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How crouch gait can dynamically lead to stiff-knee gait?
Abstracts / Gait & Posture 30S (2009) S1–S153
in understanding how pathology (e.g. spasticity and contracture) affects function. Future work will include developing a database of normal F–L curves to enhance clinical interpretation. References [1] [2] [3] [4]
Arnold, et al. Gait Posture 2006;23(3):273–81. Schwartz, et al. J Biomechanics 2008;41(8):1639–50. Delp, et al. IEEE Trans Biomed Eng 2007;54(11):1940–50. van der Krogt, et al. Gait Posture 2007;26(4):532–8.
doi:10.1016/j.gaitpost.2009.08.113 O110 How crouch gait can dynamically lead to stiff-knee gait? Marjolein van der Krogt 1,∗ , Daan Bregman 1 , Martijn Wisse 2 , Caroline Doorenbosch 1 , Jaap Harlaar 1 , Steven Collins 2 1 2
VU University Medical Center, Amsterdam, Netherlands Delft University of Technology, Delft, Netherlands
Summary A forward dynamic model of human gait was developed and used to study possible causes of stiff-knee gait. Conclusions Our modelling results showed that a crouched posture in stance intrinsically leads to decreased knee flexion in swing. This indicates that stiff-knee gait may partially arise from natural dynamics of the system, rather than from abnormal neuromuscular functioning alone. Introduction Lack of adequate knee flexion during the swing phase of gait (stiff-knee gait) is a common gait deviation in children with cerebral palsy. It is often accompanied by a flexed-knee (crouch) gait pattern in stance. The aim of this study was to investigate the effect of a crouched posture, as well as the effects of push-off strength and hip torque, on knee flexion in swing. Patients/materials and methods We developed a dynamic walking model of human gait (Fig. 1A), with a passive knee in swing. The model was powered by an instantaneous push-off impulse [1,2]. It produced stable, cyclic gait patterns for a range of stance leg knee flexion (crouch) angles. The effect of crouch angle in stance on knee flexion in swing was evaluated. Furthermore, we evaluated the influence of push-off impulse size and the addition of a hip flexion torque in early swing on knee flexion in swing.
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Results Without the presence of crouch, the model showed sufficient knee flexion and clearance in swing. When increasing the crouch angle of the model in stance, the knee flexed much less in swing, resulting in a ‘stiff-knee’ gait pattern (Fig. 1B). This led to reduced clearance in swing. Increases in push-off impulse size and hip flexion torque led to more knee flexion in swing. However, the effect of a crouched posture on stiff-knee remained, independent of these factors. Discussion The decreased knee flexion in swing with crouch angle can be explained by the passive dynamics of the model’s swing leg due to differences in position of the leg at swing initiation. These findings indicate that decreased knee flexion in swing can occur purely as a result of crouch, without any differences in actuation. Patients walking in crouch may thus experience problems with knee flexion in swing due to the intrinsic dynamics of the altered posture. Based on the current results, treatment of these patients at the (stiff) knee level, e.g. with rectus femoris transfer or botulinum toxin treatment, may not achieve the desired effects if the stiffknee has a dynamic cause. Treatment of these patients may better be directed at improving their upright posture, which may by itself improve their knee motion in swing and reduce stiff-knee gait. References [1] McGeer. Int J Robot Res 1990;9:68–82. [2] Kuo. J Biomech Eng 2002;124(1):113–20.
doi:10.1016/j.gaitpost.2009.08.114 O111 Does treadmill walking modify fractal dynamics and local dynamic stability of the gait? Philippe Terrier ∗ , Olivier Dériaz Institut de Recherche en Réadaptation, Sion, Switzerland Summary The purpose of the present study was to analyze the difference between motorized treadmill walking (TW) and overground walking (OW). The methods were trunk accelerometry and nonlinear analysis. We observed that the fractal dynamics normally observed in the stride intervals were modified in TW condition. In addition, TW increased the local dynamic stability of the gait.
Fig. 1. (A) Schematic representation of the model; (B) Knee angles versus gait cycle for a range of imposed stance leg knee angles.
in understanding how pathology (e.g. spasticity and contracture) affects function. Future work will include developing a database of normal F–L curves to enhance clinical interpretation. References [1] [2] [3] [4]
Arnold, et al. Gait Posture 2006;23(3):273–81. Schwartz, et al. J Biomechanics 2008;41(8):1639–50. Delp, et al. IEEE Trans Biomed Eng 2007;54(11):1940–50. van der Krogt, et al. Gait Posture 2007;26(4):532–8.
doi:10.1016/j.gaitpost.2009.08.113 O110 How crouch gait can dynamically lead to stiff-knee gait? Marjolein van der Krogt 1,∗ , Daan Bregman 1 , Martijn Wisse 2 , Caroline Doorenbosch 1 , Jaap Harlaar 1 , Steven Collins 2 1 2
VU University Medical Center, Amsterdam, Netherlands Delft University of Technology, Delft, Netherlands
Summary A forward dynamic model of human gait was developed and used to study possible causes of stiff-knee gait. Conclusions Our modelling results showed that a crouched posture in stance intrinsically leads to decreased knee flexion in swing. This indicates that stiff-knee gait may partially arise from natural dynamics of the system, rather than from abnormal neuromuscular functioning alone. Introduction Lack of adequate knee flexion during the swing phase of gait (stiff-knee gait) is a common gait deviation in children with cerebral palsy. It is often accompanied by a flexed-knee (crouch) gait pattern in stance. The aim of this study was to investigate the effect of a crouched posture, as well as the effects of push-off strength and hip torque, on knee flexion in swing. Patients/materials and methods We developed a dynamic walking model of human gait (Fig. 1A), with a passive knee in swing. The model was powered by an instantaneous push-off impulse [1,2]. It produced stable, cyclic gait patterns for a range of stance leg knee flexion (crouch) angles. The effect of crouch angle in stance on knee flexion in swing was evaluated. Furthermore, we evaluated the influence of push-off impulse size and the addition of a hip flexion torque in early swing on knee flexion in swing.
S77
Results Without the presence of crouch, the model showed sufficient knee flexion and clearance in swing. When increasing the crouch angle of the model in stance, the knee flexed much less in swing, resulting in a ‘stiff-knee’ gait pattern (Fig. 1B). This led to reduced clearance in swing. Increases in push-off impulse size and hip flexion torque led to more knee flexion in swing. However, the effect of a crouched posture on stiff-knee remained, independent of these factors. Discussion The decreased knee flexion in swing with crouch angle can be explained by the passive dynamics of the model’s swing leg due to differences in position of the leg at swing initiation. These findings indicate that decreased knee flexion in swing can occur purely as a result of crouch, without any differences in actuation. Patients walking in crouch may thus experience problems with knee flexion in swing due to the intrinsic dynamics of the altered posture. Based on the current results, treatment of these patients at the (stiff) knee level, e.g. with rectus femoris transfer or botulinum toxin treatment, may not achieve the desired effects if the stiffknee has a dynamic cause. Treatment of these patients may better be directed at improving their upright posture, which may by itself improve their knee motion in swing and reduce stiff-knee gait. References [1] McGeer. Int J Robot Res 1990;9:68–82. [2] Kuo. J Biomech Eng 2002;124(1):113–20.
doi:10.1016/j.gaitpost.2009.08.114 O111 Does treadmill walking modify fractal dynamics and local dynamic stability of the gait? Philippe Terrier ∗ , Olivier Dériaz Institut de Recherche en Réadaptation, Sion, Switzerland Summary The purpose of the present study was to analyze the difference between motorized treadmill walking (TW) and overground walking (OW). The methods were trunk accelerometry and nonlinear analysis. We observed that the fractal dynamics normally observed in the stride intervals were modified in TW condition. In addition, TW increased the local dynamic stability of the gait.
Fig. 1. (A) Schematic representation of the model; (B) Knee angles versus gait cycle for a range of imposed stance leg knee angles.