WO2010140984A1

WO2010140984A1 - Finger function rehabilitation device

Info

Publication number: WO2010140984A1
Application number: PCT/SG2010/000209
Authority: WO
Inventors: Ludovic Dovat; Olivier Lambercy; Chee Leong Teo; Roger Gassert; Etienne Burdet
Original assignee: National University of Singapore
Current assignee: National University of Singapore
Priority date: 2009-06-03
Filing date: 2010-06-03
Publication date: 2010-12-09
Anticipated expiration: 2011-12-03

Abstract

A device for finger function rehabilitation comprising: fixations for engaging each finger; an actuator for selectively applying an active force to said fixations, and; a force transfer assembly connecting each of said fixations to the actuator.

Description

Finger Function Rehabilitation Device

Field Of The Invention

The present invention relates to the physical rehabilitation of finger function, and more particularly, devices for said rehabilitation.

Background Of The Invention

Stroke is one of the leading causes of adult disabilities in the world, with more than 15 millions cases every year. A major part of stroke survivors suffer from hemiparesis, i.e. a paralysis of one side of the body, resulting in a severe decrease in their ability to perform typical activities of daily living (manipulating objects, handwriting, eating, driving, etc.). Impaired finger function resulting from stroke can be summarized as failure to extend fingers, poor finger coordination, loss of finger independence, poor explorative movements, slow and clumsy object manipulation and grasping, and inability to control and maintain constant grip force.

However, the plasticity of the brain can help reorganize the neural connections damaged by the stroke, and thus to slowly partially recover the impaired functions. Rehabilitation is performed after stroke in order to stimulate the recovery, typically by performing intense movement repetition involving the impaired limb. Studies have shown that the rehabilitation program has to be task-oriented, focused on activities of daily living and repetitive movement oriented to provide an efficient therapy. It is also known that rehabilitation is also critical to other neuropathology injuries (Parkinson disease, spinal cord injuries, traumatic brain injuries, cerebral palsy) and physical rehabilitation.

Compared to classical rehabilitation performed in hospitals and specialized centers, undergoing treatment at home gives people the advantage of practicing skills and developing compensatory strategies in the context of their own living environment. However, home-based rehabilitation programs require specialized equipment for use at both the medical facility and at home. Motivation is also a problem for a subject training alone as he would not take advantage of the group effect.

Devices such as soft balls used in rehabilitation centers are used to train finger function. However, soft balls are incapable of measuring patients' performances and provide them accurate feedback of their performance.

Another known device disclosed in US patent number 5,451 ,191 has been realized to train finger function. The device uses a cable and spring configuration to train fingers, and so the application of force is passive, or reactive, against a force applied by the fingers. As such, it lacks ability to provide active movement to train fingers and to measure force and position movement of the fingers, but instead is limited to operating under resistive load conditions. It follows that such a device will be limited in its effectiveness by the degree of finger function of the patient. In severe cases, where the patient is unable to apply an efficacious force, this system will be ineffective.

Summary Of The Invention

In a first aspect, the invention provides a device for finger function training or rehabilitation comprising: fixations for engaging each finger; an actuator for selectively applying an active force to said fixations, and; a force transfer assembly connecting each of said fixations to the actuator.

In a second aspect, the invention provides a method for training or rehabilitating finger function, the method comprising the steps of: engaging each finger with a fixation assembly; applying an active force to each finger through the fixation.

Therefore, the invention provides for an actuator applying an active force to the fingers, rather than relying on a passive/reactive force of the prior art, which depends on the fingers to provide the applied active force in order to function.

Further, in one embodiment, the device may include means for taking measurements for the purpose of monitoring the patient's instantaneous treatment and/or objective assessment of longer term rehabilitation. For instance, the device may include one or more load sensors, such as load cells, in communication with the force transfer assembly. This may provide a measure of the force applied by the device to any one or all of the patient's fingers. For resistive treatment, the load sensors may also measure the load applied by the patient's fingers.

In the case of treatment using isometric training, the cables are restrained from movement, and accordingly there will be no displacement measured. However, the load sensor may be used to measure the force applied by the finger, or fingers, which are connected to the actuator in mode 3, that is, disconnected from both motors.

For treatment involving flexing or extending the fingers, a displacement sensor may be used. Such a displacement sensor may include an encoder mounted to a pulley or spindle of known diameter within the device, across which cables connected to the patient's fingers move. Such an encoder may record the rotation of said pulley or spindle, and so be able to record the displacement of the cable and consequently the movement of the finger.

The load and displacement may be recordable, whereby the displacement and load sensors are in communication with a data acquisition system recording to memory, a chart recorder and/or a visual display for the patient and therapist to view the instantaneous results. Further, the sensors may be in communication with a control system having control of the actuators. For instance, a threshold load may be pre-determined and stored within the control system. On exceeding the threshold, the control system may stop operation of the actuator to prevent injury to the patient. Further, the control system may also determine when the load is approaching the threshold load, and provide a warning to the patient/therapist. The control system may slow the rate of load application when proximate to the threshold load.

The control system may also have a pre-determined threshold displacement, such that on reaching the threshold, the control system stops the actuator to prevent over extension of the fingers. The control system may also provide a warning and/or slowing of the actuator on being proximate to the threshold

The pre-determined load and/or displacement threshold may be determined on a case by case basis, depending on the condition of the patient. There may also be an absolute maximum threshold for the load and/or displacement, for which the control system prevents the device from exceeding.

In a further embodiment, the control system may control the motor so as to emulate a linear or nonlinear relationship based on the application of force by the finger. For instance, for a linear relationship between input data from the sensors, the control system may control the motor to output a linear relation between force and position, and thus acting as a virtual spring. Similarly, a nonlinear relationship may be output, such as varying the applied force from the motor based on finger position to, say, maintain a uniform load on the finger during its full range of movement, which otherwise may not occur because of variation in the position of the finger through flexing.

Accordingly, in several different embodiments, the finger rehabilitation device may offer an automatic system that is portable and can be used at home, in rehabilitation centres, hospitals, etc to help stroke patients recover finger function. In one embodiment, it may be used as an independent module or, alternatively, it may be fixed to a structure (e.g. non-actuated structure) or to a robotic device.

The present invention may provide the advantage of offering a large range of movement to allow an efficient and complete training, from assisted finger extension to resisted grasp movement with the five fingers together. An interface may provide the possibility for training independently several parts of the hand, e.g. the jaw of thumb and index fingers, or thumb against index and middle fingers. The interface may be able to train the right or left hand and to adapt the position of the wrist for an improved comfort.

Other rehabilitation systems include non-actuated devices such as soft balls used in rehabilitation centers, which do not measure patients' performances, and robotic devices, which may be large, complex or expensive, limiting private use in the home.

The finger rehabilitation device may permit each fingertip freedom to move in at least three degrees-of-freedom (DOF), with a large range of movement from the fingers closing together to full extension.

In one embodiment, the device may comprise a cable driven system actuated by one or several motors. The rehabilitation device may offer several combinations of movement by means of a clutch system that allows engaging or disengaging of each finger to the motor(s).

In one embodiment according to present invention, the finger rehabilitation device may comprise a cable system to train the five fingers of either hand by means of at least one motor and five clutch systems to combine the action of these motors. In a further embodiment, for two motors which will be developed hereafter, each finger is attached to a cable linked to a clutch that can be automatically switched between three modes:

(i) actuation by the first motor capable of applying an active load, or operating under resistive load conditions;

(ii) actuation by the second motor, capable of applying an active load, or operating under resistive load conditions, and; (iii) blocked, and so preventing movement of the fingers, permitting isometric exercises, possibly against load sensors for recording and feeding back data.

In a further embodiment, each finger and the thumb may operate under a different mode, such that the first motor may be under resistive load conditions and the second motor applying an active load. For example, the treatment may then require the active load applied to the thumb and index finger whilst the remaining fingers are under a resistive load, blocked from movement (mode 3) or disconnected from the device altogether. In this case, the thumb may be connected to one motor and the index finger connected to another motor, with the remaining fingers blocked through connection in mode 3. In this example, the arrangement would allow for training of pinching tasks.

It will be appreciated that the device according to the present invention includes embodiments having any combination of the three modes applied in any combination to the fingers.

In a further embodiment, the two motors may be engaged in different gear ratios. In this case, different loading rates or load application may be available for selection between the first and second motors. In one embodiment, the actuator may include a "slip interface" between components. For instance, in the case of a motor, the motor may be connected to the force transfer assembly in a friction wheel arrangement rather than toothed gears. Hence, a maximum applied load may be limited to the friction between the wheels, providing a safety aspect.

The combinations between the three modes offer a large variety of movements and tasks with various finger co-ordinations using possibly less than five actuators.

The fingers actuation let the fingertip free to move in space. In one embodiment, when the clutch is actuated by one of the motors, the related cable is pulled by the motor, which generates a force that extends the finger.

The finger fixation may include an assembly, which in one embodiment may include a cable tensioning device. As the motor pulls the cable in one direction, the cable tensioning device, such as a bow spring, applies a force in the opposite direction in order to maintain the cable under tension. The bow spring is also used to generate small forces in direction of finger flexion. An alternative cable tensioning device may include a compression spring concentric with the cable. In a further embodiment of the present invention, a plurality of finger fixation assemblies may be adjusted to fit any hand, a particular trapezoidal shape of the structure allows rotating the device and thus adjusting the orientation of the wrist, and the rehabilitation device offers the possibility to train either right or left hand. A flexible arm support can be adapted to any subject.

For clarity, the thumb will be included in the description of "fingers" unless specifically identified as being distinct, such as for the mounting of the associated finger fixation assembly on the frame.

Brief Description Of The Drawings

Figure 1 is an isometric view of one embodiment of a finger rehabilitation device according to present invention.

Figure 2 is a close up view of the finger rehabilitation device according to Figure 1.

Figures 3A and 3B are isometric views of a finger rehabilitation device according to a further embodiment of the present invention.

Figure 4 is an alternative isometric view of the finger rehabilitation device according to Figure 1. Figures 5A to 5C are various views of a finger fixation assembly according to a preferred embodiment of the present invention.

Figures 6A to 6E are various views of a force transfer assembly according to a further embodiment of the present invention.

Figures 7A to 7C are various views of an actuator according to one embodiment of the present invention.

Figure 8 is an exploded view of a clutch lever according to one embodiment of the present invention.

Figure 9 shows a visual feedback of the finger rehabilitation device according to present invention.

Figure 10 is an elevation view of a clutch engagement according to a further embodiment of the present invention.

Figure 11 is an elevation view of a clutch engagement according to a further embodiment of the present invention. Figure 12 is an elevation view of a clutch engagement according to a further embodiment of the present invention.

Figure 13 shows an example of results of a pilot study to train finger independence.

Figure 14 shows an example of exercise scheme known as Isometric exercise.

Figure 15 shows an example of exercise scheme known as Elastic exercise.

Figures 16A to 16C are various views of the kinematic chain of mechanism of the finger rehabilitation device according to present invention.

Figures 17A to 17D are various views of the mounting of the finger rehabilitation device on different types of structures.

Detailed Description of Preferred Embodiments

Referring to figures 1 to 4 show the general assembly of a finger rehabilitation device 100 according to one embodiment of the present invention. The arm 110 of a subject 115 (stroke patient) is fixed on a support 145 that can be adjusted for an optimal comfort. The actuation system is enclosed in a box to prevent any harm to the subject. Due to the trapezoidal shape of the box 135, it can be placed 130 at several orientations 135 and thus be adapted for a comfortable wrist position. The subject 115 places each finger 125 inside a finger strap 155. The finger strap is actuated by means of a cable pulling in one direction and a bow spring in the other. The device 100 is composed of five subsystems, one for each finger, each subsystem being composed of a finger fixation and a clutch system 140.

Referring to Figures 5A to 5C, the finger fixation consists of a finger strap 1 (Velcro) to attach the finger. The finger can be attached at any finger joint, like DIP, PIP or MCP. The finger strap 1 is fixed on a support 2. A load cell 3, measuring compression and traction forces, is also mounted on this support 2. This force sensor 3 is thus placed between the finger and the actuating system (cable driven system and bow spring) and measures the interaction forces between the subject and the device. The component 4 links the force sensor 3, the cable 5 and the bow spring 6 together. The bow spring 6 has two purposes: the first objective is to maintain a certain tension in the cable system and the second one is to provide forces in the other direction, as the cable can pull in only one direction. The bow spring can be made of steel, or plastic depending on the desired force amplitude. The cable 5 is guided into the box through a pulley 7. The pulley 7 is mounted on a shaft 8 rotating around two ball bearings 9. An encoder (composed of a disk 10 and an encoder 11) is also mounted on the shaft 8 and measures the angular position of the pulley and thus the position of the finger. In order to avoid the cable 5 to slip out of the pulley 7, a ball bearing 12 is mounted on a shaft 13 and pushes the cable inside the groove. The pulley 7 and the encoder 10 are enclosed and protected within the part 14. The support 15 can be rotated around the ball bearing 16 to provide more flexibility. The whole subsystem "finger fixation" can be shifted along the profile 16 to provide a comfortable movement adapted to the subject's hand.

With reference to Figures 6A to 6E, these show how the finger fixation can be shifted along the profile 16 and how the cable is guided from the finger fixation to the actuation system. The cable is guided through the pulleys 17 and 18. The pulley 17 is mounted on a quick fastener 19 and can be easily shifted according to the displacement of the finger fixation. The pulley 18 remains aligned with the actuation system. An important feature of the system is the possibility to train either the right or the left hand. The finger fixations of the four fingers (index, middle, ring and little) can be easily shifted to fit both hands, but the thumb fixation needs to be switched from one side of the device to the other one. The cable path is thus different for the thumb. Figure 6A to 6E further show the displacement of the thumb fixation from a right hand (Fig 6D) to a left hand (Fig 6E). The cable is guided through the four pulleys 20, 21 , 22 and 23. Like for the other finger fixations, the pulley 20 is mounted on a quick fastener and can be easily shifted to be aligned with the thumb fixation while the pulley 23 is aligned with the actuation system. The pulleys 21 and 22 allow the large displacement of the thumb fixation. Referring to Figures 7A to 7C, these show one embodiment of an actuation system with two motors allowing three modes: (i) actuation by the first motor 160,; (ii) actuation by the second motor 170; and (iii) blocked 165, to prevent movement of the fingers and so permit isometric training.

In the embodiment, the actuation system is composed of five clutch systems, one for each finger, and two motors. The motors actuate two shafts by means of timing belts, the motor 24 actuates the shaft 27 and the motor 25 actuates the shaft 26, respectively. Five gears 28 are mounted on both shafts to provide the torque when the corresponding clutch gear is engaged. Therefore, each of the five clutch systems can be engaged to one or the other shafts corresponding to the modes (i) and (ii) previously mentioned. A pin 29 supported by the profile 30 provides the third mode (iii) by blocking any rotation of the clutch gear when it is engaged.

Referring to Figure 8 shows an exploded view of a lever, or clutch lever, system that is used to switch between the three modes. The basis of the clutch system is the servomotor 31 that automatically rotates a lever in order to engage the clutch gear 32 with one of the gears 28 mounted on the motor shafts 26 and 27 (modes (i) and (ii)) or the pin 29 (mode (iii)). The servomotor actuates the lever that is composed of two parts 33 and 34. The two parts 33 and 34 are linked together with the component 35. These levers are mounted on two ball bearings 36 and rotate around the shaft 37. The clutch gear 32 and the pulley 38 are mounted on the shaft 39 at the extremity of the levers. This shaft 39 is also mounted on two ball bearings 40. The clutch gear 32 provides the torque to the pulley 38 when it is engaged in one of the three modes. The cable 5 is wound up the pulley 38 and transmits the force to the subject's finger. The conic shape of the pulley 38 avoids the cable to cross and tie a knot. The pulley 41 is mounted on a ball bearing and guides the cable toward the cone-shape pulley 38. The components 42 and 43 support the levers, the component 44 supports the servomotor, the components 45 support the actuation shafts 26 and 27 and the components 46 support the two motors.

A virtual environment is necessary to help the subject keep motivated during the training. Referring to Figure 9, a finger independence scheme is implemented. The objectives of this exercise are:

(i) strengthen muscles of individual fingers in order to improve the function of finger independence; and

(ii) improve the ability to control the force applied by each finger. The exercise consists of isometric forces generated by individual fingers. The exercise has been designed to keep the subject motivated and the principle is based on the game Hangman (a game in which one player tries to guess the letters of a word 190, and failed attempts are recorded by drawing a gallows and a stick figure of someone hanging on it, stroke by stroke). The subject is instructed to select different letters in order to compose a word (e.g. the subject has to select one by one S-Y-D-N-E-Y 190 to form the word "Sydney"). To select a letter 180, the subject has to apply a certain amount of force (between 5% and 25% MVC) with a specific finger 185. Any force applied by another finger has a negative effect to encourage the subject to control each finger individually. The placement 175 of each letter is important: the letters that are most often used (especially vowels) are placed so that the subject has to apply a large force. The letters are also distributed to emphasize the thumb- index pair, required in many ADL. The words have been selected to capture the subject's interest. This is why it has been decided to use names of cities or countries that interest the subject.

The implemented virtual environment consists of three different feedbacks and informs the subject on his performances: (i) visual, (ii), audio and (iii) tactile feedbacks. During this training, the fingers under training are connected to the actuator in mode 3, that is, disconnected from both the first and second motors, with the respective gear engaged with the pin 29 to prevent movement of the cables, and consequently, the fingers being trained.

A trial was conducted using the preferred embodiment of the rehabilitation device. The results of a 16-weeks training with two post-stroke patients, each performing a specific exercise with the first prototype of the robotic device. These subjects (65-83 y with right hemiplegia, right-handed) were representative of the population for which the interface has been initially designed, capable of minimal movement of the hand and fingers. The two patients had similar hand function impairment preventing them from using their right hand for typical ADL such as key pinch, combing, and handwriting.

Subject 1 : Isometric exercise or Hangman

The objectives of this exercise are to: (i) strengthen muscles of individual fingers in order to improve finger independence and, (ii) improve the ability to control the force applied by each finger. The exercise consists of isometric forces generated by individual fingers. The exercise has been designed to keep the subject motivated and the principle is based on the game Hangman The subject is instructed to select different letters in order to compose a word. To select a letter, the subject has to apply a certain amount of force, such as between 5% and 25% MVC (Maximal Voluntary Contraction), to avoid fatigue with a specific finger. Any force applied by another finger has a negative effect to encourage the subject to control each finger individually.

Figure 13 shows that the number of successful tasks performed by individual fingers increases with the training. As reported by the subject, it was much easier in the end of the training to accomplish a specific task with individual fingers. Figure 14 shows the evolution during the training while the subject has to apply a certain amount of force with the middle finger and then maintain this force. Evolution of force from the beginning (A), the middle (B) and the end (C) of the training while the subject has to reach and maintain a target force (between dotted lines) with a specific finger (middle finger in this case). P1 is the section before the subject reaches the target force for the first time and P2 is the section while the subject tries to maintain the target force.

The major improvement is the increase in finger independence leading to a better dexterity of individual fingers. Indeed, the factor of independence (ratio between the maximal force applied by two fingers) improves for every pair of fingers. The time required to reach the target area, i.e. time of the section P1 is also significantly reduced (more than 40%). Finally, the quality of force, i.e. the smoothness of the force, is clearly improved for the thumb, the index and middle fingers. The patient was assessed before and after training to compare the functional improvements and table 1 summarizes some of the improved hand functions.

Subject 2: Elastic exercise In this exercise, the subject has to move the five fingers against a load (resistive load for the closing movement and assistive load for the opening movement) generated by the robotic interface (between 5% and 25% MVC). Moreover, during the movement, the fingers must be coordinated such that they have forces of identical amplitude. Visual feedback informs the subject on his performance during the training. The benefits of training with this exercise may be to: (i) enhance finger coordination, (ii) strengthen the finger muscles, and (iii) increase dexterity of the five fingers.

Figure 15 shows the evolution during the training while the subject performs a closing movement (improvement is similar for the opening movement). Evolution of position, velocity and force from the beginning (A), the middle (B) and the end (C) of the training while the subject has to close the hand while applying the same force with each of the four fingers (the subject was not able to perform the exercise with the thumb).

The significant improvement in finger coordination is the major output of this exercise especially for the pair index-middle, middle-ring and ring-little. Training also provides a better balance of forces between the index, the middle and the ring fingers (the little finger remains weaker than the other fingers). The smoothness of the movement, as well as the force (evaluated by standard methods, e.g. analysis of the velocity or frequency), is significantly improved. Another important improvement is the decrease in finger stiffness. Indeed the force required to assist the subject during the opening phase of the exercise is reduced by 30% at the end of the therapy. The above two presented exercises illustrate the benefit of the finger rehabilitation device to help post-stroke patients recover finger function. Several improvements have been quantified directly from measurements provided by the device, such position, velocity and force.

In another preferred embodiment, more than two motors can be used to provide more flexibility. For instance, Figure 10 shows a clutch system 195 switching between four shafts 200A to D actuated by four motors (not shown). The gear ratio 205, 210 can also be modified to provide a torque adapted to any subject or exercise as shown in Figure 11.

Figure 12 shows another modification to transmit the torque by friction. Indeed, the gears are replaced by two pulleys 215, 220 with high coefficients of friction.

The actuation of the fingers is critical in rehabilitation of hand function. Considering that the complete finger movement is composed of four degrees-of- freedom (DOF), i.e. three flexion/extension (at the three joints: MCP (metacarpophalangeal), PIP (proximal interphalangeal) and DIP (distal interphalangeal)) and one abduction/adduction at the MCP joint, the actuation mechanism should also have at least four DOFs.

A mechanism to actuate these four DOFs could be very complex, especially if we want to train the five fingers together (the system would need more than 20 actuators). Therefore, a mechanism where only one DOF is actuated to help the subject flex and extend his finger. With this method, the distal extremity of the finger (fingertip) is actuated in one direction (flexion/extension of the MCP joint), while the other joints are not constrained. Figure 16A illustrates the kinematic chain of the mechanism. Many systems can be implemented to satisfy the kinematics, for instance:

(i) a linear guide system mounted on a ball joint or (ii) as shown on Figure 16B a cable-based system. Another advantage of the mechanism is that it can be very compact and can be placed on a specific frame (Figure 16C) to train the five fingers together. The frame can then be placed on a fixed structure (Fig. 17B) if we want to train hand function individually, or on a mobile structure, if we want to combine it with another system, e.g. the mechanism could be mounted on a robotic arm 245 (Fig. 17C) or an exoskeleton 250 (Fig. 17D) used to train arm movements.

Claims

Claims:

1. A device for finger function rehabilitation comprising: fixations for engaging each finger; an actuator for selectively applying an active force to said fixations, and; a force transfer assembly connecting each of said fixations to the actuator.

2. The device according to claim 1, wherein the fixations comprise a fixation assembly engaged with each finger, said fixation assembly including an attachment for engaging the finger, a cable mounted at one end to the attachment and an opposed end to the force transfer assembly corresponding to that finger, said cable including a cable tensioning device for maintaining the cable in tension.

3. The device according to claim 1 or 2, further including a frame arranged to support the finger fixation assemblies in a position suitable for engagement with the fingers of a patient.

4. The device according to any one of the preceding claims, wherein the force transfer assembly comprises an assembly of cables and pulleys arranged to direct the active applied force from the actuator to the cable of the finger fixation assemblies.

5. The device according to any one of claims 2 to 4, wherein the cable tensioning device includes a bow spring member coupled to a member at each end of the cable, said bow spring member pre-loaded to apply a force to said members, and thus apply a tensile force to said cable.

6. The device according to any one of the preceding claims wherein the actuator comprises an assembly of at least one motor mounting to a shaft, said shaft in communication with each of said force transfer assemblies so as to apply a force to the fingers on rotation of the shaft.

7. The device according to claim 6, wherein the force transfer assembly terminates at a spindle with communication between the force transfer assembly and the shaft comprising selective engageability between the spindle and the shaft.

8. The device according to claim 7, wherein the spindle is mounted to a pivotable level wherein pivoting lever from a central position to a first engaged position engages the spindle to the shaft so as to apply the active force to the finger corresponding to said spindle.

9. The device according to any one of claims 6 to 8 wherein the actuator further includes a second motor associated with a second shaft said first and second shaft rotating in opposite directions such that the lever is selectively moveable from the central position to the first engagement position to engage the first shaft and pivotable from the central position to a second engagement position to engage the second shaft such that the actuator applies active forces in opposed directions depending on whether the lever is engage with the first or second shaft.

10. The device according to claim 9, wherein the lever in the central position engages a member locking said spindle and consequently preventing movement of the cable associated with said spindle.

11.The device according to anyone of the preceding claims, further including a load sensor for measuring the active force applied to said fingers.

12. The device according to claim 11 , wherein said load sensor is a load cell mounted in series with the cable of the finger fixation assembly.

13. The device according to anyone of the preceding claims, further including a displacement sensor for measuring the movement of the cable corresponding to movement of the finger.

14. The device according to claim 13, wherein the displacement sensor is an encoder mounted to a pulley within at least one of the finger fixation assemblies such that movement of the cable rotates the pulley and measures the corresponding displacement.

15. The device according to claims 13 or 14, further including a recording system for recording active force and/or movement corresponding to each finger.

16. The device according to any one of claims 13 to 15, further including a control system arranged to receive input from the respective sensors, and comparing the input to a threshold limit for either said force or movement, such that on exceeding the threshold for the force or movement, the control system stops operation of the actuator.

17. The device according to claim 16, wherein on the load and/or measurement input being proximate to the respective threshold, the control systems is arranged to signal the patient or slow operation of the actuator.

18. A method for rehabilitating finger function, the method comprising the steps of: engaging each finger with a fixation assembly; applying an active force to at least one of said fingers through the fixation.

19. The method of claim 18, further including the step of measuring the active force applied to said at least one finger.

20. The method of claim 18 or 19, further including the step of measuring movement of said at least one finger resulting from the application of the active force.

21. The method of claim 19 or 20, further including the steps of receiving data from said measuring step, and recording said data.