AU9721601A - Device for producing continuous passive motion - Google Patents

Description

Regulation 3.2

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT

(ORIGINAL)

Name of Applicant(s):Smith Nephew, of Z.I. de Tournes-Cliron, F-08540 Toumes, France Actual Inventor(s): Laurent Beny and Rene Griesmar Address for Service: DAVIES COLLISON CAVE, Patent Attorneys, of 1 Little Collins Street, Melbourne, Victoria 3000, Australia Attorney Code:DM Invention Title: "Device for producing continuous passive motion" The following statement is a full description of this invention, including the best method of performing it known to us: -1- DEVICE FOR PRODUCING CONTINUOUS PASSIVE MOTION TECHNICAL AREA: This invention pertains to a-device intended to produce a continuous passive motion that is generally referred to as "CPM", which corresponds to the abbreviation of the English expression "Continuous Passive Motion". Such device is frequently used in the physical and.

functional rehabilitation of the jointed limbs of a patient. This invention is specifically intended to be used as a device that will allow the lower limb of a person to undergo forced bendingstretching motions.

A treatment that is often prescribed for the rehabilitation of limbs, in particular the lower limbs, is the rehabilitating mobilization that consists in subjecting the limb to be rehabilitated to forced bending-stretching exercises according to programs that involve mobilization cycles where the frequency, amplitude and speed can be adjusted. That is the case, in particular, for the passive mobilization splints described in patent applications EP 0 590 973 and EP 0 230 218.

However, a patient may not have the required muscular power or capacity to actively control the alternating bending and stretching of a -limb. That is why a rehabilitation method is recommended which involves the passive motion of the limb to be rehabilitated by applying external forces to the limb.

Such passive motion can be applied manually by experienced therapists, but this method requires a true and comprehensive knowledge of human anatomy and involves a significant physical effort. Although the patent application EP 0 230 218 mentions the possibility of a partial adjustment, said adjustment is not complete and, above all does not provide for the device to be adapted equally to a right or left limb. Therefore, such passive motion is frequently applied to the limb to be rehabilitated through a device, generally referred to as a splint, capable of imposing adjusted bending-stretching cycles on the limb to be rehabilitated.

PREVIOUS TECHNIQUE: The previously described method proposed a relatively high number of technical solutions to build such devices.

One of the disadvantages of the CPM devices used in accordance with the previously described method is the fact that they are generally bulky, while a full bending-stretching motion is required for the splint of a lower limb that consists of long jointed segments. Such bulkiness can hinder the implementation, which involves the placement of such device directly on the mattress of the patient's bed.

Another disadvantage is due to the fact that such devices are generally driven by one or several direct drive units, which requires a motor output that is sufficient to maintain a mechanization that is always adequate for the mass of the limb to be moved. Consequently, this requirement calls for motors that burden the device and increase its bulkiness.

Another disadvantage concerns the degree of difficulty, or even impossibility, encountered when adjustments are made to match the proximal joint axis of the device with the coxofemoral joint of the limb to be rehabilitated, which applies to all anatomical configurations and all limb lengths that may be encountered. However, it is recognized that such requirement conditions the application of the passive rehabilitating motions imposed on the limb to be rehabilitated, without any induced residual physical stress.

The purpose of the invention is to eliminate the above-mentioned disadvantages by proposing a CPM device which must also be readily adaptable to either a right or left limb, offering the same anatomical adjustability.

P 'OPERICAE'67357-9S-cls do-061O 201 -3- DESCRIPTION OF INVENTION: According to this invention there is provided a device for producing a continuous passive motion for the bending and stretching of the jointed limb of a person according to a predetermined motion cycle, comprising a base supporting a jointed assembly having an upper limb supporting element, a lower limb supporting element, and an adjustable attachment element and a slider extending over the transverse width of the base; 10 wherein the upper and lower limb supporting elements are pivotally linked to each other at an axis transverse to the base, ~the upper element is detachably connected to the base by a bar or extension S"which is pivotally linked to said adjustable attachment element, and wherein the adjustable attachment element is mounted in position along the 15 slider by a set screw.

o. BRIEF DESCRIPTION OF THE DRAWINGS: •Other advantages of this invention will emerge from the description given below in reference to the attached drawings, where: 20 fig. 1 is a perspective projection of the device for producing a continuous .ooo.i passive motion (CPM) according to this invention; fig. 2 is a perspective projection of the proximal end of the CPM device according to this invention, which shows the jointed attachment element in its middle position for transportation and storage; and fig. 3 represents the general outlay of the CPM device according to this invention.

BEST APPLICATION OF THIS INVENTION: In reference to fig. 1 and according to this invention, a CPM device that is generally designated by 10, comprises a base 20 that is provided with a distal end 21 and a proximal end onto which a limb supporting element 30 is mounted. The supporting element 30 is attached to the base 20, more specifically to the distal end 25, by a jointed attachment element 35 that is attached to said end in a removable manner by a stretching element 55. The attachment element is preferably mounted on the distal end 25 with a set screw 36 that combines with a slider 37 constituted by the end 25, to extend over the entire transverse width of the base 20. Thus, the element 25 can be arranged on the right side, as shown in fig. 1, on the left side or in the middle of the base 20, as shown in fig. 3.

Therefore, the CPM device can be set for use with a left limb or a right limb, or for storage and transportation by immobilizing the attachment element 35 in the appropriate position .o with the set screw 36. The immobilization of the attachment element 35 in the middle of the slider 37, as shown in fig. 2, makes it possible to fold the CPM device into a unit that has smaller dimensions.

The supporting element 30 consists of a jointed structure that comprises upper and lower elements supporting the limb. Actually, the jointed structure consists mainly of a crural segment S: or cradle 31 and a tibial segment or cradle 32, which are arranged in prolongation of one another and linked about an axis x-x' that is transverse to the overall path of the jointed structure.

The crural segment 31 consists of two proximal bars 65a and 65b, linked by a brace that is itself fitted with a comfort hammock to support the thigh of the lower limb to be rehabilitated. The bars 65a and 65b are tubular and provided with locking buttons 60a and that make it possible to link either of said bars to an extension 55, which is itself attached to the element 35 through a pivot 40. The extension 55 is preferably telescopic and its length can be adjusted through an adjusting mechanism The tibial segment 32 consists of two bars 90a and 90b connected by a brace, not shown in the drawing, which allows for the mounting of a comfort hammock to support the leg of the limb to be rehabilitated. The bars 90a and 90b have a footrest 100 on their distal end, which is preferably attached in a removable manner and can be adjusted with buttons 75a and 75b. The bars 90a and 90b are linked to the bars 65a and 65b through pivots 80a and 80b that constitute the axis x-x'.

According to the invention, the bars 90a and 90b are provided with extensions 130a and 130b which extend towards the base and are fitted with sockets, rings or similar devices 72a and 82b, which are capable of sliding over the supporting bars 70a and 70b of which the proximal ends are linked to bars 65a and 65b through pivots 82a and 82b, which are located between the axis x-x' and the proximal ends of said bars. The distal ends of the supporting bars 70a and are mounted through pivots 120a and 120b over a driving element 125, such as a carriage, which is part of a driving mechanism supported by the base 20. This mechanism comprises a screw 115 that is mounted on the base 20 and combines with the carriage and two guides 110a and 110b, which are also mounted on the base 20, to support and guide the carriage. The screw 115 is :linked through a flexible coupling to a back-geared motor 105 that is preferably supported by the distal end 21 of the base The rotary motion of the screw 115 generated by the motor leads to the linear displacement of the driving carriage 125 along the guides 110a and ll0b, which produces, through supporting bars 70a and 70b, the bending-stretching motion of the jointed structure which, in turn, imposes said motion on the limb that it is supporting through segments 31 and 32.

It should be noted that the mounting of the tibial segment over the supporting bars 70 produces, for each bar 90, some type of collapsible quadrilateral that comprises a sliding point constituted by the corresponding socket 72. Such mounting introduces a multiplying effect in the motion, which makes it possible to obtain the bending-stretching motion of the jointed structure 30, by providing a limited travel of the carriage 125. Therefore, such arrangement allows for reduced spatial requirements, in particular for the base 20. Such arrangement also makes it possible to implement a motor 105 of reduced output, which further reduces the spatial requirements, as well as the weight of the device.

An electronic control box 140 (fig. 3) is used to preset the stretching limit, the bending limit and the motion speed. A "reproducing" potentiometer installed on pivot 80b closes the control circuit.

Another advantage of the construction of the device results from the mounting of the crural segment over the base 20, through an extension 55. This allows for the use of the shorter bars 65a and 65b, which offer a greater adaptability when the device must be used on short femurs. Furthermore, the lateral adjustability of the linkage to the right or to the left through the element 35 makes it possible to eliminate any functional interference between the base 20 and the thigh of the patient, regardless of whether the limb to be immobilized is to the right or to the left, as the element 35 can be equally attached to the right or to the left.

It should also be noted that the extension 55 is telescopic and adjustable, which allows for the accurate adjustment of the length of the crural segment between the axis x-x' and the pivot and, therefore, makes it possible to adapt at least one such adjustment in order to match said pivot with the coxofemoral or acetabular joint of a lower limb to be rehabilitated.

Preferably, the attachment element 35 is permanently attached to the base. When the device must be used for a left limb instead of a right limb, the extension bar 55 is separated from the proximal bar 65a, the attachment element 35 is loosened to allow the device to slide over the slider 37, and the device is reattached on the left side. This adaptability is especially useful if the CPM device is installed in a patient.

Another advantage of the device is due to the fact that the proximal bars and the lower bars supporting the limb can be deployed telescopically, thus offering a wide range of atypical settings for patients ranging in size between 112 cm and 206 cm.

The reference to any prior art in this specification is not, and should not be taken as, an acknowledgment or any form or suggestion that that prior art forms part of the common general knowledge in Australia.

Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises" and "comprising", will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

LIST OF REFERENCES 0* CPM device Base -Distal end of base Proximal end of base Jointed structure Cmural segment -Tibial segment -Adjusting buttons -Extension bar -Cmural segment bars -Upper cradle for limb -Pivots Supporting bars Sliding point links -Bars of tibial segment -Footrest -Back-geared motor -Guides -Screw -Driving element -Extension -Electronic control box 21 31 32 36, 50, 60a, 60b, 75a, 65a, 40, 80a, 80b, 82, 82b, 120a, 120b 70a, 72a, 72b 90a, 100 105 ll0a, il0b 115 125 130a, 130b 140 POTENTIAL INDUSTRIAL APPLICATION: This invention can be particularly beneficial if it is applied in the construction of mobilization splints intended for in-home rehabilitation purposes.

Claims (14)

1. A device for producing a continuous passive motion for the bending and stretching of the jointed limb of a person according to a predetermined motion cycle, comprising a base supporting a jointed assembly having an upper limb supporting element, a lower limb supporting element, an adjustable attachment element and a slider extending over the transverse width of the base; 10 wherein the upper and lower limb supporting elements are pivotally linked to each other at an axis transverse to the base, the upper element is detachably connected to the base by a bar or extension o.. which is pivotally linked to said adjustable attachment element, and wherein the adjustable attachment element is mounted in position along the 15 slider by a set screw.

2. The device according to claim 1, wherein the slider is positioned at the proximal S"end of the base. ooooo 20

3. The device according to claim 1 or 2, wherein the adjustable attachment element is adjustably mounted in position on the slider in a direction transverse to the slider.

4. The device according to any one of claims 1 to 3, wherein the bar or extension can be selectively connected to a left side or right side of the upper limb supporting element or in the middle of the base.

The device according to claim 4 wherein the bar or extension is connected to the middle of the base enabling the device to be folded into a unit of smaller dimensions.

6. The device according to any one of claims 1 to 5 wherein the bar or extension is telescopic. P 'OPERCAE'7357-98-dh- do- 13!12,01 9

7. A device for producing a continuous passive motion according to claim 1, substantially as herein described and with reference to the accompanying drawings.

8. Device for producing a continuous passive motion for the bending and stretching of the jointed limb of a person, according to a predetermined motion cycle, comprising a driving element capable of moving to-and-fro along a linear path defined as the base element upper and lower elements supporting the limb, linked for pivoting about an axis x-s' that is substantially transverse relative to said path; and a linking element connecting said upper element to said driving element, 10 characterized by the fact that said linking element is mounted so as to pivot in S:relation to both said upper support element and said driving element about axes that extent substantially transverse relative to said path, characterized by the fact that said lower element supporting the limb is adapted to be retained in sliding engagement against said linking element.

9. Device according to claim 8, characterized by the fact that the linking element is connected to the upper element supporting the limb to pivot on a transverse axis located S°between the pivoting axis and an adjustable attachment element connecting said upper element to the base.

10. Device for producing a continuous passive motion for the bending and stretching of the jointed limb of a person according to a predetermined motion cycle, of the type that comprises a base supporting a jointed assembly that consists of an upper limb supporting element and a lower limb supporting element, which are linked together according to a transverse axis, characterized by the fact that the upper element is connected to the base in a removable manner by a side bar or extension, which is itself linked to an adjustable attachment element through a pivot.

11. Device according to claim 10, characterized by the fact that the bar or extension is linked to the jointed attachment element that is supported by a set screw over a transverse slider that is part of the base. P'OPERCAE\67357-98<lmsdoc-13/12,01

12. Device according to claim 11, characterized by the fact that the set screw can be adjusted crosswise over the slider, which is supported by the proximal part of the base.

13. Device according to claim 10 or 11, characterized by the fact that the bar or extension can be adapted to the left side or the right side of the upper element supporting the limb.

14. Device according to either claim 10, 11 or 13 characterized by the fact that the bar is telescopic. DATED this 13th day of December 2001 Smith Nephew Kinetic SA 15 by DAVIES COLLISON CAVE Patent Attorneys for the Applicant oooo