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At least 109 records · Page 6Linked to original sources
PubMed2004

Residual function in peripheral nerve stumps of amputees: implications for neural control of artificial limbs.

PURPOSE: It is not known whether motor and sensory pathways associated with a missing or denervated limb remain functionally intact over periods of many months or years after amputation or chronic peripheral nerve transection injury. We examined the extent to which activity on chronically severed motor nerve fibers could be controlled by human amputees and whether distally referred tactile and proprioceptive sensations could be induced by stimulation of sensory axons in the nerve stumps. METHODS: Amputees undergoing elective stump procedures were invited to participate in this study. Longitudinal intrafascicular electrodes were threaded percutaneously and implanted in severed nerves of human amputees. The electrodes were interfaced to an amplifier and stimulator system controlled by a laptop computer. Electrophysiologic tests were conducted for 2 consecutive days after recovery from the surgery. RESULTS: It was possible to record volitional motor nerve activity uniquely associated with missing limb movements. Electrical stimulation through the implanted electrodes elicited discrete, unitary, graded sensations of touch, joint movement, and position, referring to the missing limb. CONCLUSIONS: These findings indicate that both central and peripheral motor and somatosensory pathways retain significant residual connectivity and function for many years after limb amputation. This implies that peripheral nerve interfaces could be used to provide amputees with prosthetic limbs that have more natural feel and control than is possible with current myoelectric and body-powered control systems.

Action Potentials↗
PubMedDate not supplied

[Possibilities of myoelectric control of artificial limb prostheses].

This article summarizes the main possibilities for myoelectrical control of prostheses and other rehabilitation devices. In this context fundamental cybernetic aspects, the question of achieving optimal differentiation of antagonistic signals, and 16 possibilities of myoelectrical control, ranging from simple n-state threshold detectors to rate sensitive controllers, to intelligent controllers and pattern recognition techniques, are considered.

Artificial Limbs↗
PubMed2004

An interpretative phenomenological analysis of the embodiment of artificial limbs.

PURPOSE: To gain an understanding of the embodied perceptual experience of successful prosthesis. METHOD: The data for this study were transcripts derived from in-depth semi-structured e-mail (n=21) and face-to-face (n=14) interviews, and the documentary analysis of an e-mail discussion group for prosthesis users. This qualitative data was subject to an Interpretative Phenomenological Analysis. RESULTS: Analysis of the research data identified six themes in the perceptually embodied experiences of prosthesis users: Adjusting to a prosthetic; The Balance of the Body; Awareness of the Prosthesis; The Knowing Body; The Phantom Becomes the Prosthesis: Extending the Body; and The Prosthesis as Tool or Corporeal Structure. CONCLUSION: The often-cited reasons for the rejection of prostheses are frequently part of the initial experiences of 'successful' prosthesis users also. This suggests the need to sufficiently motivate potential prosthesis users in the period between an experience of prosthesis use as unnatural and wieldy to one of pre-reflective, natural use. In addition, two broad forms of prosthesis experience were identified: one in which the prosthesis was experienced as a corporeal structure; and one in which it was viewed as a tool. While future work may be able to explore the psychosocial correlates of these experiences, it is nonetheless the case that persons with these differing experiences were able to enjoy the benefits imbued by prosthesis use.

Adaptation, Psychological↗
PubMed2000

[History of artificial limbs for the leg].

Following the development of prosthetics for the lower limb since the middle of the 18th century one will find very interesting similarities to modern prostheses. This becomes evident when looking at former knee and ankle joint mechanisms or socket designs. Also, the materials used for the prostheses underwent very interesting variations. In our paper we will describe the development of socket designs and several materials from the beginning of the 19th century. Several still obtainable books dealing with 200 years of prosthetics development, were reviewed. Charles White describes in the year 1761 a supramalleolar amputation using the flap technique and the specially built BK prostheses the socket. V. Brünninghausen describes in 1809 a socket made of tin sheet. It was built oval, as the normal transverse section of the thigh is. Stump adhesion was obtained when a shortly trimmed dog fur--panelling the socket and covering the stump--was attached like brushes end on end. A similar fitting was described by Heine in 1811, v. Dornblüth in 1831, and Mrs. Eichler in 1836. Hermann first mentioned the need of a perpendicular construction of prostheses. Parmelee developed in 1868 the first suction socket. The first tuber-enclosing socketdesign was made by Riedel in 1911. We will show documents from this time and will also show, that muscle-physiological aspects had a very important influence on socket designs.

Amputation, Surgical↗
PubMed1987

Extent of artificial limb use following rehabilitation.

The extent of prosthesis use is reported for 104 lower limb amputees from the onset of gait training up to 2 years later. Subjects were divided into groups according to age (greater than or equal to 65 years or less than 65 years) and amputation level. An analysis of variance including the factors of age and level of amputation was done. Unilateral trans-tibial (UTT) amputees progressed more quickly during the inpatient gait training program that did unilateral trans-femoral (UTF) subjects (p less than 0.05). UTT subjects also walked more than UTF subjects just prior to discharge (p less than 0.05), during the first year after discharge (p less than 0.01), and during the second year after discharge (p less than 0.01). Similarly, younger patients progressed more quickly in gait training (p less than 0.05) and walked more than older subjects throughout the study period (p less than 0.05). There were no significant interactions between age and amputation. The extent of walking of these amputees is compared with the minimal levels required for them to function in different living environments. At the time of discharge from the inpatient gait training program, older unilateral amputees and trans-femoral amputees were not able to walk the 600 steps a day necessary to manage with a moderate level of support in a one-level apartment or home. The declining number of steps taken in the follow-up period indicated that the UTF subjects might benefit from some special attention paid to their community support needs. These findings are also viewed in the context of limited data available on the extent of walking of non-amputees.

Adolescent↗
PubMed2002

Estimation of forces at the interface between an artificial limb and an implant directly fixed into the femur in above-knee amputees.

This article describes the method used for estimating the forces and moments, acting during locomotion, at the interface between an artificial leg and an implant directly fixed into the femur, in above-knee amputees. Twelve transfemoral amputees completed a predefined gait assessment during which kinetic (ground reaction loads and torque) and kinematic (limb orientation) gait data were recorded. A developed mathematical model enabled the ground reaction forces to be translated to the level of amputation. It is assumed that the loads calculated at the stump-socket interface would approximate those experienced by the proposed implant. The longitudinal force and the moment in the sagittal plane were the two most significant loads at the stump. These data were essential to obtain to facilitate the analysis of stress arising at the implant-bone interface that has been subsequently undertaken.

Adult↗
PubMed2006

["Bionic" arm prostheses. State of the art in research and development].

BACKGROUND: A new generation of arm prostheses is being developed worldwide. These so-called bionic prostheses are intended to offer additional functions, such as sensory feedback, extended range of possible movement, intuitive movement control as far as possible, and a more natural cosmetic appearance. STATE OF THE ART IN RESEARCH AND DEVELOPMENT: In recent years, prosthetic components with much enhanced performance have been developed for use at various levels of the upper limb. Artificial hands that allow for additional grips are are being tested in clinical settings. Innovative methods of signal acquisition and communication with the patient are being intensively researched. CONCLUSION: Several patients have been provided with prototypes of new arm prostheses. At the moment, the results are limited by the restricted communication between patient and prosthesis. However, we can expect the options for prosthesis control to be extended in the near future.

Arm↗
PubMed1998

Body image and patients with amputations: does the prosthesis maintain the balance?

This paper attempts to establish whether dissatisfaction with the artificial limb and/or body image relate to achieved mobility following lower limb amputation in established limb wearers. Patients attending limb fitting clinics (n = 107, 62% male, mean time from amputation 13.9 years; range 1-54) participated. The measures were a specially designed Attitude to Artificial Limbs Questionnaire, a Body Image Questionnaire adapted from an eating disorders instrument including reference to body shape, the Hospital Anxiety and Depression Scale and the Harold Wood Stanmore Mobility Scale. The rehabilitation physician rated prosthetic suitability on a Numerical Rating Scale. The results showed patients were moderately satisfied with their artificial limb, had little experience of body image disruption or distress and there was no overall relationship between these variables and mobility. However, those with a more negative body image were more anxious and in younger patients who sustained more traumatic than vascular amputations, the correlation between body image and mobility was significant, anxiety was higher and physician satisfaction with the prosthesis was lower. It is concluded that body image disruption, anxiety and depression are not common in established limb wearers except in young people with traumatic amputations.

Adult↗
PubMed1968

Rehabilitation of patients with through-knee amputation.

One hundred and one patients with through-knee amputations attending the Manchester limb-fitting centre are reviewed. Most amputations were performed for trauma or vascular disease. The interval from amputation to measurement for the first prosthesis averaged 12 weeks in cases of primary healing, and 21 weeks when healing was delayed. Artificial limbs were successfully fitted to 83%, and only 10% failed to use either a limb or a pylon. Three-quarters of those with outdoor mobility returned to work.Disarticulation through the knee has several advantages over above-knee amputation: in particular, the long end-bearing stump facilitates balance and control of the prosthesis. Disadvantages are a tendency to slow healing of the wound, lack of an internal knee mechanism in the artificial limb, and the bulky appearance of the limb. The results of rehabilitation could be improved by careful selection of patients and attention to operative detail; stump bandaging and exercises; earlier attendance at the limb-fitting centre to be measured for pylon or artificial limb; and improvements in design and production of prostheses.

Adult↗
PubMed1994

Control of prosthetic gait.

Recent advances in two types of prosthetic gait are particularly noteworthy, namely work on limb and neural prostheses. Current work on artificial limbs has been oriented towards improving devices, with commercialization as the driving force. Progress has been made in understanding how the compliant properties of the foot, ankle and knee joints of artificial legs affect the energetics and kinematics of gait. Work is continuing on automated systems for fabricating sockets with improved fit to increase the comfort of artificial limbs. Neural prostheses use electrical stimulation to activate paralyzed muscle. Advances have been made in understanding how to model the patterns of neural prosthetic gait and how neural prostheses respond to disturbances. Work in real-time control of stimulated muscle has progressed in the area of system identification and in using natural sensors for feedback signals. There still remains a wide gap, however, between able-bodied gait and the gait that can be achieved using current neural prosthesis systems.

Extremities↗
PubMed2005

Direct neural sensory feedback and control of a prosthetic arm.

Evidence indicates that user acceptance of modern artificial limbs by amputees would be significantly enhanced by a system that provides appropriate, graded, distally referred sensations of touch and joint movement, and that the functionality of limb prostheses would be improved by a more natural control mechanism. We have recently demonstrated that it is possible to implant electrodes within individual fascicles of peripheral nerve stumps in amputees, that stimulation through these electrodes can produce graded, discrete sensations of touch or movement referred to the amputee's phantom hand, and that recordings of motor neuron activity associated with attempted movements of the phantom limb through these electrodes can be used as graded control signals. We report here that this approach allows amputees to both judge and set grip force and joint position in an artificial arm, in the absence of visual input, thus providing a substrate for better integration of the artificial limb into the amputee's body image. We believe this to be the first demonstration of direct neural feedback from and direct neural control of an artificial arm in amputees.

Amputees↗