Erik Christiaan Prinsen

Adaptation Strategies of the Lower Extremities of Patients With a Transtibial or Transfemoral Amputation During Level Walking: A Systematic Review

OBJECTIVE To describe adaptation strategies in terms of joint power or work in the amputated and intact leg of patients with a transtibial (TT) or transfemoral (TF) amputation. DATA SOURCES MEDLINE, CINAHL, Physiotherapy Evidence Database, Embase, and the Cochrane Register of Controlled Trials were searched. Studies were collected up to November 1, 2010. Reference lists were additionally scrutinized. STUDY SELECTION Studies were included when they presented joint power or work and compared (1) the amputated and intact legs, (2) the amputated leg and a referent leg, or (3) the intact leg and a referent leg. Eligibility was independently assessed by 2 reviewers. A total of 13 articles were identified. DATA EXTRACTION Data extraction was performed using standardized forms of the Cochrane Collaboration. Methodologic quality was independently assessed using the Downs and Black instrument by 2 reviewers. The possibility of data pooling was examined. Significant differences found in studies that could not be pooled are also presented. DATA SYNTHESIS Significant results (P<.05). For work TT, for the concentric work total stance phase knee, the amputated was less than the intact/referent side, and the referent was less than the intact side. For the eccentric knee extensor (K1) phase, the amputated was less than the intact side, and the intact was greater than the referent side. For the concentric knee extensor (K2) phase, the amputated/referent was less than the intact side. For the concentric work total stance phase hip, the amputated/intact was greater than the referent side. For the concentric hip extensor (H1) phase, the amputated/intact was greater than the referent side. For power TT, for the peak power generation stance phase knee, the amputated was less than the referent side. For peak power generation swing phase knee, the amputated was less than the referent side. For the eccentric knee flexor (K4) phase, the amputated was less than the intact side. For the eccentric hip flexor (H2) phase, the amputated was greater than the intact side. For work TF, for the concentric plantar flexor (A2) phase, the referent was less than the intact side. For the H1 phase, the referent was less than the intact side. For the H2 phase, the amputated was greater than the intact/referent side, and the referent was greater than the intact side. For power TF, for the K2 phase, the referent was less than the intact side. Sensitivity analysis did not alter the conclusions. CONCLUSIONS Adaptations were seen in the amputated and intact legs. TT and TF use remarkably similar adaptation strategies at the level of the hip to compensate for the loss of plantar flexion power and facilitate forward progression. At the knee level, adaptations differed between TT and TF.

Detection of the onset of gait initiation using kinematic sensors and EMG in transfemoral amputees

In this study we determined if detection of the onset of gait initiation in transfemoral amputees can be useful for voluntary control of upper leg prostheses. From six transfemoral amputees inertial sensor data and EMG were measured at the prosthetic leg during gait initiation. First, initial movement was detected from the inertial sensor data. Subsequently it was determined whether EMG could predict initial movement before detection based on the inertial sensors with comparable consistency as the inertial sensors. From the inertial sensors the initial movement can be determined. If the prosthetic leg leads, the upper leg accelerometer data was able to detect initial movement best. If the intact leg leads the upper leg gyroscope data performed best. Inertial sensors at the upper leg in general showed detections at the same time or earlier than those at the lower leg. EMG can predict initial movement up to a 138 ms in advance, when the prosthetic leg leads. One subject showed consistent EMG onset up to 248 ms before initial movement in the intact leg leading condition. A new method to detect initial movement from inertial sensors was presented and can be useful for additional prosthetic control. EMG measured at the prosthetic leg can be used for prediction of gait initiation when the prosthetic leg is leading, but for the intact leg leading condition this will not be of additional value.

Comparison of muscle activity patterns of transfemoral amputees and control subjects during walking

BackgroundOnly few studies have looked at electromyography (EMG) during prosthetic gait. Differences in EMG between normal and prosthetic gait for stance and swing phase were never separately analyzed. These differences can give valuable information if and how muscle activity changes in prosthetic gait.MethodsIn this study EMG activity during gait of the upper leg muscles of six transfemoral amputees, measured inside their own socket, was compared to that of five controls. On and off timings for stance and swing phase were determined together with the level of co-activity and inter-subject variability.Results and conclusionsGait phase changes in amputees mainly consisted of an increased double support phase preceding the prosthetic stance phase. For the subsequent (pre) swing phase the main differences were found in muscle activity patterns of the prosthetic limb, more muscles were active during this phase and/or with prolonged duration. The overall inter-subject variability was larger in amputees compared to controls.

Influence of a user-adaptive prosthetic knee on quality of life, balance confidence, and measures of mobility: a randomised cross-over trial

Objective: To study the influence of a transition from a non-microprocessor controlled to the Rheo Knee® II on quality of life, balance confidence and measures of mobility. Design: Randomised crossover trial. Setting: Research department of a rehabilitation centre. Subjects: Persons with a transfemoral amputation or knee disarticulation (n=10). Interventions: Participants were assessed with their own non-microprocessor controlled knee and with the Rheo Knee® II. The low-profile Vari-Flex with EVO foot was installed in both knee conditions, followed by eight weeks of acclimatisation. The order in which knees were tested was randomised. Main measures: Prosthesis Evaluation Questionnaire with addendum, Activities-specific Balance Confidence scale, Timed “up & go” test, Timed up and down stairs test, Hill Assessment Index, Stairs Assessment Index, Standardized Walking Obstacle Course and One Leg Balance test. Results: Significant higher scores were found for the Rheo Knee® II on the Residual Limb Health subscale of the Prosthesis Evaluation Questionnaire when compared to the non-microprocessor controlled prosthetic knee (median [interquartile range] resp. 86.67 [62.21-93.08] and 68.71 [46.15-94.83]; P=0.047) In addition, participants needed significantly more steps to complete an obstacle course when walking with the Rheo Knee® II compared to the non-microprocessor controlled prosthetic knee (median [interquartile range] resp. 23.50 [19.92-26.25] and 22.17 [19.50-25.75]; P=0.041). On other outcome measures, no significant differences were found. Conclusions: Transition towards the Rheo Knee® II had little effect on the studied outcome measures.

Effect of Chemodenervation of the Rectus Femoris Muscle in Adults With a Stiff Knee Gait Due to Spastic Paresis: A Systematic Review With a Meta-Analysis in Patients With Stroke

OBJECTIVE To determine the effect of motor branch block (MBB) or neuromuscular block (NMB) of the rectus femoris on knee kinematics during swing, functional outcome, and energy cost in adults with spastic paresis presenting a stiff knee gait. DATA SOURCES PubMed, Embase, CINAHL, and Cochrane Library were searched. Studies were collected up to February 26, 2013. Reference lists were additionally scrutinized. STUDY SELECTION No restrictions were applied regarding study design. Patients were adults suffering from a central neurological disorder. Interventions had to include MBB or NMB. Outcome measures had to include knee kinematics during the swing phase. Study selection was independently performed by 2 reviewers. DATA EXTRACTION Two reviewers independently assessed the methodological quality of included studies. Data on kinematics, functional outcome, and energy cost from patients with stroke were extracted from the total population and when possible pooled. DATA SYNTHESIS A total of 9 articles describing 12 different studies were included. Knee kinematics (peak knee flexion or knee range) during swing improved significantly in all the included studies. The average increase in peak knee flexion varied from 1.9° to 15.4°. Data pooling of peak knee flexion in patients with stroke showed a significant improvement of 7.37° (P=.000) in NMB studies and of 9.35° (P=.002) in MBB studies. Data pooling of knee velocity at toe-off showed a significant improvement of 53.01°/s in NMB studies. In MBB studies, this improvement was not significant. Data pooling of knee range of motion, functional outcomes, and energy cost showed no significant difference. CONCLUSIONS According to this review, chemodenervation of the rectus femoris shows a significant improvement in peak knee flexion during swing. The effect on functional outcomes and energy cost is still unclear.

The influence of a user-adaptive prosthetic knee across varying walking speeds: A randomized cross-over trial

Previously conducted trials comparing the gait pattern of individuals with a transfemoral amputation using a user-adaptive and a non-microprocessor-controlled prosthetic knee (NMPK) found mixed and conflicting results. Few trials, however, have compared user-adaptive to non-adaptive prosthetic knees across different walking speeds. Because of the ability of variable damping, the effect of user-adaptive knees might be more pronounced at lower or higher walking speeds. Our aim was to compare the Rheo Knee II (a microprocessor-controlled prosthetic knee) with NMPKs across varying walking speeds. In addition, we studied compensatory mechanisms associated with non-optimal prosthetic knee kinematics, such as intact ankle vaulting and vertical acceleration of the pelvis. Nine persons with a transfemoral amputation or knee disarticulation were included and measured with their own NMPK and with the Rheo Knee II. Measurements were performed at three walking speeds: preferred walking speed, 70% preferred walking speed and 115% preferred walking speed. No differences on peak prosthetic knee flexion during swing were found between prosthetic knee conditions. In addition, prosthetic knee flexion increased significantly with walking speed for both prosthetic knee conditions. At 70% preferred walking speed we found that vaulting of the intact ankle was significantly decreased while walking with the Rheo Knee II compared to the NMPK condition (P=0.028). We did not find differences in peak vertical acceleration of the pelvis during initial and mid-swing of the prosthetic leg. In conclusion, comparison of walking with the Rheo Knee II to walking with a NMPK across different walking speeds showed limited differences in gait parameters.

Added value of a user-adaptive prosthetic knee in planned gait initiation: off to a good start?

Advancements in prosthetic knee design have led to biologically inspired microprocessor-controlled prosthetic knees. The added value of these devices has been extensively studied in walking. However, trials into the activity pattern of persons with an amputation show that the majority of ambulation activities are short in duration. This means that a high percentage of ambulatory activities involves the initiating of gait. Therefore the aim of this paper is to study the added value of a user-adaptive prosthetic knee in gait initiation. Ten persons with an amputation were included and measured with their own non-microprocessor controlled prosthesis and with the Rheo Knee II. In addition, a control group of ten persons without an amputation were included. Measurements were performed using two force plates and a six-camera Vicon system. The persons with an amputation started gait alternately with their intact and prosthetic leg. The results indicated that persons with an amputation heavily rely on the intact leg for the generation of propulsive forces. In addition, the reduced role of the prosthetic leg led to a lower velocity of the centre of mass at the end of the first step in persons with an amputation when compared to the control subjects. The transition towards the Rheo Knee II had no effect on the studied outcome parameters. In conclusion, there is no effect of the transition towards a user-adaptive prosthetic knee on intact leg reliance seen during gait initiation.

Objective Evaluation of Functional Walking in Stroke Survivors

Regaining balance function is often one of the key goals of stroke rehabilitation. Improvements in balance function can be the result of restitution or compensational strategies. In previous studies, the processes of restitution and compensational strategies have been established for straight-line walking. The development of these processes, however, are still largely unknown for other gait activities such as turning and side-stepping. Here, we present a fully ambulant gait analysis system that can be used for an objective evaluation of balance during functional tasks. The results of two individuals are presented: one individual with adequate balance function and one individual with impaired balance function. The analysis showed that the individual with adequate balance function was able to walk with increased instability when compared to the individual with impaired balance function. Based on these results, we conclude that the fully ambulant system is feasible for an objective quantification of balance function.

WeR5 - Human likeliness as a benchmarker for wearable robotics

In recent years benchmarking has become an increasingly important topic for the wearable robotic community. One of the key abilities used during the benchmarking of wearable robots is motion ability. Successful motion ability is achieved once the wearable robot is capable of achieving human-like motion while integrating user controlled volitional movements. This requires an in-depth understanding of the mechanisms underlying commonly observed gait impairments. Only then, a wearable robot can allow the user to make the movements he or she desires while providing support where needed. In this conference contribution we present results of research into the mechanisms underlying gait impairments. We take individuals with a transtibial amputation as an example of unilaterally impaired individuals. These results illustrate how an increased understanding of the gait pattern can assist in the development and evaluation of wearable robots.

The influence of a user-adaptive prosthetic knee on planned gait termination

The added value of user-adaptive prosthetic knees has been predominantly evaluated in level walking or ramp/stair negotiation. Previous studies indicate that the activity pattern of individuals with an amputation mainly consists of short periods of continuous walking, indicating that a high percentage of ambulatory activity involves gait termination. The potential added value of user-adaptive prosthetic knees in gait termination has not been studied yet. Ten individuals with an amputation were measured with their own non-microprocessor controlled prosthetic knee and with the Rheo Knee II (a user-adaptive prosthetic knee). Spatiotemporal, kinematic and kinetic variables were measured. We found that the Rheo Knee II had no effect on the studied outcome parameters when compared to the non-microprocessor controlled prosthetic knee. We also found that the intact leg was responsible for producing the deceleration forces irrespective whether the last step was made by the intact or prosthetic leg. In conclusion we found that the prosthetic leg is limited in producing deceleration forces. Although user-adaptive prosthetic knees claim to increase stance stability, the added value of the Rheo Knee II on the studied outcome parameters is limited.