Abstract:
A differentially responsive sole for shoes is disclosed which includes a conventional outer sole, an inner sole and an inner liner, the inner sole having a plurality of empty chambers located to support biomechanical weight bearing pressure prints for which a norm has been established. Measurements are made of the individual user at the points and the chambers filled with an elastomer of certain durometer and compressive strength to compensate for the weight load at each weight bearing pressure point.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to a differentially responsive sole of the type with chambers to be filled with material to provide for individual out of normal weight distribution among weight bearing pressure points. 
     2. Description of the Prior Art 
     With the increase in running and walking marathons where competition is high, there has been considerable interest in improving footwear, and in tailoring it to an individual&#39;s particular weight bearing abnormalities. Many cushions and other devices have been proposed as described in the following U.S. patents to Wolstenholme et al., No. 3,892,077, Zente, No. 3,922,801, Turner et al., No. 4,364,188, Batra, No. 4,398,357, Meyers, No. 4,445,283, and Oatman, No. 4,658,515. While some of these structures provide a degree of cushioning for the user&#39;s feet, none of them provide for adequate compensation that is designed to satisfy the needs of an individual&#39;s particular foot weight bearing problems, and to accommodate or correct these problems using reproducible data. 
     During the past decade developments in sensory devices have provided researchers with new diagnostic information about the way people use their feet during ambulation. Some of this information can be used to illustrate how a person distributes, percentages of his or her body weight among selected Biomechanical Weight Bearing Pressure Points (B.W.B.P.P.) of the feet during ambulation. A normal distribution amongst the B.W.B.P.P) has been determined, and minor variations from these norms have been known to cause discomfort and problems both muscular and orthopedic. The resultant problems can occur in the foot, the leg, and even in the hips and lower spine. 
     The sole of the invention cushions the foot at selected locations where a person is overloading a point and stiffens where a person is underloading a point, the sole therefore providing for customizing to an individual&#39;s weight distribution pattern. 
     SUMMARY OF THE INVENTION 
     The sole of the invention includes a plurality of stragetically located empty chambers that are filled with an elastomer whose hardness and compressive strength, is determined by measuring selected biomechanical weight bearing pressure points (B.W.B.P.P.), and determining individual point values, so that the characteristics of the material for each of the individual points is determined and can then be formulated and placed into the chambers to provide an optimum sole response. 
     The principal object of the invention is to provide a differentially responsive sole for shoes that is tailored to the individuals particular measured load placing peculiarities for selected locations of feet. 
     A further object of the invention is to provide a sole of the character aforesaid which is simple and inexpensive to construct but durable and long lasting in use. 
     A further object of the invention is to provide a sole of the character aforesaid that should improve the users running and walking capabilities. 
     Other objects and advantageous features of the invention will be apparent from the description and claims. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     The nature and characteristic features of the invention will be more readily understood from the following description taken in connection with the accompanying drawings forming part hereof in which: 
     FIG. 1 is a bottom plan view of a typical individual&#39;s feet illustrating ten weight bearing points to be measured; 
     FIG. 2 is a bottom plan view of the sole of the invention; 
     FIG. 3 is a vertical sectional view enlarged taken approximately on line 3--3 of FIG. 1; 
     FIG. 4 is a vertical sectional view enlarged taken approximately on the line 4--4 of FIG. 1; and 
     FIG. 5 is a vertical sectional view enlarged taken approximately on the line 5--5 of FIG. 1. 
     It should, of course, be understood that the description and drawings herein are illustrative merely and that various modifications and changes can be made in the structure disclosed without departing from the spirit of the invention. 
     Like numerals refer to like parts throughout the several views. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now more particularly to the drawings and FIGS. 1 to 5 inclusive in FIG. 1 a typical individual&#39;s feet F and F&#39; are illustrated with ten chambers where individual weight bearing points will be determined. A shoe SH is shown in fragmentary form which includes a sole S, two layers, S1 which is the outer sole, S2 which is the inner sole, and an inner liner L1. The outer sole S1 is of conventional configuration and the inner sole S2 has the ten chambers located in it as described below. The shoe SH also includes a heel H as shown in FIG. 5 and fill points FP for the chambers to be described. More or less chambers can be used as desired however it has been determined that ten stragetically located chambers provide the necessary support for most uses. These ten chambers are: 
     C1 Hallux 
     C2 Digits 
     C3 1st Metatarsal 
     C4 2nd Metatarsal 
     C5 3rd and 4th Metatarsal 
     C6 5th Metatarsal 
     C7 medial Arch 
     C8 Lateral Arch 
     C9 Medial Heel 
     C10 Lateral Heel 
     The normal at peak load for these areas are: 
     C1 20% of Body WEight 
     C2 Neutral 
     C3 12% of Body Weight 
     C4 20% of Body Weight 
     C5 14% of Body Weight 
     C6 8% of Body WEight 
     C7 Neutral 
     C8 Neutral 
     C9 16% of Body Weight 
     C10 16% of Body Weight 
     These norms have been selected for standard dress shoes under walking conditions. A different set of norms are used for each type of shoe and the predominant mode of ambulation (walking, jogging, running, etc.). In addition, three neutral chambers are included in this example, which will be filled with an elastomer at the mean compressive strength. The mean compressive strength is determined by considering the type of shoe, the mode of amublation, and the user&#39;s body weight. These neutral chambers are important for filling all areas of the sole, forming a custom arch support and may become active if a person&#39;s pathology causes these areas to become weight bearing. 
     The assumptions used in determining an individual foot profile as described below are based on existing materials and data gathering equipment. Many other systems and materials are available and these assumptions are in no way restrictive or the only means to make the sole useful. The elastomer is available from Polytech Corp., P.O. Box 384, Lebanon, N.J. 08833, and the data gathering device is available from The Langer Biomechanical Group, Inc., 21 EAst Industry Court, Deer Park, New York 11729. 
     THE ELASTOMER 
     1. The elastomer (E) is a type which is modifiable in its compressive strength (D) by the addition of a plasticizer and/or a foaming agent (P) at manufacturing. 
     2. The elastomer without modification has a set hardness of 55 Shore A Durameter. 
     3. For each 400 parts of the elastomer the addition of 1 each part of the modifier P will have the effect of reducing the compressive strength to cushion 1 pound per square inch more of pressure at peak compression. 
     4. Since the mean compressive strength of the elastomer will require a certain amount of P for normal, the reverse is also true. The lowering of each 1 part of P will stiffen the elastomer to resist 1 pound per square inch more of pressure at peak compression. 
     5. These changes in compressive strength are all relative to the mean compressive strength. 
     6. The unmodified compressive strength (ID) will cushion 100 pounds per square inch. 
     THE DATA 
     1. A data source should be available to analyze the foot strike of an individual corresponding to the chambers (c) of the sole. 
     2. The data will be representative of the type of ambulation that the sole will be used for. 
     3. The data will be formatted as a percent of total body weight (PW) plus or minus the norm for that specific weight (B.). 
     4. Neutral chambers will have no data unless required. 
     DETERMINATION OF THE MEAN COMPRESSIVE STRENGTH 
     The mean compressive strength (D) is determined by considering the shoe type (ST) that the sole will be used in (i.e. dress shoe, running shoe, etc.) and the body weight of the user (W). 
     
         D=W*ST 
    
     ST is a factor to set the largest percent of body weight PW) that the sole would undergo while in use. Each type of use (running, walking, dancing, tennis, etc.) has its own maximum percent of body weight stress and it also has a unique percentage distribution pattern amongst the chambers of the sole. 
     The W factor is to establish the best compessive strength for the normal weight, while allowing enough range of modification in the elastomer to compensate for out of normal weight readings. 
     The formulas for mixing the mean compressive strength elastomer is as follows. 
     
         P(D)=ID-D 
    
     
         D=E+P(D) 
    
     DETERMINATION OF COMPRESSIVE STRENGTH FOR EACH CHAMBER 
     The following formula is used to establish the compressive strength for any chamber. 
     
         D(C)=E+P(D)+(P*(W*PW) 
    
     Measurements were made of a typical individual as follows: 
     EXAMPLE 
     Subject: male 
     Body weight: 187 pounds 
     Shoe type: casual shoe 
     Shoe use: walking 
     
         ______________________________________DATAPeak force       Normal    Out______________________________________Left foot:1       12% B.W.     20% B.W.  -8%2       neutral3       18% B.W.     12% B.W.  +6%4       23% B.W.     20% B.W.  +3%5       16% B.W.     14% B.W.  +2%6       14% B.W.     8% B.W.   +6%7       neutral8       neutral9       15% B.W.     16% B.W.  -1%10      13% B.W.     16% B.W.  -3%Right foot:1       16% B.W.     20% B.W.  -4%2       neutral3       14% B.W.     12% B.W.  +2%4       20% B.W.     20% B.W.  0%5.      14% B.W.     14% B.W.  0%6       11% B.W.     8% B.W.   +3%7.      neutral8.      neutral9       14% B.W.     16% B.W.  -2%10      15% B.W.     16% B.W.  -1%______________________________________ 
    
     The data was obtained by using the well known Langer measuring equipment, however it is expected that other such equipment would also provide useful data from which suitable soles could be constructed. 
     Mean 
     ST=0.35 
     D=187*0.35 
     D=65.5 lbs/sq inch 
     AMOUNT OF P FOR MEAN 
     ID=100 lbs/sq. inch 
     P(D)=100-65.5 
     P(D)=34.5 
     MEAN FILLER 
     The cushioning needed for D is obtained by adding 34.5 parts [P(D)] to every 400 parts of E 
     
         D=E+[P(D)*[E/400]] 
    
     So for 600 grams of E 
     
         34.5*600/400=51.75 
    
     You would add 51.75 grams of P 
     CHAMBER FILLER 
     The cushioning needed for a chamber D(C) is obtained by multiplying the out of norm load (PW) (plus or minus) by the total weight (W). Then multiplying that result by the parts of P needed per pound per sq. inch cushioning. Then adding that to the mean P(D). 
     
         D(C)=E+[P(D)*[E/400]]+[[P*CW*PW]]*[E/400]] 
    
     APPLICATION TO TEST CASE 
     Each batch will have a 600 gram amount of E. Also a ratio of 1 part P to modify 400 parts E by 1 lb. per sq. inch of cushioning. Results will be rounded to the nearest hundredth gram. Neutral chambers will be filled with mean compressive strength elastomer. 
     
         ______________________________________chamber        E batch  Total P______________________________________Left foot1              600 gr   29.31 gr2              600 gr   51.75 gr3              600 gr   78.58 gr4              600 gr   60.17 gr5              600 gr   57.36 gr6              600 gr   78.58 gr7              600 gr   51.75 gr8              600 gr   51.75 gr9              600 gr   48.94 gr10             600 gr   43.33 grRight foot1              600 gr   40.08 gr2              600 gr   51.75 gr3.             600 gr   57.36 gr4              600 gr   60.17 gr5              600 gr   51.75 gr6              600 gr   60.17 gr7              600 gr   51.75 gr8              600 gr   46.14 gr10             600 gr   48.94 gr______________________________________ 
    
     Construction of the soles with the described material in the identified chambers resulted in soles which compensated for the user&#39;s weight bearing pattern. While the tests were conducted for a walking shoe, tests for athletic and other special purpose shoes can be expected to develop useful data which can be used to manufacture soles for use in such shoes. 
     It will thus be seen that soles have been provided with which the objects of the invention are achieved.