GB2458741A

GB2458741A - Curved sole having three pivot points

Info

Publication number: GB2458741A
Application number: GB0900515A
Authority: GB
Inventors: Stephen Hutchins
Original assignee: Individual
Current assignee: Individual
Priority date: 2008-04-04
Filing date: 2009-01-14
Publication date: 2009-10-07
Anticipated expiration: 2029-01-14
Also published as: GB2458741B; GB0806188D0; GB0900515D0

Abstract

A sole for adapting footwear, wherein the ground-contacting portion of the sole has a curved profile. The curved profile comprises three conjoined curve portions, the centres of curvature of the curve portions being on the anatomical hip, knee and ankle of the intended wearer. The sole may reduce dorsiflexion moments externally applied to the ankle whilst simultaneously placing the ankle into relative plantarflexion. The sole may also reduce the sagittal plane ankle power required for walking.

Description

A sole for adaptin2 footwear The present invention relates to a three-curve rocker sole for adapting footwear, and designed to offload the calf muscles of the wearer during ambulation.

Shoes are currently available with a variety of styles sole configuration, ranging from flat-soled sandals and training shoes, to high heeled, and platform soles, the variety being primarily driven by fashion. Additionally, curved sole shoes are known, such as MBT�, which has a specially designed sole, intended to exercise a large number of muscles, whether walking or standing.

However, the object of the present invention is to offload the calf muscles during ambulation to reduce the externally-applied ankle dorsiflexion moments acting on the ankle, whilst simultaneously placing the ankle into relative plantarfiexion, when compared to an un-adapted shoe.

According to the present invention there is provided a sole for adapting footwear, wherein the ground contacting portion of the sole has a curved profile, characterised in that the curved profile comprises three curve portions, the centres of curvature of the curve portions are on the anatomical hip, knee and ankle.

The rocker profile of the invention comprises of three curves in its profile, which is specifically designed to reduce the externally-applied ankle dorsiflexion moments acting on the ankle whilst simultaneously placing the ankle into relative plantarfiexion compared to an unadapted shoe.

Further, the profile has been designed to reduce sagittal plane ankle power required for walking.

This has been achieved by placing the centres of curvature of the curves on the anatomical hip, knee and ankle.

The resulting profile can be seen in the appended figures in which: Fig I illustrates a shoe including a three curve sole of the present invention; Fig 2 is a photograph of a shoe adapted according to the invention; and Fig 3 illustrates a sole according to the invention.

With reference to the drawings, Figs 1 and 2, respectively, show the profile of a shoe having a sole of the invention. The aspects of each portion of the sole are as follows: The anterior (forefoot) curve An anterior curved profile was drawn from a centre based on the anatomic centre of the knee in the sagittal plane positioned along the vertical leg position. The radius of this curve was from knee centre to the toe end of the shoe. The point at which this anterior curve coincided with the metatarsal head level, was taken to be the transition point between the forefoot curve and the mid-foot curve. Metatarsal head level was taken from anthropometric data as a point in the sagittal plane corresponding to 62.5% of the shoe length anterior/posterior and corresponded with the widest point of the forepart of the shoe.

Utilisation of a curved forefoot portion to the profile could potentially lead to a reduction in magnitude of the ground reaction force (GRF) due to reduced thrust being required for propulsion. This would be achieved by utilising a smooth transition from midfoot to forefoot onto a curve of reduced radius.

The forefoot curve centre was chosen because, during the third rotational phase of gait, the GRF passes through a mean position approximating to knee centre in the sagittal plane. The GRF passes posterior, through and then anterior to knee joint centre during late stance. Influencing the GRF to be less anterior in its line of action in relation to knee joint sagittal plane centre compared to an unadapted shoe would theoretically result in a reduced applied knee and by cascading effect ankle dorsiflexion moment.

Again, therefore, by influencing the GRF to centre more consistently during late stance on knee centre by providing a "forward roll" using a reduced profile radius, a more effective surrogate motion could be produced. The reduced radius of curvature would reduce resistance to dorsiflexion at late stance produced by a less flexible sole unit with the profile added. This would theoretically in turn reduce the power required to be provided by the triceps surae to initiate heel lift.

The midfoot curve The midfoot portion of the profile was formed by a curve drawn with a radius of hip to ground plus again the appropriate additions, with its centre approximated to be along the vertical line simulating vertical tibia position taken from anthropometric data. The reasons for this were as previously stated: * This mid-section was designed to give stable mid-stance for reasons previously stated whilst still facilitating a gradual roll forwards to blend with the forefoot section of the profile (rather than being completely flat); * . The GRF passes initially anterior and then posterior to the hip during normal ambulation stance phase; with a mean position approximating to hip centre. The addition of a central curve based on hip joint centre would theoretically reduce the rate of posterior/rearward progression of the GRF past hip centre and reduce the resulting moment from the GRF acting on the hip which would theoretically reduce ankle dorsiflexion moment by a cascading effect.

The rearfoot curve The rearfoot curve was taken as a curve centred on the ankle joint centre assuming a vertical lower limb, with a radius of ankle joint to ground in the sagittal plane plus an additional length to blend in with the midfoot curve.

This curve was similar to that utilised in the two-curve rocker profile.

The resulting profile would therefore theoretically roll a claudicant from heel strike gently onto the stable mid-stance portion of the profile and then onward to a distal curve of reduced radius to facilitate a surrogate motion approximating for the third rotational phase of gait.