Shoe sole insert

[0002] The invention relates to an orthotic shoe sole insert and in particular an insert for correction of the human foot disorder, generally known as cavovarus foot.

[0003] Although many orthotic devices are provided for insertion into the shoe, the vast majority of these inserts are custom made or manufactured to correct the human flat foot. The typical orthotic insert does not alleviate the human foot disorder, generally known as a cavovarus foot. In this disorder, the foot assumes a posture of an inward tipping of the heel (heel supination or varus), and a related forefoot pronation (forefoot valgus). Further with this foot disorder the first metatarsal is plantarflexed and the arch is excessively high (cavus). This disorder results in the chronic inversion sprains of the ankle and subtalar joint, which can result in surgical reconstruction. The disorder may also cause a common stress fracture to the fifth metatarsal as well as stress fractures to the other metatarsals. Other injuries that can result from a cavovarus foot include recurrent dislocation or subluxation of the peroneal tendons, peroneal tendonitis, peroneal tendon splitting, overload callous under the base or head of the fifth metatarsal, metatarsalgia, hallux sesamoiditis, excessive external rotation of the talus and tibia resulting in varus strain of the knee joint, compressive medial compartmental knee overload and arthritis, and increased lateral collateral knee ligaments and iliotibial tract strain and tendonitis. A painful plantar fasciitis may also occur and with longstanding cavovarus foot deformities. A very painful varus ankle arthritis may develop, necessitating ankle arthrodesis (fusion), or total ankle arthroplasty (replacement). Other stress related disorders may occur to the ankle, knee, hip, and spine.

[0004] Most orthotic shoe inserts address the human foot disorder known as “flat foot.” With this disorder the arch of the foot is collapsed into a lowered position. The flat foot inserts are generally designed to push upwardly on the naviculocuneiform area and to support the collapsed medial longitudinal and transverse arches, or by placing additional material in the area between the dorisiflexed metatarsal and the shoe, forming a medial forefoot wedge. Other designs for orthotic inserts either simply conform to the bottom of the foot with metatarsal pads placed proximal to certain metatarsal heads to relieve the force on these areas, or the inserts have hollowed out portions under areas of pressure in the plantar surface of the foot.

[0005] The invention addresses the aforementioned concerns by providing a removable insert for a shoe directed to patients with high arches. In one aspect of the invention, a full length orthotic shoe sole insert is provided for overlying the sole of a shoe of a patient having a high arch and adapted for aligning the foot during movement by providing a small built up heel base portion in the insert, with a midfoot portion of having an arched area lower than the arch of the patient, and a forefoot portion, wherein the forefoot portion has a built-up portion beginning lateral to the head of the first metatarsal and lateral sesamoid of the foot.

[0006] In another aspect the build up portion of the forefoot portion of the insert has a constant thickness beginning just lateral to the first metatarsal head and lateral sesamoid.

[0007] The shoe sole insert may also include a valgus wedge starting in the transverse arched region of the foot. The valgus wedge may thicken laterally beginning proximal to the lateral first metatarsal head and increase in elevation distally from the heel portion. Further, the insert may have a depression for receiving the first metatarsal head of the foot.

[0008] In a further aspect of the invention the insert is sized to the patient by measuring from the posterior heel of the foot to the first metatarsal head, rather than from the heel to the end of the toes.

[0009] Other objects, advantages and applications of the present invention will become apparent to those skilled in the art when the following description of the best mode contemplated for practicing the invention is read in conjunction with the accompanying drawings.

[0010] The description herein makes reference to, the accompanying drawings wherein like reference numerals refer to like parts throughout the several views, and wherein:

[0011] FIG. 1 is a side elevational view of a skeletal foot;

[0012] FIG. 2 is a top view of the skeletal foot of FIG. 1;

[0013] FIG. 3 is a prospective view of the full length orthotic shoe sole insert according to the present invention;

[0014] FIG. 4A is a sectional view of one embodiment of the orthotic shoe sole insert taken along lines 4—4 of FIG. 3;

[0015] FIG. 4B is a sectional view of a second embodiment of the orthotic shoe sole insert taken along lines 4—4 of FIG. 3;

[0016] FIG. 4C is a sectional view a third embodiment orthotic shoe sole insert taken along lines 4—4 of FIG. 3.

[0017] FIG. 5 is a lateral side elevational view of the orthotic shoe sole insert taken along lines 5—5 of FIG. 3;

[0018] FIG. 6 is a medial side elevational view of the orthotic shoe sole insert of FIG. 3, taken along line 6—6;

[0019] FIG. 7 is a schematic view of a bottom of a foot and a grid ruler for showing the sizing method for an orthotic shoe sole insert as described in the present invention.

[0020] Referring to the drawings and especially FIGS. 1 through 6, the invention provides a removable insert 10, worn in a shoe and which is designed to align the foot during activity of a person suffering from cavovarus foot, wherein the arch is excessively high. FIGS. 1 and 2 are skeletal views of a foot 50 and will be used in reference with explanations regarding the insert shown in FIGS. 3 through 6.

[0021] The heel portion 12 of the insert has a deep cup shaped portion 14. The cup shaped portion 14 of the heel portion 12 controls rear foot motion by supporting the calcaneus 16 of the foot by allowing it to sink and rest within the cup shaped portion of the insert 10. This configuration also cushions the heel by containing the fat pad of the heel, which has a tendency to migrate away from the bottom of the heel of a foot having a high arch, generally referred to as a cavus foot. The fat pad of the heel further has the tendency to deform circumferentially as the plantar surface is compressed as the heel strikes the ground. Therefore, around the deep cup shaped heel portion 14 there is a flaring portion 18 to contain the fatty and fibrous heel pad to provide increased resistance to vertical compression of the heel pad using the hydrostatic mechanism and improve heel pad shock absorption. The base 20 of the heel portion 12 has a slight elevation. The elevation together with the addition of the shock absorbing material used in the manufacture of the insert provides increased shock control at the heel strike. This feature also provides heel elevation to compensate for a tight Achilles tendon complex and the equinus that often is present in the cavus foot. As an alternative, the heel portion may have a lateral heel wedge 13 formed therein to increase the valgus positioning of the heel.

[0022] The medial arch portion 22 of the shoe insert 10 will have a less prominent or lowered surface than the increased elevation of the medial arch that is generally designed for a person having a flat foot. This lowered medial arch portion surface will allow the cavus arch 24 to pronate and not be limited by coming in contract with the medial arch surface 22. This design feature will also keep the most prominent portion of the arch 24 from inducing a traction force on the plantar fascia.

[0023] Looking especially at FIGS. 4A-C, the elevation of the lateral aspect of the forefoot 26 of the insert is a unique aspect of the invention. There is a valgus wedge 28 that starts at the transverse arch region 30 (shown in FIG. 3) at a mid-foot portion of the insert spaced from the heel and increases in elevation gradually, distally. The transverse arch region 30, as shown in the figures, underlies the transverse arch located at the anterior part of the tarsus and hinder part of the metatarsus of the foot. As can be seen in FIG. 4A, the most prominent point in the elevation is located in the approximate region of the fifth metatarsal head 32a, decreasing in elevation near the sulcus region 34 between the toes and the metatarsal heads 32a, b, c, d, e. The wedge 28 also decreases proportionately in elevation from the lateral to medial aspect of the device as shown in FIG. 4C. The lateral aspect is shown in FIG. 5 with the lateral edge designated at 21 and the medial aspect is shown in FIG. 6 with the medial edge designated at 23. Due to varying types of the forefoot 26 deformity, the forefoot 26 may be configured to have a valgus wedge 28 thickening laterally, beginning near the lateral first metatarsal head 32eand lateral sesamoid area 38. The valgus wedge 28 may vary between 2 and 20° as required. The forefoot 26 could also have a depression 36 formed for receiving the first metatarsal head 32b, as shown in FIG. 4A. As an alternative, the correction of the valgus wedge 28 may be neutral under the second metatarsal head 32dto the fifth metatarsal head 32awith a depression 36 formed for the first metatarsal head 32eas shown in FIG. 4B.

[0024] The depression 36 is formed at the first metatarsal head 32eand sesamoids 38 to accommodate the plantar flexed first ray 40 of the cavus foot. The plantar flexed first metatarsal head 32eacts pathologically by striking the ground or shoe first, and preventing the entire foot from pronating. By supporting the surrounding areas of the foot and allowing the first metatarsal head 32eand sesamoids 38 to drop below the level of the lateral metatarsal heads 32a-32d, the insert 10 of the present invention allows the cavus foot to have a more normal biomechanical function.

[0025] The distal end 42 from the heel portion 12 has a longer extension 43 ahead of the forefoot portion 26 that will allow for the insert 10 to be trimmed to fit the majority of foot sizes. The sizing for the insert will be discussed hereinafter.

[0026] The insert 10 of the present invention is preferably fabricated from ethyl vinyl acetate (EVA). This material is lightweight and durable and has desirable shock absorbing properties. Ethyl vinyl acetate has a relatively low thermal mold temperature (250° F.). This feature of the material provides for the insert to be spot modified with heat as needed. The material has a medium to firm density, (between 40 to 60 durometers) although design variations may include the use of a softer material having less than 25 durometers for vulnerable and potentially high pressure areas such as the heel 12, medial arch 24, first metatarsal head 32eand sesamoid areas 38, and head and base of the fifth metatarsal 32a. Of course other material, including other soft foam material, may be used to fabricate the insert 10, although the other material may not have all of the benefits of EVA.

[0027] To properly size the insert of the present invention a new method for measuring the foot has been devised using a specialized grid as shown in FIG. 7. Current sizing scales measure and fit from the back of the heel to the end of the longest toe. While this method has become standard, it does not address the distance from the heel to the area of the first metatarsal 32ewhich is the arch length. The area of the metatarsal is where the foot flexes and is the widest part of the foot, especially in the cavus foot. Generally the arch length measurement from one patient to another all having the same toe length measurement are not equal and may vary up to 2 whole sizes in some patients. Although the traditional Brannock measuring device has a sliding piece that measures arch length, it is not utilized or even understood by the majority of sales people today.

[0028] Measuring for the insert of the present invention will not utilize traditional sizes such as 7 D, 9 B, 10 AA, etc. Sizing for the insert will be a combination of alphabetical symbols based on the arch length with the smallest size starting with A and increasing alphabetically. The insert will be available in two widths, regular and wide which will accommodate most patients. If the need arises for other widths, such as narrow, those will be offered in the future.

[0029] Looking at FIG. 7, a schematic of a grid device 60 is shown illustrating a new method for measuring a foot to provide a properly sized insert 10. A right foot 50 is positioned on grid device 60 such that the heel of the foot 50 is placed in a heel insert 62 of the grid device 60. Located approximately midway along the length (L) of grid device 60 is an alphabetic grid 64. The alphabetic grid 64 provides an alphabetic symbol to measure the axial distance between the heel and the first metatarsal head 32e. The proper size is chosen by matching the alphabetic symbol (letter) that is closest to the middle of the first metatarsal head 32e. In the example shown in FIG. 7 “D” would be the correct length size.

[0030] The width measurement is designated by the grid portions 66 designated as R for a regular width and W for a wide width. The grid portions 66 are located adjacent the right edge of the grid device 60 (for a right foot measurement). The grid portion 66 into which the right most portion 68 of the right foot 50 extends on grid device 60 will indicate the width. Grid portion 66 measures the widest span of foot 50 across the medial sesamoid through the fifth metatarsal head 32a(as shown by phantom line W). In the example shown in FIG. 7, “R” would be the correct width size. Therefore, using the example and grid 60 shown in FIG. 7, the correct size insert for this foot would be a “D-R”. A mirror image of grid device 60 would be available for a left foot measurement.

[0031] The insert and improved method for measurement of the same will properly align the foot during movement, alleviate pain by cushioning the foot at its sensitive pressure points, and prevent potential serious injury to the foot and leg by prolonged abnormal foot posture.

[0032] While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiments but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims, which scope is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures as is permitted under the law.