CA2094745A1 - Modular hip prosthesis - Google Patents

Abstract

"MODULAR HIP PROSTHESIS"
ABSTRACT:
A modular hip prosthesis can be custom fitted to a particular patient by a surgeon prior to surgical insertion.
The prosthesis features a body having a neck portion for carrying a rounded head element, a transitional mid-section of the prosthesis body includes generally rectangular and generally rounded cross-sectional areas, and a stem section has a generally rounded cross-sectional area. The stem is tapered to receive a tubular extension sleeve with a hollowed portion corresponding in shape to the stem portion of the prosthesis. The tubular extension sleeve has an open end portion receptive of the lower tapering stem of the prosthesis body. The stem portion includes an internal bore, and an attachment in the form of an elongated screw is provided for connection to the stem internal bore for securing the extension sleeve and the prosthesis body together, forming a compressive sealed connection therebetween. Pads can be attached to the transitional mid-section of the prosthesis body for increasing the cross-sectional shape of the prosthesis at the transitional mid-section. The pads are loaded continuously to connect to the prosthesis body by the hip joint reaction force. Removable collars can be added to the prosthesis to form a transverse load carrying interface with the upper end of the patient's femur. Frustroconically-shaped extension sleeves can be added to the prosthesis neck for extending the neck length.

Description

209~745 s~cRGRouND o~ T~ INvEN~rQN;
L gi~ld of the Inven~io~
The present invention relatss to ~ ~odular hiP prosthesis system wherein v~-ious co~ponent pa~ts of an $mplant kit oan be sele¢ted during the su~gical procedure 80 that the implant can be custom ~itted to a patient, and inc~u~ing removable mod~lar anterior and posterior pads that can be of a va~ie~y of custom con~igurations and sizes a~e secured with a wsdge lock fit connection that co~tinuously self tigntens the pads to the prcsthesis ~ody du~ing use, as the ~ip joint ~eaction ~orce pushes ~he pro~thesis into the fe~u~. Other mo~ular ~eatures includ~ re~ovable n~ck exten~ns, d~stal ~izer~, and modular colla~s, 2. ~eneral B~c~around Increasingly, sur~eons want to be abl~ to cu~tom fit S fe~oral prostheses to patients. In~tead of ha~i~g to choose a properly si~ed prosthesis from a group o~ pre-for~ed im~lants. ;t ~~ h~ advantageous to have a basic design which c~n be modified with variou~ ~omponent parts. This would eliminate the need to ~aintain a large inventory and would provide be~ter ~itting implant~.
custom ~itted i~plants are particularly impo~tan~ in rev~sion cases where an implant has to ~e ~emoved and replaced gince old cement must be ~emoved and ~one ~e~orption OCCUrB in ~any ca-~ss~ Unp~ed~ctable, proxi~al and/or di~tal bone loss or defor~ity o~ten occu~ ~hich must be accommodated by the ~epla¢ement prosthesis.
For initial implan~s! ba~ic ~a~iations in pat~ent anatomy are often con~onted by the ~urgeon~ Some patients haYe ~emoral necks that can be signi~icantly longer or ~ho~ter than 2 0 others. ~orti¢al ~haft defect~, ~hich are not unco~on, are not discovered until during operation. Variation6 in intramedulla~y canal diameter can als~ oo¢u~, whi~h i~ not accompanied ~y a properly size~ implant, can result in distal toggle.
In ~hort, it i3 dif~icult, i~ not i~pos~iblc, to prediot t~e ex~ot shape ~f a hip implant which i5 ~uitable ~or all patient~. Since it is i~practic21 ~hd ~ould be prohibitively expensive to ~aintain an inve~tory of impl~nts ~or most pa~ients, compromises must sometime~ be ~ade in supplying implants which fit re~onably well bu~ coul~ ~e improved upon.

209~7~S
Several hip prost~eses are known which are formed of replaceable or interc~anqeable ~omponent parts.
U.S. Patent No. 3,~41,590 entitled "Acetabular ReplacPment Prosthesis and Method o~ Assembling" iss~ed to Michele di~closes a selective individuali~ed techni~ue for acetabulum socket replacement per se, or in conjunction with a hip replacement prosthesis (referring to ~he Mi~hele U.S.
Pat. No. 3,~,393) for a total hip replacement, designed for all ages including the ~e~y young. A sele~tive anchorage for a cup pro~the~is o~ a size selected from the llm~ted number of d~ffe~ently ~ized aups i5 made available. Anchorage of t~e a¢etabular so~Xet replacement conforms to variations in dime~ions, -~hap~s and posi~ions of ~he ~medullary) c~nals of the acetabulum pelvi~ of the individual patisnt and include~
at least two elongated and convergent or divergent fa~tener~.
A removable collar o~ low modulu~ o~ elasticity ~aterial ie shown in U.S. Patent No. 4,01Zl796 entitled "Interpositioning Collar For Prosthetic Bone In6e~" issued to weisman et al. The collar is interpositioned between a collar o~ a metal pro~thetic hip ste~ i~pl~nted ~n the intramedullary canal o~ the f~ur and th~ adjacent calcar or o~ter edge of the ~ne. A ~lange depends fro~ the inser~ between ~he upper portio~ o~ the stem~and the inner wall of ~he bone. ~he interpositioned ~ollar is ei~her a ~ull elongated tapered 0-2~ shape or 1~ iB open on one side of a tapered U-shape.
U.S. Patent No. 4,404,6~1 entitled ~Modular Prosthesis A~se~bly" issue~ ~o Bu~ing et al., provide~ a modular hip pros~hesis as~embly ~o~ replacement o~ at least part o~ a joint and part of a bone s~aft includlng a mounting co~po~e~t provided with a connection portion and a~ least two joint components of similar s~ape bu~ dif~erent dimensions and which _ 3_-can be connected alte~na~lve~ nting component, each ~f the join~ component~ ha~ing an engage~ent portion and a connectiOn pa~ adap~ed ~or connection to the con~e~tion pO~ion of the mounting component, the joint components each providins part of a bone s~aft and part o~ a ioint which can cooper~te with an appropriate part of a natu~al or art~flcial joint.
U.S. Patent No. 4,57~,081 entitled "~one Prosthesis"
i~sued to Harder et al., discloses a bone prosthe~i~
co~prising at lea~t one joint component replacing a natural ~oint hal~, which i5 provided wlth a ~hank adapted to be connected to the bone, wherein a set of ~oint components is provided, and the ~hank i~ design~d a~ a bone replacement member, with a aonne~tioh portion provided adapted to be connected to the bone at one end and at t~e other end ~o the 6hank, One o~ the co~ponents is a hip prosthesi~ with a rounded head and a hollowed hi~ component th~ ¢onne~s to elongated mo~nting components. Xn another hip prosthesis emb~dimen~, a neck w~th a cone shape rsceives a suitable ~oint head with an inner cone.
A ~emoral component for hip pro~the~i~ is ~hown in U.S.
Patent ~o. 4,608,055 issued ~o Morrey et ~ he prosthesis di~closed in the '05~ patent includes a stem portion and a combined integral head and neck portion. The stem po~tion inaludes a proxi~al por~ion and a dis~al portion which are angularly related With respect to one another and with the proxi~al port~on ~ncluding a recess ~orm~d therein for receipt o~ the tapered portlon o~ the head and neck co~ponent. ~he h~ad and nec~ component includes a ~ubstantially part sph~rical head portion atta~hed to a ne~k p~rtion and a tapered portio~ angularly attached to the neck portion via a 20947~
basilar neck portion with the tapered portion being adapted to b~ permanently inserted into the reces~ portion of the proxlmal end of the ~bove des~ribed stem portion. The 6tem portion includes ~ plu~ality o ~ece~ses on the periphery and longitudinal ex~ent thereof for receiving fi~er ~etal pads which are provided to allow boney ingrowth therein in order to retain the emoral component perm~nently instal7ed i~ the p~oxlmal end of the femur.
~n u.s. Patent No. 4,676~797 entitled "Unit For R~seation 0 Prosthcsis", a resection prost~e~is assembly unit includes a head member, an end me~ber and an inter~ediate me~ber ~etw~en the head and end ~e~bers, of which one member is provided wlth a conical pin and another membe~ i6 provided w~th a coni~al pin and another member is provided with a conical bore. The latter two membere are provided with respective first surrace~
that extend ~an~e~ely to an insertion direction and which ~ac~ ~no ~noth~ ~hcl ~r~ ~r~.~d ~ rt 1-r~ P ;~ rR~P!2~ wh~n the two me~bers ~re oonne~ted together. One o$ th~ two member6 is f-~ther provided with a second sur~ace extend ing in the insert~on diroction, and the ~ecess being provided to receive a wedge inserta~le into the rece-~s to bear again~t the ~irst 6ur~a¢es for ~orcing the two ~embers apa~t wh~ le the forces exerted by the wedge zxe absor~ed by the first surfaces and ~e wedge is guided by t:he second ~urface.
Additionally, end fi~ing distal si~er~ ~ttached in a ~imilar ~ashion ~ould allow the surgeon to tailor the prosthesi~ tip to the cana7 diameter th~r~by reducin~ distal toggle.

~Q7~
8~NHARY OF $RE lNVEN~ION:
The present inv~ntion provides a modu~ar hip prosthesis which can b~ custom ~itte~ to a particular patient by a surgeon prior to surgical insertion of ~he pro~thesis.
s The apparatus includes a pro~thesis body having a generally wider l~rger, i.e., upper ~id-se~tion portion and an upper neck adapted for ca~rying a rounded head portion that fits eit~er the patient'~ acetabulum or a prosthetic acetabular co~ponent.
A lower stem extends from the mid-sect~on and te~inates at a lower rounded tip~ The ~tem is adapted for place~ent in the intra~ed~llaxy canal of the patient'6 fe~ur~ Dis~al ste~
sizers a~e provided w~i~h allow~ the lengtb of the fe~oral sha~t to be aUg~ented with ext~nsions that lock with the pri~dry ~ha~t usi~g ~ tapered a~a¢hmen~, m i# ~tta¢h~ent allows ths su~geon to ext~nd the stem length beyond any cortl~al sha~t de~ect he may encounter intraoperati~ely.
Th~ distal sizer in preferably the ~orm of a t~bular s~e~
extension sleeve includes a hol~owed portion corresponding in shape to the stem. The sizer include~ an open end portion which is recepti~e vf the ste~ for insertion ~he~einto. The ~ower ~tem portion inoludes an internal bore. Coxrespondihg fr~s~o~oni~al surface~ of the distal ~izer an~ stem a~low a tight ~ o be achieved between distal size~ and stem. ~n another embodi~ent, an attachment me~be~, p~efer~bly in ~he for~ o~ a threaded draw bolt, forms an attac~ment between the internal bore of the stem and the extension ~leeve holding the extension sleeve to the prosth~Yis body.
The ste~ and ~lee~e corre~ponding tape~ed or f~s~ro-conical su~$~es form ~ ~ight friation fit which seals wear particles from body tissue~ that typically wear o~ dur~ng insertion of the stem to ~he sle~v~. A comme~c~ally available impact driver tool can load the sleeve to th~ stem, and the co~respon~in~ t~pered regions reglster very t~ghtly together forming a 6eal and an i~erfQrence liXe ~it.
In one embodiment, when a draw bolt is ~ghtened, its non-t~readed end presses against the hip stem to provide tension in the bolt and co~preL~ive f~rce between the ste3 and sleeve in correo-ponding taperRd regions of the ste~ and ~leeve.
o me tubular ~te~ ex~en~ion slecve is of a gene~lly un~form cross-sect~on. lts upper end ha~ an annular ~apered seGtion th~t reg~sters with correspondingly tapered section of the stem. The prosthesis body in one embodiment has a longitudinal central open ended bore that extends substanti~lly the length of the prosthesi~ body. The at~acbment includes an elongated f~stener, prefer~bly ~h elongated threaded bolt that is adapted for placement within the elongated bore, extending substantially the length o~ the bore upon assembly. The bolt provides an upper head end portion which can be manipulated ~y the ~urgeon at the top of the ~rosthesis ~or tightening or loo~ening the ~it between the sleeve and pros~he~is body.
The ~tem extension ~leeve pr~vides a th~e~ded ~ection th~t ~an engage the lower end portion of the bolt to form a thr~aded conneotio~. ~his at~a~h~ent ~i sleeve and prosthe~is body ~an also be m de using a very sho~t ~o~t which i~ af~ixed ~hrough an opening in the botto~ of the extension sleeve, and into a ~ore in the bottom o~ the stem. The stem extension slee~es oan be of va~ying leng~hs and diameters, and can be s~raight or curved. The sleeve hollow ~o~e po~tion can ex~end ~9~74S
substantially the length of th~ sleeve, or can extend a partial distance along t~e sleeve.
The as~embly draw bol~ can be tightened after the prosthesl3 and extension ~lee~e are in position so that the extension oan twi~t to track the intermedullary can~l dur~ng insertion. ~fter placement, the dra~ bol~ can be used to lock the ~xten~ion and p osthesis body together.
The prosthesis body has a ~rustroconica7ly-~haped neck po~tion for oarrying a ~ounded head element. Between the neck portion and thc distal end is a transitional ~id-section ha~ing ge~er~lly reotangula~ upper cross-seotional area and a gensrally rounded lower cross-sectional area. EXten~ion sleeves having conical inner and outer surfaces and can be added to the neck por~ion ~or elongating the nsck portion with 1~ respect to the prosthe~is body and the head.
Removable transver~e bearing ~ollars can be adjustably affixed ~o the mid-section o~ the prosthesis body, generally ~rans~erse to ~he lo~gitudinal axis o~ the prosthesis body for for~ing a load carrying interface bstween t~e p~osthe5is body and t~e upper end of the pa~ient's ~emur. In one embodiment, the removable be~ring collar can hav~ extension~ that will compen ate for proximal bone lo~s, i.e. at the top of ~he pat:ient ' s fe~ur.
Removable pads are attachable ~o the ~id-~ection Of ~he pro~the~is ~or ch~nging the oro~s-se~tt ~nal con1gu~ation of the prosthesis at the mid-section . one or more ~ocket~ are formed in the prosthe~is at the mid-~action ~or carrying the ~odul~r pad~. In one e~bodiment, a wedge look co~nec~ion se~es each pad ~o the prosthesis body. A locking msmber on 30 the ba~k of each paa lo~Xs each pad to the pros~hesi~ at c~rrespond~ng engaging wedge su~faces thereon. The pads each 2~ 7~ ~
ca~ry corresponding locXing tab members which insure complet~
interlocking engagement of the p~ds to the prosthesis body be~ore forming th~ wedge lock connection. This safe~ feature requires that the surgeon ~ully engage each pad into it~
socket befo~e being able ~o ~lide the p~d into the wed~e-lock positi~n. The tabs on the locking m~mber o~ each pad 6nga~e a recess or undercut in ~he so~ke~ of ~he pros~hesis body to constxain the pad fro~ moving ~n a direction away ~rom the prosthesi~ ~ody, after as~emb~y is compl~ted.
Pad shape can be varied to custo~ fit the patient's anatomy ~aximizing stability to tran~fer shear load or compression load ~e~ween the pro~thesis and the patlent's bone as desired. Th~ pads can be vf dif~er~ ng material~ uch as poxou~ or roughsn~d coatings to promote tissue ingrow~h or on grow~h. ~lso, manufacturing methods which might weaken the integrity of the prosthesis body, such as the addition o~ a coating of beads, can be used for ~he ~e~ovable pads, thus not affe~ting the structural integrity of the pros~hesi~ ~ody.

IEP DE~CRIPTION OF T~E ~RAWING8:
~0 For a further under~anding of the nature and object~ o~
the prese ffl invention, reference should bQ had to the follo~ing detailed description, taken in conj~hction with the accompanying drawings, in which like par~s are given like reference numerals, and wherein;
FIGURE 1 is ~ side vie~ illustratin~ a plurality of hip prosthesis bodies as used with ~he modular hip syste~ of the presen~ in~ention;
~G~RE 2 is a ~id~ view of a pair of hip prosthesis bodies Of differing sizes illustrating inser~ion of the ~od~la~ collar portio~s thereoY;
~. , 7 ~ S
FIGUR~ 3 ls ~ side view illustrating a plurality of sleeve exten~ion parts as used in the ~odula~ hip p~osthesis system of the present invention;
FIGURE 4 is a 5ide view of a plurality o~ modular pads ~or use with the hip prosthesis ~odie~ of FIGURES 1 and 2, illustrating vary~g pad cro~s-~ectio"al configurations;
FIGURE 5 is a perspeotive exploded view illu~trating the pre~erred embodiment of the appa~atu~ o~ the present invention;
FIGURE 6 ls a t~p view of the prosthesis body portion of the preferred e~bodi~ent of ths apparatus of ~he present in~en~ion;
FIGURE 7 is a side view of the pro~thes~s body port~on of ~he preferred e~bodiment o~ the app~r~us of the present invention;
FIGURES 8 and g are top and side views l~lustrating the ~ssem~ly bolt portion of the pre~erred embod~ment of the apparatus of the present inven~ion;
FIGURES 10 and ll are top and side sectional views of the 20 stem extension ~leeve portions o~ the prefexred e~odiment of the apparatus of ~he prescnt invention;
FI~UQE 1~ ~ a ~ectional view illu~trat~ng an alternate con~truction of the neck exten3ion sleeve po~ion of ~he prefe~red e~bodi~ent of the appar~tus of the present in~ention;
FI~URE 13 ~s a plan view illustrating the ~odular collar portion o~ the pre~erred e~bod~ment o~ t~e appara~us of the present invention;
FI~URE 14 is a partial sectional vie~ illustrating t~e preferred embodim~nt of the appara~us of the present invention wit~ ~he p~sthesi~ body and s~e~ extension sleeve assembled;

209~7~i FIGURE 15 il~ a sec~ional ~levational f~ag~entary view illustrating t~e a~e~bly of ~od~la~ pads to tbe p~ostheeis body;
FIGURE 16 is a ~ectional view taken along 1~ - 16 of s FIGURE 15;
FIGURE 17 is a sectional elevational view of a second construction of the preferred embodiment of the apparat~s of ~he present invention illu~t~ating the assemPly of the modula~
pads to the procthesis ~ody;
1~ FIGURE 18 is a side exploded view of a ~econd embodiment o~ the modula~ ~ip p~o~thesis pads of the present invention;
FIGURE 19 is a side ~ragmentary view of the second embodiment of the modular hip prosthe~i~ of thc present inventi~n;
FIG~E 20 is a rear view illuctr~ting the construction of the modular pad o~ ~he second embodiment of the apparatus of the present invention;
~ IGUR~ 21 is a side view illustrating the con~tru~ion ~f ~h~ ~odular pad of ~he second e~bodiment of the appar~tus of 2~ the present invention;
~ IG~R~ 22 is an end view illust~ating the construction of the modular pad of the second embodiment of ~he apparatus of the pre~ent inventioh.
~ IGURE 23 i~ a ~eotional view taken along line~ 23-23 of F~GUR~ 19;
FIGURE 24 lC a ~e~tional view taken along lines 24-24 of FIGUR~ 19; and FIGURE 25 is a ~e~tional view taken along lihes 25-25 of FIGURE 19.

, 2~,0~ 7~ ~
FIGURE 26 is a side sectional view of a di~tal sizer fo~
use with t~e modular hip prost~e~ ystem ~f t~e pre~nt in~en~ion;
FIGURE ~7 i~ a ~ide view of aD alternat~ embod~ment of the distal sizer portion of the modular hip prosthetic syst~m of the present inveh~ion;

FIGURE 28 is a sectional ~iew taken along lines 28-28 of FIGURE 27;
~ IGURE 29 ~s ah end view of the distal -~izer of FIGURE
lo 27;
FIGURE 30 is a side view of anothe~ alternate embodiment o~ the distal sizer po~lon o~ the modular hip prosthesis ~y~te~ of th~ present invention;
FIGURE 31 i~ d s2ctional view taken along llnes 31 31 of FIGU~E 30.

~ETA~ED DE~CRIPTION OF T~E PREFE~R~ EM~ODIMEN~:

~ GURES 1 - 5 illutra~e generally the preferred embodiment o~ the apparatu~ o~ the p~ssnt ;nvention designa~ed gene~lly by th~ numeral l~. In FIGUR~ 5 there can be seen a pro~the~is body 11 which include~ a w~dened mid-se¢tion 12, a lower elon~ated generally cylindrica~ly shaped stem 13 and ~n uppe~ neck 1~. ~he mid-section incl~des an uppar generally ~eotangu~ar cro~s-sectional portion 15 an~ a low~r gen~rally rounded Cro88-seCt~ onal portion 1~ whi~h z5 oom~unlcates with the gene~ally cylindrical ~em i3.
~ he ~e~ 13 includes ~hree sect~ons in~luding an upper l~g~r cylindrical sec~ion 17, a f~u tro-conical ~pered transition eaction 18 and a lo~e~most smaller-diameter ~ylindrical portion l9. The prosthesis body ll would pre~erably be ~upplied to hospi~als ~nd surgeons in ki~ ~orm 209~
with a plurality o~ pros~hesis bodies 11, ~odu~ar pads 26, ~eads 27, collars 21, 2~ and extension sleeves or distal sizers 30 being of~ered in variQus sizes such a~ i8 shown in FIGURES 1 - 2, including prosthesis bodies llA - llJ, pads 26A-26H and sleeve~ 30, 30A.
Each prosthèsis body 11 in~ludes a generally U-shaped ~nn~ r r~.P~ ~n ~h~h ~Y+~n~ n~ ~n~ ~o Af th~
tr~nsitional ~id-section 12 portion of the body 11 and 1 receptive of generally U-~haped oollars 21 or 22 (~IGURE 2).
Recess 20 has a shape corresponding to the inner edge portion 21C o~ collar 21. ~olla~ Zl ~s th~s generally V-shaped in plan view ~FIGURE 13). Another e~bodi~ent of U-~haped collar 22 provides a similar, general}y U-shaped body in plan view, but also ihcludes ~ do~nwardly ex~ending tab 23 which can be lS used to help transfe~ load be~ween the pro~the-~ig 10 and the femur where proximal bone tissue has erode~, Lock pin 21B ~FIGU~E 13) ext~nds ~hrough openings 20A, 21A in order to secure collars 21, 22 to prosthesis body 11.
One of the openings 21~ ~an be $o~med as a blind ~oc~et hole with a transverse cloQure wall 21D and thus not extend all the ~ay ~o the outer sur~a~e o~ the collar ~o that the pin 21B
cannot ~e driven too far and project f~o~ the o~er aurface of ~he collar 31.
Each pros~hesis body 11 includes a pair of left and right sock~ts 24, 25 which are receptive of one or more ad~ustment pads 26A - 26~. The cross-ssctional configuration o~ each pad ~6~ - 26H Gan ~ary ihcluding thicker portions of the pad at ~ho top as compared ~ith the th~ckne~s at the bottom ~uch as for example ~an be seen i~ ~G~RE 4 wit~ pad 26~ and pad 2~H

3~ ~hich are th~cksr at on~ edge as compared wi~ pad~ 26A and 2~E. The pads 26A - 26H can be added by the urgeon to gi~re a ` ~ ~Jy ~
custom f it to the prosthe~i8 body 11 in tho area or thQ mld~
section 12.
~eck 14 is a frustroconically-shaped necX receptive o~
head 27 and of frustroconica? neok extension slseves 45. Head 27 provides a socke~ 28 co~sesponding in shape to neck 14. A
plurality of h~ads 27 can be provided in various Qizes as part of the kit, for matching each respective prosthesis body llA

Each stem 13 is pre~erably rounded a~ i~s lo~er tip. The lowermoQt por~ion 19 o~ tem 13, which is o~ a smalle~
dia~ete~, ~nd the ~rustro-conical transitio~ port~on 1~ o~
stem 13 form an attachment with a ste~ extension sleeve 30 (~IGURES 3, 5, 10, 11, and 14). The sleeve 3~ is e~o~gated and generally cyl~nd~ical and has an open end 31 whic~ allows insertion of the stem 13 thereinto. ~he lowermos~ end por~ion of the ~leeve 30 includes a generally curved distal end po~tion 3Z.
Extension sleeve 30 is hollow providing a lo~gitudinally extending ~ore 33 which extends between open end 31 and threade~ aperture 34. ~perture 34 extends downwardly f~om bor~ 33, communicating with end 32. Th~eaded aperture 34 i~
recep~ive of ~he externa~ threads 35 o~ a ~raw bolt 36. Bolt 36 in~l~des ~n uppe~ost head portion 37 and a lower threaded por~ion 35. Pro~thesis body 11 thu~ includes a longitudinally extending contral bore llA that is receptive of ~lon~a~ed bolt The upper e~d portion of extension sleeves 30, 30A
include~ a frustro-conical inner annular sur~a~e ~IGURES 3 and 11) ~hich corresponds in shape to the frustro-¢onical ~ransition por~ion 18 of stem 13 so that extension sleeves 30, 30A and stem 13 can ~orm a fri~t~onal tight fit upon asse~bly 209~7~5 (~ee FIGURE 14). Draw bolt 36 would be tightened arter placement of pro3t~esiC body 11 and a ~leeve 30 or 3~ into t~e intramedull~ry ~anal. Thus the exten~ion sle~ve 30 or 30A
can havs a ~lexibility by using a thin wall thlckness, rOr exa~le, so that it is fre~ to track the natural path of the intramedullary canal durlng ~nsertion. After inser~ion, bolt 36 is tightened, drawing the frustro-conical inner surface of sleeve 30, 30A and ~ransition portion 18 of stem 13 together.
Ex~ension sl~eve 30 can be a ~ho~t ~ersion having a l~ngi~udi~ally ext~nding bore 33 which ~omm~nicat~s with aperture 34, extending ~o end 32. ln another embodiment (see ~G~R~ 3), extension Qleeve 30A ca~ ~e eloAgated ex~ending well bey~nd t~r~aded aperture 34. As shown in the longer ~leeve in Fig. 3, ~he longitudinal axis of eX~ension sleeve 30A ~an chan~e an~le Qlightly or have a curvature in or~er to track the intramedullary canal, with the lower end portion 3g of each extension slesve 30A ~eing s~lid and being slightly sk~wed with re~pect to the longitudinal axis of open ~ore 33.
~hi~ ~llows ~he ex~en~ion sleeve 30A to track the natural path ZO of the intramedullary cana~ whi~h is not perfectly straig~t nor a pure elon~ated cylinder. Thus, ~he elongated extension sleeves 30A can curve or bow to conform naturally to t~e fe~ur of ~ patient for a cu5~0m f~.
A plurality of he~ds 27 o~ di~ering sizes would be provided. The dis~ance bet~een the prosthesi~ b~dy and the head 27 could be varied usln~ exten~ion ~e~ers 4S or 50.
~xtension me~er 45 would bR a hollowed trunion stru~ture, having a conical o~er surfa~e 46 and a corre~ponding conical inner sur~ace 47. A smaller open end portion 4~ an~ a larger ~0 open ehd po~ n 49 de~lne ~erebetween a bore which is occupied by nec~ 14 upon assembly of ex~ension ~ember 4~

2~9474~
thereupon. ~ecause o~ the smaller e~d 48, a head 27 could simply be slipped upon the extension member 45 with the ~ocket 28 of head 27 registering upon the outer surfaoe 46 of the extension member 45. An impact driver ~ould load a selected extension m~her on the ~ead 27 ~ith a p~edetermined load, wl~n cne conlcal sur~aces rlttlng ~gntly toge~her. In the prefe~red e~bodiment, extension m~mbers 45 of differing leng~hs and o~ di~ferent cross-sectional di~ensions would be provided to corre~pond to the plurali~y of differing neck size~ ~hat accompany the plurality oP pro~the~i~ bodies as provided in kit form ~see FIGU~E 1). An alterhative construction of necX extension ~e~bers i~ shown in ~I~U~ 12 wherein the extension me~ber SO includes ~ aonical outer sur~ace 51, a coni~al inner surface 52 with a ~all end por~ion 53 having a thxeaded opening 54 that communicates with ~ocket 56 at large dia~eter end portion 55 of extension ~e~ber 50. ~hus, the socXet 2~ of a particular sele~ted head 27 would be registered ~ightly upon the end o~ extension ~e~ber 50 in a w~dge ~i~ fashion. In order to remove the mem~er 50 from neck 14, the ~h~eadsd opening 54 wou~d be th~eadably engag~d with a removal tool in the $or~ of an e~ongat~d shaft ~aving one end portion which is threaded and t~e oppo~ite end portion defining a handle, ~nd/or an inertia weight sliding ~long the shaft, for example.
~5 Tn ~IGURES 15 - 17, pads ~fi ~e shown as removably attached to pro~thesis body 11~ In FIGU~E 15, it should be understood that only the as~em~ly for ~ecuring one pad 24 or 25 is sho~n.
~ the embodi~ent of FIGURE 17, ~he pads 26 are held in pl~ce ~y a single atta~hmen~ mechanism that is carried - 2~9~74S
generally betw~en t~e pa~ orming a connection therebet~een.
In the embodi~ent ~f FIGURE 15 th~re is provided an annular bu~hlng 61 which is an ~xtension o~ e~ch pad 26.
Bushing 61 includes a plurality o~ arcuate ~emb~rs 62 - 65 with spaces 66 therebetween so that the bushing 61 can expand and grip the beveled annular ~all 74 ~f opening 60 in prosthesis body 11 which i~ ~ou~led, A bolt 7~ i threadably a~tached to threa~ed bushing 61 so tha~ ~hc threads 72 o~ bolt 70 register with and threadably engage the ~h~eads 68 of buehing 61. Upon such th~eadaPle connec~ion, the individual ar~uate member~ 6~ - 6~ of bushing 61 expand (see arrows 73 o~
FIGURE 15) ~earing against the annular wall 74 o~ opening 50.
~n opening 67 in pad 26 communicates with a tooled opening 71 in bolt 70 ~o that a tool such as an a~len ~ren~h ~or exa~ple can be inserted through opening 67 and into registration with the slot 71 which would be ~o~e~pondingly shaped to receive the too~ used.
In t~a e~bodi~en~ of FIGURE 17, a single assembly bolt 80 i6 used to 6e~ure a pair o~ p~ds 2~ together upon p~Qsthesis body 11. The prosthesis ~ody 11 in~ludes a cylindrical transver~e opening 79 which is occupied ~y annular bushing 81 integrall~ atta~hed to pad 26. Bushing 81 incl~de~ an inner .socket portion 83 which is threaded with inte~nal threads 82.
Assembly bolt 80 provides cor~e~ponding exte~nal threads B9 which ~hreada~ly engag~ the threads 82 o~ bushing 81. A
s~cket ~ is receptive of a tool such as an allen wrench ~or example and ~ota~e~ therewi~h to tighten pads 26 together.
Pad 26 provides a bus~.ing 85 which carrie~ an annular ret~ining ring 8~, which can be a ~plit ~ing or the like. An opening 90 allow~ access through pad 26 ~o the ~ooled opening ~. Asse.mbly bolt 80 includ~s2D ~ ~ ~ Iy circula~ annular head portio~ 9~ which is held against p~d 2s with ring 8~. A~
the th~eaded ~olt 80 is tighten~d, pad~ 2~ are thus pulled togethe~ and tightly against pros~hesis body 11.

:~ FI~ Z~ a~ a~ c~ . vr ~,1.~
apparatus of the present invent~on wherein removable pads 40A, 40B attach to pros~hesis bod~ ll with a wedge fit that sclf tightens the connection between each pad 40A, 40B and the prosthesis as hip ~oint reaction force pushes the pro~thesi~
into the fem~r during use. A ~a$ety feat~e of each pad 40A, 40B and pro~thesis body 11 connection is a locking me~ber With tabs that forc~ th~ surgeon to ~ully engage the pad 40A, 40B
into a provided opening lOO on ~he pro~the~is ~ody 11 ~e~ore a ~liding of t-~e pad 40A, 40B into locking engage~ent wi~h t~e prosthesis body 1~.
~ n FI~U~E 19, there.can be seen a ~ragmentary view of prosthesis bo~y 11 having a socket 25 therein with a peripheral edge wall 25W. Similarly, the opposi~e side cf prosthesis body ,11 would have a socket 24 providing a peripheral side wall 25W. Eac~ socket 24, 25 receives a modular pad 40A, 40B respec~ively. ~n ~ ES lg-~Z, pad 40A
is shown which registers during operation with the pad ~ocket ~4. The modular pad ~OB would be a mirro~ i~age of the views shown ~o~ pad 40~ o~ FIGURES 20-~2.
Each modul~ p~d 40A, 40B carrie~ on itC rear surface 39 wedge locking ~e~ber ~1 havin~ a pai~ of opposed in~lined lccking ~ur~aces ~2 which form an acute angl~ with respect to one another, as shown in FIGURE 20. During use, ~he ~rgeon places modular pad 40A in~o its ~imila~ly ~haped ~ocket 24 regi~tering the locking mem~er 41 into openlng 100. ~he lo~king mem~eX 41 ca~ies ~ pair of tabs 43 whi~h initially I ~ _ register at t~e enl.lrged end portion l~OB of openlng lOo.
Similarly, t~e inclined l cking surfaceS 42 of locking membe~
41 reaister with si~ila ~y shaped locking surfaces 101 of openin~ loo. The tabs 43 ust be re~is~ered wlt~ the enlargea s lOOB end o~ open$ng lOO. otherwise, the locking ~ember 41 will not fit in~o the op ning loO. This p~ovides a safety feat~re because the surg on must fully plaae the particula~
pad 40A, 40B into its soc~ et Z4, 25 be~ore attempting to wed~e lock the pad 40A, 40B t ¦ the pro~thesis bod~ ll. Once the locXing ~ember 41 h~ bee fully ~egistered within ~he opening lOO, the s~geon then si ply s~ides the pad upwardly to~rd the ~pper end 15 of the p o~thesi~ body 11. The tabs 43 t~en slide under ~houlder~ 102 and regi~ter in u~deraut slots 103, as shown in FIGURE 24. As each pad 4OA, 4OB i~ ~oved into locking position by ~he ~rgeon, the su~f~oes 4~ o~ the wedge locXing member 41 engag the inclined surfaces 101 of the opening 100. A tight ~ ~ge-l~ck ~it i~ obtaineq ~y ~orcing the surfaccs 42, 101 t ether u~ing an impact drive~ or a malle~ and a hand held dr ver element o~ punch. Each p~d 40A, 40B secure~ tightly to the prosthesis bod~ ~ecau~e the surfa~es ~Z wedge ~it to the surfa~e~ 101.
In the p~eferred em~ ~diment, ~he outer periphery o~ e~ch pad 40A, 40B has a shape orresponding to ~he perip~eral wall 24W, 25W of each socket 4, 25. ~owever, the pad~ 40A, 40B
are sized slightly smal er than the outer configuration of each socket 24, ~5 as de~ ned by their peripheral ~ide walls, ~4w, 2Sw. ~his provid s room to move e~ch pad 40A, 40B
- slightly so th~t slidin action can be used to pexfect the wedgP loc~ conne~tion ~twsen ea~h pad 40A, 4~ and its respecti~e soc~et z4, ~5 . Thus, the outer edge of each pad 20947~
~o~, 40~ would ~a sp~ced inw~dly r~om t~ pe~ipheral wall 24W, 25W ~f each soc~et ~4, ~S by ~ small measure.
A very tight wedge lack connection ~an be ~or~ed between each pad 40A, 40B and the prosthesis body 11 u8ing an impact driver. In the p~efe~red em~odiment, each pad includes a qenerally flat lower su~ace 106. A ~imila~ flat ~urfa~e 1~7 is provided at the bottom ~f e~ ocket 24, 25. Howeve~, upon manual assembly Of the padg 40A, 40B to the prosthesis body 11 by the surgeon, an impact driver ~n be used to tighten the pads 40A, 40B to th~ pro~thes~s body 11 using the impact driver. An impaot driver is a commerc~lly available product which car~ies a tooled end portion ~aving, for exa~ple, a com~ercial screw drive~ tip or wedge tip. The impact dr~ver tool tip ~not shown) i~ ~hen placed in the space 1~ forme~ between the surface~ lO~ and 107 a~ter the su~eon pla~e~ the respective pads 40A, ~OB in their respective sockets 24, 25. The prosthesis i~ pla~ed on a flat surface ~nd ~he surgeon simp~y p~esse downwardly on the impact driver, ~c~ivating the tool tip po~tion o~ the ~mpa~t driver to force the sur~ace 106 away ~rom the ~urfaoe 107. The s~geon then turns ~he prosthesis ove~ and repeat~ the sa~e procedure for the se~ond pad~ It has been ~ound that usin~ a commercially available, relatively small i~pac~ dri~sr, s~ch as s~pplied by Sta~xett Company, as much as 300 pounds of load can ~e gener~ted holding e~ch pad 40A, 40B to the prosthe~is ~ady 11.
In the event th~t one of the pads 4OA o~ 4OB were to become loose, because t~e surgeon possi~ly did not apply ah f~r~-.Q t~ tl~ n prosthesis body 11, the present invention provides a sa~ety feature for ~ontin~ously loading each p~d 4~A, 4UB to the prost~esi~i body ~l. T~is is lnsurei bec~u~e the pad oute~
~urface 3~ is typically beveled ~o ~hat thQ bottom o~ the pad is narrower a~d the t~p of the pad i~ wider, a~ ~hown in ~XGURES 21 and 22, Thus, when the pad is in~alled, it ~elf tightens as ~he hip joint reaction force of the patient pushes ~h~ prosthesis furthe~ in~o the fémur. ~he femur presse~ on the outer surface 38 o~ the pad, forcin~ it upwardly and ~urther forcing the wedge lock surf~ce~ 42 of e~oh pad 40A, 40B against ~he -curfaces lO1 o~ the opening lO0.
An additional safety feature of the present invention is that the ~alls 24W, 25W of the socket~ 24, 25 contain the pads 40A, 40B if the pads a~é inad~erten~ly disengaged ~rom the lo~k~ng ~;:hani-em.
~no~her ~a~ety ~eat~ re o~ the p~e~en~ inventio~ ar~ the locking tabs 43 which ~o ce the surgeon to fully engage the pads 40A, 40B into the r respect~e ~lots 24, 25 before attemptinq to ~lide the ~edg~ incline~ locking surfaaes 42 into en~agement ~ith the ocking sur~aces lOl. I~ ~he surgson doe~ not fu~ly engage th !pads 40A, 40B ~nto opening ~01, t~e locking tabs prevent we~l ~ loe~ing o~ the ~urface 42 to t~e - ~ur~ace 101.
The pre~ent in~enti n ~ro~ides thus a simple and qui~

modular pad construction that allows for installing different contours on ei~her the ~nterior or po~erior side of the p~osth~sis ~o tha~ the fe~ oral ~a~ity can be ~o~pletely $illed in order to o~tain a ~e :te~ bone-prosthe~is contact. ~he present in~ntion could ~ supplied ~ith a number o~ tria~
sockets i~ kit form~ ~o t~ at the kit co~ld be used ~o size the apparatus p~re~tly. The ~, ~he surge~n wo~ld have the a~al pros~h~si~ and its modul ~r pads in pre-p~ckaged ste~ilized condltlon ~hus, the eur~oon could use the trl~l ~it to s1ze 2~9~74~
th~ prQsth~si~ and it~. mo~ular parts and then simply open the ~o~responding part ~ro~ a ~terile package when the correct fit had been obtained.
FIGURES ~6 - 29 illu~trate an alternate embo~iment o~ the distal sizer desi~nated by the numeral 1~0 in ~IGURE ~6.
~istal sizer 120 l~cludss a lower hemisph~rically-shaped distal end po~tion 121 and upper end portion 12Z which attaches to the stem 13 of pros~hesi~ body 11 of FIGURES 1, Z
and ~. In FIGURE 2~, a bo~e 123 communicate~ wi~h the upper~ost o~ p~ox~l end 122 o~ distal ~izex 120.
Bore 123 includes a frustroconical sect~on 124 ~nd a generally cylindrical section 125 ~er~ina~i~g at conically-shaped ~nd portion 126. The d~ctal sizer 120 provid~s a ~urved ~ection 128 that begin~ at the middle 127 portion o$
1 F. t-ho ~; ct~ n ~ n~ t' Q ~ a l o~r~ 1 7 ~ . A4~
In ~he em~odi~en~ of ~GURE 27, a .di-~tal sizer 130 is provided ha~ing a bore 131 whioh in~ludes a f~ustroconical portion 13~, a genexal~y cylindrical ~e~tion 133, and a conic~l end portion 134. The prosthesi~ 130 oute~ wall 135 is g~nerally cyli~drically ~haped. The lower or di~tal end portion 136 provides a pair of lo~gitudinally extending and inte~eating slots 137, 13~. The sl~t~ 137, 138 form a plurali~y o~ dis~l si~er ~e~ments 139-142, as ~hown in FIGURE
2~. ~ao~ of the slot~ 138, 137 te~mi~ates at 143 which i~ at the central portion o~ distal sizer 130.
~ In th~ ~mbodiment of FIGURE 29, a single ~lot 137 i~
illustrated which ~orms a pair of distal sizer ~egment~ 144, 145. In the embodi~en~ of ~GURE 29, the di~ izer ~o~ld be aon~tru~ted like the embodiment of ~GURE Z7 wi~h the ex~ep~ion ~ha~ a single slot 137 is p~ovid~d rather t~an the ~wo ~lots 137, 13~ of th~ e~bodiment of FIGURES 27-28.

20947~5 In FIGURES 30-31, a further embodiment of ~he distal sizer is provided designated as l~o. ~istal sizer 150 provides a he~ispherically-Shaped low~ end portion 151 and an upper end portion 152. The distal sizsr 150 is provided with an internal bore o~ the shape and con~iguration of t~e bores 131 of FIGURES 26 and ~7. This Wo~ld p~ovide for attachment of the sizer 15~ to the ~tem 13 ~f prosthe~is body 11 of Th~ distal sizer 150 i8 generally cylindrically shaped in 0 cross-~ection but provides a plurality of clr~umfe~entially spaced, longitudinally extending projections 153, Each projection 153 has a trough 154 and a pair o~ sidewall 155, l~b portion~ with a cre~t 157 between adjacent projections 153.
Because many varying and di~e~ent embodim~nts may be ma~e wit~in the scope of the inventive concept herein taught, and because many modi~ications ~ay Pe made ln the e~bodi~ents he~ein det~i~ed ~n a~o~dance with the descriptive require~ent of the law, i~ is to be understood that the details hexein a~e 0 to be interpreted as illustrati~e and not in a limiting sense.
What is claime~ as invention is:

Claims (34)

1. A modular hip prosthesis that can be custom fitted to a particular patient by a surgeon prior to surgical insertion, comprising:
a) a hip prosthesis body having an upper end portion with a neck adapted for carrying a rounded head portion that fits the patient's acetabulum, a mid-section with anterior and posterior sides and a lower stem portion adapted for placement in the intramedullary canal of the patient's femur;
b) removable proximal and distal extension members attachable respectively to the neck and stem for selectively conforming the prosthesis to the adjacent acetabulum and femoral bone tissue by selectively increasing the prosthesis neck for spacing the rounded head portion away from the mid portion along a line that intersects the patient's acetabular socket and/or increasing the stem length below the mid-section; and on either or both sides thereof;
c) each member having holding means for attaching each respective member to the prosthesis body the holding means including corresponding frustroconical surfaces on each extension member and on the prosthesis body; and d) wherein the prosthesis body includes a first of said frustroconical surfaces on the prosthesis body neck and a second of said frustroconical surfaces at the upper end portion of the stem.

2. The modular hip prosthesis of Claim 1 wherein the distal stem extension member has a bore of a generally uniform cross-section along a majority of its length.

3. The modular hip prosthesis of Claim 1 wherein the distal stem extension member is substantially straight.

4. The modular hip prosthesis of Claim 1 wherein the distal stem extension member is curved to conform to the shape of the intramedullary canal.

5. The modular hip prosthesis of Claim 1 wherein there are a plurality of proximal extension members of differing lengths.

6. The modular hip prosthesis of Claim 1 wherein there are a plurality of distal extension members of differing lengths.

7. The modular hip prosthesis of Claim 5 wherein at least one of the proximal extension members is a frustroconical tubular member having a smaller diameter end portion with a transversely extending annular portion at the end portion.

8. The modular hip prosthesis of Claim 1 wherein the distal extension member has an upper end with a frustroconically-shaped annular surface communicating with the bore.

9. The modular hip prosthesis of Claim 5 wherein the prosthesis neck terminates at an upper end with a transverse flat surface at least some of the proximal extension members are of a length that places a portion of the proximal extension member beyond the upper end of the neck during use.

10. A modular hip prosthesis that can be custom fitted to a particular patient by a surgeon prior to surgical insertion, comprising:
a) a hip prosthesis body having a proximal end portion with a neck portion for carrying a rounded head portion that fits the patient's acetabulum, and a distal stem portion for placement in the intramedullary canal of the patient's femur;

frustroconically-shaped annular surface communicating with the bore.

b) a tubular stem extension sleeve having a hollowed portion corresponding generally in shape to the stem and including bore receptive of the stem;
c) attachment means for securing the extension sleeve and prosthesis body together; and d) the attachment means comprising first and second respective frustroconically-shaped portions of the distal stem portion of the bore.

11. The modular hip prosthesis of Claim 10 wherein the distal stem extension has a bore of a generally uniform cross-section along a majority of its length.

12. The modular hip prosthesis of Claim 10 wherein the distal stem extension member is substantially straight.

13. The modular hip prosthesis of Claim 10 wherein the distal stem extension member is curved to conform to the shape of the intramedullary canal.

14. The modular hip prosthesis of Claim 10 wherein the extension member has a longitudinally extending portion that increases flexibility of one portion of the extension member.

15. The modular hip prosthesis of Claim 10 further comprising means for increasing the flexibility of one portion of the extension member along its length.

16. The modular hip prosthesis of Claim 10 wherein the extension member has externally projecting means for engaging surrounding bone tissue.

17. The modular hip prosthesis of Claim 15 wherein the flexibility increasing means comprises a longitudinally extending slot that extends along a portion of the extension member.

18. The modular hip prosthesis of Claim 15 wherein the flexibility increasing means comprises a pair of intersecting slots, each extending longitudinally along a portion of the length of the extension member.

19. The modular hip prosthesis of Claim 16 wherein the externally projecting means comprises a plurality of longitudinally extending and circumferentially spaced projections.

20. The modular hip prosthesis of Claim 16 wherein the externally projecting means comprises a plurality of closely spaced longitudinally extending ridges of generally uniform size.

21. A modular hip prosthesis that can be custom fitted to a particular patient by a surgeon prior to surgical insertion, comprising:
a) a hip prosthesis body having an upper end portion with a neck adapted for carrying a removable rounded head portion that fits the patient's acetabulum, a mid-section with anterior and posterior sides and a lower stem portion adapted for placement in the intramedullary canal of the patient's femur;
b) removable proximal extension members of differing lengths, each selectively attachment to the neck for selectively conforming the prosthesis to the patient's adjacent acetabulum bone tissue by selectively increasing the length of the prosthesis neck to selectively space a rounded prosthesis head portion away from the mid portion along a line that intersects the patient's acetabular socket;
c) each extension member having holding means for attachment to the prosthesis body, the holding means including corresponding frustroconical surfaces on extension member and d) a rounded head prosthetic portion having a frustroconically shaped socket; and e) the extension members each having a frustroconical exterior surface that can form a tight fit with the external surface of a selected extension member,

22. The modular hip prosthesis of Claim 21 wherein the extension member has a transverse portion at one end portion.

23. The modular hip prosthesis of Claim 21 wherein the extension member has inner and outer frustroconical surfaces.

24. The modular hip prosthesis of Claim 21 wherein at least some of the extension member have a transversely extending annular projecting portion at one end.

25. The modular hip prosthesis of Claim 21 wherein there are a plurality of proximal extension members of differing lengths, some having transversely extending annular portions and some having open end portions.

26. The modular hip prosthesis of Claim 21 wherein each of the plurality of extension members is sized to fit the neck of a single prosthesis body.

27. The modular hip prosthesis of Claim 22 wherein at least one of the proximal extension members is a frustroconical tubular member having a smaller diameter end portion with a transversely extending annular portion at the end portion.

28. The modular hip prosthesis of Claim 21 wherein the extension member and neck are each metallic in construction.

29. The modular hip prosthesis of Claim 25 wherein the prosthesis neck terminates at an upper end with a transverse flat surface, and at least some of the proximal extension members are of a length that places a portion of the proximal extension member beyond the flat surface during use.

30. In a femoral prosthesis having a neck with an upper and terminating at a transverse face, the neck having a first taper and a femoral head prosthesis portion having a blind bore with a second taper, the improvement comprising:
a) a coupler for coupling said femoral head prosthesis portion to said prosthesis at the neck, comprising a body having a first larger diameter end and a second smaller diameter end said body generally tapering inwardly from said first end to said second end;
b) wherein the first end is open for fitting over the neck of the prosthesis and said body having an outer surface with an uninterrupted single taper corresponding to said second taper and an inner surface having an uninterrupted single taper corresponding to said first taper; and c) wherein said body is of a length that extends the second end and a portion of the body to a position adjacent the transverse face of the neck.

31. The femoral prosthesis of Claim 30 wherein there are a plurality of femoral head prosthesis portions, and comprising at least one femoral head prosthesis portion having a blind bore sized and shaped to form a connection directly to the neck.

32. A modular femoral prosthesis, comprising:
a) a prosthesis body having an upper neck portion and a lower stem portion for placement in a patient's intramedullary canal;
b) a removable femoral prosthesis head portion for placement in a patient's acetabulum;
c) a plurality of couplers wherein the plurality of couplers are available in a plurality of differing lengths to enable the desired length coupler to be selected for interpositioned engagement between the femoral prosthesis head and the neck of a femoral prosthesis to provide a desired distance therebetween;
d) wherein each coupler comprises a hollow sleeve having a first end and a second end;
e) wherein the first end of each coupler in the set is open for fitting over the neck of the femoral stem, and the second end of at least one of the couplers in the set includes an end wall generally transverse to a longitudinal axis of said coupler; and f) wherein the first end of each coupler in the set including said end wall has a greater length than said at least one other of the couplers having the open second end.

33. The set of implant components of Claim 32, wherein said coupler generally tapers inwardly from said first end to said second end.

34. The set of implant components of Claim 32, wherein said end wall has a small opening therethrough.