Abstract:
A modular prosthetic acetabulum apparatus for use in reconstruction of a hip joint by placement in an acetabulum cavity has a supporting plate with a shape suitable for placement in the acetabulum cavity, an anchor cooperative with the supporting plate for adjustably positioning the supporting plate in the acetabulum cavity, a spacer locked onto the supporting plate and selectively rotatable with respect to the supporting plate, and a cup affixed within the spacer. The supporting plate has an annular internal surface cooperative and complementary to a tapered annular exterior surface of the spacer. The cup has a tapered exterior surface complementary to and cooperative with an annular tapered interior in the spacer.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present application is a continuation-in-part of U.S. application Ser. No. 10/484,548, filed on Jan. 22, 2005, and entitled “Modular Acetabular Cup, And Anchoring Screw For Fixing A Prosthetic Implant Such As An Acetabular Cup”, presently pending. U.S. application Ser. No. 10/484,548, claims priority from International Application No. PCT/FR02/02622, filed on Jul. 22, 2002 claiming priority from French application Ser. No. 10/09796 of Jul. 23, 2001. 
     
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0002]    Not applicable. 
       NAMES OF THE PARTIES TO A JOINT RESEARCH AGREEMENT 
       [0003]    Not applicable. 
       INCORPORATION-BY-REFERENCE OF MATERIALS SUBMITTED ON A COMPACT DISC 
       [0004]    Not applicable. 
       BACKGROUND OF THE INVENTION 
       [0005]    1. Field of the Invention 
         [0006]    This invention relates to a modular prosthetic acetabulum for surgically treating the reconstruction of the hip joint in the case of total restoring of hip prostheses, with or without bone-material deficiency. The present invention further relates to an anchoring-screw device for fastening a prosthetic implant, such as the acetabulum. The present invention is intended to restore all of the biomechanical criteria of the joint by individually treating, through the modularity of the prosthetic implant, the basic elements relating to the fastening and orientation of the implant. As such, the modular acetabular prosthetic implant is adapted to the various needs that would arise for various patients while, at the same time, allowing for the efficient placement of the implant. 
         [0007]    2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 37 CFR 1.98. 
         [0008]    The current technique for acetabulum reconstruction shows a deficiency in the area of both the intra-ossa anchoring of the existing prosthetic devices and their bio-mechanical positioning. The anchoring with a limited primary fastening can indeed have, in the course of time, a harmful affect on the integration of the implant. This is the result of the compressive and twisting forces to which it is subjected. This can give rise to a loosening and/or a breaking of the installed material. 
         [0009]    The positioning of the implant is often dependent on the state of the osseous acetabulum to be treated. The positioning of the implant does not allow a free orientation in all those planes which would allow the restoration of normal bio-mechanics of the joint. This can be prejudicial to the stability of the joint. It often causes dislocation and/or loosening of the implant. 
         [0010]    These and other objects and advantages of the present invention will become apparent from a reading of the attached specification and appended claims. 
       BRIEF SUMMARY OF THE INVENTION 
       [0011]    The present invention is a modular prosthetic acetabulum apparatus for use in reconstruction of a hip joint by placement in an acetabulum cavity. The apparatus includes a supporting plate having a shape suitable for placement in the acetabulum cavity, an anchor cooperative with the supporting plate for adjustably positioning the supporting plate in the acetabulum cavity to a desired depth, a spacer locked onto the supporting plate and selectively rotatable with respect to the supporting plate, and a cup affixed within the spacer. The supporting plate has an annular interior surface which tapers so as to have a wide diameter at an end of the supporting plate and a narrow diameter spaced from supporting plate. The anchor is in the form of an anchoring screw. The spacer has an annular internal area. This annular tapered internal area of the spacer has a wide diameter at a first end of the spacer and a narrow diameter inwardly of the first end of the spacer. The spacer has an annular external area formed adjacent a second end of the spacer. This annular tapered external area has a narrow diameter adjacent the second end of the spacer and a wide diameter positioned inwardly of the second end of the spacer. The annular tapered external area of the spacer is juxtaposed against the tapered interior of the supporting plate such that the spacer is selectively rotatable within the supporting plate. The cup has a tapered exterior surface received in the tapered interior area of the spacer. The cup has an equatorial rim extending therearound and extending outwardly therefrom. The equatorial rim is positioned against the first end of the spacer. 
         [0012]    The supporting plate has a plurality of external legs. At least one of the plurality of external legs has eyelets formed therein. Another of the plurality of external legs has an obturator hook extending therefrom. The fastening screw is of a spongy or cortical material received through one of the eyelets of the external leg. The supporting plate also has at least one internal leg. The internal leg has an eyelet formed therein. This eyelet has a frustoconical wall. The fastening screw is received through the eyelet and has a bearing surface with a hemispherical profile. The bearing surface bears against the frustoconical wall of the eyelet. The plurality of external legs of the supporting plate comprise a pair of external legs having eyelets formed therein. The plurality of external legs also comprises a single leg having the obturator hook formed thereon. The plurality of external legs are disposed at an acute angle with respect to each other on one side of the supporting plate. The single leg with the obturator hook extends from an opposite side of the supporting plate. 
         [0013]    The tapered exterior surface of the cup is juxtaposed against the annular interior area of the spacer so as to be selectively rotatable within the annular interior area. The cup is, in the preferred embodiment, formed of a metallic material. Each of the supporting plate, the anchor, and the cup has an osteoconductive coating thereon. 
         [0014]    The spacer has a locking collar extending outwardly from an exterior surface thereof. This locking collar extends around more that one-half of a circumference of the spacer. The locking collar has a plurality of eyelets formed in spaced relationship to each other along the locking collar. The supporting plate has a peripheral shoulder extending outwardly therefrom adjacent the end of the supporting plate. The peripheral shoulder has a plurality of tapped holes formed therein. At least one connecting screw is received in one of the plurality of eyelets and in one of the plurality of tapped holes so as to fix a rotation position of the spacer with respect to the supporting plate. Each of the plurality of tapped holes has a wall with a frustoconical shape. The connecting screw has a head with a shape bearing against the wall. 
         [0015]    The cup has a smooth internal portion. A polymeric insert is received in the internal portion such that the polymeric insert moves freely therein. The insert has a hemispherical cavity suitable for receiving a head of a prosthetic femoral element. Alternatively, a ceramic insert is received in female portion of the cup. This insert has a hemispherical cavity for receiving a head of a prosthetic femoral element. 
         [0016]    The anchoring means comprises a body having a cylindrically-shaped proximal portion and a sharp tip at a distal portion. The body has a spongy self-tapping outer thread. The proximal portion having a tapped channel formed axially therein. A threaded piston is received by the tapped channel. The threaded piston has a head and a tapped well. The tapped well is suitable for receiving a locking counter-screw therein. The counter-screw has a head with a curved hemispherically-shaped bearing surface. The eyelet has a profile complementary to the bearing surface. 
         [0017]    The modular prosthetic acetabulum of the present invention presents a global solution for the surgical treatment of the hip joint reconstruction by taking into consideration of its mechanical, anatomical and biological requirements. This prosthetic acetabulum allows proper installation through the primary and secondary fastening means by way of the anchoring and fastening screws. The proper anatomical orientation of the implant is accomplished through its broad modularity. The stability is achieved by the Morse-tapers-type system for assembling each of the components together. The primary fastening of the prosthetic acetabulum is assured by the supporting plate through the use of anchoring screws. This allows an anchoring in a healthy osseous area by using all of the available supports without any orientation constraint. The multiplication of the anchoring and resting points of the supporting plate in the peripheral area are achieved through the supra-acetabular legs and the obturator hook and in the internal area through the ability of the acetabular legs to achieve a maximum stability of the supporting plate and, hence, of the implant. 
         [0018]    In the case of bone destruction, the supra-acetabular fastening legs can also be fastened by means of anchoring screws identical to those being used for fastening the acetabular legs. The association of anchoring screws and support plate represents a true osteosynthesis. Its primary mechanical stability remains an essential element in the life expectancy of the reconstruction and allows for efficient loading into the patient. 
         [0019]    The secondary fastening of the prosthetic acetabulum is optimized by filling the acetabular cavity with grafts and/or bone substitutes. This takes part in the reconstruction of the destroyed bone stock. A double osteoconductive coating can be applied primarily on the back of the acetabular leg or legs of the supporting plate as well as onto the back of the cup which is accommodated in the supporting plate through the spacer. 
         [0020]    The orientation of the supporting plate, the spacer and the cup allows for a swiveling and/or rotation in all planes. This serves to act as an interface between the supporting plate and the cup and to allow one to center the anatomical resting point within the cup. This increases the congruency and the size of the bearing surface. The adjustment of the anatomical orientation of the prosthetic acetabulum is ensured by the cup. The metal cup is able to swivel over 180° in the vertical anteroposterior plane and by the swiveling spacer and the vertical and horizontal planes. As such, these components allow for the very fine adjustments of the anatomical axes of the joint. 
         [0021]    The Morse-tapers-type assembling of the various components of the prosthetic acetabulum of the present invention ensures the locking of the entire end and makes long-term stability reliable. 
         [0022]    The present invention, in which the insert is fixed to the cup, can serve to meet specific purposes, such as for very young or very active patients. This characteristics of the prosthetic acetabulum of the present invention guarantee the restoring of normal biomechanics and enhance the life expectancy of the prostheses. This allows for a faster rehabilitation and return to active life. 
         [0023]    The anchoring screw is used in the present invention serves to fasten the prosthetic implant. The anchoring screw includes a suitable means for ensuring the fine adjustment of the height of the bearing surfaces of the implant. This allows for the anchoring of the implant in the bone tissue while ensuring a balanced adjustment of the compressive forces. The threaded piston associated with the fastening screw of the present invention allows, according to the depth of insertion into the tapped channel, the ability to adjust the height of the bearing surfaces of the prosthetic implant. The counter-screw ensures the tightening of the implant. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0024]      FIG. 1  is a perspective view exploded view of a prosthetic acetabulum in accordance with the preferred embodiment of the present invention. 
           [0025]      FIG. 2  is a cross-sectional view showing the assembly of the spacer and the cup within the supporting plate. 
           [0026]      FIG. 3  is a detailed cross-sectional view of the circled area of  FIG. 2 . 
           [0027]      FIG. 4  is a plan view of the assembled prosthetic acetabulum of the present invention. 
           [0028]      FIG. 5  is a cross-sectional view of the assembled prosthetic acetabulum in accordance with an alternative embodiment of the present invention. 
           [0029]      FIG. 6  is an isolated perspective view of the supporting plate of the prosthetic acetabulum of the present invention. 
           [0030]      FIG. 7  is a cross-sectional view of an anchoring screw as used in the prosthetic acetabulum assembly of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0031]    Referring to  FIG. 1 , there is shown the prosthetic acetabulum apparatus in accordance with the preferred embodiment of the present invention. The prosthetic acetabulum apparatus of the present invention includes a supporting plate  1 , a spacer  2 , a cup  3  and an anchoring screw  4 . The spacer  2  has a distal area  21  received within a proximal area  16  on the supporting plate  1 . The cup  3  has an annular external area  33  received with annular tapered interior area  24  of the spacer  2 . 
         [0032]    The supporting plate  1  is suitable for being implanted into the acetabular cavity. The supporting plate  1  has a collar  17  extending at one end thereof. The collar  17  has a plurality of tapped holes  18  formed therethrough. The proximal area  16  is a tapered annular area which has a wide diameter at the collar  17  at the end of the supporting plate  1  and a narrow diameter inwardly of the collar  17  of supporting plate  1 . A plurality of legs  13  and  15  extend outwardly of the collar  17 . The supra-acetabular legs  13  extend at an acute angle with respect to each other. A plurality of eyelets  14  are formed through the supra-acetabular legs  13 . The leg  15  has an obturator hook formed inwardly therefrom. The leg  15  extends outwardly of the collar  17  on a side of the support plate  1  opposite the supra-acetabular legs  13 . Internal legs  11  extend inwardly at the opposite end of the supporting plate  1  from the collar  17 . Internal legs  11  have eyelets  12  formed therein. Each of the internal legs  11  has a lug formed thereon. A bearing ring  10  is formed at the end of the supporting plate  1  opposite the collar  17  and extends annularly therearound. 
         [0033]    The spacer  2  has a ring  20  at a first end thereof and a distal area  21  at an opposite end thereof. A peripheral collar  22  extends around the spacer  2  between the ring  20  and the distal area  21 . The distal area  21  is annular tapered external area. This annular tapered external area serves to fit complementarily within the tapered interior of the proximal area  16  of supporting plate  1 . The peripheral collar  22  is configured so as to fit against the collar  17  during assembly. The peripheral collar  22  has a plurality of eyelets  23  formed therethrough. The peripheral collar  22  extends for at least more than one half the circumference of the spacer  2 . The plurality of eyelets  23  are arranged in side-by-side relationship along the peripheral collar  22 . As such, as the spacer  2  is rotated relative to the to the supporting plate  1 , the eyelets  23  can align with the plurality of tapped holes  18  so as to allow for the fine adjustment of the spacer  2  with respect to the supporting plate  1 . The ring  20  has an annular tapered exterior surface thereon. The annular tapered exterior surface of ring  20  tapers so as to have a wide diameter at the first end of the spacer  2  and a narrow diameter inwardly of this end of the spacer  2 . 
         [0034]    The cup  3  has a hemispherical cavity  31  formed therein. A surface  30  projects outwardly of the equatorial ring  32  of the cup  23 . The equatorial ring  32  extends around more than one-half the circumference of the cup  3  between the projection  30  and the opposite end. The tapered external area  33  is formed so as to have a wide diameter adjacent to the equatorial ring  32  and a narrow diameter at the end of the cup  3 . This tapered exterior area  33  is configured to fit within the tapered interior area  24  of the spacer  2 . This arrangement allows fine adjustment between the cup  3  and the spacer  2  by simple rotation of the cup  3  with respect to spacer  2 . As such, the arrangement of these tapered areas of the supporting plate  1 , the spacer  2  and the cup  3  creates a Morse-tapers system whereby the proper adjustment of the components can be established. 
         [0035]    The anchoring screw  4  has a particular configuration as illustrated in detail in  FIG. 7 . The anchoring screw  4  is configured so as to fix the supra-acetabular legs  13  to the bone material in the hip. The anchoring screw  4  can extend through the eyelets  14 . Each of the eyelets  14  has a generally frustoconical wall. The head of the anchoring screw  4  is configured so as to be juxtaposed against frustoconical wall of the eyelets  14 . The arrangement of the eyelets  14  allows the surgeon to properly choose an appropriate location for the anchoring of the supporting plate  1  onto the acetabulum area. 
         [0036]    Fastening screws  5  are provided so as to join the spacer  2  in a desired location relative to the supporting plate  1 . The fastening screws  5  will extend through at least some of the eyelets  23  on the peripheral collar  22  of spacer  2 . The fastening screws  5  can then join with the supporting plate  1  by entering the select ones of the tapped holes  18 . As can be seen, when the spacer  2  is properly rotated, at least some of the eyelets  23  will align with at least some of the tapped holes  18 . The fastening screws  5  can then be placed through the eyelets  23  and joined to the tapped holes  18 . Each of the eyelets  23  on the peripheral collar  22  of spacer  2  have a frustoconical wall. Each of the fastening screws  5  will have a head with a surface that will be juxtaposed against such frustoconical walls when the fastening screws are properly installed. 
         [0037]      FIG. 2  illustrates the manner in which the tapered surface of each of supporting plate  1 , the spacer  2  and the cup  3  are joined together so as to form the Morse-tapers system. The support plate  1  has an annular internal tapered area formed at the proximal area  16 . As can be seen, the wide diameter of the tapered internal wall of the proximal area  16  is at one end of the supporting plate  1 . The narrow diameter of the annular tapered internal area  16  is inwardly of this end of the support plate  1 . The spacer  2  has its distal area  21  with a similarly tapered outer surface as the tapering of the internal area of the proximal area  16  of support plate  1 . As can be seen, this annular externally tapered area  21  has a narrow diameter at one end of the spacer  2  and a wide diameter inwardly of this end of the spacer  2 . As such, when the spacer  2  is fitted within the support plate  1 , the tapered surfaces will be juxtaposed against each other. The spacer  2  can then be suitably rotated so as to achieve its proper angular orientation with respect to the support plate  1 . 
         [0038]    The support plate  1  is illustrated in  FIG. 2  as having a tapered area  24  at an opposite end of the spacer  2 . This tapered interior area  24  will have a wide diameter at the opposite end of the spacer  2  and a narrow diameter inwardly therefrom. The cup  3  has an annular tapered external area  33  formed along an outer surface thereof. This annular tapered external area  33  will have a narrow diameter spaced away from the equatorial rim  32  and a wide diameter adjacent to the equatorial rim  32 . It can be see that the equatorial rim  32  will reside against the opposite end of the spacer  2  when the cup  3  is installed into the interior of the spacer  2 . The tapered surfaces will allow a proper rotation of the cup  3  with respect to the spacer  2  so as to achieve further fine adjustment of the cup  3  with respect to the spacer  2 . 
         [0039]      FIG. 3  shows, in greater detail, how the proximal area  16  of the support plate  1  is tapered by an angle  16   a . The annular tapered external area at the distal area  21  of spacer  2  is tapered by an angle  21   a . The annular tapered internal area  24  of spacer  2  is tapered by an angle  24   a . The annular tapered external area  33  of the cup  3  is tapered by an angle  33   a . In the present invention, the angle of taper  16   a  will be equal to the angle of taper  21   a . Similarly, the angle of taper  24   a  will be equal to the angle of taper  33   a.    
         [0040]      FIG. 4  shows how the support plate  1  receives the spacer  2 .  FIG. 4  also shows that the cup  3  is received within the interior of the spacer  2 . The cup  3  has a hemispherical cavity  31  formed in an interior thereof. The supra-acetabular legs  13  are illustrated as extending outwardly on one side of the support plate  1  at an acute angle with respect to each other. The leg  15  with the obturator hook extends outwardly on an opposite side of the support plate  1  from the supra-acetabular legs  13 . 
         [0041]      FIG. 5  shows an assembly of the components of the present invention. In  FIG. 5 , the support plate  1  has the supra-acetabular legs  13  extending outwardly therefrom. The leg  15  with the obturator hook extends outwardly on an opposite side of the support plate  1 . The internal legs  11  are formed so as to extend inwardly at one end of the support plate  1 . Eyelets  12  are formed through the internal legs  11  so as to allow for the receipt of anchoring screws  4  therein. 
         [0042]    The spacer  2  is received within the proximal area  16  of the support plate  1 . The cup  3  is received within the interior of the spacer  2 . The equatorial rim  32  resides against the end of the spacer  2  so as to provide support therefore. Insert  6  is received within the hemispherical cavity  31  of the cup  3 . The insert  6  can be of the nature of a polymeric insert which moves freely within the hemispherical cavity  31 . This insert  36  has a hemispherical cavity  60  formed therein. Hemispherical cavity  60  is suitable for the receipt of a head of a prosthetic femoral element. 
         [0043]      FIG. 6  is an isolated view of the support plate  1 . As can be seen in  FIG. 6 , the support plate  1  has supra-acetabular legs  13  extending outwardly therefrom. Eyelets  14  are formed in the legs  13 . The collar  17  extends around an end of the support plate  1 . The internal legs  11  each have an eyelet formed therein. The leg  15  with the obturator hook is formed at an opposite side of the collar  17  from the supra-acetabular legs  13 . 
         [0044]      FIG. 7  illustrates the anchoring screw  4  which allows the surgeon to perform the adjustment of the positioning of the support plate  1  in the bone cavity. The anchoring screw  4  is preferably grooved in order to facilitate its installation. The anchoring screw  4  has a threaded distal portion  40  having a tip  41  and a spongy outer thread  42 . The anchoring screw  4  has a proximal portion  43  having the shape of a cylinder with a tapped channel  44  extending in an axial direction thereof. A threaded piston  45  can be screwed into the tapped channel  44 . The threaded piston  45  is provided with a head  46  and a tapped well  47  for receiving a locking counter-screw  43 . The threaded piston  45  allows for the adjustment of the height to the bearing surfaces of the support plate  1 . The counter screw  48  ensures the proper holding of the support plate  1 . The threaded piston  45  can be adjustably inserted into the tapped channel  44 . The various threads can have, preferably, reversed pitches. 
         [0045]    After anchoring the distal portion  40  into the bone material, the screwing or unscrewing of the piston  45  allow for the adjustment of the height of the head  46 . This serves as a support for the supporting plate  1  and, more particular, for the internal legs  11 . After having determined the adequate length of insertion of the piston  45  in the channel  44 , the supporting plate  1  is made integral by means of the locking counter-screw  48  as screwed into the well  47 . The proximal portion  43 , the piston  47  and the counter screw  48  are each provided with an operating die, such as an axial hollow die. 
         [0046]    It should be noted that the fastening screws  5 , the locking counter-screw  48 , as well as the fastening screws (not shown) of the external supra-acetabular legs  13  have heads with a curved, hemispherical profile. This head has a bearing surface thereon. The various components  22 ,  34 ,  11  and  13 , respectively, have eyelets  23 ,  35 ,  12  and  14  thereon. Each of these eyelets have a countersink with a profile complementary to the head of the various screws. As such, the orientation of the screws, along with the various components, can be achieved along a desired axis. The base of the proximal portion  43 , i.e. the area of connection with the distal portion  40  is truncated. The outer thread  42  is extended into it so as to achieve a safe anchoring. 
         [0047]    The foregoing disclosure and description of the invention is illustrative and explanatory thereof. Various changes in the details of the illustrated construction can be made within the scope of the appended claims without departing from the true spirit of the invention. The present invention should only be limited by the following claims and their legal equivalents.