. Medium effect was found on COP velocity movement in AP in EO (d = 0.50) and in EC (d = 0.52). Discussion: The outputs indicate a significant correlation between stump length and COP parameters during stance modification, especially in the stance on foam mat with eyes closed. It shows that amputees with longer stump have better stability during stance [1]. Amputees with stump hyposensitivity had less stable stance than amputees with normal sensitivity. Further research encompassing a larger number of subjects would be appropriate to validate these results. References
S97
on discrete characteristics of trajectories, such as local minimum or maximum of a given joint angle. However, this only reflects a single point in time and therefore offers a limited picture of the physiological functionality within a gait cycle. Materials and methods: For the comparison of the two different approaches kinematic data (3d motion capturing, Vicon, plugin-gait modeling) of a group of n = 30 patients suffering from juvenile idiopathic arthritis (JIA; 13.1 ± 4.1 y; 42.6 ± 14.1 kg; 149.4 ± 13.5 cm) and n = 15 healthy controls (11.0 ± 2.0 y; 38.1 ± 9.9 kg; 147.0 ± 13.0 cm) were analyzed. For HMM modeling, gait cycles were divided into 16 equidistant states which together represent a compact model of the measured time series data (Fig. 1). We introduced a reference based index for the comparison of the pathologic gait and healthy controls using an effect size calculation for each state [2]. Results: The classical method identified for example a significant reduction in maximum hip extension of patients. In contrast, HMM approach not only found this reduction but additionally identified reduced hip extension angles throughout mid to terminal stance phase (7 states, effect size d > 0.7) (Fig. 2). Discussion: Using the HMM approach, information of the whole time series of kinematic data can be used to characterize the func-
[1] Lenka P, Tiberwala DN. Effect of stump length on postural steadiness during quiet stance in unilateral trans-tibial amputee. Al Ameen J Med Sci 2010;1:50–7. [2] Quai TM, Brauer SG, Nitz JC. Somatosensation, circulation and stance balance in elderly dysvascular transtibial amputees. Clin Rehabil 2005;19:668–76.
http://dx.doi.org/10.1016/j.gaitpost.2015.06.177
Session OS21 Methods and Models
Fig. 1. Time series generated by an explicit state duration HMM.
Continuous time series analysis using a Hidden Markov Model enhances informations about joint angle functionality of human gait F. Kreuzpointner 1,∗ , M. Karg 2 , M. Hartmann 3 , W. Seiberl 1 , J.-P. Haas 3 , A. Schwirtz 1 1 Department of Biomechanics in Sports, Technische Universität München, München, Germany 2 Department of Electrical and Computer Engineering, D. R. Cheriton School of Computer Science, Waterloo, ON, Canada 3 Deutsches Zentrum für Kinder- und Jugendrheumatologie, Garmisch-Partenkirchen, Germany
Research question: In order to evaluate possible shortcomings of a classical analysis using discrete parameters, we compared this method [1] with a new approach using the entire characteristic of a whole gait cycle by means of an explicit state duration Hidden Markov Model (HMM) [2]. Introduction: In many clinical laboratories and research articles description, analysis and interpretation of human gait is based
Fig. 2. Modeled hip joint angle and effect size between patients and healthy reference group (colored squares on top; green: small, yellow: medium, red: large effect). (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)