| 1. |
- Abrahamsson, Sven Olof, et al.
(författare)
-
Dehydration inhibits matrix synthesis and cell proliferation : An in vitro study of rabbit flexor tendons
- 1991
-
Ingår i: Acta Orthopaedica. - : Medical Journals Sweden AB. - 1745-3674 .- 0001-6470. ; 62:2, s. 159-162
-
Tidskriftsartikel (refereegranskat)abstract
- Segments of the deep flexor tendon of the rabbit were exposed to air; the effects of dehydration on in vitro synthesis of proteoglycan, collagen, non-collagenous protein, and cell proliferation were compared with tendon segments that were kept moist with physiologic saline. After 20 min of expo-sure to air, the tendons lost half and after 40 min all of their ability to synthesize matrix components and to proliferate, whereas irrigated tendons remained viable during the entire experiment.
|
|
| 2. |
|
|
| 3. |
|
|
| 4. |
- Ageberg, Eva, et al.
(författare)
-
Principles of brain plasticity in improving sensorimotor function of the knee and leg in healthy subjects: A double-blind randomized exploratory trial
- 2009
-
Ingår i: BMC Musculoskeletal Disorders. - : Springer Science and Business Media LLC. - 1471-2474. ; 10
-
Tidskriftsartikel (refereegranskat)abstract
- Background: Principles of brain plasticity is used in the treatment of patients with functional limitations to improve sensorimotor function. Training is included in the treatment of knee injury to improve both patient-reported function and sensorimotor function. However, impairment in sensorimotor function often persists despite training. Therefore, it was suggested that training programs need to be more effective to improve sensorimotor function after knee injury. The aim of the current study was to investigate if principles of brain plasticity that have been successfully used on the hand and foot to improve sensorimotor function can be applied on the knee. We hypothesized that temporary anesthesia of the skin area above and below the knee would improve sensorimotor function of the ipsilateral knee and leg. Methods: In this first double-blind exploratory study, 28 uninjured subjects (mean age 26 years, range 19-34, 50% women) were randomized to temporary local cutaneous application of anesthetic (EMLA (R)) (n=14) or placebo cream (n=14). Fifty grams of EMLA, or placebo, was applied on the leg 10 cm above and 10 cm below the center of patella, leaving the area around the knee without cream. Measures of sensory function (perception of touch, vibration sense, knee kinesthesia) and motor function (knee muscle strength, hop test) were assessed before and after 90 minutes of treatment with EMLA or placebo. The paired t-test was used for comparisons within groups and the independent t-test for comparisons between groups. The number of subjects needed was determined by an a priori sample size calculation. Results: No statistically significant or clinically relevant differences were seen over time (before vs. after) in the measures of sensory or motor functions in the EMLA group or in the placebo group. There were no differences between the groups due to treatment effect (EMLA vs. placebo). Conclusion: We found no effect of temporary cutaneous anesthesia on sensorimotor function of the ipsilateral knee and leg in uninjured subjects. The principles used in this study remain to be tested in subjects with knee injury.
|
|
| 5. |
- Antfolk, Christian, et al.
(författare)
-
A Tactile Display System for Hand Prostheses to Discriminate Pressure and Individual Finger Localization
- 2010
-
Ingår i: Journal of Medical and Biological Engineering. - : Taiwanese Society of Biomedical Engineering. - 1609-0985. ; 30:6, s. 355-359
-
Tidskriftsartikel (refereegranskat)abstract
- No current commercially available myoelectrically controlled prosthetic hands provide conscious sensory feedback to the user. A system aiming at relocation of sensory input from a prosthetic hand equipped with force sensors to the forearm skin of amputees, a tactile display, has been developed and constructed. The system consists of five piezoresistive force sensors or, alternatively, a prosthetic hand equipped with force sensors, five digital servomotors with a lever and a circular plastic disk pushing on the skin, control electronics based on an MSP430 microcontroller and a test application implemented in LabVIEW running on a PC. The tactile display system is intended to be integrated into the socket of a hand prosthesis and used as a conscious sensory feedback system for hand amputees using a myoelectrically controlled hand prosthesis. The system will provide continuous force feedback from sensors in the fingertips of each prosthetic finger and will likely improve the users' controllability and perception of the prosthetic hand. Here we report on tests made on "a five site" localization discrimination task and three pressure level discrimination tasks on the forearm of five healthy participants (non-amputees) using the LabView application to generate the stimulations. A mean five-finger discrimination accuracy of 86% and a mean three-level pressure discrimination accuracy of 93% were achieved, indicating the system to be a viable method of producing sensory feedback on the level of individual fingers.
|
|
| 6. |
- Antfolk, Christian, et al.
(författare)
-
Artificial Redirection of Sensation From Prosthetic Fingers to the Phantom Hand Map on Transradial Amputees: Vibrotactile Versus Mechanotactile Sensory Feedback
- 2013
-
Ingår i: IEEE Transactions on Neural Systems and Rehabilitation Engineering. - 1534-4320. ; 21:1, s. 112-120
-
Tidskriftsartikel (refereegranskat)abstract
- This work assesses the ability of transradial amputees to discriminate multi-site tactile stimuli in sensory discrimination tasks. It compares different sensory feedback modalities using an artificial hand prosthesis in: 1) a modality matched paradigm where pressure recorded on the five fingertips of the hand was fed back as pressure stimulation on five target points on the residual limb; and 2) a modality mismatched paradigm where the pressures were transformed into mechanical vibrations and fed back. Eight transradial amputees took part in the study and were divided in two groups based on the integrity of their phantom map; group A had a complete phantom map on the residual limb whereas group B had an incomplete or nonexisting map. The ability in localizing stimuli was compared with that of 10 healthy subjects using the vibration feedback and 11 healthy subjects using the pressure feedback (in a previous study), on their forearms, in similar experiments. Results demonstrate that pressure stimulation surpassed vibrotactile stimulation in multi-site sensory feedback discrimination. Furthermore, we demonstrate that subjects with a detailed phantom map had the best discrimination performance and even surpassed healthy participants for both feedback paradigms whereas group B had the worst performance overall. Finally, we show that placement of feedback devices on a complete phantom map improves multi-site sensory feedback discrimination, independently of the feedback modality.
|
|
| 7. |
- Antfolk, Christian, et al.
(författare)
-
Design and technical construction of a tactile display for sensory feedback in a hand prosthesis system
- 2010
-
Ingår i: BioMedical Engineering Online. - 1475-925X. ; 9
-
Tidskriftsartikel (refereegranskat)abstract
- Background: The users of today's commercial prosthetic hands are not given any conscious sensory feedback. To overcome this deficiency in prosthetic hands we have recently proposed a sensory feedback system utilising a "tactile display" on the remaining amputation residual limb acting as man-machine interface. Our system uses the recorded pressure in a hand prosthesis and feeds back this pressure onto the forearm skin. Here we describe the design and technical solution of the sensory feedback system aimed at hand prostheses for trans-radial/humeral amputees. Critical parameters for the sensory feedback system were investigated. Methods: A sensory feedback system consisting of five actuators, control electronics and a test application running on a computer has been designed and built. Firstly, we investigate which force levels were applied to the forearm skin of the user while operating the sensory feedback system. Secondly, we study if the proposed system could be used together with a myoelectric control system. The displacement of the skin caused by the sensory feedback system would generate artefacts in the recorded myoelectric signals. Accordingly, EMG recordings were performed and an analysis of the these are included. The sensory feedback system was also preliminarily evaluated in a laboratory setting on two healthy non-amputated test subjects with a computer generating the stimuli, with regards to spatial resolution and force discrimination. Results: We showed that the sensory feedback system generated approximately proportional force to the angle of control. The system can be used together with a myoelectric system as the artefacts, generated by the actuators, were easily removed using a simple filter. Furthermore, the application of the system on two test subjects showed that they were able to discriminate tactile sensation with regards to spatial resolution and level of force. Conclusions: The results of these initial experiments in non-amputees indicate that the proposed tactile display, in its simple form, can be used to relocate tactile input from an artificial hand to the forearm and that the system can coexist with a myoelectric control systems. The proposed system may be a valuable addition to users of myoelectric prosthesis providing conscious sensory feedback during manipulation of objects.
|
|
| 8. |
- Antfolk, Christian, et al.
(författare)
-
Sensory feedback from a prosthetic hand based on air-mediated pressure from the hand to the forearm skin.
- 2012
-
Ingår i: Journal of rehabilitation medicine : official journal of the UEMS European Board of Physical and Rehabilitation Medicine. - : Medical Journals Sweden AB. - 1651-2081. ; 44:8, s. 702-707
-
Tidskriftsartikel (refereegranskat)abstract
- Objective: Lack of sensory feedback is a drawback in today's hand prostheses. We present here a non-invasive simple sensory feedback system, which provides the user of a prosthetic hand with sensory feedback on the arm stump. It is mediated by air in a closed loop system connecting silicone pads on the prosthetic hand with pads on the amputation stump. The silicone pads in a "tactile display" on the amputation stump expand when their corresponding sensor-bulb in the prosthesis is touched, evoking an experience of "real touch". Methods: Twelve trans-radial amputees and 20 healthy non-amputees participated in the study. We investigated the capacity of the system to mediate detection of touch, discrimination between different levels of pressure and, on the amputees also, the ability to locate touch. Results: The results showed a median touch threshold of 80 and 60 g in amputees and non-amputees, respectively, and 90% and 80% correct answers, respectively, in discrimination between 2 levels of pressure. The amputees located touch (3 sites) correctly in 96% of trials. Conclusion: This simple sensory feedback system has the potential to restore sensory feedback in hand amputees and thus it could be a useful tool to enhance prosthesis use.
|
|
| 9. |
- Antfolk, Christian, et al.
(författare)
-
Sensory feedback in upper limb prosthetics.
- 2013
-
Ingår i: Expert Review of Medical Devices. - : Informa UK Limited. - 1745-2422 .- 1743-4440. ; 10:1, s. 45-54
-
Tidskriftsartikel (refereegranskat)abstract
- One of the challenges facing prosthetic designers and engineers is to restore the missing sensory function inherit to hand amputation. Several different techniques can be employed to provide amputees with sensory feedback: sensory substitution methods where the recorded stimulus is not only transferred to the amputee, but also translated to a different modality (modality-matched feedback), which transfers the stimulus without translation and direct neural stimulation, which interacts directly with peripheral afferent nerves. This paper presents an overview of the principal works and devices employed to provide upper limb amputees with sensory feedback. The focus is on sensory substitution and modality matched feedback; the principal features, advantages and disadvantages of the different methods are presented.
|
|
| 10. |
- Antfolk, Christian, et al.
(författare)
-
SmartHand tactile display: A new concept for providing sensory feedback in hand prostheses.
- 2010
-
Ingår i: Scandinavian Journal of Plastic and Reconstructive Surgery and Hand Surgery. - : Medical Journals Sweden AB. - 1651-2073. ; 44, s. 50-53
-
Tidskriftsartikel (refereegranskat)abstract
- Abstract A major drawback with myoelectric prostheses is that they do not provide the user with sensory feedback. Using a new principle for sensory feedback, we did a series of experiments involving 11 healthy subjects. The skin on the volar aspect of the forearm was used as the target area for sensory input. Experiments included discrimination of site of stimuli and pressure levels at a single stimulation point. A tactile display based on digital servomotors with one actuating element for each of the five fingers was used as a stimulator on the forearm. The results show that the participants were able to discriminate between three fingers with an accuracy of 97%, between five fingers with an accuracy of 82%, and between five levels with an accuracy of 79%. The tactile display may prove a helpful tool in providing amputees with sensory feedback from a prosthetic hand by transferring tactile stimuli from the prosthetic hand to the skin at forearm level.
|
|
