WO2014001793A1

WO2014001793A1 - Orthosis for lower leg and foot

Info

Publication number: WO2014001793A1
Application number: PCT/GB2013/051682
Authority: WO
Inventors: Ronald Barney WHITE
Original assignee: Coventry University
Priority date: 2012-06-26
Filing date: 2013-06-26
Publication date: 2014-01-03
Also published as: GB201421891D0; GB2518770A; GB201211328D0

Abstract

An orthotis (1) for the lower leg and foot, comprises a foot portion (3), a calf portion (2) secured around the calf of the patient, and an elongate member (4) connecting the calf portion and the foot portion. Part (A) of the elongate member is deformable resiliently to permit dorsiflexion and plantarflexion. An adjustment mechanism (11, 15) adjusts the resistance to dorsiflexion and plantarflexion and comprises a first adjustment element such as a plate (11) on the front of the elongate member and a second adjustment element such as a plate (15) on the rear of the elongate member. One of the adjustment elements (11) is adjustable to control primarily the resistance to dorsiflexion, and the other of the adjustment elements (15) is adjustable to control primarily the resistance to plantarflexion. Adjustment may be effected by altering the longitudinal position of the plate (11, 15) on the elongate member and/or by changing the plate, using threaded fasteners (14, 18) to secure the plate to the elongate member.

Description

Orthosis for Lower Leg and Foot

This invention relates to an orthosis for the lower leg and foot. Some medical conditions or injuries result in altered walking or gait patterns for people. An example of this is a stroke. Following a stroke some people will need extensive therapy to assist them in regaining an ability to walk. Some will use assistive devices like walking sticks or walking frames, and some will require an Ankle-Foot Orthosis (AFO). Current orthoses tend to be designed for a specific function and are not readily adaptable to the changing abilities that people tend to display following a stroke. Custom made orthoses can be made which will suit the patient at one period during their recovery, but will not be suitable for other periods. It is particularly necessary to be able to adjust the resistance to dorsiflexion and plantarflexion. Dorsiflexion is when the relative movement of the foot is up towards the leg of a person, and plantarflexion is when the relative movement of the foot is downwardly away from the leg of a person.

In US Patent 7,270,644 there is disclosed an ankle foot orthosis which has a calf portion which is located around the calf of the patent, and a foot portion on which the patient's foot rests, which are interconnected by a resilient member. In one embodiment this comprises first and second spring elements, both of which are secured to the foot portion but only the first spring element is secured to the calf portion. The second spring element is attached to the first spring element by a clamping element which can be positioned at various points along the lengths of the first and second spring elements. In one configuration the clamp is towards the top of the first spring element and it is said that this provides substantially the same plantarflexion and dorsiflexion. In another configuration the clamp is further down the first element and it is said that this provides greater plantarflexion. A problem with this is arrangement is that adjustment of the clamp position will invariably affect both plantarflexion and dorsiflexion.

An object of the present invention is to provide an improved orthosis for the lower leg and foot. Viewed from one aspect the present invention provides an orthosis for the lower leg and foot, comprising a foot portion on which the foot of a patient is to rest, a calf portion including a fastening arrangement to secure the calf portion to the calf of the patient, an elongate member connecting the calf portion and the foot portion, at least part of the elongate member being deformable resiliently to permit dorsiflexion and plantarflexion, and an adjustment mechanism to adjust the resistance to dorsiflexion and plantarflexion; wherein the adjustment mechanism comprises a first adjustment element on the front of the elongate member and a second adjustment element on the rear of the elongate member, one of the adjustment elements being adjustable to control primarily the resistance to dorsiflexion, and the other of the adjustment elements being adjustable to control primarily the resistance to plantarflexion.

The ability control the resistance to dorsiflexion and plantarflexion independently make it possible to adjust the orthosis more closely to suit the needs of an individual patient.

In a preferred embodiment, the adjustment of said one of the adjustment elements to control primarily the resistance to dorsiflexion has substantially no effect on the resistance to plantarflexion; likewise the adjustment of said other of the adjustment elements to control primarily the resistance to plantarflexion has substantially no effect on the resistance to dorsiflexion.

In some embodiments of the invention the adjustment elements could be, for example, damper elements such as piston cylinder arrangements provided with valves so that they resist movement in one direction but not in the other, the degree of resistance being adjustable. In such an arrangement, the damper element on the front of the elongate member could be set up to resist either dorsiflexion or plantarflexion, and the damper element on the rear of the elongate member would be set up to resist the other of dorsiflexion and plantarflexion. However, damper elements will add to the cost, complexity and bulkiness of the orthosis.

In preferred embodiments, therefore, the first adjustment element comprises a first supplementary element which is connected to the elongate member and extends along the front of the elongate member to a free end of the first supplementary element; and the second adjustment element comprises a second supplementary element which is connected to the elongate member and extends along the rear of the elongate member to a free end of the second supplementary element. In such an arrangement, the resistance to dorsiflexion can be adjusted by changing the first supplementary element and / or changing the point of attachment of the first supplementary element to the elongate member in the longitudinal direction. The resistance to plantarflexion can be adjusted by changing the second supplementary element and / or changing the point of attachment of the second supplementary element to the elongate member in the longitudinal direction.

In such an arrangement, when the elongate member flexes in the forward direction to permit dorsiflexion, the first supplementary element will be placed under compression and will resist flexion. The degree of resistance will depend on the point of attachment of the first supplementary element to the elongate member and / or the characteristics of the first supplementary element. At the same time, because the second supplementary element is not placed in compression and has a free end, it will not resist that movement. Conversely, when the elongate member flexes in the rearward direction to permit plantarflexion, the second supplementary element will be placed under compression and will resist flexion. The degree of resistance will depend on the point of attachment of the second supplementary element to the elongate member and / or the characteristics of the second supplementary element. At the same time, because the first supplementary element is not placed in compression and has a free end, it will not resist that movement.

The arrangement may be such that is both supplementary elements are mounted at their extreme position in one direction, the elongate member will have maximum flexibility, and if both supplementary elements are mounted at their extreme position in the other direction, the elongate member will have minimum flexibility. When there is minimum flexibility the arrangement may be such that for a patient the elongate member will be effectively rigid.

The attachment of either supplementary element to the elongate member may be by means of a threaded fastener passing through an aperture in the supplementary element and into a threaded hole in the elongate member. There may be two or more such threaded fasteners, preferably longitudinally spaced, for each supplementary element. In such an arrangement there could be provided a series of apertures in the supplementary element and / or a series of threaded holes in the elongate member, so that the point of attachment of the supplementary element can be adjusted. Alternatively, a number of replacement supplementary elements could be provided, with fixing holes in different places, so that one supplementary element could be removed and replaced by a different one.

Preferably, each supplementary element is elongate and is attached to the elongate member at one end , the other end being free. Preferably, each supplementary element has its upper end attached to the elongate member and its lower end free. In a preferred arrangement, the elongate member is more rigid further up the elongate member where the supplementary elements have their respective points of attachment, and more flexible lower down.

However, it will be appreciated that it would be possible to have a supplementary element which is elongate and attached to the elongate member at a point towards the middle of the supplementary element, so that there are two free ends. In some embodiments, each supplementary element is also resiliently deformable. The flexibility of the supplementary element my vary along its length. In one embodiment, the supplementary element is most rigid adjacent its point of attachment to the elongate member, and most flexible adjacent the free end. There may be a gradual increase in flexibility towards the free end. Changes in flexibility can be achieved, for example, by changing the thickness of the material of the supplementary element. There could be a number of supplementary elements, with differing flexibility characteristics, so that one supplementary element could be removed and replaced by another with different properties. In some embodiments of the invention there is a longitudinally extending recess in the elongate member, in the region of where the supplementary elements are attached. There could be single recess, on either the front or the rear of the elongate member so that either the first or the second supplementary element is positioned in the recess; or there could be one recess on the front of the elongate member and one recess on the rear of the elongate member, so that each of the first and the second supplementary elements is positioned in its respective recess.

Preferably the foot portion of the orthosis has a degree of flexibility at the heel end of the foot portion and at a forefoot part of the foot portion. The two flexibilities of the foot portion can be varied by using one or more supplementary sole portions used in conjunction with the foot portion. A supplementary sole portion may be attached to the underneath of the foot portion (or to another supplementary sole portion), for example by a hook and loop fastening system (such as Velcro™ or the like) or by any other means, preferably releasably. A single supplementary sole portion can be selected from a range of supplementary sole portions having different characteristics. Two or more supplementary sole portions could be used together to create different characteristics. Preferably, the elongate member is attached to the foot portion at a side edge of the foot portion, and in one embodiment to the inside edge of the foot portion. The elongate member may extend down the central region of the leg to a lower part which then turns laterally and extends down to where it is attached to the side of the foot portion.

In preferred embodiments of the invention there are the following features and advantages:

1. The adjustment of dorsiflexion and plantarflexion are independent, which is a very important feature for clinical use.

2. Adjustment in the rigidity of the sole of the orthosis is also independent at the heel and the forefoot. Adjustments can be made for different stages of gait, and more specifically for different stages of a stance phase.

3. The adjustability of the ankle rigidity and the foot rigidity are variables during the formal rehabilitation process and after when the patent's function continues to change with time, albeit more slowly. 4. The adjustments can be made by the patients or unskilled people, as well as health care professionals to help ensure that only sufficient support is provided, rather than unnecessary or excessive support.

5. The adjustments are quantifiable, in that the patients have a way of gauging aspects of the amount of support that the orthosis provides and hence the progress that they are making in their rehabilitation.

The preferred approach taken is to use the orthosis to enhance rehabilitation and then to discontinue use of the orthosis when possible. There is

transitory therapeutic use when possible, rather than use and dependence without reducing the amount of support. The preferred approach is for standing and then walking / gait rehabilitation and function.

The orthosis is preferably made of a suitable lightweight material such as carbon fibre material. This enable the orthosis to have reduced weight and improved appearance and the ability to be worn under clothing unobtrusively.

In some embodiments of the invention, the elongate member has an upper portion, a lower portion and an intermediate portion, and the intermediate portion is relatively flexible with respect to the upper portion. In some embodiments the intermediate portion is also relatively flexible with respect to the lower portion. The upper portion may be more rigid than the lower portion, which may have a degree of flexibility which is substantially less than that of the intermediate portion. The intermediate portion may be curved so as to provide a profile which is concave with regard to the front of the orthosis. The radius or curvature may be constant or may be varying, and in one embodiment the radius of curvature of the intermediate portion decreases towards the lower portion. Where the resistance to flexion is adjusted by the use of supplementary elements, these may be connected to the upper portion of the elongate member, and the degree of resistance to flexion may be adjusted by adjusting the extent to which a supplementary element extends down into the intermediate region. The invention may be viewed from a number of different aspects. For example viewed from another aspect, the invention provides an orthosis for the lower leg and foot, comprising a foot portion on which the foot of a patient is to rest, a calf portion including a fastening arrangement to secure the calf portion to the calf of the patient, an elongate member connecting the calf portion and the foot portion, at least part of the elongate member being deformable resiliently to permit dorsiflexion and plantarflexion, and an adjustment system to adjust the resistance to

dorsiflexion and plantarflexion; wherein the adjustment system comprises a first adjustment element secured to the front of the elongate member to control primarily the resistance to dorsiflexion, and a second adjustment element secured to the rear of the elongate member to control primarily the resistance to plantarflexion, the first and second adjustment elements being removable and replaceable independently of each other. The first adjustment element may be replaced at a different longitudinal position on the elongate member to vary the resistance to dorsiflexion. Additionally or alternatively, the first adjustment element may be replaced by an adjustment element having different characteristics, so as to vary the resistance to dorsiflexion. The second adjustment element may be replaced at a different longitudinal position on the elongate member to vary the resistance to plantarflexion. Additionally or alternatively, the second adjustment element may be replaced by an adjustment element having different characteristics, so as to vary the resistance to

plantarflexion. Viewed from another aspect, the invention provides a method for adjusting the characteristics of an orthosis for the lower leg and foot, the orthosis comprising: a foot portion on which the foot of a patient is to rest, a calf portion including a fastening arrangement to secure the calf portion to the calf of the patient, an elongate member connecting the calf portion and the foot portion, at least part of the elongate member being deformable resiliently to permit dorsiflexion and plantarflexion; a first adjustment element secured to the front of the elongate member to control primarily the resistance to dorsiflexion; and a second adjustment element secured to the rear of the elongate member to control primarily the resistance to plantarflexion; wherein the method comprises the step of adjusting the resistance of the orthosis to dorsiflexion independently of the resistance of the orthosis to plantarflexion, by removing the first adjustment element and replacing the first adjustment element at a different longitudinal position on the front of the elongate member; and / or the step of adjusting the resistance of the orthosis to plantarflexion independently of the resistance of the orthosis to dorsiflexion, by removing the second adjustment element and replacing the second adjustment element at a different longitudinal position on the rear of the elongate member.

Viewed from another aspect, the invention provides a method for adjusting the characteristics of an orthosis for the lower leg and foot, the orthosis comprising: a foot portion on which the foot of a patient is to rest, a calf portion including a fastening arrangement to secure the calf portion to the calf of the patient, an elongate member connecting the calf portion and the foot portion, at least part of the elongate member being deformable resiliently to permit dorsiflexion and plantarflexion; a first adjustment element secured to the front of the elongate member to control primarily the resistance to dorsiflexion; and a second adjustment element secured to the rear of the elongate member to control primarily the resistance to plantarflexion; wherein the method comprises the step of adjusting the resistance of the orthosis to dorsiflexion independently of the resistance of the orthosis to plantarflexion, by removing the first adjustment element and replacing the first adjustment element by a modified first adjustment element having different flexion characteristics, the modified first adjustment element being secured at the same or a different longitudinal position on the front of the elongate member; and / or the step of adjusting the resistance of the orthosis to plantarflexion independently of the resistance of the orthosis to dorsiflexion, by removing the second adjustment element and replacing the second adjustment element by a modified second adjustment element having different flexion characteristics, the modified second adjustment element being secured at the same or a different longitudinal position on the rear of the elongate member. ln either method, in addition to adjusting the resistance to dorsiflexion and / or plantarflexion, the orthosis may be adjusted in respect of the degree of flexibility at the heel end of the foot portion and / or at a forefoot part of the foot portion.

Adjustment of these characteristics of the foot portion may be achieved by attaching to the foot portion a supplementary sole portion.

Either method may be used for adjusting the characteristics of an orthosis for the lower leg and foot of a patient who has been affected by a stroke, i.e. a

cerebrovascular incident, and who has need for ambulatory assistance.

Viewed from another aspect of the invention, the invention provides a method of treatment of a patient who has been affected by a stroke and who has need for ambulatory assistance, by carrying out any of the methods as described above. Some embodiments of the invention will now be described by way of example and with reference to the accompanying drawings, in which:

Figure 1 is a diagrammatic side view of an orthosis in accordance with the invention;

Figures 2(a) and 2(b) are views of supplementary sole portions; Figure 3 is a diagrammatic top perspective view of the calf portion of the orthosis; Figure 4 is a diagrammatic view of part of the orthosis;

Figure 5 is a diagrammatic top view of the foot portion of the orthosis; Figure 6 is a diagrammatic view of part of an alternative orthosis; and

Figure 7 is a diagrammatic side view of a modification of the orthosis of Figures 1 to 5.

Referring now to Figure 1 there is shown an ankle foot orthosis 1. This includes a calf portion 2 for engaging around the calf of a patient, a foot portion 3, and an elongate member 4 which interconnects the calf portion and the foot portion. As shown in Figure 3, the calf portion has an interior 5 and straps 6 which can be fastened around the patient's calf. The lower end 7 of the elongate member 4 is curved forwardly and is directed to the side of the foot portion 3, being connected to the inside edge of the foot portion as shown in Figure 5.

The elongate member is designed to be resiliently deformable, at least in the region marked "A" on Figure 1 , so as to permit forwards flexing in the direction of arrow "B" to accommodate dorsiflexion, and rearwards flexing in the direction of arrow "C" to accommodate plantarflexion. The degree of resistance to dorsiflexion and plantarflexion is adjustable independently, in the manner described below.

An intermediate part 8 of the front face of elongate member 4 is recessed, to assist in providing flexibility in region "A". As shown in Figure 4, this recessed part 8 is provided with a series of longitudinally spaced threaded bores 9 in the front face of the recessed portion, in this case consisting of four threaded bores. A similar series of longitudinally spaced threaded bores 10 is provided on the rear face of the of the elongate member. A first supplementary plate 11 is provided for the recessed part 8 of the elongate member. This is elongate and has two longitudinally spaced apertures 12 and 13 passing through it, in this case three being shown. These apertures are aligned with two adjacent threaded bores 9 , and threaded fasteners 14 pass through the apertures and are screwed into the threaded bores, for example using an alien key. This attaches the upper end of the first supplementary plate 1 1 to the elongate member, with the lower end being free. By removing the threaded fasteners 14, the first supplementary plate can be re-positioned to use a different pair of bores 9 before being secured again, thus altering the vertical position of the first supplementary plate. Alternatively, a different supplementary plate can be used, using the same or a different pair of threaded bores. A second supplementary plate 15 is provided for the other side of the elongate member. This is elongate and has two spaced apertures 16 and 17 passing through it. These apertures are aligned with two adjacent threaded bores 10, and threaded fasteners 18 pass through the apertures and are screwed into the threaded bores, for example using an alien key. This attaches the upper end of the second

supplementary plate 16 to the elongate member, with the lower end being free. By removing the threaded fasteners 18, the second supplementary plate can be re- positioned to use a different pair of bores 10 before being secured again, thus altering the vertical position of the first supplementary plate. Alternatively, a different supplementary plate can be used, using the same or a different pair of threaded bores.

As the flexible part of the elongate member is flexed forwardly, first supplementary plate 11 is placed under compression and resists movement, whereas second supplementary plate 15 does not impede movement. As the flexible part of the elongate member is flexed rearwardly, second supplementary plate 15 is placed under compression and resists movement, whereas first supplementary plate 11 does not impede movement. In each case, the degree of resistance is dependent on the vertical position of the supplementary plate.

When both supplementary plates are mounted to their fullest extent up the elongate member 4, there is maximum flexibility of the elongate member. When both supplementary plates are mounted at their lowest points, there is maximum rigidity of the elongate member and in some cases there may be no flexibility of this part of the orthosis when in use by a patient. Figure 6 shows an alternative arrangement for adjusting the degree of resistance to dorsiflexion and plantarflexion separately. A flexible portion 19 of an elongate member has on its front face a damper arrangement 20 which has a cylinder 21 attached to an upper part of portion 19, and a push rod 22 connected at 23 to a lower part of portion 19. The damper is such that flexing of portion 19 in the direction of arrow "D" that tends to cause the pushrod 22 to move into the cylinder 21 is resisted, whereas movement in the opposite direction of arrow "E" is not. An adjuster 24 is provided to adjust the degree of resistance. The flexible portion 19 of an elongate member has on its rear face a damper arrangement 25 which has a cylinder 26 attached to an upper part of portion 19, and a push rod 27 connected at 28 to a lower part of portion 19. The damper is such that flexing of portion 19 in the direction of arrow "E" that tends to cause the pushrod 27 to move into the cylinder 26 is resisted, whereas movement in the opposite direction of arrow "D" is not. An adjuster 29 is provided to adjust the degree of resistance. As shown in Figure 1 , the foot portion 3 is flexible in the heel region 30 and the forefoot region 31 Figures 2(a) and 2 (b) show supplementary insoles 32 and 33 that can be attached to the foot portion 3 of the orthosis, either separately or in combination, to alter the characteristics of the foot portion.

Figure 7 shows an orthosis 34 which is a modification of the orthosis of Figures 1 to 5. There is a calf portion 35, corresponding to calf portion 2, for engaging around the calf of a patient, a foot portion 37 corresponding to foot portion 3, and an elongate member 36 which interconnects the calf portion and the foot portion and is a modification of member 4 of the earlier embodiment. In all other respects, the orthosis is the same at that of the earlier embodiment, and there is a first, front, supplementary plate 38 corresponding to plate 1 1 , and a second, rear,

supplementary plate 39 corresponding to plate 15, which are mounted to the member 36 in the same manner as in the earlier embodiment.

As in the previous embodiment, there is a region 40 of the member 36 which is relatively rigid and is straight, as are plates 38 and 39. The is also a lower region 41 of the orthosis in which there is a very limited degree of flexibility. A central region 42 of the member 36 is designed to be resiliently deformable, in a manner similar to that of the region marked "A" on Figure 1 , so as to permit forwards flexing to accommodate dorsiflexion, and rearwards flexing to accommodate plantarflexion. The degree of resistance to dorsiflexion and plantarflexion is adjustable

independently, in the manner described earlier, using plate 38 and/or plate 39. The difference over elongate member 4 of the earlier embodiment, is that in region 42 the member 36 curves so that it has a slight concavity with respect to the front of the orthosis. The purpose of this slight concavity is that when the dorsiflexion resistance is increased, by adjusting the blade 38 downwards to increase the rigidity of the orthosis, there is less tilting forwards of the calf band 35. This allows for better matching of the characteristics of the orthosis to the needs of patients such as stroke survivors. In this embodiment, in region 42 the radius of curvature is not constant, and decreases towards the region 41.

The movement of the blades 38 39 upwardly and downwardly to increase and decrease rigidity respectively, prevents point loading on the elongate member 36. The embodiments of the invention are easily responsive to the changing needs of someone with an altered gait pattern following a stroke or as a result of any other condition.

The embodiments of the invention provide an ankle-foot orthosis, to help people who have an altered gait pattern. The orthosis is adjustable both by the person who uses the orthosis or a health care professional; adjustable for both resistance to movement and range of movement at the ankle (dorsiflexion and plantarflexion are independent of each other); adjustable for "heel" resistance to shock absorption at heel strike of gait; and adjustable for resistance to dorsiflexion at the forefoot in the late stance phase of gait. There is controlled movement and adjustability of resistance at the ankle. The orthosis provides quantifiable feedback for a stroke survivor or other patient with gait problems and for a treating clinician regarding the functional improvements.

At least in some embodiments of the invention, there is provided an orthotis (1) for the lower leg and foot, which comprises a foot portion (3), a calf portion (2) secured around the calf of the patient, and an elongate member (4) connecting the calf portion and the foot portion. Part (A) of the elongate member is deformable resiliently to permit dorsiflexion and plantarflexion. An adjustment mechanism (1 1 , 15) adjusts the resistance to dorsiflexion and plantarflexion and comprises a first adjustment element such as a plate (1 1) on the front of the elongate member and a second adjustment element such as a plate (15) on the rear of the elongate member. One of the adjustment elements (11) is adjustable to control primarily the resistance to dorsiflexion, and the other of the adjustment elements (15) is adjustable to control primarily the resistance to plantarflexion. Adjustment may be effected by altering the longitudinal position of the plate (1 1 , 15) on the elongate member and/or by changing the plate, using threaded fasteners (14, 18) to secure the plate to the elongate member.

Claims

1. An orthosis for the lower leg and foot, comprising a foot portion on which the foot of a patient is to rest, a calf portion including a fastening arrangement to secure the calf portion to the calf of the patient, an elongate member connecting the calf portion and the foot portion, at least part of the elongate member being deformable resiliently to permit dorsiflexion and plantarflexion, and an adjustment mechanism to adjust the resistance to dorsiflexion and plantarflexion; wherein the adjustment mechanism comprises a first adjustment element on the front of the elongate member and a second adjustment element on the rear of the elongate member, one of the adjustment elements being adjustable to control primarily the resistance to dorsiflexion, and the other of the adjustment elements being adjustable to control primarily the resistance to plantarflexion.

2. An orthosis as claimed in claim 1 , wherein the first adjustment element comprises a first supplementary element which is releasably connected to the elongate member and extends along the front of the elongate member from the point of connection to a free end of the first supplementary element; and the second adjustment element comprises a second supplementary element which is releasably connected to the elongate member and extends along the rear of the elongate member from the point of connection to a free end of the second supplementary element.

3. An orthosis as claimed in claim 2, wherein the point of connection of the first supplementary element to the elongate member is changeable in the longitudinal direction so as to vary the resistance to dorsiflexion; and the point of connection of the second supplementary element to the elongate member is changeable in the longitudinal direction so as to vary the resistance to plantarflexion.

4. An orthosis as claimed in claim 3, wherein the elongate member is provided with a first series of longitudinally spaced threaded bores for receiving at least one threaded fastener to attach the first supplementary element to the elongate member; and the elongate member is provided with a second series of

longitudinally spaced threaded bores for receiving at least one threaded fastener to attach the second supplementary element to the elongate member.

5. An orthosis as claimed in claim 2, 3 or 4, wherein each of the first and second supplementary elements is in the form of an elongate plate.

6. An orthosis as claimed in any of claims 2 to 5, wherein at least one of the supplementary elements is positioned within a longitudinally extending recessed portion provided on the elongate member.

7. An orthosis as claimed in any of claims 2 to 6, wherein the elongate member has an upper portion, a lower portion and an intermediate portion, and the intermediate portion is relatively flexible with respect to the upper portion.

8. An orthosis as claimed in claim 7, the intermediate portion is also relatively flexible with respect to the lower portion.

9. An orthosis as claimed in claim 7 or 8, wherein the upper portion is more rigid than the lower portion.

10. An orthosis as claimed in claim 7, 8 or 9, wherein the intermediate portion curved so as to provide a profile which is concave with regard to the front of the orthosis.

1 1. An orthosis as claimed in claim 10, wherein the radius or curvature of the intermediate portion varies.

12. An orthosis as claimed in claim 1 1 , wherein, the radius of curvature of the intermediate portion decreases towards the lower portion.

13. An orthosis as claimed in any of claims 7 to 12, wherein each of the first supplementary element and the second supplementary element is connected to the upper portion of the elongate member, and the degree of resistance to flexion is adjusted by adjusting the extent to which the first and/or second supplementary element extends down into the intermediate region of the elongate element.

14. An orthosis as claimed in any of claims 2 to 13, wherein the first

supplementary element is replaceable by a modified first supplementary element so as to vary the resistance to dorsiflexion; and the second supplementary element is replaceable by a modified second supplementary element so as to vary the resistance to plantarflexion.

15. An orthosis as claimed in any preceding claim, wherein the foot portion has a degree of flexibility at the heel end of the foot portion and at a forefoot part of the foot portion.

16. An orthosis as claimed in claim 15, in combination with at least one supplementary sole portion which can be releasably attached to the foot portion so as to vary the degree of flexibility at the heel end of the foot portion and / or at the forefoot part of the foot portion.

17. A method of adjusting an orthosis which is as claimed in any of claims 2 to 14, comprising the step of repositioning the first supplementary element and / or repositioning the second supplementary element.

18. A method of adjusting an orthosis which is as claimed in claim 14, comprising the step of replacing the first supplementary element with a modified first supplementary element; and / or replacing the second supplementary element with a modified second supplementary element.

19. A method as claimed in claim 17 or 18, wherein the foot portion has a degree of flexibility at the heel end of the foot portion and at a forefoot part of the foot portion, and adjusting the orthosis includes the step of attaching a

supplementary sole portion releasably to the foot portion so as to vary the degree of flexibility at the heel end of the foot portion and / or at the forefoot part of the foot portion.

20. A method of adjusting an orthosis which is as claimed in claim 16, comprising the step of attaching a supplementary sole portion releasably to the foot portion so as to vary the degree of flexibility at the heel end of the foot portion and / or at the forefoot part of the foot portion.

21. A method as claimed in any of claims 17 to 20, carried out to adjust the orthosis for the ambulatory needs of a patient who has suffered a stroke.

22. An orthosis for the lower leg and foot, comprising a foot portion on which the foot of a patient is to rest, a calf portion including a fastening arrangement to secure the calf portion to the calf of the patient, an elongate member connecting the calf portion and the foot portion, at least part of the elongate member being deformable resiliently to permit dorsiflexion and plantarflexion, and an adjustment system to adjust the resistance to dorsiflexion and plantarflexion; wherein the adjustment system comprises a first adjustment element secured to the front of the elongate member to control primarily the resistance to dorsiflexion, and a second adjustment element secured to the rear of the elongate member to control primarily the resistance to plantarflexion, the first and second adjustment elements being removable and replaceable independently of each other.

23. A method for adjusting the characteristics of an orthosis for the lower leg and foot, the orthosis comprising: a foot portion on which the foot of a patient is to rest, a calf portion including a fastening arrangement to secure the calf portion to the calf of the patient, an elongate member connecting the calf portion and the foot portion, at least part of the elongate member being deformable resiliently to permit dorsiflexion and plantarflexion; a first adjustment element secured to the front of the elongate member to control primarily the resistance to dorsiflexion; and a second adjustment element secured to the rear of the elongate member to control primarily the resistance to plantarflexion; wherein the method comprises the step of adjusting the resistance of the orthosis to dorsiflexion independently of the resistance of the orthosis to plantarflexion, by removing the first adjustment element and replacing the first adjustment element at a different longitudinal position on the front of the elongate member; and / or the step of adjusting the resistance of the orthosis to plantarflexion independently of the resistance of the orthosis to dorsiflexion, by removing the second adjustment element and replacing the second adjustment element at a different longitudinal position on the rear of the elongate member.

24. A method for adjusting the characteristics of an orthosis for the lower leg and foot, the orthosis comprising: a foot portion on which the foot of a patient is to rest, a calf portion including a fastening arrangement to secure the calf portion to the calf of the patient, an elongate member connecting the calf portion and the foot portion, at least part of the elongate member being deformable resiliently to permit dorsiflexion and plantarflexion; a first adjustment element secured to the front of the elongate member to control primarily the resistance to dorsiflexion; and a second adjustment element secured to the rear of the elongate member to control primarily the resistance to plantarflexion; wherein the method comprises the step of adjusting the resistance of the orthosis to dorsiflexion independently of the resistance of the orthosis to plantarflexion, by removing the first adjustment element and replacing the first adjustment element by a modified first adjustment element having different flexion characteristics, the modified first adjustment element being secured at the same or a different longitudinal position on the front of the elongate member; and / or the step of adjusting the resistance of the orthosis to plantarflexion independently of the resistance of the orthosis to dorsiflexion, by removing the second adjustment element and replacing the second adjustment element by a modified second adjustment element having different flexion characteristics, the modified second adjustment element being secured at the same or a different longitudinal position on the rear of the elongate member.

25. A method as claimed in claim 23 or 24, carried out to adjust the orthosis for the ambulatory needs of a patient who has suffered a stroke.