CA2260078C - Method of making injection molded orthotics - Google Patents

Abstract

A method of making functional orthotics from a multiplicity of uniquely designed injection molds which have been constructed by studying large numbers of replicas produced from uncorrected replicas that replicate the contour of the feet of a multiplicity of patients. In one form of the method of the invention, following a careful dimensional stu dy of the corrected replicas, they are grouped into families, the members of which exhibit lower surface contours that are substantially identical. An injection mold is then made for each of the identified families, in a manner such that the mold will produce an orthotic having an upper surface that corresponds to the lower surface of the corrected orthotic that makes up the group. Companion data is then developed which correlates the corrected replicas of each identified family with the uncorrected replicas from which they were made. A study of t he uncorrected replicas then provides data as to the contour of the patient's feet which they replicate. This data can then be compared with new patient data provided by the prescribing doctor and the mold can be selected which will produce an injection molded orthotic which i s appropriate for the particular patient.

Description

MET$OD OF MAKING IN,TECTIOti MOLDED ORTIiOTICB
8 H? E C I F I C 11 T I O Z7 Background of the Invention Field of the Invention The present invention relates generally to orthopedic appliances. More particularly, the invention concerns a novel.
method for making injection molded, finished functional orthot-ics by using various critical measurements made of the patient's feet.
Discussion of the Prior Art Orthopedic appliances, or. foot supports, having various shapes and configurations have been known f.or many years. The prior art'appliances range from simple foam, leather, corn, or sponge rubber arch supports that can be purchased in drugstores to sophisticated, custom-fitted orttnotics formed of various rigid or semirigid materials. 'These latter devices, while much more effective than the former, are typically quite expensive and are generally constructed by orthopedic laboratories in accordance with detailed prescriptions provided by the examining doctor..
Generally speaking, the primary function of an orthotic is to correctly limit the complex motions of excessive pronati_on and supination. Pronation may be simply described as the flattening or rolling inward of the foot as the foot strikes the ground as during walking or running. Excessive pronation can cause the tibia and fibula to rotate inwardly sometimes placing severe strain on the leg muscles. 5upination, on the other hand, is the rolling outward of the foot during walking or running. When either of these motions become excessive, painful damage to the knees, ankles and feet can occur.
In making the more sopliisi~icated functional orthotics, the conventional practice, which has remained essentiall.y_ unchanged 1.

for many years, is to first make an impression oi: the patient:'s foot. This impression, which may le made :i.n plaster <>( l~~~r i s c>r in a crushable, foam-like material., is forwarded to tLn:~ c,ntl~opu-di.c laboratory along with the exami.niny doctor's in:;t:roct.i«n::;.
One method of making the impression, or negative ciE.pression, using foam blocks is described in U.S. Patent No. 3,320,347 issued to Greenawalt. This method, as described by Gneenawalt., comprises placing a foam block on the floor, centering one of the patient's feet relative to the block and then having tire patient:
stand so that his weight is equally divided on both feel:. As tile patient's weight is placed on the foam block, the foam ce:Lls of the block will be crushed and a negative impression of tire pa-tient's foot will be created.
Tine thrust of the Greenawalt method is to use the .i.mpression made in the crushable foam block to make various measurements>, visual observations and touch evaluations whicln serve as tl~e basis for constructing the corrective arch support. F'o r ~xampl.~., measurements are made of the length and width of the i mpression and observations of the position of the metatarsal heads, of plantar abnormalities in the inner and outer longituc:linal arch and of the presence and degree of supinati on are made. '1'hee~e measurements and observations are th en used in layincl out. the dimensions and sizes of the leather blanks which are t:o be used for constructing the corrective arch support.
Another prior art approach followed by many ort:hoped:i..r_ laboratories in constructing functional o3-th otics invo:l.ves pour-ing a solution of plaster of Paris into tile impression, or nega-tive depression, to make an uncorrected repl.i.ca or cast of the patient's foot. This having been done, t:lre uncorrected replica which provides an exact duplication of the contours of the lower surface of the pat.ient's foot, is correct:e<1 in i:lte manner pr<:-scribed by the examining doctor. ):or exarnpl.e, the uncorrected replica is often wedged or adjusted to simtrlat_e the pos.it:i.on of the foot in the neutral position or i.n the position wh.ic~h t~lm-doctor coishes to control foot functioro. The neutral pos i t.i.on c~( the foot is the position wherein the fool= i;; neither srcp.inatecl nor pronated and tl~e midtar sa 1. j of nt i s maxi ma 1.1 y prcmar t.cd . 1 0 this neutral position, the foot typically transfers force most:
effectively. In biomechanical terms the foot must ideal.l.~~ absorb the force of gravity at heel contact and then create a rig.i.d lever to correctly propel the body forcoard for. the next step.
When the foot is not in or near the neutral position, it cannot.
absorb force nor can it create an effective lever for i~ropelling the body forward in a proper manner. Such a problem can cause the foot structure to break down and, over time, lead to severe neck pain, back pain, foot pain, bunions, heel spur, and tire like.
The "wedging step involves first b.isectin<I the posterior aspect of the calcaneus and then wedging the cast rrTlt i.l th:i.s bisection is generally perpendicular to the horizontal plane.
The wedging, per se, is generally accomplished by adding a plaster forefoot p.l.atform to the cast:. Preferably, tl~c~ Irl.atform extends from about one centimeter proximal to the first. ntetatan-sal head and the fifth metatarsal. Head t:o the sulcus area arr<1 spans the positive mold from the medial aspect (outside ec.3ge of first toe) to the lateral aspect (outside edge of fifth toe).
Typically, the wedged mold is then further modified with a plaster of paris buildup to account for fat pad expansion around the heel and along the lateral foot border, to allow for compres-sion of the medial arch and transverse arch, and to create a smooth transition from the forefoot pl.atfor.m to the arch arrcl midfoot.
It is apparent from the foregoi.nd that the methoel I or cor.--recting the uncorrected rep l.i.ca .i.s a oomlslcx, time-c-.on ,,tr,tirrd, atrcl highly labor intensive operation. frtri:lter, the prior art method is somewhat imprecise and is highly clepetrdertt on the s?, i.ll of tla particular technician involved.
Although the same basic principles are used by t)re l.abora--tort' technician to correct the uncorrected repl.i.ca fcvrmed from the impression of tire patient's foot, experience has ~:la~wo tlmt.
no two people will correct a particular replica in exact7.y tl~e same way. Thus, if two identical uncorrected retplicas wer:'e t:o 1>e sent to two different orthopedic laboratories, the orthoti.c returned to the doctor would be different in various respects.
This is because the laboratory technician who makes tire correa.-tions i.s of necessity required to make various subjective deci-sions based upon his own experience and capabi.li.t:i.es. F'or° exam-ple, no two feet are the same length and width even o~~ the same patient. Nevertheless the examining doctor, or otheu lir.ensen professional, typically wants the two orthotics made for- the same patient to look symmetrical. Accordingly, the technician is forced to subjectively judge where the forefoot p3.atfor-ms should be located and Crow much expansion should be placed on each foot.
No two technicians or laboratories will make the same dec:i.sions in the same way.
Further contributing to the impreciseness of the prior art techniques for making functional orthot:ics is the methoo3 wt forming the orthotic from the corrected replica. l~asi.cll:l.y, t:hi.s method involved thermal forming of a layer of polyolefi.n plastic sheet over. the lower surface of tl-re corrected replica . If tire forming step is correctly done and the polyol.efi.n sheet is prol:r-erly heated and cooled, thre upper surface of the ~;heet will.
correspond substantially to the lower surface of tare corrected replica. One such method of thermal fot-ming is described in U.S.
Patent No. 4,702,255 issued to Schenkel. however, iL t:he Iorming step is incorrectly done, precise repl..i_cation of the l.o~~rer sur-face of the corrected replica will not: result.
For the foregoing reasons, the products made by different laboratories are somewhat different and even the corrections made within a single laboratory may be different from foot'. to foot..
Further contributing to deficiencies i.n prior art ort:hotics is the absence of reliable methods for analyzing the pat_ient:'s fort impressions and the inability of a given orthot.i.c cc~n:.;t~.r-uctc,<i from the impression to, in fact, proper-1.}~ control tloe p,.rt.i.ent's foot.
Frorn an exhaustive study made by the present i aventor oL
literally thousands of orthotics made in accordance wi.tU tire prior art processes discussed in the preceding paragraphs, a most:
surprising discovery was made. Since the conventional vrisdom has been that the foot of each patient is unique with no t:wo feet being alike, those working in the field have presumed t=ioal-. no two orthoti.cs made by the previously discussed prior art for°oce:;<, would be alike. Surprisingly, the studies made by the present inventor 'indicate that this, in fact, is not the case. These:
studies included the careful measurement of the contour of eac:l of a large number of uncorrected rep7_icas presented for correc-tion followed by the careful measurement of the corrected cor'rt011r of each corrected replica produced :in the laboratory in accor-dance with the processes described in the preceding paragraphs.
An analyses of the measurements showed that, while the uncorreci~-ed replicas typically varied in certain respects, many of t1 a corrected replicas and the orthotics formed therefrom were nearly functionally identical and fell into rather. well defined groups.
Based on the discovery that: families of different, but related uncorrected rep.li.cas, ~~rhen corrected by traci:it-i.ona l processes, produced nearly ident:_i.ca1 corrected repl:ic:,s, the present inventor reasoned that a permanent corrected replica i_n the nature of a male-forming master, could be construe:ted and used repeatedly to form final orthotics for each of these identi-cal families. In this way, the substantial amount of labor re-quired to correct each replica of the group of uncorrected repli-cas which made up the family could be avoided. Con tinuj.ng studies by the inventor of additional uncorrected t:~eplicas re~~e.ived 1~y the laboratory enabled the identification of a large number identifiable groups of uncorrected replicas which, when correct-ed, would produce a substantially functionally icleni: ica i f i ni.sltecl orthotic. This information then made it possible to cc,nl-,eruct a number of forming masters for each of the identified families.
After a large inventory of forming masters were then comstrt.tcted, the next step in the development was to analyze each tte~a uncot--rected replica received by the laboratory and identify it: with one of the previously identified families of uncorrected replicas which, when corrected, would produce a virtually idenl~i~.al. fin-fished orthotic. The forming master associated with tire ic7enti-fied family was then used to form the finished orthotic for tl~e newly received uncorrected replica rather titan laboriously con-structing' a corrected replica and using it to form the fi.ni.shed orthotic for the patient.
The approach to making f finished ort:hoti.cs describec7 in the preceding paragraphs was successfully commercialized and ttte orthotics made by the process were marketed by KLM Laboratories, Inc. , of Valencia, California, under the name and style "SYS'f1?t~i RX" . While this novel. process was less labor intensive than the traditional prior art process whereby each uncorrected replica was corrected and then used to form tire f:in.ished ortltot:ic_, the many processing difficulties and substantial labor i.n volved i.n high temperature forming of the ortltoti.c from a selected one of the male-forming molds remained. In a manner presently to he described, the methods of the present invention el.egantl.y avoids the difficult, costly and time consuming step of high temperature forming and finishing of the orthoi:i.c:s from the male-formiruj masters and produces even a higher dttal.ity finished product at a significantly lower cost.
Before discussing rite details of the present invention, it should be pointed out that others working in the field have also devised means for reducing the labor Costa involved in t.hc tra~nl correction of each of the uncorrected replicas received by time processing laboratory. One such approach is discl.osecl iu U.:;.
Patent No. 5, 054, 148 issued to Graml~it~e. 7'he c~rumbi ne pror'or;;~
involves the use of a computer-controlled mill. to pr:-~c3acc~ each individual orthotic from a monolithic workpiece. In acr:ordance with the process, the spec.if.ic contour:' of the top and t~ottmm surface of. an orthotic for a part.icul.ar pat=ient is fir~;t de-scribed and stored in terms of x, y, z coordinates and subse-quently formatted such that a particular x, y, z coordircat:e, i.e.
a specific longitudinal and lateral position on a we>rkpiec;e yields a part.i.cu.lar height (z) po~;it:.i.oning of the macl~.ine tool.
The machine tool is then guided along parallel paths through the workpiece while the machine tool's l~e.igtrt i~ automatically a<1-jested to~conform with the desired surface contour.
Although the Grumt?ine process and other. somewhat: similar prior art, computer-controlled milling operations deve)o~:~ed by others working in the field have proven generally satisfactory, a considerable investment in sophisticated tooling such as scan-ners, computers and large computer-controlled milling machines is required. Tn add.ition, each order requires a unique set. ap and milling process which increases the overall. cost per order.
Another prior. art .approach to maki.nd custom-made shoe in-serts is described i.n LJ. S. Patent Pto. 4 , E37G, 75d issued t_o Itol.l.-off et al. This patent discloses a foot: impression unit: cnhich .is provided with an array of gauging elements, a control meclrani sm for urging the gauging elements into contarct with the undersur-face of a person's foot to form an impressi.oo of. the undersurfae;e of the foot and a sensing mechanism for scanning the gaug.im~
elements to produce digital signals indicative of the positions of the gauq.ing elements. These c3i.rJitaJ. signal:.; are ~;tored anc3 processed by a computer to provide a stored data r. econd servinct as a digital representation of the impress.i.on of the ur~c.3ersurfacc:
.7 of the foot. The computer may also be employed to provi<3<:: :;tore<l additional information for modifying that data record ir.~ c«mpem-sate for a perceived defect of the foot with the x, y, ., informo-Lion derived. Once again, the custom-made shoe insert ..s made lej~
a conventional. computer controlled milling machine using the stored data for a particular patient. Once again, ouch order requires expensive and time consuming set-up and milling opera-tions.
As will be better understood from the discussion which follows, the methods of the present invention uniquely overcome most of the c9rawbacks of the pr for art processes for proclucin~l orthotics by providing a fast, accurate, efficient, and 11011--labor intensive injection molding process for making high qual.i.ly precision orthotics in very high volumes.
summary of the Invention >3y way of brief summary, one form of the method of the present invention for making an injection molded orthoi=is :invol.-yes first selecting a multiplicity of uncorrected replicas of the human foot, each of which is to be later modified to create a corrected replica. The contoured lower :~ur.face of. each uncor-rected replica of the multiplicity of_ uncorrected replicas se-lected is then analyzed to identify thereon a multiplicity of x, y coordinates. 'this done, the contoured surface is spaced apart from a reference plane and for each x, y coordinate identified thereon, the distance between the coordlltate and the reference plane, that is the z coordinate, i.s determined and recorded to develop a first set of x, y, z coordinate data. The: x, y, z coordinate data thus developed d~~f i.nc~~; i=he topogral.~lty of- t:hn lower surface of the patient's foot as replicated by the uncor-rected replicas which were produced from negative casts taken by the examining doctor of the patient's foot. In an alternate method of the invention, the deta.il.s of which will.. later be f3 discussed, the negative casts received from the doctor, rather than the uncorrected replicas, are analyzed to develop tlae fir_-t set of x, y, z data.
Following the correct.i.on by tradi.t:.i.omnl method:; oC t:h uncorrected replicas, each of the corrected replicas i.k~us formed is used to produce a functional orthotic. Each of tho finished orthotics thus produced is then studied to i.dent.ify t:ltosc> fin-fished orthotics that are substantially functionally identica:l..
The substantially identical finished orthotics are then grouped into a plurality of discreet, finished orthotic groups. Once these groups of finished orthotics are determined and appro-priately identified, an injection mold for each family is con-structed. The injection mold for each family i.s carefully con-structed so that the internal cavity of the mold, when filled with a moldable plastic will produce a finished orthot.i.c that .is substantially identical to the plurality of finished art:hoti.c, which make up the particular group that was identified. Fty reviewing the recorded data, it can he easily ascerta.i.ned which uncorrected replicas were used to produce the corrected replicas and which finished orthotics were made from these correct repli-cas. It follows that each .i.njectic~n mold can then be identified with the particular group of uncorrected replicas from which ttie finished orthotic was derived. In this regard, for each group of uncorrected replicas, the x, y, z coorcli.nate data corresponding to that group is identified and recorded dud, in this way, a plurality of groups of x, y, z comparison data are developed.
Each group of x, y, z comparison data is then identified with a particular injection mold.
Once each of t:he injection mold; is associated with a par-ticular comparison group, a newly received uncorrected replica can be analyzed and identi.fi.ed wi.t:h a particu7.ar mold L>y compar-ing the x, y, z data of the uncorrected replica with the x, y, z comparison data to determine tl~e droop w.i.t:h which i t-. i s most:

closely associated. Once this i.s done, the proper mo:l.d c:an 1~
selected. Then, using dais mold, a precise orthotic cairn r~adil~
be constructed for. use by the patient. In actual. practice, matching of the patient with the proper comhar ison x, y, ,, data group is accomplished by first developing x, y, z data for the contoured lower surface of the pati.ent's foot. This 1>at:ient x, y, z data is then compared with the earlier definecl and tobrrlatc.d comparison group data to identify the particular comparison group within which the patient x, y, z data falls. It is there a si.mp:le matter to identify the particular injection mold which corre-sponds to the selected group of comparison ):, y, z clarta and t:o use that injection mold to produce the finished or thot i c for tUe particular patient.
An alternate method of the invention for developiru~ w ompari-son x, y, ~ z data which can be used to se l.ect the correct-. i.njec.-tion mold for a given patient involves tl~e careful. aua lye>is oL
the corrected replicas formed by tradi.tiona:l rnethod:; from the uncorrected replicas made using the impression provided by the examining doctor. More particularly, i.n 3cco~:~dance with this alternate method of the invention, the contoured lower surface of each corrected replica is analyzed to identify thereon a multi-plicity of x, y coordinates. 'fh.i.s done the contoured _.urface of the corrected replica is spaced apart from a referred plane and the distance between the reference plane and each of the x, y coordinates is determined and recorded to develop a second set of x, y, z coordinate data. This second set. of x, y, z data su1-stantiall.y defines the topography of the lower surface of tire corrected replica, and reflects the corrections prescribed by the examining doctor that are believed aec:essary to properly control the foot functions of the particular patient.
After creating the second set of x, y, z coordinate data, this data is studied to identify those corrected replicas that are substantialJ.y identical. 'this done the substant.iall.y .identi--L CI

WO 9$/07342 PCT/US97/14234 cal corrected replicas are grouped lnto a plurality of d:i.screeL, corrected replica families. Once t:ireac° i:am.ilies of cc~rrect<e.l replicas are determined and al.~prolor.iate7.y i.dent.i.fied, an i.njew-tion mold for each family is constm~ctecl. ~1'1e iryjectic>rr molcj fc~u r each family is carefully constructed so that the internal cavity of the mold, when filled with a moldable plastic twill. pro<.luce a finished orthotic which is substantially identical to the p.lura:l-ity of finished orthotics formed using the particular family of corrected replicas. By reviewing the recorded data, it can be easily ascertained which uncorrected replicas were used to pro-duce the corrected replicas and the finished orthotic~s made therefrom which make up each fatni..ly. It follows then that, <ts before, each injection mold can be identi.f.i.ecl with the parti.c:ula.rr group of uncorrected replicas which, when corrected, produces the finished orthotic that corresponds to the orthot.ic produced luy the particular injection mold. Once the particular group of uncorrected replicas is identified, the x, y, z, data eor respond-ing to that group is identified and the plurality of groups of comparison x, y, z data can be dev~..Loped.
With the foregoing in mind, it is a primary object of the present invention to provide a method of making, through use of an injection mold, a funr_ti.onal orthotic that is a qua l.i.Y.y edua.7 to or better than that of a functional orthotic made from a corrected replica that is constructed by conventional. prior art techniques from an uncorrected replica of tire patient's foot.
Another object of the invent.LOII LS to provide a method of the aforementioned character in which the prescription data typical ly provided by the exam.i n i nc3 doctor can be used i:o qu ick.l y and easily identify a particular injection mo7.d that wi.l.l produce a finished orthoti.c: than is substarrtiol.l.y identical to t.lm~t whi<~l~
would have been heat formed from a correc:tecl reelic-a of the pati.ent's foot that was made by conventional- prior- ant tectr-piques.

Another object of the invention is to provide n mettrod ~fv making a plurality of specially configured injection molls wlrichr can be used repeatedly to produce hic~lr c:lullit.y, func~l:i_c~m~l c~n-tltotics for. virtually every type of proL>l.em for wlriclr fu~~cW.iomW
orthotics are prescribed by an exami.n.ing cloct:or.
Another object of t:he invention i.s to provide a rnetlrod as described in the preceding paragraphs in which a defini.ti.on of the contour of the pat.ient's foot, provided either by means of a negative or positive replica of tire patient's foot, or- by other contour data obtainable by scanning techniques, or the: 7.ike, crrrr be used to quickly and easily select tire proper injection mo:Ld to be used in making an orthotic for a part.icul.ar patient.
Still another object of the invention .i.s to provide a metlrcxl of making precision functional orttrotics by injection mol.di.ng techniques, which techniques, are c:onsiderab:Ly more effic.i.ent and substantially less labor intensive t.harr presently pr act-.iced, prior art techniques.
Yet another object of tire invention .i.s to provide a method of making precision, high-quality fur~ctJ_Ull~ll orthotics on an a~-needed basis from a pati.ent's foot contotrw data that. .is on file even in the absence of the ori.gi.nal. impression of the p<-rt_ient's foot, and in the absence of a corrected replica of the patient's foot.
brief Description of the Drawings Figure 1 i.s a generally perspective view of one form of functional orthotic produced in accordance w.i tlr the met_lnod of tare invention.
Figure 2 is a plan view of tine :Lower surface of a ~~orrected replica, which is formed by tradi.ti.ona:L methods from i:he uncor-rected replica which replicates the Lower surface of t:lre foot of the patient. exemplary x, y coordinates used to i.cic~nt.i.fy tlm surface contour are indicated in the drawing.
Figure 3 is a generally perspective view of the corrected replica shown in Figure 2, the contoured aurface cW - which i.~;
spaced apart from a reference plane wtrich i.s scrper i mposed over the contoured surface and from which z coordinates tlrai: rvepresent the distance between the x, y coordinates and the reference plane, can be determined.
Figure 3A is a fragmentary, i.ll.ustrat.i.ve view of a section of the corrected replica illustrating the manner of d et:erm.i.nation of the z components oL the contoured surface.
Figure 4 is an exploded, generally perspective v i.ew of c» ~e form of lIl jeCtlOrl mold constructed in accordance with the method of the invention.
Figure 5 is a generally diagrammatic representation of tire various steps of one form of the method of the invention to produce an injection molded orthoi:ic.
Figure 6 is a generally perspective view of the orthotic shown in Figure 1, the contoured surface of which is spaced apart from a reference plane which is superimposed over tlue contoured surface and frorn which z coordinates that represent the di.stanc:~
between the x, y coordinates and the reference plane, can be determined.
Figure 7 is a generally perspective view of a foot impres-sion of the character received from the examining doctor, the contoured surface of which is spaced apart from a reference plane which is superimposed over the contoured surface thereof and from which z coordinates that represent the distance between t.tre x, y coordinates acrd the reference plane, can be determined.
Discussion of the Invention Referring to the drawings and particularly to Figure 1, one form of the functional. orthotic produced in accordance with the method of the invention is there shown and general.) y clc~s.ignated by the numeral 14. 'fh a three-dimensional, curved supporting surface 16 of the functional orthoti.c 1~4 includes tale heel recJiorr lt3 properly contoured to support the users heel , the arc:lr region 20 contoured to proy>erly support tire user:-s ar.c~U mui t.lre i metatarsal region 22 disposed proximate the heads of flue users metatarsal joints.
As previously discussed, functional orthotics of t:lre type generally illustrated in Figure ~. are typically proc.3uced .in accordance with a relatively standard prior art procedure. 'fhe first step in this procedure involves the examination of the patient by the doctor and the forming by the doctor of a negative cast of the patient's foot using plaster of paris, crushable foam, or the like (see, for example, Figure 7). This negative cast is then forwarded to an orthotic laboratory, aloud wii:lt any special instructions the doctor may Have concerning th a constru~_-Lion of the orthot.ic for the patient.
At the orthoti.c laboratory the negative cast is used to make a plaster of paris positive, or uncorrected replica of the pa-tient's foot. ~'he uncorrected replica is then modified by t:lre laboratory in accordance with the doctor's instruction s to pro-duce a corrected replica (see, for example, Figure 3). As pre-viously discussed, the corrections made to the uncorrected repli-ca may include wedging , the heel. portion by the addition of a plaster platform to simulate the foot i.n the neutral position.
Additionally, the wedged replica may then be further modified with strategically placed plaster of pari.s buildups to account for fat pad expansion around the heel and along the laLeual foot border to allow for compression of the medial arch and transverse arch and to create a smooth transition from t:he foot platform to the arch and mid-foot.
After the corrected replica is fi.ni.slred to tire satisfaction of the laboratory technical staff, a thermoplastic mater_-ia.l, such as polypropylene, i s heat molded t o tlr~ plantar surfatce of the corrected replica. Finally, the formed tluermoplastic mat.e.rial is appropriately trimmed and polished to produce the fin.islred func-tional orthotic having the general physical ctraracteri.stics of the orthotic illustrated in rigure 1.
It has long been recognized that the prior art processes of the character described in the preceding laaragraphs are somewhat inefficient and tr.ighly labor intensive. I~or this reason, tire present inventor began an exhaustive study t:o attempt: to c.level.op an improved and less costly method of rnahing functional orthot-ics. In this connection, it has always bean assumed that each human foot, like a snowflake, is unique, and that each func~.tional.
orthotic made for a particular patient is similarly unique. lVitlr this in mind, the present inventor. set. out to verify or refute this long-standing belief by carefully analyzing large numbers of.
human foot impressions provided by the examining doctor and l.lre uncorrected replicas that irad beero made i.n thc~ laboratory fwom these impressions. Next, the inventor studied the c:onrected replicas that had been produced from the uncorrected replicas and finally, analyzed the functional orth oti.cs that had been made from the corrected replicas. These studies, the details of which will be discussed in the paragraphs which follow, surpr.isi.ng.Ly revealed that, in actuality, the functional orthotics produced by the prior art process were not ind.i.vidually unique, but= rather, could be grouped into families of substantially identical or-thotics. l9ore particularly, the present inventor discovered tlr~t although there were subtle differences among the three dimension-al surfaces exhibited by tire finished ortlrotics, the orthot.i.c:s could nevertheless be justifiably grouped into some 54o basic configurations and rarely would a selected one of these basic orthotic configurations not be sui.tabl.e for corrective use by a particular patient. In fact, the study .i.rrd_icates that from these 540 basic configurations, on the order of 60 configurations c<~n produce about 75 percent of the orthotics made by the .l.aboratooy 1. 5 on any given clay.
Turning to figures 2 through 5, one Loan of t1e rnet.lrod oL
the invention for making injection molds ~~uitable ton use in injection molding C.inished ortlroti.cs of tire general. type ~;irowrt in r Figure 1 is there illustrated. figure 2 shows a corre<:t~d repli-ca made from an uncorrected replica, wlll.clr, in turn, was made from a foot impression provided by tire examining doctor. Fi.grrre depicts generally the methods of tt~e invention and slows at tire left margin of the drawing the progression of the methods, namely selection of the casts or impressions 24, selection of the uncor-rected replicas 26 formed from the casts, and t11e11 analyz.i.ng either the selected corrected rep liras 2tl made from the uncor-rected replicas, or, alternati.vel.)~, analyzing the selected f.i.rr-fished orthotics 14 to derive the coord.inat~s necessan-y t=o make the family of injection molds 30 of the inventior7. For example, the first step of one form of the method of the invention for making the injection molds and tire finished orthotics involves the selection of a multiplicity of uncorrected repli.c~as of tlae human foot, such as by way of simplification, rep.l.icas UR-1 through UR-10 (Figure 5) which have been made from the negative casts or impressions I-1 through I-~ 0 rece.i ved by tl~e l ai.~omator. y .
It is to be understood that, whi..l.e I~'igure 5 slows only ten casts, ten uncorrected replicas, ten corrected replicas and ten fi_r~islr~d orthotics, many thousands of casts, repl..icas and orth otics are .in fact analyzed in the accomplishment of the method of the inven-tion, but only ten of each are sh nom in Figure 5 in an attempt to simplify the explanation of the process of the invention.
Following selection for study oC the casts 24, the uncor-rected replicas 26 made therefrom an<:1 the corrected rep.l..i.cas ?F3 formed from the uncorrected replicas (F.igure 5), the next step .in the method of the invention involves i.denti.Lying t:l~e mW.t.iplic.i-ty of functional orthot.ics lA, produced Lrom t;he correc;l:ed nepl i.-cas, for example, orttrotics O-1 through O-1 0, as idelrt i.L.i ed in Figure 5 which corrected replicas were made by conventional. tec:lr-piques frorn the multiplicity of corrected replicas 2t3, wh.i.ch ar.-a identified in Figure 5 as CR-J. through CR-10. T4ext, t:lr~~ fum.--t.ional orthotics O-1 through O-:1.0 are c~r.efully examined R.o identify those which exhibit substantially identical contoured upper, or foot engaging surfaces. ~I~h.i.s clone, a plurality of first subgroups is identified by selecting from tl~e multiplicity of functional orthotics o-1 through O-10 those finished orthotics which are of substantially ident.i.cal configuration. Dy way of example, and as illustrated in Figure 5, orthotics O-4, O-G arid O-8 were grouped into first subgroup O-A, while orthoti.cs o-9, O-2 and O-l0 were grout.~ed into first subgroup O-C. T1 s grouping was possible because it was determ.i.ned tlnat the contoured upper:
surfaces of orthotics O-4 , 0-6 and O-t3 were substantially :i.dent.i.-cal and that the contoured upper surfaces of orthotics U-9, O-2 and O-10 were also substantially i.clent:.ical. Similarly o.rthotie:s 0-1. and U-3 were grouped into subgroul.~s o-t3 and orthot.i.ca 0-p and 0-7 were grouped into subgroups 0-D.
Once subgroups O-A, O-B, O-C and O-U are .identified, the final step in one farm of the method of the invention for making the injection molds comprises the step of constructing for: emir of said plurality of subgroups an injeci_.i.on mold 30. As drown .in Figure 4, the several injection molds constructed in accordance with the methods of the invention each have an internal cavity 30a (Figure A), which, when filled with a moldable plastic, will produce a finished orthotic craving a contoured upper ~r foot engaging surface which is su bstanti.al7y identical to the con-toured upper surfaces of tire functional orthoti.cs that make uh each of the subgroups, wh.iclr upper surfac_:es are forme<3 by pres~~-ing a heated thermoplastic blank against a correct rep:Lica .in the manner previously described herein.
The molds 30 are identified in r.i.gure 5 as It~1-1, Ihi-2, IM-3 and IM-4. Once the x, y, z data for eil:her the low contoured 1 '7 PCTlU597/14234 surface of the corrected replica or the x, y, z data for the upper foot engaging contoured surface of the orthoti.c for each subgroup is known, the x, y, z data for the bottom s1 oe engag.i.ng surface of the orthotic can similarly be determined by methods well known to those skilled in the art such as by calculation or by using the same measurement techniques previously descr.i.bed ror determining the x, y, z data for the contoured surface. Having the x, y, z data for both the upper and lower surfaces of tire orthotic, it is a simple matter to construct the injection mold 30 by techniques well understood by to those skilled in t:he injection molding art.
The methods of the invention for making finished functional orthotics for particular patients using the injection molds thus developed obviously involves many of the same steps involved in t the methods of the invention for making the injection molds.
However, these methods include additional analysis of tire infor-mation derived during mold development and also include the further important step of generating from the information derived sets of comparison data which can be recorded in comparison tables of x, y, z comparison data. Referring particularly to Figures 1 through 5, developing this important comparison data generally comprises the steps of determining for each of the orthotic subgroups 0-A, 0-B, 0-C and 0-D the shape of the con-toured surfaces of the foot impressions and uncorrected replicas which were used to construct the corrected replicas which, in turn, were used to form the orthotics that make up eaclu of rite orthotic subgroups 0-A, 0-B, 0-C, and 0-D. 'then, after determito-ing the shape of the shoe engaging surface of the particular patient for which the orthotic is to be constructed, this shape can be compared with the sets of comparison data developed to determine which subgroups of foot impressions and uncorrected replicas exhibit contoured surfaces that correspond most closely to the shape of the patients foot. 'This done, the orthotics formed from the corrected replicas made from the identified uncorrected replicas can be identified. 'then it is an easy matter to select the correct mold to be used, which, of c:ouo tee, is the mold that will produce the orthotics thus identified.
'fhe derivation of the plurality of sets of comparison data necessary to construct an injection molded orthotic based on data derived from the examining doctor can be accomplished in several ways. For example, the x, y, z data for the foot impressions which make up each subgroup that corresonds to orthotic subgroups 0-A, 0-B, 0-C, and 0-D can first be determined in the manner illustrated in Figure 7 of the drawings. Alternatively, the same x, y, z data can be developed in substantial.l.y the same manner through analysis of the uncorrected replicas which make up each subgroup that corresponds to the orthotic subgroups 0-A, 0-B, 0-C, and 0-D.
Still another approach to the development of the comparison sets of x, y, z data involves the careful analysis of x, y, z data of the corrected replicas which were made from the uncor-rected replicas selected for the study. More particularly, as depicted in Figure 2, in this particular form of the invention, tire lower contoured surface of each of tire multiplicity of cor-rected replicas constructed by the laboratory is analyzed in terms of a multiplicity of x, y coordinates of the general char-acter shown by way of example in Figure 2. It is to be under-stood that in actual practice, many more x, y coordinates than those shown in the drawings were identified on the contoured surface of the corrected replicas. however, for sake of clarity of explanation, only a few such coordinates are shown in tire drawings. For example, in the actual. mapping of the contoured surfaces, of the finished orthotics, the foot impressions, and the corrected replicas, the x or latitude lines are preferab.l.y spaced apart by a distance about 1.0 and 1.4 millimeters and the y, or longitude lines, are preferably spaced apart by a distance WO 98!07342 of between about 0.5 and 0.7 millimeters (see figures 3 amt G).
After the x, y coordinates are defined, the foot impressions 24 , uncorrected repl.i.ca 26, or ttie finished orthot.ic 14 , as t.l~e case may be, is positioned at a spaced-apart location from a reference plane "P" which is typically perpendicular to the bisection of the calcaneus in the manner depicted in Figures 3, 6, and 7. This done, the previously discussed z coordinates are determined. 'the z coordinates represent the distance between t:l~e reference plane "P" and each of the multiplicity of points OIl t.lie -contoured surface which are defined by the intersection of t:l~e coordinate x, y lines (see also Figure 3A). The z coordinates can be identified in a number of ways well. known to those shil.lecl in the art. For example, conventional inspection techniques using surface plates and dial gages can be used. Additionally, h impression units such as described in the previously men tinned prior art patent: to Rolloff. et al , No. 4 , 8 7G, 758 can to used in conjunction with a suitable computer and computer software to produce digital signals representative of tt~e contoured surface under consideration. Similarly, the contoured surfaces can i.~e scanned directly using computer assisted scanning devices suc:l~
as, for example, a laser digitizer of a ci~aracter which is readi-ly commercially available from sources such as Cyberware Compa«y of Pacific Grove, California.
Considering particularly the method of the invention.whicl~
involves the mapping of the contoured surface of the multiplicity of corrected replicas CR-1. through CR-n, particular reference should be made to Figures 2, 3, 3A and 5. As is shown i.n Figure 5, corrected replicas are constructed from the multipli.c.ity of uncorrected replicas UR-1 through UR-n, which, in turn were formed from impressions I-7. through I-n. As was the case in accomplishing the method of_ the invention for making the injec-tion molds, the multiplicity of corrected replicas Clt-1 throng h CR-n are first divided into subgroups wherein each corrected replica of a particular subgroup exhi.bi.ts a substantially .iden ti-cal lower contoured surface. If the orttrot.i.cs of t)re fi~:st orthotic subgroup, as for example those of ortlootic subgroup e-J1 (see Figure 5) , are then associated with the corrected rep:lic.a s from which they were formed, the resulting corrected r:-ep.i.ica subgroup would consist of corrected replicas CR-4, CR-G and CR-L3.
Similarly, the corrected replicas associated with ortlrotic sul>-group 0-B would consist of corrected repJ. icas CIt-1 and C'R-J . l.n a similar fashion, the corrected replica subgroups associated with orthotic subgroups 0-C and 0-I~ earl readily be determined.
Once the corrected replica or second subgroups are thu s identified, it is then possible to identify a plurali.lr.y of third subgroups by identifying for each third subgroup the uncorrected replicas UR-1 through UR-n which were corrected to foam tire k corrected replicas which make up the second subgroup. For exam-ple, the third subgroup of uncorrected repltcas assOC:.iated with the second subgroup of corrected replicas comprising CR-4, CR--G
and CR-8 consist of uncorrected replicas UR-4, UR-6 and UR-E1.
Similarly, the third subgroup of uncorrected replicas associated with corrected replicas CR-1 and CR-3 consist of uncor_rec:ted replicas UR-1 and UR-3.
Using the x, y, z data derived irr tire manner discussed in the preceding paragraphs, the comparison tables of the invention can readily be developed. hs previously discussed, these import-ant comparison tables are used to select a particular mold 30 for a particular patient based upon the particular shape of the lower shoe engaging surface of the patient's foot. In actually formu-lating the comparison tables, the x, y, z data previously devel-oped for each of the multiplicity of corrected replicas or fin-fished orthotics is analyzed and correlated witlz the appropriate uncorrected replica subgroup. For example, as indicated in Figure 5, a first set of x, y, z comparison data might consist of the x, y, z coordinate data for corrected replicas CR-4, CR-G and CF2-8. Similarly, a second set of x, y, z data might consist of the x, y, z coordinate data from corrected replicas CR-7 and C)Z-3 and so on.
For each of the sets of corrected repl.i.ca comparison x, y, z data thus developed, the mold 30 which is associated with brat set is identified. For example, as is evident from Figure 5, i~he mold 30 which is associated with the first set oT corrected replica comparison x, y, z data is designated as IM-1. Similar-ly, the mold 30 which is associated with the second seL of cor-rected replica comparison x, y, z data is designated as IM-2 and so on. It is also apparent from a study of Figure 5 that U.lre corrected replicas CR-4, CR-6 and CR-8 were constructed Irom uncorrected replicas UR-4, UR-6 and UR-8, which, 111 turn, were formed from foot impressions or casts I-4, L-G and I-8 With the foregoing analysis in mind, in carrying ou t one form of the method of the invention, for making a finished ortlro-tic, when the prescription for a particular patient is received from the examining doctor, the correct mold for producing the orthotic for the new patient can be quickly identified i.n the following manner. First, from the prescription data received, which may include an impression of t:he patient's foot, the x, y, z data for contoured lower surface of floe patient's foot is determined in tire manner illustrated in Figure 7. This patieni:'s x, y, z data is then compared with tire groups of x, y, ~ data found in the comparison table to identify the particular group within which the patient x, y, z data falls. once this is done, the injection mold which corresponds to the selected comparison group of x, y, z data is identified, and, using the selected injection mold, the finished ortlrotic for the patient is then injection molded.
It is to be understood that, as previously discussed, the patient x, y, z data can be determined .in a number of ways. For example, as indicated in Figure 7, physical measurements of tire impression received from the examining doctor can be used t:o identify the contour of the shoe engaging portion of the le~-tient's foot. In accordance with ttri.s mettrod, x, y mooW inr:~l-es are first identified on the surface of the cavity 24a of tire impression (Figure 7). This done, the z coordinates, wloich are the distances between a reference plane "P" spaced apart fL~om cavity 24a and the points defined by the intersection of the x-y lines, are determined. These z coordinates can be determined in a number of ways well known in the art such as, for example, through use of a depth gage, by electronic scanning or by using mechanical impression units of the general type described in U.S.
Patent 4,876,758. After this x, y, z data is obtained and recorded, it can be correlated in the manner shown in Figure 5 with the uncorrected and corrected replicas which evolve from the impressions and, finally with the first subgroups of orthotica produced from the corrected replicas. 'fine multiplicity of sets of comparison data which make up the comparison tables can then be derived in the manner previously discussed and then used to select the correct injection mold for molding a finished orthotic for a given patient from which the patient x, y, z data has been determined.
Alternatively, the equipment and techniques described i.n U.S. Patent No. 4,876,758 issued to Itolloff et al can be used to measure the mold cavity. Further, mechanical or electronic scanning of the uncorrected replicas made from the foot impres-sions can be accomplished, or the patient's feet themselves can be analyzed by techniques well known to those skilled .in tare art to determine the foot contour. In any event, once the patient x, y, z data is derived by any one of the aLorementioned methods, it can quickly be compared with the comparison data tables and the proper mold 30 selected from tle nnalt.i.p7_icity of some five hundred and forty or more molds which nave been constructed, identified and cataloged in accorc3ane:e wit.t the previous.ty de-scribed methods of the invention.
Having now described the invention In detail in accordance with the requirements of the patent statutes, those slci.l7ed. .in this art will have no difficulty in malting changes and moc3ifi.<:a-tions in the individual parts or their relative assembly in order to meet specific requirements or conditions. Such c:hanc~es and modifications may be made without departing from tine scope and spirit of the invention, as set forth in the following claims.

Claims (24)

I CLAIM

1. A method of making injection molds for use in molding orthotics comprising the steps of:
(a) selecting a multiplicity of corrected replicas of the human foot, each having been made from an uncorrected replica of the human foot having an uncorrected contoured lower surface, each said corrected replica exhibiting a corrected contoured lower surface from which an orthotic can be formed by heating and pressing a thermoplastic blank thereagainst;
(b) examining each said corrected replica of said se-lected multiplicity of corrected replicas to identify those having substantially identical contoured lower surfaces;
(c) identifying a plurality of corrected replica subgroups by grouping said multiplicity of corrected repli-cas which were examined into subgroups in which said cor-rected replicas which make up each said subgroup exhibit substantially identical contoured lower surfaces; and (d) constructing for each of said plurality of sub-groups an injection mold having an internal cavity which, when filled with a moldable plastic, will produce a finished orthotic having a contoured upper surface substantially identical to the contoured lower surfaces of said corrected replicas which make up each said subgroup.

2. A method as defined in Claim 1, including the further step of generating x, y, z data for a selected one of the cor-rected replicas which make up each said corrected replica sub-group to form a plurality of sets of comparison x, y, z data, comprising the steps of:
(a) identifying on the contoured lower surface of each said selected corrected replica a multiplicity of x, y coordinates;
(b) for each said selected corrected replica, defining a plane spanning said contoured lower surface thereof and spaced apart therefrom; and (c) for each said selected corrected replica, deter-mining and recording for each x, y coordinate identified thereon the distance between the coordinate and said plane, whereby for each said injection mold constructed, a set of x, y, z data can be assigned thereto, said set of x, y, z data defining the contour of the lower surface of the cor-rected replicas which make up the corrected replica subgroup for which the mold was constructed.

3. A method as defined in Claim 2 in which:
(a) said x coordinates are identified on the said lower surface of each said selected corrected replica in a manner such that each said x coordinate is spaced from the adjacent x coordinate by a distance of between about 1.0 and about 1.4 millimeters; and (b) said y coordinates are identified on said lower surface of each said selected corrected replica in a manner such that each said y coordinate is spaced from the adjacent y coordinate by a distance of between about 0.5 millimeters and about 0.9 millimeters.

4. A method as defined in Claim 2 comprising the further step of identifying said uncorrected replicas from which each said group of corrected replicas was constructed to form a plu-rality of uncorrected replica groups and for each said plurality of said uncorrected replica groups selecting an uncorrected replica and then for each said selected uncorrected replica:
(a) identifying on the contoured lower surface thereof a multiplicity of x, y coordinates;
(b) for each said selected uncorrected replica, defin-ing a plane spanning said contoured lower surface thereof and spaced apart therefrom; and (c) for each said selected uncorrected replica, deter-mining and recording for each x, y coordinate identified thereon the distance between the coordinate and said plane.

5. A method as defined in Claim 4 in which said uncorrect-ed replicas were made from impressions of the human foot and in which the method comprises the further step of identifying the impressions of the human foot from which each said group of corrected replicas was constructed to form a plurality of foot impression groups and for each said plurality of foot impression groups selecting foot impression and then for each said elected foot impression:
(a) identifying thereon a multiplicity of x, y coordi-nates;
(b) for each said selected foot impression defining a base plane spanning said foot impression and being spaced apart therefrom; and (c) for each said selected foot impression, determin-ing and recording for each x, y coordinate identified there-on the distance between the coordinate and the base plane.

6. A method of making injection molds for use in molding orthotics comprising the steps of:
(a) selecting a multiplicity of orthotics made from a multiplicity of corrected replicas, said corrected replicas having been made from uncorrected replicas having a lower contoured surface substantially replicating the shoe-engag-ing surface of the human foot;
(b) examining each said orthotic of said multiplicity of selected orthotics to identify those having substantial-ly identical contoured upper surfaces;
(c) identifying a plurality of orthotic subgroups by dividing said orthotics examined into subgroups in which said finished orthotics which make up each said subgroup exhibit substantially identical contoured upper surfaces;
and (d) constructing for each of said plurality of subgroups an injection mold having an internal cavity which, when filled with a moldable plastic, will produce a finished orthotic having a contoured upper surface substantially identical to the contoured upper surface of said orthotics which make up each said subgroup.

7. A method as defined in Claim 6, including the further step of generating x, y, z data, for a selected one of said orth-otics which make up each said orthotic subgroup to form a plural-ity of sets of comparison x, y, z data, comprising the steps of:
(a) identifying on the contoured upper surface of each said selected functional orthotic a multiplicity of x, y coordinates;
(b) for each said selected functional orthotic defin-ing a plane spanning said contoured upper surface thereof and spaced apart therefrom; and (c) for each said selected functional orthotic deter-mining and recording for each x, y coordinate identified thereon the distance between the coordinate and said plane, whereby for each said injection mold made, a set of x, y, z data can be assigned thereto, said set of x, y, z data defining the contour of the upper surface of the functional orthotics which make up the functional orthotic subgroup for which the mold was constructed.

8. A method as defined in Claim 6 comprising the further step of identifying said corrected replicas from which each said group of orthotics was constructed to form a plurality of cor-rected replica subgroups and for each said plurality of said cor-rected replica subgroups selecting a corrected replica and then for each said selected corrected replica:
(a) identifying on the contoured lower surface thereof a multiplicity of x, y coordinates;

(b) for each said selected corrected replica, defining a plane spanning said contoured lower surface thereof and spaced apart therefrom; and (c) for each said selected corrected replica, deter-mining and recording for each x, y coordinate identified thereon the distance between the coordinate and said plane.

9. A method as defined in Claim 8 comprising the further step of identifying the uncorrected replicas from which each said group of corrected replicas was constructed to form a plurality of uncorrected replica subgroups and for each said plurality of said uncorrected replica groups selecting an uncorrected replica and then for each said selected uncorrected replica:
(a) identifying on the contoured lower surface thereof a multiplicity of x, y coordinates;
(b) for each said selected uncorrected replica, defin-ing a plane spanning said contoured lower surface thereof and spaced apart therefrom; and (c) for each said selected uncorrected replica, deter-mining and recording for each x, y coordinate identified thereon the distance between the coordinate and said plane.

10. A method as defined in Claim 9 in which said uncorrect-ed replicas were made from impressions of the human foot and com-prising the further step of identifying the impressions of the human foot from which each said subgroup of corrected replicas was constructed to form a plurality of foot impression groups and for each said plurality of foot impression subgroups selecting foot impression and then for each said selected foot impression:
(a) identifying thereon a multiplicity of x, y coordi-nates;
(b) for each said selected foot impression defining a base plane spanning said foot impression and being spaced apart therefrom; and (c) for each said selected foot impression, determin-ing and recording for each x, y coordinate identified there on the distance between the coordinate and the base plane.

11. A method of making injection molds for use in molding orthotics comprising the steps of:
(a) selecting a multiplicity of uncorrected replicas of the human foot, each having an uncorrected contoured lower surface and each of which is later to be corrected to form a corrected replica having a corrected contoured surface from which an orthotic can be made;
(b) identifying a multiplicity of corrected replicas made from said multiplicity of uncorrected replicas;
(c) identifying the multiplicity of orthotics made from said multiplicity of corrected replicas;
(d) examining each said orthotic of said multiplicity of orthotics to identify those having substantially identi-cal contoured upper surfaces;
(e) identifying a plurality of first subgroups of orthotics by dividing said multiplicity of orthotics exam-ined into subgroups in which said finished orthotics which make up each said subgroup exhibit substantially identical contoured upper surfaces; and (f) constructing for each of said plurality of first subgroups an injection mold having an internal cavity which, when filled with a moldable plastic, will produce a finished orthotic having a contoured upper surface substantially identical to the contoured upper surface of said orthotics which make up each said subgroup.

12. A method as defined in Claim 11, including the further step of generating a comparison set of x, y, z data, comprising the steps of:
(a) identifying a plurality of second subgroups by dividing said multiplicity of corrected replicas into second subgroups in which said corrected replicas which make up each said second subgroup exhibit substantially identical lower contoured surfaces;
(b) identifying a plurality of third subgroups by identifying for each said second subgroup the uncorrected replicas which were corrected to form said corrected repli-cas which make up said second subgroup;
(c) for each said uncorrected replica of each of said plurality of third subgroups:
(i) identifying on the contoured lower surface thereof a multiplicity of x, y coordinates;
(ii) defining a plane spanning said contoured lower surface and spaced apart therefrom; and (iii) determining and recording for each x, y coordinate identified on each said uncorrected replica of said third subgroups the distance between the coordinate and said plane.

13. A method as defined in Claim 12 in which said uncor-rected replicas were made from a multiplicity of impressions of the human foot and including the further step of identifying the impressions of the human foot from which each said group of uncorrected replicas was constructed to form a plurality of foot impression subgroups.

14. A method as defined in Claim 13, including the further step of selecting from each said foot impression subgroup an individual foot impression and then for each said selected indi-vidual foot impression:
(a) identifying thereon a multiplicity of x, y coordi-nates;
(b) for each said selected individual foot impression, defining a base plane spanning said contoured surface and spaced apart therefrom; and (c) for each said selected individual foot impression determining and recording for each y, y coordinate identi-fied on each said selected individual foot impression the distance between the coordinate and the base plane.

15. A method of making injection molds for use in molding functional orthotics comprising the steps of:
(a) selecting a multiplicity of impressions of the human foot, each having a cavity having a contoured surface which cavity is later to be used to form an uncorrected replica which, in turn, is later to be corrected to form a corrected replica having a corrected contoured surface from which an orthotic can be formed;
(b) identifying the functional orthotics made from said corrected replicas;
(c) examining said functional orthotics to identity those having substantially identical contoured upper surfac-es;
(d) identifying a plurality of first subgroups by dividing said functional orthotics examined into subgroups in which said finished orthotics which make up each said subgroup exhibit substantially identical contoured upper surfaces; and (e) constructing for each of said plurality of sub-groups an injection mold having an internal cavity which, when filled with a moldable plastic, will produce a finished functional orthotic having a contoured upper surface sub-stantially identical to the contoured upper surfaces of said functional orthotics which make up each said subgroup.

16. A method as defined in Claim 15 including the further step of generating a set of x, y, z comparison data, comprising the steps of:
(a) identifying a plurality of second subgroups by dividing the corrected replicas into second subgroups in which said corrected replicas which make up each said second subgroup exhibit substantially identical lower contoured surfaces;
(b) identifying a plurality of third subgroups by identifying for each said second subgroup the uncorrected replicas which were corrected to form said corrected repli-cas which make up said second subgroup;
(c) identifying a plurality of subgroups of foot impressions by identifying for each subgroup the foot im-pressions used to form said uncorrected replicas which make up said third subgroup;
(d) for each said foot impression of each of said plurality of foot impression subgroups:
(i) identifying on the contoured surface of the cavity thereof a multiplicity of x, y coordinates;
(ii) defining a plane spanning said contoured surface and spaced apart therefrom; and (iii) determining and recording for each x, y coordinate identified on said contoured surface the distance between the coordinate and said plane.

17. A method of making an injection molded orthotic for use by a patient having a foot exhibiting a contoured shoe-engaging surface comprising the steps of:
(a) selecting a multiplicity of orthotics made from a multiplicity of corrected replicas, said corrected replicas having been made from uncorrected replicas having a lower contoured surface substantially replicating the shoe-engag-ing surface of the human foot;
(b) examining each said orthotic of said multiplicity of selected orthotics to identify those having substantial-ly identical contoured upper surfaces;
(c) identifying a plurality of orthotic subgroups by dividing said orthotics examined into subgroups in which said finished orthotics which make up each said subgroup exhibit substantially identical contoured upper surfaces;

(d) constructing for each of said plurality of sub-groups an injection mold having an internal cavity which, when filled with a moldable plastic, will produce a finished orthotic having a contoured upper surface substantially identical to the contoured upper surface of said orthotics which make up each said subgroup;
(e) formulating a plurality of sets of comparison data by determining for each of said orthotic subgroups the shape of the contour of the contoured surfaces of the foot impres-sions and uncorrected replicas which were used to constructs the corrected replicas which, in turn, were used to form the orthotics which make up each of said orthotic subgroups;
(f) determining the shape of the contour of the shoe-engaging surface of the patient's foot;
(g) comparing said shape of the contour of the shoe-engaging surface of the patient's foot thus determined with said sets of comparison data to identify the particular set of comparison data that defines the shape of the contoured surfaces of said foot impression and uncorrected replicas that most nearly correspond to said shape of the contour of the shoe-engaging surface of the patient's foot;
(h) identifying said orthotic subgroup which consists of orthotics formed from the corrected replicas made from the uncorrected replicas which exhibit a contoured surface shape that corresponds to the shapes defined in the identi-fied set of comparison data;
(i) selecting the injection mold constructed for said identified orthotic subgroup; and (j) molding from said selected mold a finished ortho-tic for the patient.

18. A method as defined in Claim 17 in which the shape of the contour of the contoured surfaces of said foot impressions was determined for each said foot impression by a method compris-ing the steps of:
(a) identifying on said contoured surface a multiplic-ity of x, y coordinates;
(b) defining a base plane spanning said foot impres-sion and being spaced apart therefrom; and (c) determining and recording for each x, y coordinate identified thereon the distance between the coordinate and the base plane.

19. A method as defined in Claim 17 in which the shape of the contoured surfaces of said uncorrected replicas was determined for each said uncorrected replica by a method compris-ing the steps of:
(a) identifying on said contoured surface a multiplic-ity of x, y coordinates;
(b) defining a base plane spanning said contoured surface of. said uncorrected replica and being spaced apart therefrom; and (c) determining and recording for each x, y coordinate identified thereon the distance between the coordinate and the base plane.

20. A method of making an injection molded orthotic for use by a patient having a foot exhibiting a contoured shoe-engaging surface comprising the steps of:
(a) selecting a multiplicity of corrected replicas of the human foot, each having been made from an uncorrected replica of a human foot having an uncorrected contoured lower surface, each said corrected replica exhibiting a corrected con toured lower surface from which an orthotic could be formed by heating and pressing a thermoplastic blank thereagainst;
(b) examining each said corrected replica of said selected multiplicity of corrected replicas to identify those having substantially identical contoured lower surfac-es;
(c) identifying a plurality of corrected replica subgroups by grouping said multiplicity of corrected repli-cas which were examined into subgroups in which said corrected replicas which make up each said subgroup exhibit substantially identical contoured lower surfaces;
(d) constructing for each of said plurality of sub-groups an injection mold having an internal cavity which, when filled with a moldable plastic, will produce a finished orthotic having a contoured upper surface substantially identical to the contoured lower surfaces of said corrected replicas which make up each said subgroup;
(e) formulating a plurality of sets of comparison data by determining for each of said corrected replica subgroups the shape of the contour of the contoured surfaces of the foot impressions and uncorrected replicas which were used to construct the corrected replicas which make up each of said corrected replica subgroups;
(f) determining the contour of the shoe-engaging surface of the patient's foot;
(g) comparing said contour of the shoe-engaging sur-face of the patient's foot thus determined with said sets of comparison data to identify the particular set of comparison data that defines the shape of the contoured surfaces of said foot impression and uncorrected replicas that most nearly corresponds to said shape of the contour of the shoe-engaging surface of the patient's foot;
(h) identifying the corrected replica subgroup which consists of corrected replicas constructed using the uncor-rected replicas which exhibit a contoured surface shape that corresponds to the shapes defined in the identified set of comparison data;

(i) selecting said injection mold constructed for said identified corrected replica subgroup; and (j) molding from said selected mold a finished ortho-tic for the patient.

21. A method as defined in Claim 20 in which the shape of the contour of the contoured surfaces of said foot impressions was determined for each said foot impression by a method compris-ing the steps of:
(a) identifying on said contoured surface a multiplic-ity of x, y coordinates;
(b) defining a base plane spanning said foot impres-sion and being spaced apart therefrom; and (c) determining and recording for each x, y coordinate identified thereon the distance between the coordinate and the base plane.

22. A method as defined in Claim 20 in which the shape of the contoured surfaces of said uncorrected replicas was deter-mined for each said uncorrected replica by a method comprising the steps of:
(a) identifying on said contoured surface a multiplic-ity of x, y coordinates;
(b) defining a base plane spanning said contoured surface of said uncorrected replica and being spaced apart therefrom; and (c) determining and recording for each x, y coordinate identified thereon the distance between the coordinate and the base plane.

23. A method of making an injection molded orthotic for use by a patient having a foot exhibiting a contoured lower surface comprising the steps of:
(a) selecting a multiplicity of replicas of the human foot, each of which is later to be used to form by conventional techniques a corrected replica having a corrected contoured surface from which an orthotic can be formed;
(b) selecting a multiplicity of corrected replicas from those made from said multiplicity of selected replicas of the human foot;
(c) selecting a multiplicity of functional orthotics from those made from said multiplicity of selected corrected replicas;
(d) identifying a plurality of first subgroups by examining each said functional orthotic of said multiplicity of functional orthotics selected to identify those functional orthotics having a substantially identical con-toured upper surface;
(e) producing a multiplicity of injection molds by constructing for each of said plurality of first subgroups an injection mold having an internal cavity which, when filled with a moldable plastic, will produce a finished orthotic having a contoured upper surface substantially identical to the contoured upper surface of said functional orthotics which make up each said subgroup;
(f) identifying a plurality of second subgroups by dividing said multiplicity of corrected replicas selected into second subgroups in which said corrected replicas which make up such said second subgroup exhibit substantially identical lower contoured surfaces;
(g) identifying a plurality of third subgroups by identifying for each said second subgroup the uncorrected replicas which were corrected to form said corrected repli-cas which make up said second subgroup;
(h) producing a first set of comparison data by ana-lyzing said plurality of said third subgroups of uncorrected replicas and for each said uncorrected replica of each of said plurality of said third subgroups:
(i) identifying on the contoured lower surface thereof a multiplicity of x, y coordinates;
(ii) defining a reference plane spanning said contoured lower surface and spaced apart therefrom;
(iii) determining and recording for each x, y coordinate identified on each said uncorrected replica of said third subgroups the distance between the coor-dinate and said reference plane;
(i) determining and recording x, y, z data for the contoured lower surface of the patient's foot by determin-ing, for each of a multiplicity of x, y coordinates defined on said contoured lower surface thereof, the height of the coordinate above a reference plane to develop patient x, y, z data;
(j) comparing said patient x, y, z data with said comparison groups of x, y, z data to identify the comparison group of x, y, z data within which said patient x, y, z data falls;
(k) selecting said injection mold which corresponds to said selected comparison group of x, y, z data; and (l) molding from said selected injection mold the finished orthotic.

24. A method as defined in Claim 23 in which the multiplicity of replicas of the human foot selected comprise impressions of the human foot made by the examining doctor.