Patent Application
20080004711
a. A posterior and medial view of an external proximal femoral prosthesis, respectively.
b. A detail description of an external proximal femoral prosthesis, in both posterior and medial views, respectively.
The present invention is directed to an external proximal femoral prosthesis for THA. Referring to
Referring to drawings, a preferred embodiment of left femoral neck-locking component is illustrated in
In general, the diseased or fractured femoral head can be resected at the level below the head; most preferably a resection is just below the head. The intact neck and the tronchantic bed of femur could be sculpted by ancillary equipment (not shown). The hollow shell would be tightly anchored onto the outside of the retention neck, the trochantic bed and calcar of the proximal femur. An important feature of the overall design of implantation, which is discussed in greater detail below, is to allow for less cutting the femoral neck and ideal installation of prosthesis on outside of remnant of proximal femur.
In a more general embodiment, as described in
As detailed of a preferred embodiment in
As described in
Said neck 60 of said shell 50 possesses a circumferential object with a longitudinal center 62, which is coaxial with a longitudinal axis of said shell 50. Said neck is rigidly jointed on a shoulder 73 of said cup 70 (integral with said hollow cup and necks). A major function of said neck is mainly to adapt into a cavity of a prosthetic head, to provide a various length of prosthetic neck to fit into a different profile of patient and to allow a central screw pass through and engage upon cortical bone on lateral side of proximal femur. Since articulation and acetabulum components used are not part of the present invention, they may be of any commercially available kind, which is suitable. For instance, a prosthetic head used could be one from either total head resurfacing technique or existing total hip arthroplasty(stem one) technique. More particularly, a shape and diameter of the cavity as well as materials of prosthetic head may be matched, which are varied from application to application, if necessary or desired.
As defined in
Said conical section 64 of neck has an uninterrupted outer surface and is configured frusto-conical, which is continuously tapered from a proximal end of conical section 64 to the up edge of said base section 65 by a way of increasing diameter, in order to mate with internal structures of a defined socket of said articulation component (a prosthetic head) used, in term of its length, diameter, and tape angle, if it has, as well as other textures on its body.
Said base section 65, in general, has a cylindrical shape with a predetermined length, and diameter. It forms a transition zone between said conical section 64 of neck and said shoulder 73 of said cup portion 70, In a preferred embodiment, a variation on the length of said base section 65 is effective to make distance adjustment, in order to allow total prosthetic height fitting into each individual profile of patient's femur, in term of a proper leg length and a range of swing angle of prosthesis installed in a particular patient. A preferred range of said length of said base section is about 2-10 mm.
Said interior feature of said neck possesses a bore 67 at the center of said neck, which is along said longitudinal axis 51 of said shell. Said bore 67 has been configured a structure selected from following options:
In a preferred embodiment, a through-hole 681 serves a pass for central screw going through it from proximal side to lateral direction and engaging toward cortical bone in lateral shaft (for self-tapping screw 923A) or the lateral side plate 121 (for regular thread 923B), in case a patient has a weak or thin lateral shaft, respectively. Said hole comprises a first cylindrical section 682 with a first diameter at the proximal part and a second cylindrical section 684 with a second diameter thereafter. Said second diameter here is less than said first diameter. Such a structure forms a stage 683 inside said bore. A deepness of said first cylindrical section 682 essentially is equal or slightly larger than a length of abutment (head) at proximal end of a central screw 90. Said stage 683 is a “site packet” of said central screw 90, while anchoring said shell.
In another preferred embodiment, said bore 67 is a hole with internal thread, which matches the thread of a central screw. Said central screw has inserted from lateral side of femur, passed through a bore on said lateral plate 121 and intra-medullar tissue and engaged on said hole. If do so, it would connect said shell with said lateral plate 121 and fasten it on proximal femur. Such an option could be applied in a case of that patient has cortical bone of poor quality, particularly in lateral side of the femur.
Said cup 70 generally has asymmetric bell shape with a circumferential wall 74, which has a typical thickness of wall at a range from 0.5 to 4 mm, from its section to section. Said cup 70 has an inner surface and an outer surface of said hollow wall, which have features selected from the group consisting of the following:
Said cup 70 has a structure, which comprises of three sections: a shoulder 73, a circumferential wall 74 and a peripheral collar 75, respectively. It is important to emphasize that since an inner profile of said cup closely matches that of the proximal femur, its orientation once installed would match the orientation of the proximal femur( nature hip). So said cup has orientation of lateral, anterior posterior and medial facet, respectively, corresponding to those in proximal femur.
Said shoulder 73 forms an arch-wise, bowl-shape ending wall at proximal end of said cup, which rigidly connects and supports said neck 60 of said shell, and serves as a smooth transition zone between neck and the body of said shell.
Said circumferential wall 74 possesses an inner contour 741 configured to seat against exterior surfaces of the remnant neck of proximal femur 12. Its inner dimension has a plurality of transverse cross sections along a view of said longitudinal axis, which is closely matching the exterior transverse cross contour of a sculpted femoral neck 12. Said wall has been hollowed by a plurality of apertures 742. The shape of said apertures has configured open windows selected from the group consisting of: a plurality of round hole, elongated round hole and others thereof. Said apertures 742 on said wall are well distributed on area around posterior and anterior face of said wall 74 and but not in a middle section (lateral and medial side) between them, which is considered as a major area where loading stress is distributed.
Said collar 75 of said cup 70, in principle, is radially, outwardly, uninterrupted flaring from a distal area of said wall 74 at a lower latitude( the end), particularly in lateral, posterior and medial direction, respectively. More particularly, in said medial direction, said collar is continually elongating toward calcar region of femur and forms “tongue-like” shape collar 754. In more detail, the collar around lateral direction 751 covers area between the lateral root of the femoral neck toward greater trochanter and one around the direction of posterior of said wall covers area between the posterior root of the neck and trochantic crest, so called trochantic bed or groove 753. Said collar around the direction of medial of said cup covers area between the medial root of neck and femoral calcar, called calcar collar, which has an elongated “tongue-like” shape and more flat (less sloped) than other side of collar. The section of said collar will embed into the outer surface of femoral calcar, which is considered as an area with higher thickness and hardness in femoral bone and loading more compressive stress. So said collar 75 of said hollow cup 70 possesses a shape, which closely follows the anatomical contours of both trochantic bed (groove) and femoral calcar on the proximal femur, respectively. Such a structure would offer the prosthesis a broader area to load maximum compression stress from head in harder surface. It is important to emphasize that such a collar 75 only intends to cover a groove area and area of proximal calcar and avoids covering the greater and lesser trochanters. In order to do so, particularly, a feature of collar near lower lesser trochantic area is there is a bow section 761, at which said collar is bowed slightly, smoothly and upwardly. A typical shape of anterior facet of the cup is close to match with the surface of the “cliff-like” anterior side of femoral neck and shaft.
Said distal portion 80 serves a function of stabilization of said shell on femoral remnant. In first embodiment of the distal portion, it possesses at least one elongated stem 811, by way of example and not by way limitation, which is extended from and is integral with said inner wall of said cup 70 at lower attitude. The preferred number of stems is two. Thereby, the first stem 811A of said distal portion preferred located at area near lateral root of femoral neck. The second one 811B preferred located at area between a posterior root of femoral neck and lesser trochanter.
A longitudinal axis of the stem 811 is perpendicularly to a bottom plane of said cup 70. A length of said stems is selected from the group consisting of, when said cup installed,
There can be texture on outside surface of said stem 811. Such a texture 812 could be saw-tooth like ribs, spike, or protrusions on outside lateral surfaces.
Said distal portion 80, in 2nd preferred embodiment, possesses at least one screw-threaded hole (not shown) by way of example and not by way limitation, on said collar area of said cup 70 (of, but not on, greater trochanter and lesser trochanter). More preferred arrangement of said threaded holes would be at least two of them in separated location. The first one is preferred located at area near the lateral root of femoral neck. The second one preferred located at area of said collar between the posterior root of femoral neck side and lesser trochanter. Accordance of this configuration, a function of the thread hole(s) serves a base for the thread pin(s). So said elongated pin with thread at its proximal end, in a preferred embodiment, could couple with an anchoring rivet to penetrate into either intra-medullar tissue of femur and screw through the hole. In another preferred embodiment, the end section of said threaded pin could further passes through the lateral cortices and joint with or inserted into the bore on said lateral plate.
In additional preferred embodiment of the distal portion, a function of the threaded hole(s) and serve for accepting said threaded fastening screw from lateral side of femur, which passes through bores on said lateral plate, intra-medullar tissue and engages on such holes. Such a connection between said shell and said lateral plate would increase a stability of shell implanted against large amount of stress and provide a broader application of the prosthesis, particularly in concerns of differing bone quality of femur of various patients.
Said shell 50, as entire piece, is made of a biocompatible materials selected from the group consisting of stainless steel, Cobalt-Chrome(Co—Cr), Cobalt-Chrome-Molybdenum (Co—Cr—Mo), Titanium (Ti) and its alloys, ceramics, composite materials and their combinations.
Continuing still further, in accordance with additional principles and teachings of the present invention, an unique and novel structure of said tension anchor components has configured a means selected from the group consisting of: thread engaged fasten means, endo-expandable anchoring device; lateral means 121 and their combinations.
Thread engaged fasten means comprises, basically of a set of screws: a central fasten screw 90, and collar fasten pins which serves a function of connecting and fastening said femoral prosthesis on the remnant of the shaped proximal femoral bone.
Said central screw 90, in a preferred embodiment, comprises a flanged cylindrical head in its proximal end 921 with a proper length and a X shaped recess for tool, such as drive wrench, distal end 922 with a thread and bolt section 923 extended the proximal end to distal end. A distal end of screw with smaller diameter than one of bolt section has a type of thread selected from the group consisting of: a typical thread for self-tapping screw 923A and a regular thread 923B.
In a preferred embodiment of said central screw, said self-tapping screw 923A is insertable through said hole 681, which could couple with one of option of endo-expandable anchoring means, seats on said stage 683 on said neck, then self-drills into a pre-drilled hole of intra-medullar tissue and further engages into lateral cortical bone of the femoral shaft.
In the meantime, said endo-expandable anchoring means would expand during screw engaging. Thereof it firmly fastens said shell into the sculpted remnant of proximal femur. Said screw is made of materials selected from the group consisting of biocompatible materials and bioabsorbable materials.
In another preferred embodiment of the threaded screw, Said screw 923B with a regular thread is insertable through said hole 681, seats on said stage 683 on said neck, which could couple with one of option of endo-expandable anchoring means, then passes through a pre-drilled hole of intra-medullar tissue and engages a threaded bore 125A in said lateral plate on lateral side of femur. In the meantime, said endo-expandable anchoring means would expand during the screw engaging. Thereof it connects said shell and said lateral plate together and firmly fastens said shell into the sculpted remnant of femur. Said screw being made of biocompatible metal materials or bioabsorbable materials.
In another additional preferred embodiment, said screw 923B with a regular thread is insertable through said through-hole 125A of said lateral plate 121, then couple with one of option of endo-expandable anchoring means, and passes through a bore in intermedullar bone of proximal femur, then further engages said threaded bore of said neck of said shell. Thereof it connects said shell and said lateral plate together and firmly fastens said shell into the sculpted remnant of femur, said screw being made of biocompatible metal materials.
Said collar pins, in a preferred embodiment, comprises proximal end with a thread on it, which fits into thread of hole in said collar from a side of said cup, and elongated bolt with a smaller diameter thereafter, which penetrates into said rivet and then intra-medullar tissue. There are at least two collar screws needed in lateral and posterior position of said shell, respectively. By way of the best example, if both said collar pins and said central screw installed, there is a angle between them and therefore, they forms an wedged structure against pull out of said shell from “site”.
Said collar screws, in another preferred embodiment, comprises a flanged head in its proximal end with a X shaped recess for tool, such as drive wrench, distal end with a thread and bolt section extended the proximal end to distal end. Said screw passes through bore of said lateral plate and intra-medullar tissue and engages into threads in said collar, in order to fasten said shell. There are at least two collar screws needed in lateral and posterior position of said shell respectively. By way of the best example, if both said collar screws and said central screw installed, there is a angle between them and therefore, they forms an wedged structure against pull out of said shell from “site”.
In a more general embodiment, said endo-expandable anchoring means is a set of a device, which may be axially compressed along longitudinal axis of said fastening means and thereby radially expanded by cooperating with a movement of a thread engaging/press-in member, in order to enhance a pull-out resistance of fastening means and reduce stress intensity on object, for example such intra-medullar tissue of bone. Said endo-expandable anchoring means basically having a configuration selected from the group consisting of:
In the first preferred embodiment, seen in
In the second preferred embodiment, seen in
In a third preferred embodiment, said expandable member defines a toggle wing anchoring means 130 (seen in
The pair(s) of toggle wing members 132 are pivotally mounted upon the lugs 131B and 131C of said nut member, in order to move said toggle wing around positions between said first inoperative positions at which said pair(s) of toggle wing members are parallel contracted with respect to each other so as to be disposed substantially parallel to said longitudinal axis of said screw and said second operative positions at which said pair of toggle wing members are fully radially expanded so as to, together, achieve a substantially V-shaped, or even a larger angled configuration, if necessary or desired. In preferred embodiment, said nut couples with screw 923A or 923B, and expands, when said screw engages toward its target.
By way of example, a preferred pairs of said toggle wing is one or two pairs, or more. A preferred shape of said toggle wing describes a way for better penetration ability into intra-medullar bone during its expansion, for example, a spike-like tip, bards on the side edge of the wing and v-shaped transverse of the wing in axial direction.
In particular, it is to be noted, for example, that such structures have demonstrated the fact that the expandable member, has been constructed in accordance with the principles and teachings of the present invention, and has broader contact area with tissue around and has enhanced pull-out resistance of said fastening component, when it is in the position, regarding to a conventional screw fastening device, without rising stress intensity of surrounding medullar tissue.
It should be emphasized that said screw above has a same fashion preferred in the case of fasten means. In other words, the thread of screw could be either a typical thread for self-tapping screw 923A and a regular thread 923B.
As will now be apparent to those skilled in the art, said expandable member could be made by biocompatible metal materials or bioabsorbable materials. In a preferred embodiment, said expandable member is made by bioabsorbable materials, because most of concerns of fastening said prosthesis in present invention is its early stage fixation. A more preferred embodiment is that said endo-expandable anchoring means is bio-absorbed by body thereafter.
The lateral side plate preferably elongated 121 comprises: a medial surface 122 attachable to the lateral aspect of the shaft of the proximal femur, a generally superior first end, a generally inferior second end along a lateral longitudinal axis extending between the first and second ends and a plurality of spaced apertures (see, in general,
The plate 121 is preferably bowed along the longitudinal axis anterior/posteriorly from the first end to said inferior end, in order to match the bowed lateral shape of the proximal shaft. The amount of bow may vary depending on patient anatomy, etc. In principle, it forms a generally S-shaped curve for the right femur and a generally reverse S-shaped curve for the left femur as will now be apparent to those skilled in the art.
A medial surface 122 has a plurality textures on it selected from the group consisting of projections, spikes, rough surface, ribs and others. For example, the rib are tapered as they extend radially inwardly, so they terminate in a narrow edge and a plurality of the projection in form of spikes extending generally axially inwardly form inner surface of the plate and terminating in a relatively sharp point. Further more, whereby, the projections are barb-like and have pointed ends facing the head. These projections or barbs are designed according to the so called file cut for coarse files (wood working files), if necessary or desired.
In a preferred embodiment, the plate 121 preferably has a plurality of spaced apertures 125A, therethrough for allowing screw 923B for engaging said neck of said shell and aperture 125C and 125D for accepting stems 811A and 811B from said shell, respectively, to secure the said plate 121 with said shell. In addition there is a plurality of apertures therethrough for allowing screws to secure said plate 121 on the lateral aspect of the shaft of the proximal femur (see, in general,
In another preferred embodiment, the plate 121 preferably has a threaded aperture thereby for accepting screw 923B from said neck of said shell and a plurality of spaced apertures 125C and D accepting stems 811A and 811B from said shell, to link the said plate 121 and said shell together and secure them on the proximal femur. In addition there are a plurality of apertures therethrough for allowing screws to secure said plate 121 on the lateral aspect of the shaft of the proximal femur.
The specific dimensions of feature of any devices in the present invention can be readily varied depending upon the intended application, as will be apparent to those of skill in the art in view of the disclosure herein.
The foregoing disclosure and description of the invention are illustrative and explanatory thereof, and various changes in the size, shape, materials, arrangement and procedure, as well as in the details of the illustrated construction may be made without departing from the spirit of the invention. It is to be understood that the invention is not limited to the particular embodiments described above, but is solely limited by the scope of the appended claims.
