RESUMO
BACKGROUND: Kilohertz frequency alternating currents (KHFAC) produce rapid nerve conduction block of mammalian peripheral nerves and have potential clinical applications in reducing nerve hyperactivity. However, there are no experimental measurements of the block inception time (BIT) for the complete block of mammalian motor axons, i.e. the time from the start of delivery of the KHFAC to the axons reaching a fully blocked state. NEW METHOD: A "counted cycles" method (CCM) was designed to exploit characteristics of the onset response, which is typical of KHFAC block, to measure the BIT with a millisecond time resolution. Randomized and repeated experiments were conducted in an in-vivo rodent model, using trains of KHFAC over a range of complete cycle counts at three frequencies (10, 20, and 40â¯kHz). RESULTS: Complete motor nerve conduction block was obtained in the rat sciatic nerve (Nâ¯=â¯4) with an average BIT range of 5â¯ms-10â¯ms. The fastest BIT measured was 2.5â¯ms-5â¯ms. There was no statistical difference between the block inception times for the three frequencies tested. COMPARISON WITH EXISTING METHODS: There are no comparable methods to measure the KHFAC BIT. CONCLUSION: The KHFAC BIT is faster than previously estimated. KHFAC motor nerve block is established in milliseconds. These results may assist in the design of methods to eliminate the onset response produced by KHFAC nerve block.
Assuntos
Bloqueio Nervoso , Condução Nervosa , Animais , Axônios , Estimulação Elétrica , Ratos , Nervo IsquiáticoRESUMO
BACKGROUND: Kilohertz frequency alternating current (KHFAC) waveforms reversibly block conduction in mammalian peripheral nerves. The initiation of the KHFAC produces nerve activation, called the onset response, before complete block occurs. An amplitude ramp, starting from zero amplitude, is ineffective in eliminating this onset activity. We postulated that initiating the ramp from a non-zero amplitude would produce a different effect on the onset. METHODS: Experiments were conducted in an in vivo rat model. KHFAC was applied at supra block threshold amplitudes and then reduced to a lower sub block amplitude (25, 50, 75 and 90% of the block threshold amplitude). The amplitude was then increased again to the original supra block threshold amplitude with an amplitude ramp. This ramp time was varied for each of the amplitude levels tested. RESULTS: The amplitude ramp was successful in eliminating a second onset. This was always possible for the ramps up from 75 and 90% block threshold amplitude, usually from 50% but never from 25% of the block threshold amplitude. CONCLUSIONS: This maneuver can potentially be used to initiate complete nerve block, transition to partial block and then resume complete block without producing further onset responses.
Assuntos
Estimulação Elétrica/métodos , Condução Nervosa/fisiologia , Potenciais de Ação/fisiologia , Animais , Nervos Periféricos/fisiologia , Ratos , Ratos Sprague-DawleyRESUMO
An implantable, stimulated-muscle-powered piezoelectric active energy harvesting generator was previously designed to exploit the fact that the mechanical output power of muscle is substantially greater than the electrical power necessary to stimulate the muscle's motor nerve. We reduced to practice the concept by building a prototype generator and stimulator. We demonstrated its feasibility in vivo, using rabbit quadriceps to drive the generator. The generated power was sufficient for self-sustaining operation of the stimulator and additional harnessed power was dissipated through a load resistor. The prototype generator was developed and the power generating capabilities were tested with a mechanical muscle analog. In vivo generated power matched the mechanical muscle analog, verifying its usefulness as a test-bed for generator development. Generator output power was dependent on the muscle stimulation parameters. Simulations and in vivo testing demonstrated that for a fixed number of stimuli/minute, two stimuli applied at a high frequency generated greater power than single stimuli or tetanic contractions. Larger muscles and circuitry improvements are expected to increase available power. An implanted, self-replenishing power source has the potential to augment implanted battery or transcutaneously powered electronic medical devices.
Assuntos
Fontes de Energia Bioelétrica , Estimulação Elétrica/instrumentação , Transferência de Energia , Sistemas Microeletromecânicos/instrumentação , Contração Muscular/fisiologia , Músculo Esquelético/fisiologia , Próteses e Implantes , Animais , Desenho de Equipamento , Análise de Falha de Equipamento , Projetos Piloto , CoelhosRESUMO
Though high-frequency alternating current (HFAC) can block nerve conduction, the block is invariably preceded by an onset response which is a period of repetitive nerve firing. We tested the hypothesis that slowly ramping up the amplitude of the HFAC waveform could produce block without this initial onset response. Computer simulations were performed, using the McIntyre-Richardson-Grill (MRG) model of myelinated mammalian axon. A ramped-amplitude HFAC was applied to axons of diameters ranging from 7.3 microm to 16 microm and at frequencies ranging from 3125 Hz to 40 kHz. The ramped-amplitude HFAC was also investigated in vivo in preparations of rat sciatic nerve. Sinusoidal voltage-regulated waveforms, at frequencies between 10 kHz and 30 kHz, were applied with initial amplitudes of 0 V, linearly increasing with time to 10 V. Ramp durations ranged from 0 s to 60 s. In both the MRG model simulations and the experiments, ramping the HFAC waveform did not eliminate the onset response. In the rat experiments, the peak amplitude of the onset response was lessened by ramping the amplitude, but both the onset response duration and the amount of onset activity as measured by the force-time integral were increased.
Assuntos
Potenciais de Ação/fisiologia , Terapia por Estimulação Elétrica/métodos , Estimulação Elétrica/métodos , Modelos Neurológicos , Bloqueio Nervoso/métodos , Nervo Isquiático/fisiologia , Animais , Simulação por Computador , Ratos , Ratos Sprague-DawleyRESUMO
A totally implantable piezoelectric generator system able to harness power from electrically activated muscle would augment the power systems of implanted functional electrical stimulation devices by reducing the number of battery replacement surgeries or by allowing periods of untethered functionality. The generator design contains no moving parts and uses a portion of the generated power for system operation. A software model of the system was developed and simulations performed to predict the output power as the system parameters were varied within their constraints. Mechanical forces that mimic muscle forces were experimentally applied to a piezoelectric generator to verify the accuracy of the simulations and to explore losses due to mechanical coupling. Depending on the selection of system parameters, software simulations predict that this generator concept can generate up to 690 microW of power, which is greater than the power necessary to drive the generator, conservatively estimated to be 46 microW. These results suggest that this concept has the potential to be an implantable, self-replenishing power source and warrants further investigation.
Assuntos
Fontes de Energia Bioelétrica , Simulação por Computador , Modelos Biológicos , Contração Muscular , Músculo Esquelético , Software , AnimaisRESUMO
High-frequency alternating current (AC) waveforms have been shown to produce a quickly reversible nerve block in animal models, but the parameters and mechanism of this block are not well understood. A frog sciatic nerve/gastrocnemius muscle preparation was used to examine the parameters for nerve conduction block in vivo, and a computer simulation of the nerve membrane was used to identify the mechanism for block. The results indicated that a 100% block of motor activity can be accomplished with a variety of waveform parameters, including sinusoidal and rectangular waveforms at frequencies from 2 kHz to 20 kHz. A complete and reversible block was achieved in 34 out of 34 nerve preparations tested. The most efficient waveform for conduction block was a 3-5 kHz constant-current biphasic sinusoid, where block could be achieved with stimulus levels as low as 0.01 microCphase(-1). It was demonstrated that the block was not produced indirectly through fatigue. Computer simulation of high-frequency AC demonstrated a steady-state depolarisation of the nerve membrane, and it is hypothesised that the conduction block was due to this tonic depolarisation. The precise relationship between the steady-state depolarisation and the conduction block requires further analysis. The results of this study demonstrated that high-frequency AC can be used to produce a fast-acting, and quickly reversible nerve conduction block that may have multiple applications in the treatment of unwanted neural activity.
Assuntos
Terapia por Estimulação Elétrica/métodos , Bloqueio Nervoso/métodos , Animais , Simulação por Computador , Modelos Biológicos , Condução Nervosa , Rana catesbeiana , Nervo Isquiático/fisiologiaRESUMO
High frequency alternating current waveforms have been shown to produce a rapidly reversible nerve block in animal models, but the parameters and mechanism of this block are not well understood. A frog sciatic nerve/gastrocnemius muscle preparation was used to examine the parameters for nerve conduction block in vivo. A complete and reversible nerve block was achieved in all preparations. The results indicate that a 100% block of motor activity can be accomplished with a variety of waveform parameters, including sinusoidal and rectangular waveforms at frequencies from 2 kHz to 20 kHz. The most efficient waveform for conduction block was a 3-5 kHz constant-current biphasic sinusoid. It was demonstrated that the block is not produced indirectly through fatigue.
RESUMO
OBJECTIVE: The purpose of this study was to design and implement a transducer to measure accurately the isometric elbow moments produced by individuals with tetraplegia. DESIGN: The device needed to be insensitive to off-axis moments and proximal joint motions and be capable of being used over a wide range of elbow and shoulder positions in an outpatient clinic setting. BACKGROUND: Measurement of the smaller isometric moments produced by individuals with tetraplegia is especially sensitive to the errors that can be introduced by inaccurate lever arm determination, off-axis loads, and proximal joint motions. Devices traditionally utilized for quantifying isometric strength are difficult to implement for the spinal cord injured population. METHODS: The elbow moment transducer consists of two four-bar parallelogram linkages joined by a lockable pivot. Strain gauges mounted on one beam of the parallelogram produce an output proportional to the elbow moment. RESULTS: Calibration of the device indicates that it accurately quantifies isometric elbow moments over a range that is appropriate for evaluating elbow extension strength in individuals with tetraplegia. CONCLUSIONS: A device was developed and implemented that accurately quantifies isometric elbow moments over a range that is appropriate for evaluating elbow extension strength in individuals with tetraplegia. RELEVANCE: The ability to quantitatively evaluate elbow strength in persons with tetraplegia is useful for understanding and improving the clinical outcomes of rehabilitative interventions that involve the elbow.
Assuntos
Articulação do Cotovelo/fisiopatologia , Contração Isométrica/fisiologia , Quadriplegia/reabilitação , Transdutores , Calibragem , Desenho de Equipamento , Humanos , Amplitude de Movimento Articular/fisiologia , Reabilitação/instrumentação , Sensibilidade e EspecificidadeRESUMO
OBJECTIVE: To evaluate an implanted neuroprosthesis that allows tetraplegic users to control grasp and release in 1 hand. DESIGN: Multicenter cohort trial with at least 3 years of follow-up. Function for each participant was compared before and after implantation, and with and without the neuroprosthesis activated. SETTING: Tertiary spinal cord injury (SCI) care centers, 8 in the United States, 1 in the United Kingdom, and 1 in Australia. PARTICIPANTS: Fifty-one tetraplegic adults with C5 or C6 SCIs. INTERVENTION: An implanted neuroprosthetic system, in which electric stimulation of the grasping muscles of 1 arm are controlled by using contralateral shoulder movements, and concurrent tendon transfer surgery. Assessed participants' ability to grasp, move, and release standardized objects; degree of assistance required to perform activities of daily living (ADLs), device usage; and user satisfaction. MAIN OUTCOME MEASURES: Pinch force; grasp and release tests; ADL abilities test and ADL assessment test; and user satisfaction survey. RESULTS: Pinch force was significantly greater with the neuroprosthesis in all available 50 participants, and grasp-release abilities were improved in 49. All tested participants (49/49) were more independent in performing ADLs with the neuroprosthesis than they were without it. Home use of the device for regular function and exercise was reported by over 90% of the participants, and satisfaction with the neuroprosthesis was high. CONCLUSIONS: The grasping ability provided by the neuroprosthesis is substantial and lasting. The neuroprosthesis is safe, well accepted by users, and offers improved independence for a population without comparable alternatives.
Assuntos
Estimulação Elétrica , Eletrodos Implantados , Força da Mão , Mãos/inervação , Próteses e Implantes , Quadriplegia/cirurgia , Adulto , Estudos de Coortes , Feminino , Seguimentos , Humanos , Masculino , Desenho de PróteseRESUMO
Neuroprostheses that electrically stimulate paralyzed muscles provide functional enhancements for individuals with spinal cord injury and stroke such as standing and stepping, reaching and grasping, and bladder and bowel function. For chronic applications, implanted neuroprostheses lead to reliable, low-maintenance and patient-acceptable systems. The advantages of such systems are discussed followed by a generic description of implantable stimulators. Features of current first and second generation neuroprostheses developed at our centre are discussed followed by our experience in the application of these devices in the rehabilitation of individuals with spinal cord injury.
Assuntos
Terapia por Estimulação Elétrica/instrumentação , Próteses e Implantes , Traumatismos da Medula Espinal/terapia , Braço , Engenharia Biomédica , Humanos , Perna (Membro) , Desenho de Prótese , Traumatismos da Medula Espinal/reabilitaçãoRESUMO
The purpose of this forum was to discuss with consumers having spinal cord injury what their research priorities would be for the field of functional electrical stimulation (FES) and to explore the impact of technology in the lives of people with disabilities. Both FES users and nonusers were included on the panel. The format for the discussion was primarily question and answer, with each participant giving his or her personal response to the moderator's question. Consumer research priorities depended on the individual and his or her personal priorities, preferences, background, history, and level of injury. Common themes that emerged were independence, ease of movement, ease of control, and spontaneity. From the consumers' perspective, the focus of research to restore function ought to be based on the needs and desires of the consumer, not just on the scientifically intriguing aspects of a particular technology.
Assuntos
Terapia por Estimulação Elétrica , Qualidade de Vida , Traumatismos da Medula Espinal/reabilitação , Eletrodos Implantados , Humanos , Satisfação do Paciente , Análise e Desempenho de TarefasRESUMO
The lifetime costs associated with spinal cord injury are substantial. Assistive technology that reduces complications, increases independence, or decreases the need for attendant services can provide economic as well as medical or functional benefit. This study describes two approaches for estimating the economic consequences of implanted neuroprostheses utilizing functional electrical stimulation. Life care plan analysis was used to estimate the costs of bladder and bowel care with and without a device restoring bladder and bowel function and to compare these with the costs of implementing the device. For a neuroprosthesis restoring hand grasp, the costs of implementation were compared to the potential savings in attendant care costs that could be achieved by the use of the device. The results indicate that the costs of implementing the bladder and bowel system would be recovered in 5 years, primarily from reduced costs of supplies, medications, and procedures. The costs of the hand grasp neuroprosthesis would be recovered over the lifetime of the user if attendant time was reduced only 2 hours per day and in a shorter time if attendant care was further reduced. Neither analysis includes valuation of the quality of life, which is further enhanced by the neuroprostheses through restoration of greater independence and dignity. Our results demonstrate that implantable neuroprosthetic systems provide good health care value in addition to improved independence for the disabled individual.
Assuntos
Biônica/instrumentação , Efeitos Psicossociais da Doença , Estimulação Elétrica , Próteses e Implantes , Traumatismos da Medula Espinal/economia , Biônica/economia , Estimulação Elétrica/instrumentação , Estimulação Elétrica/métodos , Incontinência Fecal/economia , Incontinência Fecal/etiologia , Incontinência Fecal/reabilitação , Mãos/inervação , Humanos , Próteses e Implantes/economia , Traumatismos da Medula Espinal/complicações , Traumatismos da Medula Espinal/reabilitação , Estados Unidos , Incontinência Urinária/economia , Incontinência Urinária/etiologia , Incontinência Urinária/reabilitaçãoRESUMO
A structured miniature repair sleeve has been designed for implantable in-line connectors that develop small current leaks post-implant. The repair sleeve has been successfully utilised in one subject following the development of current leakage in connectors on an implanted joint angle sensor.
Assuntos
Terapia por Estimulação Elétrica/instrumentação , Eletrodos Implantados , Eletrônica Médica , Falha de Equipamento , HumanosRESUMO
The purpose of this investigation was to determine whether the passive range of motion at the finger joints is restricted more by intrinsic tissues (cross a single joint) or by extrinsic tissues (cross multiple joints). The passive moment at the metacarpophalangeal (MP) joint of the index finger was modeled as the sum of intrinsic and extrinsic components. The intrinsic component was modeled only as a function of MP joint angle. The extrinsic component was modeled as a function of MP joint angle and wrist angle. With the wrist fixed in seven different positions the passive moment at the MP joint of eight subjects was recorded as the finger was rotated through its range at a constant rate. The moment-angle data were fit by the model and the extrinsic and intrinsic components were calculated for a range of MP joint angles and wrist positions. With the MP joint near its extension limit, the median percent extrinsic contribution was 94% with the wrist extended 60 degrees and 14% with the wrist flexed 60 degrees. These percentages were 40 and 88%, respectively, with the MP joint near its flexion limit. Our findings indicate that at most wrist angles the extrinsic tissues offer greater restraint at the limits of MP joint extension and flexion than the intrinsic tissues. The intrinsic tissues predominate when the wrist is flexed or extended enough to slacken the extrinsic tissues. Additional characteristics of intrinsic and extrinsic tissues can be deduced by examining the parameter values calculated by the model.
Assuntos
Articulação Metacarpofalângica/fisiologia , Modelos Biológicos , Amplitude de Movimento Articular , Adulto , Feminino , Humanos , Masculino , Articulação do Punho/fisiologiaRESUMO
Cortical signals might provide a potential means of interfacing with a neuroprosthesis. Guidelines regarding the necessary control features in terms of both performance characteristics and user requirements are presented, and their implications for the design of a first generation cortical control interface for a neuroprosthesis are discussed.
Assuntos
Córtex Cerebral/fisiopatologia , Auxiliares de Comunicação para Pessoas com Deficiência , Eletroencefalografia/instrumentação , Interface Usuário-Computador , Mãos/inervação , Força da Mão/fisiologia , Humanos , Desenho de Prótese , Processamento de Sinais Assistido por Computador/instrumentação , Traumatismos da Medula Espinal/fisiopatologia , Traumatismos da Medula Espinal/reabilitaçãoRESUMO
The feasibility of using the EEG signal to operate a hand grasp neuroprosthesis was investigated. Two able-bodied subjects and one neuroprosthesis user were trained to control the amplitude of the beta rhythm recorded over the frontal areas. After 6 months, all subjects exhibited a high level of control, being able to use this signal to move a cursor to targets on a computer screen with a high (>90%) accuracy rate. Control over the EEG signal was unaffected by upper extremity movement or electrical activation of the muscles, indicating that this signal would be adequate for neuroprosthetic use. To test this concept, the neuroprosthesis user operated his system with the cortical signal, and was able to effectively manipulate several objects.
Assuntos
Eletroencefalografia/instrumentação , Força da Mão , Mãos/fisiopatologia , Próteses e Implantes , Adulto , Estimulação Elétrica , Feminino , Mãos/inervação , Humanos , Masculino , Córtex Pré-Frontal/fisiopatologia , TransdutoresRESUMO
An implantable joint angle transducer (IJAT) was developed to provide command-control and feedback-control information for chronic use with functional neuromuscular stimulation (FNS) neuroprostheses. The IJAT uses Hall effect sensors to transduce joint angle. A titanium encapsulated array of Hall effect sensors and support circuitry is surgically implanted in one bone, and a similarly encapsulated permanent magnet in an opposing bone, across a joint. The IJAT provides consistent, reliable, high quality signals that reflect joint movement from midsized two-degree-of-freedom joints. IJAT's were implanted using a chronic in vivo dog model to demonstrate the feasibility of implantation and periodic measurement techniques, and to validate modeling techniques used for prediction of function and calibration. The flexion resolution ranged from 0.4 to 3.0 degrees over a range of 115 degrees. The maximum deviation from a linear response was 9 degrees. The resolution and linearity depend on several transducer and joint geometry parameters, and can be predicted prior to implantation and calibrated after implantation. The results of this study 1) defined the most appropriate hermetic capsule designs for the IJAT sensor and magnet, 2) defined the best orientation of the magnetic field to optimize device function, 3) provided a computer model of the IJAT to aid in placement, calibration, and evaluation of the device, 4) verified the surgical techniques used to implant the device, and 5) verified the long-term functionality and the biocompatibility of the device.
Assuntos
Articulações/fisiologia , Próteses e Implantes , Amplitude de Movimento Articular/fisiologia , Transdutores , Animais , Materiais Biocompatíveis , Calibragem , Carpo Animal/patologia , Carpo Animal/fisiologia , Carpo Animal/cirurgia , Cães , Desenho de Equipamento , Retroalimentação , Membro Anterior/patologia , Membro Anterior/fisiologia , Membro Anterior/cirurgia , Modelos Teóricos , Movimento/fisiologia , Reprodutibilidade dos TestesRESUMO
The actions of the dorsal interosseous, volar interosseous, and lumbrical muscles were investigated using applied electrical stimulation and recording the moments that were generated across the metacarpophalangeal joint in flexion/extension and abduction/adduction, the proximal interphalangeal joint in flexion/extension, and the distal interphalangeal joint in flexion/extension. These measurements were made isometrically at various joint angles and levels of stimulation with both able bodied subjects and persons who had sustained tetraplegia. It was determined that the dorsal interossei, including the first, were strong abductors of the fingers and generated a significant moment in metacarpophalangeal (MP) joint flexion and interphalangeal (IP) joint extension. The volar interossei were the primary adductors of the fingers, as well as providing a significant moment in MP joint flexion and IP joint extension. The lumbrical muscles were found to be MP joint flexors and IP joint extensors, although the moments that were generated were on average 70% lower than the interossei. The role of the lumbricals as finger abductors or adductors could not be determined from the data. This information on the actions and moment generating capabilities of the intrinsic muscles led to the incorporation of the interossei into electrically induced hand grasp provided by an implanted neuroprosthesis. The evaluation of the intrinsic muscles in the neuroprosthesis was accomplished by recording the moment generating capabilities of these muscles across each of the joints of the finger. These muscles were capable of generating moments that were 80-90% of the average attained by the able bodied subjects, and have provided a substantial improvement to the electrically induced hand grasp.
Assuntos
Dedos/fisiopatologia , Contração Muscular/fisiologia , Músculo Esquelético/fisiopatologia , Quadriplegia/fisiopatologia , Quadriplegia/reabilitação , Adulto , Fenômenos Biomecânicos , Terapia por Estimulação Elétrica , Eletromiografia , Dedos/fisiologia , Força da Mão/fisiologia , Humanos , Masculino , Articulação Metacarpofalângica/fisiologia , Articulação Metacarpofalângica/fisiopatologia , Pessoa de Meia-Idade , Movimento/fisiologia , Postura , Próteses e ImplantesRESUMO
OBJECTIVE: To measure the satisfaction with, clinical impact of, and use of an implantable hand neuroprosthesis. SETTING: Eight different medical centers. PARTICIPANTS: Thirty-four individuals with spinal cord injuries at the C5 or C6 motor level. INTERVENTIONS: Participants were implemented with a hand neuroprosthesis that provides grasp and release. The neuroprosthesis includes a surgically implanted stimulator, implanted electrodes sutured to the hand and forearm muscles, and an externally mounted controller. MAIN OUTCOME MEASURE: A survey was mailed to study participants, who were asked to respond to statements such as "If I had it to do over, I would have the hand system implanted again," using a 5-level Likert scale ("strongly agree" to "strongly disagree"). RESULTS: Eighty-seven percent of participants were very satisfied with the neuroprosthesis, 88% reported a positive impact on their life, 87% reported improvements in activities of daily living, and 81% reported improved independence. Participants reported using the neuroprosthesis a median of 5.5 days per week; 15 participants used the neuroprosthesis 7 days per week, and 5 participants reported not using the device. CONCLUSIONS: The neuroprosthesis was used by most participants. The neuroprosthesis performed satisfactorily, increased users' ability to perform activities of daily living and independence, and improved their quality of life.
Assuntos
Terapia por Estimulação Elétrica/instrumentação , Mãos/inervação , Aceitação pelo Paciente de Cuidados de Saúde , Satisfação do Paciente , Implantação de Prótese/instrumentação , Traumatismos da Medula Espinal/reabilitação , Adolescente , Adulto , Avaliação da Deficiência , Eletrodos Implantados , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Destreza Motora/fisiologia , Avaliação de Resultados em Cuidados de Saúde , Qualidade de Vida , Traumatismos da Medula Espinal/fisiopatologia , Traumatismos da Medula Espinal/psicologiaRESUMO
A device capable of simultaneously measuring the isometric moments generated about the metacarpophalangeal (MP), proximal interphalangeal (PIP), and distal interphalangeal (DIP) joints of all four fingers has been developed. The design utilizes a four-bar linkage to transmit moments, but not forces, to the device. This linkage allows the same device to fit a wide range of hand sizes without recalibration. The device was constructed out of aluminum bars which are strapped to each joint segment and to the back of the hand. Strain gauges mounted to the aluminum bars measure the bending moment on the device, which is directly related to the moment applied about the joint center of rotation. Because of the unique design of the device, it is not necessary to have accurate measurements of the joint center of rotation in order to get accurate moment information. A single device is capable of generating independent measurement of MP extension/flexion, PIP extension/flexion, and DIP extension/flexion. Four of these devices can be used to make simultaneous measurements of all the moments generated by all four fingers. The device also acts as a splint, allowing each joint to be positioned and locked at any angle through the range of motion of the joint. The device is accurate to within +/- 5.6% of each reading for moments from 10 N x cm to 100 N x cm and within +/- 2.0 N x cm for moments of 10 N x cm or less. If the device configuration is constrained, the accuracy can be improved to +/- 0.8% of full scale (100 N x cm) and +/- 0.21 N x cm for moments of 10 N x cm or less. The device can measure both flexion and extension moments up to 100 N x cm, and can allow the joints to be fixed at any angle from approximately 10 to 80 degrees.