Real time ECG artifact removal for myoelectric prosthesis control

The electrocardiogram (ECG) artifact is a major noise source contaminating the electromyogram (EMG) of torso muscles. This study investigates removal of ECG artifacts in real time for myoelectric prosthesis control, a clinical application that demands speed and efficiency. Three methods with simple and fast implementation were investigated. Removal of ECG artifacts by digital high-pass filtering was implemented. The effects of the cutoff frequency and filter order of high-pass filtering on the resulting EMG signal were quantified. An alternative adaptive spike-clipping approach was also developed to dynamically detect and suppress the ECG artifacts in the signal. Finally, the two methods were combined. Experimental surface EMG recordings with different ECG/EMG ratios were used as testing signals to evaluate the proposed methods. As a key parameter for clinical myoelectric prosthesis control, the average rectified amplitude of the signal was used as the performance indicator to quantitatively analyze the EMG content distortion and the ECG artifact suppression imposed by the two methods. Aiming at clinical application, the optimal parameter assignment for each method was determined on the basis of the performance using the suite of testing signals with various ECG/EMG ratios.     

Targeted reinnervation for improved prosthetic function

Target motor reinnervation can produce additional myoelectric control signals for improved powered prosthesis control. This reinnervation allows simultaneous operation of multiple functions in an externally powered prosthesis with physiologically appropriate pathways, and it provides more intuitive control than is possible with conventional myoelectric prostheses.Target sensory reinnervation has the potential to provide the sensory feed-back to the amputee that feels like it is in the missing limb. This concept has great potential for improving the function of people with upper limb amputations, especially for high-level amputations, in which the disability is greatest. It is hoped that future research will develop the technique further and build synergistically with other exciting research areas.     

Control of a six degree of freedom prosthetic arm after targeted muscle reinnervation surgery

Miller LA, Lipschutz RD, Stubblefield KA, Lock BA, Huang H, Williams III TW, Weir RF, Kuiken TA. Control of a six degree of freedom prosthetic arm after targeted muscle reinnervation surgery.

Objectives

To fit and evaluate the control of a complex prosthesis for a shoulder disarticulation-level amputee with targeted muscle reinnervation.

Design

One participant who had targeted muscle reinnervation surgery was fitted with an advanced prosthesis and his use of this device was compared with the device that he used in the home setting.

Setting

The experiments were completed within a laboratory setting.

Participant

The first recipient of targeted muscle reinnervation: a bilateral shoulder disarticulation-level amputee.

Interventions

Two years after surgery, the subject was fitted with a 6 degree of freedom (DOF) prosthesis (shoulder flexion, humeral rotation, elbow flexion, wrist rotation, wrist flexion, and hand control). Control of this device was compared with that of his commercially available 3-DOF system (elbow, wrist rotation, and powered hook terminal device).

Main Outcome Measure

In order to assess performance, movement analysis and timed movement tasks were executed.

Results

The subject was able to independently operate all 6 arm functions with good control. He could simultaneously operate 2 DOF of several different joint combinations with relative ease. He operated up to 4 DOF simultaneously, but with poor control. Work space was markedly increased and some timed tasks were faster with the 6-DOF system.

Conclusions

This proof-of-concept study shows that advances in control of shoulder disarticulation-level prostheses can improve the quality of movement. Additional control sources may spur the development of more advanced and complex componentry for these amputees.     

Muscle activation patterns during walking from transtibial amputees recorded within the residual limb-prosthetic interface

Powered lower limb prostheses could be more functional if they had access to feedforward control signals from the user’s nervous system. Myoelectric signals are one potential control source. The purpose of this study was to determine if muscle activation signals could be recorded from residual lower limb muscles within the prosthetic socket-limb interface during walking. We recorded surface electromyography from three lower leg muscles (tibilias anterior, gastrocnemius medial head, gastrocnemius lateral head) and four upper leg muscles (vastus lateralis, rectus femoris, biceps femoris, and gluteus medius) of 12 unilateral transtibial amputee subjects and 12 non-amputee subjects during treadmill walking at 0.7, 1.0, 1.3, and 1.6 m/s. Muscle signals were recorded from the amputated leg of amputee subjects and the right leg of control subjects. For amputee subjects, lower leg muscle signals were recorded from within the limb-socket interface and from muscles above the knee. We quantified differences in the muscle activation profile between amputee and control groups during treadmill walking using cross-correlation analyses. We also assessed the step-to-step inter-subject variability of these profiles by calculating variance-to-signal ratios. We found that amputee subjects demonstrated reliable muscle recruitment signals from residual lower leg muscles recorded within the prosthetic socket during walking, which were locked to particular phases of the gait cycle. However, muscle activation profile variability was higher for amputee subjects than for control subjects. Robotic lower limb prostheses could use myoelectric signals recorded from surface electrodes within the socket-limb interface to derive feedforward commands from the amputee’s nervous system.     

双侧髋关节离断假肢交互步态行走机构的研究

目的设计一种与双侧髋关节离断假肢其他配件连接的交互步态行走机构。方法将截瘫患者用矫形器交互步态行走原理应用于双侧髋关节离断假肢交互步态行走机构中,为1例截肢者安装交互步态行走假肢,并与穿普通加拿大式双髋离断假肢摆过步态的行走速度和能量消耗进行比较。结果患者穿交互步态行走假肢交互步行比穿普通加拿大式双髋离断假肢摆过步行能量消耗少,且减轻上肢负荷,行走外观更接近常人;后者比前者行走速度快,但是能耗高。结论本截肢者交互步态行走假肢比传统假肢步行能量消耗少,行走外观更接近常人。     

Muscle activation patterns during walking from transtibial amputees recorded within the residual limb-prosthetic interface

ABSTRACT: BACKGROUND: Powered lower limb prostheses could be more functional if they had access to feedforward control signals from the user's nervous system. Myoelectric signals are one potential control source. The purpose of this study was to determine if muscle activation signals could be recorded from residual lower limb muscles within the prosthetic socket-limb interface during walking. METHODS: We recorded surface electromyography from three lower leg muscles (tibilias anterior, gastrocnemius medial head, gastrocnemius lateral head) and four upper leg muscles (vastus lateralis, rectus femoris, biceps femoris, and gluteus medius) of 12 unilateral transtibial amputee subjects and 12 non-amputee subjects during treadmill walking at 0.7, 1.0, 1.3, and 1.6 m/s. Muscle signals were recorded from the amputated leg of amputee subjects and the right leg of control subjects. For amputee subjects, lower leg muscle signals were recorded from within the limb-socket interface and from muscles above the knee. We quantified differences in the muscle activation profile between amputee and control groups during treadmill walking using cross-correlation analyses. We also assessed the step-to-step intersubject variability of these profiles by calculating variance-to-signal ratios. RESULTS: We found that amputee subjects demonstrated reliable muscle recruitment signals from residual lower leg muscles recorded within the prosthetic socket during walking, which were locked to particular phases of the gait cycle. However, muscle activation profile variability was higher for amputee subjects than for control subjects. CONCLUSION: Robotic lower limb prostheses could use myoelectric signals recorded from surface electrodes within the socket-limb interface to derive feedforward commands from the amputee's nervous system.     

全骨盆切除后胸廓承重接受腔和交互步态行走假肢适配1例报道

目的 探讨全骨盆切除术后胸廓承重接受腔和交互步态行走假肢的设计、装配和使用方法。     

An analysis of extended physiological proprioception as a prosthesis-control technique

This research was devoted to an investigation of the practicality and potential effectiveness of applying the concept of extended physiological proprioception (EPP) to the control of upper-limb prostheses. The purpose of this study was to verify that EPP control, implemented by coupling prosthesis function to residual shoulder motion in a position-servo relationship, could be effectively applied in multifunctional prostheses for shoulder disarticulation amputees. Although Simpson has shown that the principle works, the authors wanted to quantify its effectiveness and analyze its limitations. Studies were performed analyzing the feasibility of using shoulder elevation-depression and protraction-retraction as prosthesis control inputs. The results of this study showed that a prosthesis mechanism with nonlimiting dynamic response characteristics and shoulder-activated EPP control of wrist rotation and elbow flexion/extension, exhibited functional characteristics comparable to those of the physiological elbow and wrist as defined by tracking capabilities. The results of this investigation also showed that shoulder-effected position control of prosthesis function has considerably more potential for providing effective control than similarly effected velocity control.     

The Time-dependent Changes in EMG Recorded from the Medial Gastrocnemius of Young and Elderly Amputees

[Purpose] Dysfunction of lower extremity muscles is one risk factor of falls for amputee patients. However, the change in muscle activity pattern and balance ability of amputees who have no experience in standing with prosthesis during the period from prosthesis fitting to regaining the ability to walk has never been studied. Therefore, the objectives of the present study were to elucidate changes over time in the muscle activity pattern and walking speed from first prosthesis fitting to hospital discharge. We also investigated the differences of muscle activity during standing between younger and elderly amputee patients. [Methods] Electromyography measurements were performed on the gastrocnemius of the intact leg during standing. The test subjects were asked to shift their center of gravity forward. [Results] Two unique patterns of gastrocnemius activities were observed over time. In a younger patient, the amount of muscular activity of the gastrocnemius gradually increased over time. In an elderly patient, however, the amount of muscular activity of gastrocnemius gradually decreased over time. [Conclusion] The time-dependent changes in gastrocnemius muscle activities are indicative postural control ability. Therefore, understanding the time-dependent changes in muscle activities during rehabilitation and the differences of postural control between younger and elderly patients would contribute to the development of effective rehabilitation programs for each patient.Key words: Prosthesis, Postural control, EMG     

A self-contained, mechanomyography-driven externally powered prosthesis

The measurement of the low-frequency (5-50 Hz) "sounds" or vibrations produced by contracting muscles is termed mechanomyography (MMG). As a control signal for powered prostheses, MMG offers several advantages over conventional myoelectric control, including, nonspecific sensor placement, distal signal measurement, robustness to changing skin impedance, and reduced sensor costs. The objectives of this study were to demonstrate 2-function prosthesis control based on a triplet of distally recorded, normalized root mean square MMG signals and to identify necessary future research toward full clinical implementation of MMG signals in upper-limb externally powered prostheses. A novel self-contained MMG-driven prosthesis for below-elbow amputees was designed, implemented, and preliminarily tested on 2 subjects. This prosthesis was composed of specialized software and hardware modules that emulate a 2-site electromyography sensing system. Although the use of MMG signals for prosthesis control has been shown previously, we report, for the first time, successful control within a self-contained unit in unconstrained environments. Specifically, essential requirements for practical use, such as standardized sensor attachment, basic noise elimination, and miniaturization of the system, have been achieved. Both subjects were able to voluntarily open and close the prosthesis hand with no significant delays from intention to action (approximately 120 ms). Quantitative analyses revealed 88% and 71% control accuracy for subjects 1 and 2, respectively.     

Amputation rehabilitation and prosthetic restoration. From surgery to community reintegration

PURPOSE: The purpose of this review is to summarize the literature related to the advances that have taken place in the management and rehabilitation care of limb amputation. RESULTS: Prostheses for the lower and upper limb amputee have changed greatly over the past several years, with advances in components, socket fabrication and fitting techniques, suspension systems and sources of power and electronic controls. Higher levels of limb amputation can now be fitted with functional prostheses, which allow more patients to achieve independent life styles. This is of particular importance for the multi-limb amputee. The rehabilitation of more traditional lower limb levels of amputation have also greatly benefited from the technological advances including energy storing feet, electronic control hydraulic knees, ankle rotators and shock absorbers to mention a few. For the upper limb amputee, myoelectric and proportional controlled terminal devices and elbow joints are now used routinely in some rehabilitation facilities. Experimental prosthetic fitting techniques and devices such as the use of osseo-implantation for suspension of the prosthesis, tension control hands or electromagnetic fluids for knee movement control will also be briefly discussed in this paper. CONCLUSION: It is possible to conclude from this review that many advances have occurred that have greatly impacted the functional outcomes of patients with limb amputation.     

Amputation rehabilitation and prosthetic restoration. From surgery to community reintegration

Purpose:?The purpose of this review is to summarize the literature related to the advances that have taken place in the management and rehabilitation care of limb amputation.

Results:?Prostheses for the lower and upper limb amputee have changed greatly over the past several years, with advances in components, socket fabrication and fitting techniques, suspension systems and sources of power and electronic controls. Higher levels of limb amputation can now be fitted with functional prostheses, which allow more patients to achieve independent life styles. This is of particular importance for the multi-limb amputee. The rehabilitation of more traditional lower limb levels of amputation have also greatly benefited from the technological advances including energy storing feet, electronic control hydraulic knees, ankle rotators and shock absorbers to mention a few. For the upper limb amputee, myoelectric and proportional controlled terminal devices and elbow joints are now used routinely in some rehabilitation facilities. Experimental prosthetic fitting techniques and devices such as the use of osseo-implantation for suspension of the prosthesis, tension control hands or electromagnetic fluids for knee movement control will also be briefly discussed in this paper.

Conclusion:?It is possible to conclude from this review that many advances have occurred that have greatly impacted the functional outcomes of patients with limb amputation.     

Amputation rehabilitation and prosthetic restoration. From surgery to community reintegration

Purpose: The purpose of this review is to summarize the literature related to the advances that have taken place in the management and rehabilitation care of limb amputation.

Results: Prostheses for the lower and upper limb amputee have changed greatly over the past several years, with advances in components, socket fabrication and fitting techniques, suspension systems and sources of power and electronic controls. Higher levels of limb amputation can now be fitted with functional prostheses, which allow more patients to achieve independent life styles. This is of particular importance for the multi-limb amputee. The rehabilitation of more traditional lower limb levels of amputation have also greatly benefited from the technological advances including energy storing feet, electronic control hydraulic knees, ankle rotators and shock absorbers to mention a few. For the upper limb amputee, myoelectric and proportional controlled terminal devices and elbow joints are now used routinely in some rehabilitation facilities. Experimental prosthetic fitting techniques and devices such as the use of osseo-implantation for suspension of the prosthesis, tension control hands or electromagnetic fluids for knee movement control will also be briefly discussed in this paper.

Conclusion: It is possible to conclude from this review that many advances have occurred that have greatly impacted the functional outcomes of patients with limb amputation.     

Biomechanical adaptations of transtibial amputee sprinting in athletes using dedicated prostheses

OBJECTIVE: To determine the biomechanical adaptations of the prosthetic and sound limbs in two of the world's best transtibial amputee athletes whilst sprinting. DESIGN: Case study design, repeated measures. BACKGROUND: Using dedicated sprint prostheses transtibial amputees have run the 100 m in a little over 11 s. Lower-limb biomechanics when using such prostheses have not previously been investigated. METHODS: Moments, muscle powers and the mechanical work done at the joints of the prosthetic and sound limbs were calculated as subjects performed repeated maximal sprint trials using a Sprint Flex or Cheetah prosthesis. RESULTS: An increased hip extension moment on the prosthetic limb, with an accompanying increase in the amount of concentric work done, was the most notable adaptation in Subject 1 using either prosthesis. In Subject 2, an increased extension moment at the residual knee, and an accompanying increase in the amount of total work done, was the most notable adaptation using either prosthesis. This later adaptation was also evident in Subject 1 when using his Sprint Flex prosthesis. CONCLUSIONS: Increased hip work on the prosthetic limb has previously been shown to be the major compensatory mechanism that allow transtibial amputees to run. The increased work found at the residual knee, suggests that the two amputee sprinters used an additional compensatory mechanism. RELEVANCE: These findings provide an insight into the biomechanical adaptations that allow a transtibial amputee to attain the speeds achieved when sprinting.     

Prosthesis use in adult acquired major upper-limb amputees: patterns of wear,prosthetic skills and the actual use of prostheses in activities of daily life

Purpose: To describe patterns of prosthesis wear and perceived prosthetic usefulness in adult acquired upper-limb amputees (ULAs). To describe prosthetic skills in activities of daily life (ADL) and the actual use of prostheses in the performance of ADL tasks. To estimate the influence of prosthetic skills on actual prosthesis use and the influence of background factors on prosthetic skills and actual prosthesis use. Method: Cross-sectional study analysing population-based questionnaire data (n?=?224) and data from interviews and clinical testing in a referred/convenience sample of prosthesis-wearing ULAs (n?=?50). Effects were analysed using linear regression. Results: 80.8% wore prostheses. 90.3% reported their most worn prosthesis as useful. Prosthetic usefulness profiles varied with prosthetic type. Despite demonstrating good prosthetic skills, the amputees reported actual prosthesis use in only about half of the ADL tasks performed in everyday life. In unilateral amputees, increased actual use was associated with sufficient prosthetic training and with the use of myoelectric vs cosmetic prostheses, regardless of amputation level. Prosthetic skills did not affect actual prosthesis use. No background factors showed significant effect on prosthetic skills. Conclusions: Most major ULAs wear prostheses. Individualised prosthetic training and fitting of myoelectric rather than passive prostheses may increase actual prosthesis use in ADL.

Implications for Rehabilitation

• Arm prostheses are important functional aids for adult acquired major upper-limb amputees (ULAs).

• Despite being mainly satisfied with their prostheses, reporting their prostheses as useful and showing good prosthetic skills, prosthesis-wearing major ULAs do not use their prostheses for more than about half of the activities of daily life (ADL) tasks carried out in everyday life.

• In unilateral ULAs, individualised and targeted prosthetic training may increase optimal, active prosthesis use in ADL.

• Fitting the amputee with myoelectric rather than passive prostheses may increase prosthesis use in ADL, regardless of amputation level.

     

Control within a virtual environment is correlated to functional outcomes when using a physical prosthesis

Background

Advances such as targeted muscle reinnervation and pattern recognition control may provide improved control of upper limb myoelectric prostheses, but evaluating user function remains challenging. Virtual environments are cost-effective and immersive tools that are increasingly used to provide practice and evaluate prosthesis control, but the relationship between virtual and physical outcomes—i.e., whether practice in a virtual environment translates to improved physical performance—is not understood.

Methods

Nine people with transhumeral amputations who previously had targeted muscle reinnervation surgery were fitted with a myoelectric prosthesis comprising a commercially available elbow, wrist, terminal device, and pattern recognition control system. Virtual and physical outcome measures were obtained before and after a 6-week home trial of the prosthesis.

Results

After the home trial, subjects showed statistically significant improvements (p <?0.05) in offline classification error, the virtual Target Achievement Control test, and the physical Southampton Hand Assessment Procedure and Box and Blocks Test. A trend toward improvement was also observed in the physical Clothespin Relocation task and Jebsen-Taylor test; however, these changes were not statistically significant. The median completion time in the virtual test correlated strongly and significantly with the Southampton Hand Assessment Procedure (p =?0.05, R =???0.86), Box and Blocks Test (p =?0.007, R =???0.82), Jebsen-Taylor Test (p =?0.003, R =?0.87), and the Assessment of Capacity for Myoelectric Control (p =?0.005,R =???0.85). The classification error performance only had a significant correlation with the Clothespin Relocation Test (p =?0.018, R =?.76).

Conclusions

In-home practice with a pattern recognition-controlled prosthesis improves functional control, as measured by both virtual and physical outcome measures. However, virtual measures need to be validated and standardized to ensure reliability in a clinical or research setting.

Trial registration

This is a registered clinical trial: NCT03097978.

     

Proportional myoelectric hand control: an evaluation

The authors review the principle of proportional myoelectric control, in which the motor voltage of a prosthetic hand varies in direct proportion to the EMG signal, giving the amputee control over speed and force of grip. This type of myoelectric control is contrasted with digital myoelectric control, in which the system is fully on or off, giving the amputee no control over speed of hand opening and closing, and the grip force is increased only by increasing the time of the sustained EMG signal. A survey was conducted of 33 patients wearing the proportional myoelectric hand. Patients rated quickness of opening and closing; control over speed and force; effort required to open and close; and comfort, convenience, and cosmesis of the hand; as well as giving it an overall rating in comparison with their previous terminal device. The ratings were made on a 5-level scale, so that they could be quantified. Patient responses were grouped according to previous experience with a terminal device type: group A: digital myoelectric hand; group B: body-powered terminal device; group C: no terminal device. Differences in group means were compared using Student's t test. Previous digital hand wearers gave significantly higher ratings to the proportionally controlled hand overall, especially for its quickness, control of speed and force, and the effort required to open and close the hand. Former body-powered terminal device wearers rated the proportionally controlled hand significantly better on control over speed and force and on cosmesis.(ABSTRACT TRUNCATED AT 250 WORDS)     

膀胱神经支配重建的研究

脊髓损伤后膀胱神经支配重建是膀胱功能重建的方法之一。理想上的神经病理性膀胱功能障碍的治疗是通过恢复中枢控制而康复功能性排尿 ,这需要彻底了解影响轴突再生和平滑肌神经重支配的因素。有关膀胱神经重支配的研究报道首于1907年发表 ,此后相关的实验研究及临床手术报道并不多。最近 ,有关膀胱人工反射弧建立的实验研究可能具有良好的临床应用前景。本文献综述对历史上膀胱神经支配重建的研究报道进行总结和提练 ,着重说明不同研究的技术方法。     

Total hip disarticulation prosthesis with suction socket: report of two cases

A majority of hip disarticulations are performed in young people, with malignancy being the most common cause. The exoskeletal Canadian Hip Disarticulation prosthesis had been widely used as a standard total hip disarticulation prosthesis until recently when an endoskeletal modular version became the prosthesis of choice. However, the "basket-shaped" socket provided by the standard total hip disarticulation prostheses has been a source of discomfort and a reason for prosthetic rejection by many patients. This report concerns two patients with true lower limb disarticulation at the hip joint. Both of the patients failed to adapt to the standard total hip disarticulation prosthesis but successfully used a new total contact suction socket design. This new prosthesis provided improved suspension, better patient compliance, and enhanced prosthetic acceptance and mobility.     

Co-contraction patterns of trans-tibial amputee ankle and knee musculature during gait

ABSTRACT: BACKGROUND: Myoelectric control of upper extremity powered prostheses has been used clinically for many years, however this approach has not been fully developed for lower extremity prosthetic devices. With the advent of powered lower extremity prosthetic components, the potential role of myoelectric control systems is of increasing importance. An understanding of muscle activation patterns and their relationship to functional ambulation is a vital step in the future development of myoelectric control. Unusual knee muscle co-contractions have been reported in both limbs of trans-tibial amputees. It is currently unknown what differences exist in co-contraction between trans-tibial amputees and controls. This study compares the activation and co-contraction patterns of the ankle and knee musculature of trans-tibial amputees (intact and residual limbs), and able-bodied control subjects during three speeds of gait. It was hypothesized that residual limbs would have greater ankle muscle co-contraction than intact and able-bodied control limbs and that knee muscle co-contraction would be different among all limbs. Lastly it was hypothesized that the extent of muscle co-contraction would increase with walking speed. METHODS: Nine unilateral traumatic trans-tibial amputees and five matched controls participated. Surface electromyography recorded activation from the Tibialis Anterior, Medial Gastrocnemius, Vastus Lateralis and Biceps Femoris of the residual, intact and control limbs. A series of filters were applied to the signal to obtain a linear envelope of the activation patterns. A co-contraction area (ratio of the integrated agonist and antagonist activity) was calculated during specific phases of gait. RESULTS: Co-contraction of the ankle muscles was greater in the residual limb than in the intact and control limbs during all phases of gait. Knee muscle co-contraction was greater in the residual limb than in the control limb during all phases of gait. CONCLUSION: Co-contractions may represent a limb stiffening strategy to enhance stability during phases of initial foot-contact and single limb support. These strategies may be functionally necessary for amputee gait; however, the presence of co-contractions could confound future development of myoelectric controls and should thus be accounted for.