EP1516551A2

EP1516551A2 - Orthopaedic footwear last and orthopaedic footwear

Info

Publication number: EP1516551A2
Application number: EP04255670A
Authority: EP
Inventors: Lesley Frederick Wreford; Ian Donald Hopewell; Anita Ellen Williams; Christopher James Nester
Original assignee: County Footwear (UK) Ltd
Current assignee: County Footwear (UK) Ltd
Priority date: 2003-09-20
Filing date: 2004-09-17
Publication date: 2005-03-23
Also published as: EP1516551A3; GB0322048D0

Abstract

An orthopaedic footwear last has a back cone section (26) that is sculpted to define a well-fitted back portion of a shoe. The back cone has a wide seat (25) and tapers to an elongate narrow neck (27). The forefoot section has a curvature from rear to front that provides a natural rocker. An orthopaedic shoe constructed on such a last provides stabilisation at the heel of the foot and allows for even pressure distribution at the forefoot. Controlling the heel by a well-fitted design prevents migration of the forefoot into the toe box during the gait cycle and allows a greater angle of toe spring and roll. A last board is provided with an anterior shock-absorbing layer.

Description

The present invention relates to orthopaedic footwear and a last for use in the mass production of such footwear. More specifically, the invention relates to orthopaedic footwear designed for patients with neuropathy, foot deformity, plantar pathology and/or poor tissue viability. Such patients whose foot status is generally regarded as "high risk" include those with diabetes, rheumatoid arthritis, connective tissue disorders, peripheral vascular disease and other conditions associated with compromised neurological status and poor tissue viability.
The above described patients have feet that are generally at risk from ulceration, infection, gangrene and, ultimately amputation. Appropriately designed and manufactured orthopaedic footwear can have a positive effect on the clinical prognosis for such patients. The main problem areas of the feet that need to be considered in footwear design are the plantar aspect, the anterior toes and the posterior heel.
A footwear-making last is typically a rigid mould over which the footwear is constructed and which dictates the size and shape of the footwear constructed thereon. In the manufacturing process, the last is supported firmly, a last board or "throughboard" fixed temporarily by staples or the like to the underside of the last and an upper (typically of leather) is applied over the last and secured at its edges to the throughboard using, for example adhesive. An outer sole is then attached to the throughboard and parts of the upper by, for example, gluing or stitching. The footwear is then removed from the last and finished.
The interior space of the formed footwear is an exact replica of the exterior shape of the last. A last for orthopaedic footwear is therefore a carefully crafted item whose design takes into account the particular needs of the patient. There is a need in the industry for a basic last that can be used to produce footwear for the high-risk patients described above.
Traditionally, orthopaedic footwear has been designed with a deep and wide forefoot that accommodates bunions etc. The back is sufficiently low to avoid the collar (that part defined around the opening) rubbing on the ankle bones. It has been realised that this conventional approach permits too much movement of the foot within the shoe and, in high-risk patients, has a tendency to make the foot vulnerable to ulceration. Generally, in orthopaedic footwear the forefoot is stabilised in the shoe by design of the front cone, instep and laces. These areas are generally of such a design that they serve to apply undesirable pressure to front part of the foot of high-risk patients.
A conventional collar (defined around the opening to the shoe) on orthopaedic footwear is of consistent depth around the shoe. This is a common source of discomfort for the high-risk patient as it often does not accommodate malleoli abnormalities and can lead to serious tissue trauma in patients with neurological status and little or no sensitivity on the feet. Similar trauma can be effected on the dorsum of the foot where the conventional shoe tongue does not give adequate protection against the restriction of blood circulation caused by lace tension.
To accommodate corrective orthoses, conventional orthopaedic footwear is made with extra depth throughout. This tends to create a shoe appearance which is bulky and unattractive. In attempts to conceal the shape of the orthopaedic shoe, decorative vamps and other fashion elements have been introduced involving complicated closing and prominent stitching. However, these can act as pressure points on vulnerable parts of the feet thereby causing skin lesions.
Moreover, conventional sole units used on orthopaedic footwear do not provide the stability, shock attenuation or weight distribution demanded by the high-risk patient.
It is an obj ect of the present invention to provide for orthopaedic footwear which mitigates or obviates the aforementioned disadvantages.
According to a first aspect of the present invention there is provided an orthopaedic footwear last having an upper surface and a seat surface that intersect at a featherline, and defining a back cone and a front portion, the back cone extending upwardly and outwardly from the featherline to a maximum width and then tapering inwardly and terminating in an elongate neck portion, the back cone having a maximum height to maximum width ratio in the range 1.2 to 1.3, a height to width ratio at the maximum width in the range 0.13 to 0.15 and a height to width ratio at the maximum height being in the range 2.9 to 3.25, the neck portion being between 3% and 4% of the total height of the cone and the width decreasing by about 2mm for every 5mm in length in the direction towards the top of back cone, the seat surface at the back cone being substantially planar and the curvature of the seat of the front portion from rear to front being such that with the heel pitch set at 23mm the toe spring is in the range 15 to 20mm.
This design of orthopaedic shoe last enables an orthopaedic shoe to be manufactured in which the back cone provides stabilisation for the heel of the foot and allows for even pressure distribution at the forefoot. Controlling the heel part of the foot in the shoe allows a greater angle of toe spring and roll. Securing the rear foot also prevents migration of the forefoot into the toe box during the gait cycle. The curvature of the forefoot of the last is uniquely designed to accommodate the correct toe spring which is balanced against the pitch of the heel. This provides a natural roller to the shoe that minimises movement of the forefoot and assists ambulation.
The aforementioned ratios serve to convey the difference between the back cone profiles of the present invention and that of a conventional last. To provide a comparison, the ratio of the back cone maximum height to maximum width ratio of a conventional last is generally in the region of 1.0 and the height to width ratio at the maximum height being in the range 2.3 to 2.5. When the heel pitch of the last is set at 23mm the toe spring is in the region of 9mm.
Preferably the height to width ratio at half height of the back cone is in the range 0.65 to 0.68 and the height to width ratio at two-thirds height of the back cone is in the range 1.15 to 1.19. This compares to figures of around 0.60 and 1.01 for a conventional last.
According to a second aspect of the present invention there is provided orthopaedic footwear comprising an upper, an outer sole and a last board disposed between the upper and sole, the last board comprising a rigid planar member having an anterior section with a shock-absorbing layer laminated thereto and which layer extends from the metatarsal head region to the toe area of the shoe.
Specific embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:
Figure 1 shows a conventional orthopaedic shoe according to the prior art;
Figure 2 shows a side view of a men's orthopaedic shoe manufactured in accordance with the present invention using a footwear-making last according to the present invention;
Figures 3a and 3b are side views of a footwear-making last of the present invention;
Figure 3c to 3f are, respectively, rear, front underneath plan and plan views of the footwear-making last of the present invention;
Figure 4a is a diagrammatic representation showing in a vertical plane the projected area of the back cone of a conventional orthopaedic footwear-making last of the prior art;
Figure 4b is a diagrammatic representation showing the corresponding projected area of the present invention with the profile of Figure 4a shown in dotted line for ease of comparison;
Figure 5a is a diagrammatic representation of the heel end of the last and illustrates the position of section line BC (see figures 5b and 5c) relative to reference point A which is on the extremity of the heel of the last;
Figure 5b is a diagrammatic representation showing part of the section along line BC of Figure 5a for a ladies' size five last and illustrates the height and width of the back cone at various points;
Figure 5c corresponds to Figure 5b but shows the corresponding measurement for a men's size eight last;
Figure 6a is a perspective, contoured diagram of the men's orthopaedic footwear-making last of figure 3 compared with a conventional footwear-making last of the kind shown in Figure 4a;
Figures 6b to d are side front and plan views of figure 6a;
Figure 7a shows sections through the last of the present invention superimposed on corresponding sections through a conventional last along lines 1 to 9 of figure 6b, each section being annotated with its circumference in millimetres;
Figure 7b shows sections along lines 10 to 18 of figure 6b;
Figure 7c shows sections along lines19 to 22 of figure 6b
Figure 7d shows sections along lines 23 to 25 of figure 6b;
Figure 7e shows sections along lines 26 and 27 of figure 6b;
Figure 7f shows sections along lines 28 to 30 of figure 6b
Figure 8 is a side view of the last of figure 3 showing the toe spring relative to the heel pitch;
Figure 9 is a sectioned view through the forefoot of the last illustrating the transverse curvature of the seat; and
Figure 10a is a plan view of a throughboard used in the footwear of the present invention;
Figure 10b is a side view of the throughboard of figure 10a;
Figure 11 is a side view of a shoe in accordance with the present invention showing an orthotic foot bed insert.
Referring now to the drawings, the prior art orthopaedic shoe of Figure 1 has a relatively deep forefoot represented by reference numeral 1, a relatively low back height represented by reference numeral 2 and a collar 3 that is of consistent depth.
By comparison, the exemplary shoe of the present invention shown in Figure 2 has a forefoot depth 11 that is closer in appearance to a conventional shoe and a greater back height. The increased back height is designed to accommodate a particular orthotic foot bed configuration. The collar 13 around the shoe opening is shaped to pass around the malleoli.
Referring now to Figures 3 to 6, the last of the present invention is a rigid moulded body having a back cone 20 defining the interior dimension of the rear and heel portions of the finished footwear and a forefoot section 21 defining the dimension of the forefoot including the toe section of the footwear. The bottom surface of the last describes a seat surface 22 which meets with an upper surface 23 at what is known as the featherline 24.
The back cone of the last has a seat surface 22 that is substantially planar and a lower portion 25 with side walls that extend from the featherline in a direction that is initially close to the vertical. In fact the back cone width widens slightly outwardly from the featherline to a point of maximum width Wmax, whereafter it begins to narrow steeply in a central portion 26 and the less steeply in a terminal neck portion 27 of around 20mm in height. Referring to figure 5, at the position of section BC (which is 42mm from the extremity of the heel indicated by A), the width of the neck portion decreases by 2mm for every 5mm increase in height (see figure 5). The neck portion 27 of the last enables the manufacture of footwear with a deeper rear portion so that foot beds such as orthotic inserts or insoles, shock attenuating socks or a combination of these can be used, without compromising the room available within the footwear for the patient's foot. A foot bed can be typically around 9mm in depth at its maximum (an example is shown in figure 11). The shape of the lower portion of the back cone is designed to have a seat width that is wider than a conventional last to accommodate the spread of the heel in the gait cycle and to accommodate the foot bed. The shape of the back cone can also be seen from sections 14 to 18 in figure 7b.
Figure 4b provides a comparison of the last back cone of the present invention with that of a conventional orthopaedic footwear last (shown in dotted line). It illustrates the wider seat width of the back cone of the present invention and the different curvature of the back cone extending upwardly from the featherline. In the last of the present invention the curvature is such that the seat width is maintained for a significant height and in the central section 26 of back cone the curvature is more exaggerated to provide a better fitting to the heel. By maintaining substantially the same width as the seat in the lower portion 25 the foot bed can be easily accommodated in the final shoe without the tendency for it to spread towards the interior of the upper in the region nearest the featherline. The seat 22 of the back cone 20 has no significant transverse curvature so as to accommodate the foot bed. These features of the last mimic the natural heel anatomy and the footwear manufactured thereon serves to secure the rear foot such that the forefoot is prevented from migrating into the toe box during the gait cycle.
The projected area of the back cone of the present invention has a maximum height to maximum width ratio in the range 1.2 to 1.3 which compares to around 1.0 for a conventional last, a height to width ratio at the maximum width in the range 0.13 to 0.15 and a height to width ratio at the maximum height being in the range 2.9 to 3.25 (compared to 2.3 to 2.5 for a conventional last). The neck portion which does not have a direct counterpart in conventional lasts extends for around 3% and 4% of the total height of the cone.
The curvature of the forefoot portion of the last from rear to front, as illustrated in figure 8, is designed to provide a natural rocker to the shoe so that, in use, there is a significant reduction of movement of the forefoot in the shoe. This assists in ambulation. The curvature provides for a toe spring that is balanced against the heel pitch. In the embodiment shown in figure 8 the heel pitch is set at 23mm to leave a toe spring of 17mm. Other size lasts may provide for slightly different toe springs but these are in the range of 15 to 20mm. This compares to a toe spring of 9mm for a heel pitch of 23mm in a conventional last.
Figure 9 and sections 1 to 8 of figure 7a illustrate the transverse curvature at the forefoot seat. The curvature is such that a line drawn through the midpoint on the seat to the featherline subtends and angle 6° although may be in the range 5° to 7° to the horizontal.
The orthopaedic shoe of the present invention is constructed by temporarily fixing a throughboard to the seat of the last, stretching an upper of, for example, high grade soft leather lined in soft pig grain with reversed quarter lining, around the upper surface of the last and fixing it by adhesive or otherwise to the edges of the throughboard. The sole is then attached to the throughboard and parts of the upper whereupon the shoe is removed from the last and finished.
The throughboard 60, shown in figure 10, is constructed of cellulous material 61 and has a forepart section of Poron (RTM) 62 of 3mm thickness that is laminated to the anterior section 61a of the cellulous material. The Poron layer 62 faces outwardly when the throughboard is attached to the last. In the finished shoe the throughboard reduces the interior circumference 6mm and conceals the real shoe depth. The Poron layer extends to a position approximately 12mm behind the metatarsal heads (roughly in alignment with the ball of the foot). The presence of the shock-absorbing layer not only enables the external appearance of the shoe to be enhanced but also provides added comfort to the shoe wearer.
Referring back to the finished shoe of Figure 2, the collar 13 may be padded with, for example 10mm of grey foam, contoured around the malleoli and bag-stitched to provide protection around the ankle bones and eliminate the risk of stitch chafing. Similarly, the tongue 30 of the shoe is padded with foam of 10mm thickness to protect the vascular components on the dorsum. This feature allows of the laces to be tied tight and therefore facilitates even greater foot control and stability in the shoe.
The sole 40 is constructed in a light weight, durable, EVA laminate and is tapered outwardly from the featherline to the base of the sole to provide additional stability and improve weight distribution. The taper is approximately 10° to the vertical from the rand to the outer edge of the plantar surface. This has the effect of increasing the plantar surface area by approximately 10% thus providing more ground contact and therefore greater stability in improved weight distribution. This taper extends around the featherline from just behind the metatarsal heads to the heel point. Below the heel seat, the wall of the sole is squared off (as indicated at 50) to provide greater control during heel strike in the gait cycle.
The tread on the sole is provided with a zigzag or herringbone non-slip pattern.
Figure 11 shows a shoe in accordance with the present invention shown with an orthotic foot bed fitted (shown shaded).
It will be appreciated by the skilled person in the art that numerous modifications may be made to the design described above without parting from the scope of the invention as defined in the appended claims. For example, the particular material of the shoe components may vary according to the patient's requirements and shoe style.

Claims

An orthopaedic footwear last having an upper surface and a seat surface that intersect at a featherline, and defining a back cone and a front portion, the back cone extending upwardly and outwardly from the featherline to a maximum width and then tapering inwardly and terminating in an elongate neck portion, the back cone having a maximum height to maximum width ratio in the range 1.2 to 1.3, a height to width ratio at the maximum width in the range 0.13 to 0.15 and a height to width ratio at the maximum height being in the range 2.9 to 3.25, the neck portion being between 3% and 4% of the total height of the cone and the width decreasing by about 2mm for every 5mm in length in the direction towards the top of back cone, the seat surface at the back cone being substantially planar and the curvature of the seat of the front portion from rear to front being such that with the heel pitch set at 23mm the toe spring is in the range 15 to 20mm.
A last according to claim 1 wherein the height to width ratio at half height of the back cone is in the range 0.65 to 0.68.
A last according to claim 1 or 2,wherein the height to width ratio at two-thirds height of the back cone is in the range 1.15 to 1.19.
An orthopaedic footwear last according to claim 1, 2 or 3 wherein at a section halfway along the length of the front portion of the last the angle subtended to the horizontal by an imaginary line extending from the featherline to the middle of the forefoot is in the range 5° to 7°.
Orthopaedic footwear comprising an upper, an outer sole and a last board disposed between the upper and sole, the last board comprising a rigid planar member having an anterior section with a shock-absorbing layer laminated thereto and which layer extends from the metatarsal head region to the toe area of the shoe.
Orthopaedic footwear according to claim 5, wherein the rigid planar member is cut away at said anterior section to receive said shock-absorbing layer.
Orthopaedic footwear according to claim 6, wherein said shock-absorbing layer has an upper surface that is substantially coterminous with an upper surface of the planar member.
Orthopaedic footwear according to claim 5, 6 or 7, wherein the sole has a side wall that is tapered in the range 9 to 11° to the vertical from the rand to the outer edge of the plantar surface.
Orthopaedic footwear according to claim 8, wherein the tapered side wall extends around the featherline from just behind the metatarsal heads to the heel point.
Orthopaedic footwear according to any one of claims 5 to 9, wherein the side wall of the sole is squared off at the heel tip to provide greater control during heel strike in the gait cycle.
Orthopaedic footwear according to any one of claims 5 to 10, further comprising a heel section and wherein there is provided a foot bed orthotic insert at the heel section.
An orthopaedic footwear last substantially as hereinbefore described with reference to the accompanying drawings.
Orthopaedic footwear substantially as hereinbefore described with reference to the accompanying drawings.