Method for computer aided orthotic inlay fabrication

Details Method for computer aided orthotic inlay fabrication Method for computer aided orthotic inlay fabrication

2001-03-13

2004-10-12

Rodriguez, Paul (Department: 2125)

Data processing: generic control systems or specific application

Specific application, apparatus or process

Product assembly or manufacturing

C700S098000, C036S140000, C073S172000, C600S592000, C702S033000

Reexamination Certificate

active

06804571

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to an apparatus and method for measuring the forces and distribution of forces on a user's foot and utilizing this data in combination with other factors to manufacture a custom designed orthotic inlay with an automated fabrication machine.
BACKGROUND OF THE INVENTION
Footwear has been utilized by mankind for thousands of years for protection from rough terrain, thermal extremes, and other hazards. Although primarily utilitarian in nature, footwear construction and design are often influenced by custom and aesthetics. In recent times, the design of footwear has focused more on achieving maximum comfort in general and specialized construction for athletic uses.
Regardless of the protection and other benefits of footwear, they also are frequently a source of discomfort and, sometimes, trauma. Although footwear manufacturers often attempt to produce comfortable footwear, manufacturing practice and distribution methods effectively limit the range of sizes and shapes available to the purchaser. Women's high heeled shoes, for example, are frequently uncomfortable and can lead to acquired problems of the foot. Even regular Oxford style footwear with a standard heel and adequate room for the foot is frequently uncomfortable. This is due to the limited size and shape of footwear available for a limitless variety of human foot sizes and shapes. There are frequently size differences between the feet of the same individual and even the same foot between the heel and forefoot. For example, the right foot may require a size 10-medium shoe while the left requires a size nine. Furthermore, the individual's right heel may be smaller than the predicated standard forefoot to heel width for the size 10-medium shoe. Since footwear is sold in pairs of the same size (length and width), the general rule is to obtain the largest size that will fit both feet and hope for the best. Since neither foot, in the above example, is properly fitted, abnormal loads and movement within the footwear during ambulation can be anticipated.
Another issue not addressed by footwear manufacturers and not readily appreciated by the consumer but which has a direct bearing on comfort is the concept of body weight to foot size ratio. For example, an inlay specification for a person weighing 140 pounds and wearing a size 10 shoe compared to another individual who weighs 200 pounds with the same size footwear is significantly different.
Producing comfortable footwear is made more difficult by the fact that the structure and shape of both the foot and footwear changes during movement which can generate complex plantar pressures. Local areas of high plantar pressure frequently causes pain forcing an individual to adopt unusual ambulation patterns which may, in turn, cause secondary problems in the foot, leg or back. Prolonged areas of high local pressure can result in painful blisters and skin thickening or callus formation. When this is coupled with loss of protective sensation, such as in diabetics, prolonged abnormal pressures can result in ulceration, bone infection and ultimately, amputation. The measurement of the magnitude and distribution of forces present on the plantar surface of the patient's foot during ambulation is described in detail in the Applicants' U.S. Pat. Nos. 5,678,448 and 5,323,650, which are incorporated herein in their entirety by reference.
Foot problems increase with age and may include gradual destruction, over time, of the protective fat pads located under the bony heel and under each of the toe bases. This coupled with arthritic changes in the foot results in a less adaptable foot during ambulation subject to increasing discomfort and secondary changes to include limited joint motion and muscle imbalance.
Footwear manufacturers, depending on intended use, vary sole rigidity which tends to disperse high local pressures generated by sharp objects. They generally provide a thin, inadequate, generic pad for the plantar foot for esthetics. From the above discussion, it should be obvious that a specifically designed interface (inlay) between the plantar foot and footwear is needed to match the unique foot to the generic footwear which objectively address the above issues.
Recognizing the need for an interface between the plantar foot and footwear is, of course, not new. In 1865, Everett H. Dunbar designed the leather lift. In 1905, Dr. Royal Whitman developed the first medical inlay referred to as the whittman plate. In 1910, Dr. William Scholl commercialized the first arch support, the Foot Eazer. Custom inlays (orthotics) began to be developed during the 1930's but it wasn't until the 1980's that semi-automated fabrication systems began to appear. These systems generally automate the process of making the positive mold then resort to traditional inlay fabrication techniques.
Current custom inlay design is based on the shape of the bottom of the foot and to a lessor extent, the inside shape of footwear. Traditionally, a cast mold is made by pouring plaster into a foam impression of the planter foot. Various moldable materials are pressure and/or heat fitted to the cast mold. Highly skilled inlay fabricators (podiatrist, orthotist or pedorthist) then fit the molded inlay product to the foot and shoe. Depending on the skill of the fabricator, an inlay can be fitted to achieve a fairly high degree of comfort based on trial and error methods. Unfortunately, these custom inlays or orthotics require 3 to 4 hours of labor over several days and multiple return visits by the wearer to make the necessary adjustments. Custom inlays are, therefore, time intensive to fabricate, expensive and are at best only an educated estimate of the ideal fit. The effects of changes in the foot and footwear shape during ambulation are ignored, as well as the actual forces which are being exerted on the foot.
An automated method as taught by Schartz (U.S. Pat. No. 4,517,696) and Rolloff (U.S. Pat. Nos. 4,876,758 and 5,640,779) uses a device which generates a numeric foot shape description by use of closely spaced pins pushing against the plantar surface of the foot while the individual is standing or seated. The foot being measured rests on a firm flat platform, and the pins are pushed against the foot with varying pressure, distorting the foot in the process. The displacement of each pin is separately expressed as a number. Thus, this group of numbers represents the shape of the foot. This numeric information is then suitably processed and used as input to a numeric controlled machine to produce inlays. This method is flawed in several respects. First, it modifies the actual shape of the foot during measurement. Second, the process only accumulates data on a stationary foot as opposed to measurements on a foot in motion. These methods do not provide true pressure mapping of the plantar foot. The fabrication component of this method uses pre-formed blanks and only mills the top side. The tool path is a first traverse of the perimeter of the milled area with subsequent traverses offset to the center of the work piece. This is a traditional fabrication process used for milling a rigid work piece. However, it is an inferior process for use with soft materials due to problems associated with holding the work piece and debris collection issues. Further, the use of preformed blanks creates an inventory problem because each shoe brand, style, and size is a separate stock item.
Another process requires that an individual take several steps while barefoot on a capacitive matrix force plate, as taught by U.S. Pat. No. 5,088,503 to Serts. A digital pressure map of the plantar foot is developed and augmented by fabricator input. The resultant prescription file is sent by modem to a central facility where a semi-rigid orthotic inlay is manually fabricated. This process has several significant limitations. There is no in-shoe pressure data obtained, the entire ambulation cycle is not studied, the sample size is limited to just a few steps on a force p

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