Sample Provisional Patent Application

8/2/2019 Sample Provisional Patent Application

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Doc Code: TR.PROVDocument Description: Provisional Cover Sheet (SB16)

PTO/SSApproved for use through 06/30/2010 OMS

U.S. Patent and Trademark Office: U.S. DEPARTMENT OF CUnder the Paperwork Reduction Act of 1995, no persons are required to respond to a collection of information unless it displays a valid OMS con

Provisional Application for Patent Cover SheetThis is a request for filing a PROVISIONAL APPLICATION FOR PATENT under 37 CFR 1.53(c)

Inventor(s)Inventor 1 I Remove IGiven Name Middle Name Family Name City State Country iradley Walter Thomasville GA USAll Inventors Must Be Listed - Additional Inventor Information blocks may be I Iddgenerated within this form by selecting the Add button.Title of Invention Femoral ProsthesisAttorney Docket Number (if applicable) 0018.000002US

Correspondence AddressDirect all correspondence to (select one):

@ The address corresponding to Customer Number o Firm or Individual NameCustomer Number 33422

The invention was made by an agency of the United States Government or under a contract with an agency of the UStates Government.@ No.0Yes, the name of the U.S. Government agency and the Government contract number are:


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Doc Code: TR.PROVDocument Description: Provisional Cover Sheet (SB16)

PTO/SSApproved for use through 06/30/2010 OMS

U.S. Patent and Trademark Office: U.S. DEPARTMENT OF CUnder the Paperwork Reduction Act of 1995, no persons are required to respond to a collection of information unless it displays a valid OMS con

Entity StatusApplicant claims small entity status under 37 CFR 1.27~ Yes, applicant qualifies for small entity status under 37 CFR 1.270NoWarningPetitioner/applicant is cautioned to avoid submitting personal information in documents filed in a patent application thcontribute to identity theft. Personal information such as social security numbers, bank account numbers, or credit canumbers (other than a check or credit card authorization form PTO-2038 submitted for payment purposes) is never rby the USPTO to support a petition or an application. If this type of personal information is included in documents suto the USPTO, petitioners/applicants should consider redacting such personal information from the documents beforesubmitting them to USPTO. Petitioner/applicant is advised that the record of a patent application is available to the pafter publication of the application (unless a non-publication request in compliance with 37 CFR 1.213(a) is made in tapplication) or issuance of a patent. Furthermore, the record from an abandoned application may also be available tpublic if the application is referenced in a published application or an issued patent (see 37 CFR1.14). Checks and ccard authorization forms PTO-2038 submitted for payment purposes are not retained in the application file and therefonot publicly available.

SignaturePlease see 37 CFR 1.4(d) for the form of the signature.

Signature !Thedford I. Hitaffer/ Date (YYYY-MM-DD) 2009-09-01

First Name Thedford Last Name Hitaffer Registration Number 38490(If appropriate)This collection of information is required by 37 CFR 1.51. The information is required to obtain or retain a benefit by the public whifile (and by the USPTO to process) an application. Confidentiality is governed by 35 U.S.C. 122 and 37 CFR 1.11 and 1.14. This cis estimated to take 8 hours to complete, including gathering, preparing, and submitting the completed application form to the USPTime will vary depending upon the individual case. Any comments on the amount of time you require to complete this form and/orsuggestions for reducing this burden, should be sent to the Chief Information Officer, U.S. Patent and Trademark Office, U.S. Depof Commerce, P.O. Box 1450, Alexandria, VA 22313-1450. DO NOT SEND FEES OR COMPLETED FORMS TO THIS ADDRESSform can only be used when in conjunction with EFS-Web. If this form is mailed to the USPTO, it may cause delays in hathe provisional application.


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he Privacy Act of 1974 (Pol. 93-579) requires that you be given certain information in connection with your submisse attached form related to a patent application or paten. Accordingly, pursuant to the requirements of the Act, pleasvised that: (1) the general authority for the collection of this information is 35 U.S.C. 2(b)(2); (2) furnishing of theformation solicited is voluntary; and (3) the principal purpose for which the information is used by the U.S. Patent andrademark Office is to process and/or examine your submission related to a patent application or patent. If you do nornish the requested information, the U.S. Patent and Trademark Office may not be able to process and/or examine ybmission, which may result in termination of proceedings or abandonment of the application or expiration of the patehe information provided by you in this form will be subject to the following routine uses:

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9. A record from this system of records may be disclosed, as a routine use, to a Federal, State, or local lawenforcement agency, if the USPTO becomes aware of a violation or potential violation of law or regulation.


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TITLEFEMORAL PROSTHESIS

BACKGROUND OF THE INVENTION[0001] This invention relates in general to prosthesis, parts thereof, or aidsand accessories therefor. More particularly, the invention relates to a femoralprosthesis.[0002] Total hip replacement has become the standard of care treatment toaddress a variety of degenerative and traumatic processes of the hip joint.[0003] Much has been learned and developed over the last severaldecades of practice and research. Previously, much bone resection andmarrow excavation has been necessary to accomplish implant longevity andstability. As time has proceeded, more tissue and bone sparing surgicaltechniques have been developing. These techniques in general are tofacilitate less bone loss in future revision surgeries and to decrease soft tissueinjury. Bone is lost from both stress shielding and osteolysis. The problem ofbone loss from osteolysis has largely been solved by improvement in the wearproperties of modern bearing surfaces. Stress shielding bone loss has beenimproved by loading the proximal femur with tapered stem geometries orsurface replacement devices. Surface replacement devices have a multitudeof limitations. First, the procedure can require relatively large exposure andtherefore can hardly be called tissue sparing, although bone sparing. Second,the compromised bone of the femoral head is often a poor foundation and cancause early or late failure from collapse. Lastly, femoral neck fracture canoccur.[0004] Previous devices have relied on entry into the femoral canal either ina straight entry or in a curvilinear fashion. Some have considered theproximal femoral metaphyseal bone incapable of sustaining load.[0005] Modern minimally invasive surgery, in particular, the "anterior supinemuscle sparing" approach, is made more difficult by the straight diaphyseal

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engaging stems. Shorter curved tapered stems have been made with someimprovement in the ease of implantation. However, femoral insertion can stillbe very challenging.

SUMMARY OF THE INVENTION[0006] This invention relates to a femoral prosthesis comprising a stemcomprising a shoulder at a proximal end thereof and a trunk at a distal endthereof. The shoulder may be structured and dimensioned for a tight press fitinto the neck of a femur. The trunk may comprise a wedge formed by atapered portion extending from the shoulder in the direction of the distal end ofthe stem and one or more longitudinally extending fins. The wedge and theone or more longitudinally extending fins may function to provide multi-planarstability for the stem and the surface area apart from the shoulder for fixationof the stem with the femur.[0007] Various advantages of this prosthesis will become apparent to thoseskilled in the art from the following detailed description, when read in light ofthe accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS[0008] Fig. 1 is a partial sectional view in elevation of the proximal end of afemur and a femoral prosthesis.[0009] Fig. 2A is a diagrammatic partial plan view of the femur andprosthesis shown in Fig. 1, showing hoop stress at the femoral neck.[0010] Figs. 2B-2C are diagrammatic partial plan views of other femurs andthe prosthesis, showing hoop stress at the femoral necks.[0011] Fig. 3 is an enlarged perspective view of a femoral prosthesis.[0012] Fig. 4 is an end view of the femoral prosthesis shown in Fig. 3.[0013] Fig. 5 is an enlarged perspective view of another femoral prosthesis.[0014] Fig. 6 is an end view of the femoral prosthesis shown in Fig. 5.

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[0015] Fig. 7 is an exploded sectional view of the prosthesis shown in Fig.5.[0016] Figs. 8A-8B are sectional views of prosthesis.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT[0017] Referring now to the drawings, there is illustrated in the drawings, afemoral prosthesis 10 generally comprising a stem 12 supporting a neck 14,which may be without modularity or optionally a modular neck. The neck 14may have a Morse taper, as is known in the art, to accommodate asubstantially spherical joint ball, bearing or prosthetic head 16 at the proximalend of the neck 14. The design may accommodate a wide variety of sphericalball sizes and/or materials (e.g., metal or ceramic).[0018] Close below this prosthetic head 16, the stem 12 may be providedwith a shoulder 18 at its proximal end. This shoulder 18 may be conical ortapered at an angle. The angle may be in a range between about 2 degreesand about 10 degrees, or some other suitable angle that creates a Morsetapered retentive effect in the neck of the femur 26, as will become apparentin the description that follows. The shoulder 18 may be structured anddimensioned for a tight press fit into the femoral neck 30, and thus increasehoop stress at the neck 30 (i.e., depicted by the radially directed arrows inFigs. 2A-2C). The shoulder 18 may have a fixation surface, which may berough and porous to promote impaction and/or press-fit of the shoulder 18 intothe femoral neck 30 and subsequent fixation (e.g., ingrowth or ongrowth) ofthe cortical bone of the femoral neck 30 into shoulder 18.[0019] Immediately below the shoulder 18, the stem 12 merges into a trunk20. The trunk 20 may have a generally sharply tapered portion extendingfrom the shoulder 18 in the direction of the distal end of the trunk 20 to form awedge 21, as shown for example in Fig. 8A, or a knife edge, as shown forexample in Fig. 8B. The trunk 20 may be provided with longitudinallyextending webs or fins 22. The fins 22 may function to provide a large surface

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area for initial multi-planar stability and an increased surface area for longterm fixation (e.g., bony ingrowth or ongrowth), as will become apparent in thedescription that follows. Although other fin configurations may be suitable, theillustrated stem 12 has one or more superior (i.e., higher) fins and one or moreinferior (i.e., lower) fins. One or more central fins may also be provided. Thefins 22 may provide increased surface area contact or maximize surface areacontact in the metaphyseal bone for fixation (e.g., bony ingrowth or ongrowth)and initial or preliminary cancellous bone press fit stability or fixation. Thestem 12 (e.g., the shoulder 18 and trunk 20) may be porous to provide longterm stability from bony ingrowth or ongrowth. The wedge 21 of the trunk 21may facilitate dilation and impaction of the cancellous bone. This may preventthe need for removal of substantial cancellous bone.[0020] The shoulder 18 may be shaped and dimensioned to approximatethe shape and dimension of the femoral neck to further maximize surface areacontact. The stem 12 may have an overall elongated lateral cross-section, ora cross-section that otherwise fits the anatomy of the femoral neck to reducerotation, and may have a substantially straight long axis so the stem 12 doesnot curve into the diaphysis of the femur. To this end, the superior and inferiorfins 22 may be curved to approximate the geometry of the superior andinferior part of the neck 18 (see Figs. 2A-2C). These curves may besubstantially the same geometry as the corresponding curved portions of thefemoral neck. The stem 12 and neck 14 may be metal. The metal used maybe titanium, chrome-cobalt or stainless steel based, or any metal commonlyused in hip prosthesis construction.[0021] The stem 12 may be porous, and may have a porous coating, layeror surface 24. An example of such a coating is titanium plasma spray, whichpromotes bony ingrowth or ongrowth into prosthetic implants. The coatingmay further be in the form of sintered beads, a hydroxyapatite (HA), oranother suitable form, depending on the type of metal used for the prosthesis

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10, as the prosthesis may be entirely formed from the same material (e.g.,titanium, all chrome cobalt, or other suitable material).[0022] It should be appreciated that the stem 12 of the prosthesis 10 maybe available in various sizes depending on anatomical requirements, and asmentioned above, the prosthetic head 16 may be a modular head, or a non-modular head.[0023] Fixation of the prosthesis 10 to the femur can be achieved byinserting the stem 12 into the open neck of a femur, along the anatomic orlongitudinal axis of the femoral neck, as set forth for example in thedescription that follows. Because the stem 12 is straight and oriented alongthe longitudinal axis of the femoral neck 30, rotational alignment can beallowed to shift based on anatomical variations.[0024] In Fig. 1, there is illustrated femur 26 with an osteotomy or cutextending along a plane 28 perpendicular to the longitudinal axis of thefemoral neck 30.[0025] The stem 12 may be fitted into the femoral neck 30 at an angle ~ tothe longitudinal axis 36 of the femur 26 so that the long axis 38 of the stem 12corresponds approximately to the axis of a healthy femoral neck. That is tosay, the stem 12 may be inserted from the proximal direction into the femoralneck 30 so that the long axis 38 of the stem 12 coincides with the axis madein the preoperative femur by an imaginary line connecting the center of thefemoral neck 30 with the center of the femoral head, or at an angle ~approximately corresponding to the normal anatomy of the patient (usuallybetween 120 and 150 degrees), and preferably the cervico-diaphyseal angle(i.e., the angle between the long axis of the femoral neck and the longitudinalaxis 36 of the femur 26), which varies per individual.[0026] The stem 12 may contact the inner wall 40 of the femoral neck 30 bytightly fitting the stem 12 into the femoral neck 30. The tapered collar 18 atthe proximal end of the stem 12, when inserted in the neck 30 of the femur 26,may form a tight press fit within the neck 30 of the femur 26 to provide

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optimum contact and load transfer between the engagement surfaces of thecollar 18 of the stem 12 and the neck 30 of the femur 26. The tight press fitconfiguration may increase the hoop stress at the neck 30 of the femur 26 (asrepresented by the arrows in Figs. 2A-2C), and thus increase the retentiveeffect of the shoulder 18 in the neck 30 of the femur 26. It should beappreciated that the shape of the stem 12 may differ from that of the femoralneck 30 (e.g., due to anatomic variations). The stem 12 may simply wedgeinto the "hoop" formed by the femoral neck 30 and thus increase hoop stress.It should be appreciated that the shape of the stem 12 could be custom madeto each patient, for example, using MRI or CT templating, as mentionedbelow.[0027] The surfaces of the stem 12 disposed for engaging the interior of thefemur 26 are broadly fixation surfaces. The wedge 21 and the longitudinallyextending fins 22 of the trunk 20 of the stem 12 may penetrate the spongiosa41 inside the femur 26 to secure the stem 12 in the femur 26. The overallelongated shape of the lateral cross-section of the stem 12 may hold the stem12 securely against movement about the long axis 38 of the stem 12 afterimplantation. The wedge 21 and the fins 22 may provide increased surfacecontact for initial and late fixtation. Fixation (e.g., bony ingrowth or ongrowth)may be encouraged on all surfaces of the stem 10, including shoulder 18, thewedge 21, and the fins 22. It should be appreciated that the shape and highlyporous surface of the stem 12, including the shoulder 18, the wedge 21, andthe fins 22, may, in addition to resisting rotational movement, resist movementin all planes.[0028] The distal end of the stem 12 may be cut on an angle to the longaxis 38 of the stem 12, so that the distal end is substantially pointed.Moreover, the distal end of the stem 12, when inserted in the femur 26, maybe generally aligned with or parallel to the inner surface of the lateral wall 42of the femur 26 or along the longitudinal axis 38 of the femur 26. The distalend of the stem 12 remains within the femur 26, so as to not extend beyond

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the femur 26. It should be appreciated that the distal end of the stem 12 maybe curved. For example, a curved surface may be superimposed on theangled distal end of the stem 12, or otherwise curved, such as curvedtransversely in relation to the long axis 38 of the stem, to provide clearancebetween the distal end of the stem 12 and the inner surface of the lateral wall42 of the femur 26, as clearly shown in Fig. 1.[0029] It should be appreciated that the prosthesis 10 may be installed andused without requiring any other fastener on the femur 26. The prosthesisdoes not require screws or other fasteners to be placed in the femur 26, and itdoes not require any sort of support plate on the lateral wall of the femur 26.[0030] Notwithstanding, one or more optional fasteners 43, such as pins,spikes or screws, may attach the stem 12 to the lateral wall 42 of the femur26, or just contact the inner surface of the lateral wall 42 (without penetration),which may add initial stability to the stem 12. The fasteners 43 may addstability to the construct by giving further stability to the stem 12 of theprosthesis 10.[0031] A fastener 43, for example, may pass through a tubular channel 46in the center of the stem 12 of the prosthesis 10. The head of the centerfastener 43 may be located in the base of a female Morse taper 45 in the stem12, if a modular neck is used. Additionally, fasteners 43 may also passthrough tubular channels 46 in the stem 12 of the prosthesis 10, flanking thecenter of the stem 12, adjacent the superior and inferior fins. The flankingfasteners can be used to the exclusion of the center fasteners and vice versa.For example, if a non-modular neck is used, flanking fasteners may be used tothe exclusion of the center fasteners. It should be appreciated that thefasteners 43 preferably do not penetrate the lateral wall 42 of the femur 10 tobreach the lateral wall 42. The fasteners 43 may function to further reduce thelikelihood of movement of the prosthesis 10 in all planes within the femoralneck 30. The use of fasteners 43 may be dependent on the bone quality of thepatient.

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[0032] One or more anterior/posterior fasteners 44 (e.g., screws) may beprovided. These fasteners 44 pass through anterior/posterior cylindricalchannels in the stem 12, and past though and/or threadably engage theanterior/posterior cortex of the femur 26. The fasteners 44 may allow forsome load transfer to the anterior and posterior cortex of the femur 26 throughthe fasteners 44. It should be appreciated that the prosthesis 10 can be usedwithout cement.[0033] If a modular neck 14 is used, the distal end of the neck 14 may havea male Morse taper 48 that may cooperate with a female Morse taper 45 inthe stem 12 and thus act as a joining portion in connecting the stem 12 of theprosthesis 10 for the prosthetic head 16. Adjustments in the length of theneck 14 may be accommodated with the provision of necks of varying length.The Morse tapers 46, 48 may be provided to accommodate a modular neck14. Such tapers would not be necessary if a non-modular neck is used.[0034] The prosthetic head 16 may engage a male Morse tapered 50provided at the proximal end of the neck 14. The prosthetic head 16 mayhave a female Morse taper 52 configured to receive the male Morse taperedconical head 50 at the proximal end of the neck 14, as is well known in the art.Hence, a modular neck 14 may have a Morse taper 48, 50 at each end, and alength of straight section connecting the Morse tapers 48, 50. The length ofthe straight section may vary so that necks of various sizes can be used forpatients with differing requirements.[0035] Prosthetic heads may be of various diameters depending on the typeof hip arthroplasty (i.e., hip replacement) being performed (e.g.,hemiarthoplasy versus total hip arthroplasty), and the type of acetabularcomponent used.[0036] The prosthesis 10 loads the proximal end of the femur 26, and thusprevents bone resorption. Very little bone is resected in the implantationprocess. Hence, the femoral prosthesis 10 is bone sparing. The prosthesis10 may maintain its stability on initial implantation with the press fit in the

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femoral neck 30 via high hoop stress and a large metaphyseal bone surfacecontact area. This prosthesis may provide long term reliability whilesimplifying the technique of implantation through an anterior approach. Theprosthesis 10 permits ease of insertion via the anterior approach, following theanatomic neck angle. This allows less tissue dissection because there is lessneed to elevate the femur in order to gain access to the longitudinal axis of thefemoral diaphysis.[0037] The prosthesis 10 is ideal for MRI templating in the hip. Using MRItemplating, a custom prosthesis as described above may be produced tospecifically approximate or match an individual patient's anatomy, thusproducing a custom-fit stem.[0038] In accordance with the provisions of the patent statutes, the principleand mode of operation of this invention have been explained and illustrated inits preferred embodiment. However, it must be understood that this inventionmay be practiced otherwise than as specifically explained and illustratedwithout departing from its spirit or scope.

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CLAIMSWhat is claimed is:

1. A femoral prosthesis comprising:a stem having a proximal end and a distal end, the proximal end being

dimensioned and configured to support a prosthetic neck, the stemcomprising:

a shoulder at the proximal end, the shoulder being structured anddimensioned for a tight press fit into the neck of a femur, and

a trunk at the distal end, the trunk comprising:a wedge formed by a tapered portion extending from the

shoulder in the direction of the distal end of the stem, andone or more longitudinally extending fins,

wherein the wedge and one or more longitudinally extending finsfunctioning to provide multi-planar stability for the stem and surface area apartfrom the shoulder for fixation of the stem with the femur.

2. The femoral prosthesis of claim 1, wherein the stem has anelongated lateral cross-section.

3. The femoral prosthesis of claim 1, wherein the stem has asubstantially straight long axis so the stem does not curve into the diaphysis ofthe femur.

4. The femoral prosthesis of claim 1, wherein the stem is metal.

5. The femoral prosthesis of claim 4, wherein the metal is selectedfrom the group consisting essentially of titanium, chrome-cobalt and stainlesssteel.

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6. The femoral prosthesis of claim 1, wherein the stem has a fixationsurface that promotes at least one of bony ingrowth and bony ongrowth.

7. The femoral prosthesis of claim 6, wherein the fixation surface isselected from the group consisting essentially of a porous surface, a porouslayer and a porous coating.

8. The femoral prosthesis of claim 6, wherein the fixation surface isa coating selected from the group consisting essentially of a titanium plasmaspray, sintered beads, and hydroxyapatite.

9. The femoral prosthesis of claim 1, wherein the distal end of thestem is cut generally at an angle to a long axis of the stem, so that the distalend, when inserted in the femur, is generally parallel to the longitudinal axis ofthe femur.

10. The femoral prosthesis of claim 10, wherein a curved surface issuperimposed on the angled distal end of the stem so that the distal end of thestem is curved transversely in relation to the long axis of the stem.

11. The femoral prosthesis of claim 1, wherein the distal end of thestem, when inserted in the femur, remains within the femur, so as to notextend beyond the femur.

12. The femoral prosthesis of claim 1, wherein the shoulder is shapedand dimensioned to approximate the shape and dimension of the neck of thefemur.

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13. The femoral prosthesis of claim 1, wherein the shoulder shapedand dimensioned wedge into a hoop formed by the neck of the femur, andthus increase hoop stress at the neck of the femur, and increases theretentive effect of the shoulder in the neck of the femur.

14. The femoral prosthesis of claim 1, wherein the prosthetic neck isa modular neck of unitary construction with the stem.

15. The femoral prosthesis of claim 1, wherein the stem furthercomprises one or more channels therethrough sized to receive a fastenerselected from the group consisting essentially of a pin and a screw.

16. The femoral prosthesis of claim 15, wherein the one or morechannels comprise a channel through the center of the stem along the longaxis of the stem.

17. The femoral prosthesis of claim 15, wherein the fins comprisesuperior and inferior fins and the one or more channels comprise channelsflanking the center of the stem parallel to the long axis of the stem, adjacentthe superior and inferior fins.

18. The femoral prosthesis of claim 15, wherein the one or morechannels comprise one or more anterior/posterior channels through the stemtransverse to the long axis of the stem and the one or more screws compriseone or more anterior/posterior screws that pass though and threadablyengage the anterior and posterior cortex of the femur.

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19. A method of fixating a prosthesis to a proximal end of a femurcomprising the steps of:

a) providing a femoral prosthesis cornpnsmq a stem having aproximal end configured to support a prosthetic neck, the stem comprising ashoulder at the proximal end and a trunk at the distal end, the trunkcomprising a wedge formed by a tapered portion extending from the shoulderin the direction of the distal end of the stem and one or more longitudinallyextending fins,

b) inserting the stem into an open neck of a femur so that the stemis substantially straight along the longitudinal axis of the femoral neck,

c) pressing the stem tightly into the femoral neck so that theshoulder wedges into the femoral neck and increases hoop stress at thefemoral neck and the retentive effect of the shoulder in the neck and so thatthe wedge and the fins penetrate the spongiosa inside the femur to secure thestem in the femur.

20. The method of claim 18, further comprising the step of cutting thefemur along a plane perpendicular to the longitudinal axis of the femoral neck.

21. The method of claim 19, further comprising the step of fitting thestem into the femoral neck at an angle to approximate the normal anatomy ofeach individual.

22. The method of claim 21, wherein the angle is between 120degrees and 150 degrees.

23. The method of claim 19, further comprising the step of customshaping the prosthesis to a patient using MRI templating.

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24. The method of claim 19, further comprising the step of providing afixation surface of the stem for bony ingrowth or ongrowth.

25. The method of claim 19, further comprising the step of attachingthe stem to the lateral wall of the femur via pins, spikes or screws.

26. The method of claim 19, further comprising the step of attachingthe stem to the anterior/posterior cortex of the femur.

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ABSTRACT OF THE DISCLOSUREA femoral prosthesis comprises a stem comprising a shoulder at a

proximal end thereof and a trunk at a distal end thereof. The shoulder being isstructured and dimensioned for a tight press fit into the neck of a femur. Thetrunk comprises a wedge formed by a tapered portion extending from theshoulder in the direction of the distal end of the stem and one or morelongitudinally extending fins. The wedge and one or more longitudinallyextending fins function to provide multi-planar stability for the stem andsurface area apart from the shoulder for fixation of the stem with the femur.

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Sample Provisional Patent Application

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Transcript of Sample Provisional Patent Application