Stance controlled knee flexion improves stimulation driven walking after spinal cord injury

BackgroundFunctional neuromuscular stimulation (FNS) restores walking function after paralysis from spinal cord injury via electrical activation of muscles in a coordinated fashion. Combining FNS with a controllable orthosis to create a hybrid neuroprosthesis (HNP) has the potential to extend walking distance and time by mechanically locking the knee joint during stance to allow knee extensor muscle to rest with stimulation turned off. Recent efforts have focused on creating advanced HNPs which couple joint motion (e.g., hip and knee or knee and ankle) to improve joint coordination during swing phase while maintaining a stiff-leg during stance phase.MethodsThe goal of this study was to investigate the effects of incorporating stance controlled knee flexion during loading response and pre-swing phases on restored gait. Knee control in the HNP was achieved by a specially designed variable impedance knee mechanism (VIKM). One subject with a T7 level spinal cord injury was enrolled and served as his own control in examining two techniques to restore level over-ground walking: FNS-only (which retained a stiff knee during stance) and VIKM-HNP (which allowed controlled knee motion during stance). The stimulation pattern driving the walking motion remained the same for both techniques; the only difference was that knee extensor stimulation was constant during stance with FNS-only and modulated together with the VIKM to control knee motion during stance with VIKM-HNP.ResultsStance phase knee angle was more natural during VIKM-HNP gait while knee hyperextension persisted during stiff-legged FNS-only walking. During loading response phase, vertical ground reaction force was less impulsive and instantaneous gait speed was increased with VIKM-HNP, suggesting that knee flexion assisted in weight transfer to the leading limb. Enhanced knee flexion during pre-swing phase also aided flexion during swing, especially when response to stimulation was compromised.ConclusionsThese results show the potential advantages of incorporating stance controlled knee flexion into a hybrid neuroprosthesis for walking. The addition of such control to FNS driven walking could also enable non-level walking tasks such as uneven terrain, slope navigation and stair descent where controlled knee flexion during weight bearing is critical.

[1]  B. Andrews,et al.  Augmentation of the Oswestry Parawalker orthosis by means of surface electrical stimulation: gait analysis of three patients , 1987, Paraplegia.

[2]  K. Klose,et al.  Evaluation of a training program for persons with SCI paraplegia using the Parastep 1 ambulation system: part 4. Effect on physical self-concept and depression. , 1997, Archives of physical medicine and rehabilitation.

[3]  Ciara M O'Connor,et al.  Automatic detection of gait events using kinematic data. , 2007, Gait & posture.

[4]  K J Klose,et al.  Evaluation of a training program for persons with SCI paraplegia using the Parastep 1 ambulation system: part 5. Lower extremity blood flow and hyperemic responses to occlusion are augmented by ambulation training. , 1997, Archives of physical medicine and rehabilitation.

[5]  R. Kearney,et al.  The effects of long-term FES-assisted walking on intrinsic and reflex dynamic stiffness in spastic spinal-cord-injured subjects , 2002, IEEE Transactions on Neural Systems and Rehabilitation Engineering.

[6]  E. Marsolais,et al.  Implanted functional electrical stimulation system for mobility in paraplegia: a follow-up case report. , 1999, IEEE transactions on rehabilitation engineering : a publication of the IEEE Engineering in Medicine and Biology Society.

[7]  B. Heller,et al.  A new hybrid spring brake orthosis for controlling hip and knee flexion in the swing phase , 2001, IEEE Transactions on Neural Systems and Rehabilitation Engineering.

[8]  S. Tashman,et al.  The Case Western Reserve University Hybrid Gait Orthosis , 2000, The journal of spinal cord medicine.

[9]  R. J. Triolo,et al.  Force-velocity and length-tension properties of stimulated human quadriceps muscle in spinal cord injured children , 1989, Images of the Twenty-First Century. Proceedings of the Annual International Engineering in Medicine and Biology Society,.

[10]  Scott Tashman,et al.  Development Of A Hybrid Gait Orthosis: A Case Report , 2003, The journal of spinal cord medicine.

[11]  J. R. Schnellenberger,et al.  Stance control knee mechanism for lower-limb support in hybrid neuroprosthesis. , 2011, Journal of rehabilitation research and development.

[12]  G M Davis,et al.  Benefits of FES gait in a spinal cord injured population , 2007, Spinal Cord.

[13]  A. Dollar,et al.  Estimation of Quasi-Stiffness of the Human Knee in the Stance Phase of Walking , 2013, PloS one.

[14]  Ronald J. Triolo,et al.  Restoration of stance phase knee flexion during walking after spinal cord injury using a variable impedance orthosis , 2011, 2011 Annual International Conference of the IEEE Engineering in Medicine and Biology Society.

[15]  R. Kobetic,et al.  Finite State Control of a Variable Impedance Hybrid Neuroprosthesis for Locomotion After Paralysis , 2013, IEEE Transactions on Neural Systems and Rehabilitation Engineering.

[16]  D Gordon E Robertson,et al.  Kinetic analysis of forwards and backwards stair descent. , 2008, Gait & posture.

[17]  T. Bajd,et al.  The use of a four-channel electrical stimulator as an ambulatory aid for paraplegic patients. , 1983, Physical therapy.

[18]  Ronald J. Triolo,et al.  A Variable Impedance Knee Mechanism for Controlled Stance Flexion During Pathological Gait , 2012, IEEE/ASME Transactions on Mechatronics.

[19]  Rudi Kobetic,et al.  Functional Electrical Stimulation For Walking In Paraplegia: 17-Year Follow-Up Of 2 Cases , 2003, The journal of spinal cord medicine.

[20]  A. Hosman,et al.  Who wants to walk? Preferences for recovery after SCI: a longitudinal and cross-sectional study , 2008, Spinal Cord.

[21]  Michael Goldfarb,et al.  Design of a joint-coupled orthosis for FES-aided gait , 2009, 2009 IEEE International Conference on Rehabilitation Robotics.

[22]  L. Schwirtlich,et al.  Hybrid assistive system-the motor neuroprosthesis , 1989, IEEE Transactions on Biomedical Engineering.

[23]  B. Andrews,et al.  The role of functional electrical stimulation in the rehabilitation of patients with incomplete spinal cord injury - observed benefits during gait studies , 1993, Paraplegia.

[24]  J. Ditunno,et al.  Who wants to walk? Preferences for recovery after SCI: a longitudinal and cross-sectional study , 2008, Spinal Cord.

[25]  R. Douglas,et al.  Ambulation using the reciprocating gait orthosis and functional electrical stimulation , 1992, Paraplegia.

[26]  William Durfee,et al.  Engineering evaluation of the energy-storing orthosis FES gait system , 2010, 2010 Annual International Conference of the IEEE Engineering in Medicine and Biology.

[27]  G. Obinata,et al.  An electrical knee lock system for functional electrical stimulation. , 1996, Archives of physical medicine and rehabilitation.

[28]  Richard A. Brand,et al.  The biomechanics and motor control of human gait: Normal, elderly, and pathological , 1992 .

[29]  Steven J Stanhope,et al.  Changes in knee joint function over a wide range of walking speeds. , 1997, Clinical biomechanics.

[30]  S. Gard,et al.  The influence of stance-phase knee flexion on the vertical displacement of the trunk during normal walking. , 1999, Archives of physical medicine and rehabilitation.

[31]  Aaron M. Dollar,et al.  Lower Extremity Exoskeletons and Active Orthoses: Challenges and State-of-the-Art , 2008, IEEE Transactions on Robotics.

[32]  M. Devivo,et al.  Epidemiology of traumatic spinal cord injury: trends and future implications , 2012, Spinal Cord.

[33]  R. D'ambrosia,et al.  Reciprocating gait orthosis powered with electrical muscle stimulation (RGO II). Part I: Performance evaluation of 70 paraplegic patients. , 1997, Orthopedics.

[34]  M. Pandy,et al.  Contributions of muscle forces and toe-off kinematics to peak knee flexion during the swing phase of normal gait: an induced position analysis. , 2004, Journal of biomechanics.

[35]  M. Granat,et al.  A knee and ankle flexing hybrid orthosis for paraplegic ambulation. , 2003, Medical engineering & physics.

[36]  Andrea N. Lay,et al.  The effects of sloped surfaces on locomotion: a kinematic and kinetic analysis. , 2006, Journal of biomechanics.

[37]  M. Pandy,et al.  Muscles that influence knee flexion velocity in double support: implications for stiff-knee gait. , 2004, Journal of biomechanics.

[38]  Scott L Delp,et al.  The importance of swing-phase initial conditions in stiff-knee gait. , 2003, Journal of biomechanics.

[39]  R. Kobetic,et al.  Gait Evaluation of a Novel Hip Constraint Orthosis With Implication for Walking in Paraplegia , 2010, IEEE Transactions on Neural Systems and Rehabilitation Engineering.

[40]  J. Reinbolt,et al.  Importance of preswing rectus femoris activity in stiff-knee gait. , 2008, Journal of biomechanics.

[41]  S. Simon.  Gait Analysis, Normal and Pathological Function. , 1993 .

[42]  M. Goldfarb,et al.  Preliminary evaluation of a controlled-brake orthosis for FES-aided gait , 2003, IEEE Transactions on Neural Systems and Rehabilitation Engineering.

[43]  E. Marsolais,et al.  Synthesis of paraplegic gait with multichannel functional neuromuscular stimulation , 1994 .