Artificial hip joint prosthesis

The present invention is related to an artificial hip joint prosthesis. Also, it can be decreased the time of medical treatment and administered medicine easily. Besides, it can be applied an Oriental having small pelvis.

TECHNICAL FIELD

The present invention relates, in general, to an artificial hip joint prosthesis and, more particularly, to an artificial hip joint prosthesis for connecting a pelvis with a femur, which is improved in its construction.

BACKGROUND OF THE INVENTION

As well known to those skilled in the art, among a number of joints in the human body, the pelvis and the femur can be rotated relating to one another within a predetermined angle. To this end, between the pelvis and the femur, there is intervened a hip joint for connecting the pelvis and the femur with each other in a rotatable manner.

The hip joint may be adversely influenced by stand-up walking, or may be injured by inherited factors, due to excessive exercise or through an accident. In the case that the hip joint is adversely influenced or injured, pain is caused at a boundary region where the pelvis and the femur are connected with each other. In order to replace the injured hip joint and ensure smooth rotation of the hip, an artificial hip joint prosthesis is provided. The artificial hip joint prosthesis has mainly been researched at the West with the progress in medical science, and therefore, fabricated in conformity with a body structure of a Westerner who has a larger physique and bone size than an Oriental.

Hereafter, several of the conventional artificial hip joint prostheses disclosed in the art will be briefly described.

The conventional artificial hip joint prosthesis shown inFIG. 16comprises a pelvis-contacting element110fastened to a pelvis, a stem150fastened to a femur, a head120integrally formed at a distal end of the stem150, a flexible joint member130which is coupled to the pelvis-contacting element110and in which the head120is accommodated in a freely rotatable manner, and a release prevention member160for preventing release of the flexible joint member130from the pelvis-contacting element110.

The release prevention member160is meshed with the flexible joint member130along a circumferential direction through engagement between prominences and depressions (see the section ‘A’). An inner surface of the pelvis-contacting element110is defined with a groove170, and the release prevention member160is formed with a projection161which is engaged into the groove170.

The conventional artificial hip joint prosthesis constructed as mentioned above suffers from defects in that, since the flexible joint member130and the release prevention member160are formed as separate component parts, not only the number of component parts is increased, but also appreciable wear may take place due to rotation occurring therebetween.

Also, because the flexible joint member130and the release prevention member160are decreased in thickness at a region wherein they are meshed with each other through engagement between the prominences and the depressions, when the artificial hip joint prosthesis is used for an extended period of time, the region cannot but be weakened. Further, when the release prevention member160and the flexible joint member130are meshed with each other, since a height of a release preventing configuration of the release prevention member160is substantial, the stem150integrally rotated with the head120is likely to come into collision with the release prevention member160. Therefore, if this collision occurs, as the rotation of the head120is interfered with, inordinate force can applied to the pelvis-contacting element110, whereby the possibility of the pelvis to be adversely influenced is increased. Moreover, even with the flexible joint member130inserted into the pelvis-contacting element110, positional fluctuation occurs due to play existing between the release prevention member160and the pelvis-contacting element110and the flexible joint member130and play existing between the flexible joint member130and the head120, so that collision may easily occur between respective component parts.

Another conventional artificial hip joint prosthesis as shown inFIG. 17also has the flexible joint member130ainserted into the pelvis-contacting element110a. The flexible joint member130ais formed with six coupling portions160athrough160fwhich are separated one from another in the circumferential direction and each of which is defined with a groove161a.

In this type of conventional artificial hip joint prosthesis, because the six coupling portions160athrough160fare formed separately one from another, flexibility of the flexible joint member130ais increased. However, when it is necessary to disassemble the flexible joint member130afrom the pelvis-contacting element110a, all of the six coupling portions160athrough160fshould be simultaneously and resiliently contracted radially inward. Hence, where it is necessary to perform an operation again for the hip joint after decoupling the flexible joint member130aand the pelvis-contacting element110afrom each other, inconvenience is caused.

Furthermore, in order to ensure decoupling of the flexible joint member130afrom the pelvis-contacting element110a, the groove161amust be defined on each of the coupling portions160athrough160fin the circumferential direction. Thus, when the head (not shown) is, inserted into a flexible joint member130aof increased size and rotated, the stem (not shown) is apt to collide with the flexible joint member130a.

Still another conventional artificial hip joint prosthesis as shown inFIG. 18also has the head120b, which is integrally formed at the distal end of the stem150b. After the flexible joint member130bis inserted into the pelvis-contacting element110b, the head120bis inserted into the flexible joint member130balong with a support piece162which is placed around the head120b. Then, a fixed locking piece160bis fitted between the pelvis-contacting element110band the support piece162to allow the support piece162to be biased against the head120band thereby properly support the rotation of the head120b. By the cooperation of the fixed locking piece160bwith the support piece162, release of the head120band flexible joint member130bfrom the pelvis-contacting element110bis prevented.

Nevertheless, the conventional artificial hip joint prosthesis having been just described above encounters a problem in that, after the head120bis inserted into the flexible joint member130b, there exists a space C between the flexible joint member130band the fixed locking piece160b, in which the support piece162can be moved, whereby collision may still occur between the head120band the flexible joint member130b. Also, since the support piece162should be separately prepared, the entire manufacturing procedure is complicated. Further, since the increased number of component parts, that is, the flexible joint member130b, the fixed locking piece160band the support piece162must be assembled in the pelvis-contacting element10b, assemblability is deteriorated.

The above-described conventional artificial hip joint prostheses additionally have a disadvantage in that, since sizes of the artificial hip joint prostheses are substantial, difficulties are encountered when installing them. In other words, because the region where ends of the pelvis and femur are positioned is narrow, if assembling and disassembling operations are made complicated, difficulties cannot but be encountered when installing the artificial hip joint prostheses. In addition, because the conventional artificial hip joint prostheses are initially developed for Westerners who have large physiques and bone sizes, they cannot be appropriately adapted to Orientals.

Besides, in each of the conventional artificial hip joint prostheses, since the play in which the head can be moved to and for exists, collision frequently occurs between the head and the flexible joint member, whereby drawbacks associated with abrasion and wear of the component parts may be caused.

SUMMARY OF THE INVENTION

Accordingly, the present invention solves the above problems occurring in the prior art. An, object of the present invention is to provide an artificial hip joint prosthesis that can be more easily installed utilizing a shorter installation time.

Another object of the present invention is to provide an artificial hip joint prosthesis which can be optimally adapted even to Orientals having relatively small physiques and bone sizes.

Another object of the present invention is to provide an artificial hip joint prosthesis which can minimize interference and ensure its smooth rotation, thereby preventing the pelvis and femur of the human body from being injured.

Still another object of the present invention is to provide an artificial hip joint prosthesis which allows assembly and disassembly of component parts to be easily performed and which minimizes radial movement of a rotating head so that collision does not occur between the component parts and drawbacks associated with abrasion and wear of the component parts are not caused, while release of the head is properly prevented.

Yet still another object of the present invention is to provide an artificial hip joint prosthesis which is less complex to manufacture while maintaining structural integrity, thus reducing manufacturing costs.

In order to accomplish the above objects, the present invention provides an artificial hip joint prosthesis installed between a pelvis and a femur to allow the femur to be rotated relative to the pelvis, comprising: a pelvis-contacting element fixed to the pelvis and having a truncated hollow sphere-shaped configuration; a stem fixed to the femur; a head integrally coupled to a distal end of the stem and having a truncated sphere-shaped configuration; and a flexible joint member interposed between the pelvis-contacting element and the stem to accommodate and rotatably support the head, the flexible joint member capable of being resiliently deformed outward and inward in a radial direction to be coupled to and decoupled from the pelvis-contacting element along with the head.

Here, the flexible joint member may comprise a body part having a configuration of a hollow hemisphere; a resilient part formed at an entrance of the body part to have a predetermined thickness, the resilient part possessing a ring-shaped configuration; and a depressed part (also known hereinafter as a middle part) depressed radially inward by a predetermined depth between the body part and the resilient part to extend at least partially in a circumferential direction.

At this time, for providing proper elasticity to the resilient part, it is preferred that the depressed part is formed on an outer surface of the flexible joint member to have the predetermined depth and extends in the circumferential direction.

At least one through-hole is defined through the depressed part. The through-hole is defined in the form of a slot which is rounded at both ends thereof so that cracks are not formed in the depressed part due to a stress generated in the through-hole when the resilient part undergoes contraction and expansion. Also, it is preferred that a pair of through-holes are defined through the depressed part such that they are opposite to each other.

A pair of slits are defined in the resilient part at regions corresponding to the through-holes, such that the resilient part is divided into a pair of unit resilient portions which are separated by a predetermined distance and symmetrical with each other.

A pair of flattened portions are formed on an outer surface of the resilient part at regions corresponding to the slits each to extend through a predetermined angle in the circumferential direction.

Preferably, a pair of decoupling grooves are defined on the outer surface of the resilient part to be aligned on a line which is orthogonal to another line connecting the slits and thereby spaced apart from the slits by 90° in the circumferential direction, so that the flexible joint member can be decoupled from the pelvis-contacting element by pressing radially inward the resilient part in the decoupling grooves. The pair of decoupling grooves serve as tool passage openings so that a tool can be placed between the pelvis-contacting element and the flexible joint member when the flexible joint member is coupled to the pelvis-contacting element.

Projecting ribs are formed on one of an inner surface of the pelvis-contacting element and the outer surface of the resilient part, and engaging grooves in which the projecting ribs are to be engaged are defined on the other of the inner surface of the pelvis-contacting element and the outer surface of the resilient part. By this feature, it is possible to securely couple the pelvis-contacting element and the flexible joint member with each other.

At this time, it is preferred that the projecting ribs project radially outward from the outer surface of the resilient part and extend in the circumferential direction, and the engaging grooves are defined adjacent to an entrance of and on the inner surface of the pelvis-contacting element and have a preselected depth.

In order for ensuring easy decoupling of the flexible joint member from the pelvis-contacting element, it is preferred that each projecting rib is formed in a manner such that its height is gradually decreased from the decoupling groove toward the slit.

Each projecting rib has a first inclined surface which is inclined downward by a preselected angle when viewed in a direction where the flexible joint member is inserted into the pelvis-contacting element. By this feature, the flexible joint member can be inserted into the pelvis-contacting element with reduced force.

The resilient part is formed to have an outer diameter which is greater than a diameter of the entrance of the pelvis-contacting element, whereby the resilient part is prevented from being released after being inserted into the pelvis-contacting element. The resilient part is formed to have an inner diameter which is less than a diameter of the head, whereby unintentional release of the head from the resilient part is prevented.

An inner edge of each unit resilient portion is formed with a second inclined surface which has an inclination substantially corresponding to a surface curvature of the head to allow easy insertion and removal of the head into and out of the flexible joint member.

A pair of indented portions are defined on an inner surface of the flexible joint member in a manner such that they are diametrically opposite to each other and define a diameter which is greater than the diameter of the head, to ensure smooth insertion and removal of the head into and out of the flexible joint member. The indented portions create spaces of a predetermined size between the flexible joint member and the head when the head is inserted into the flexible joint member. When the flexible joint member is inserted along with the head into the pelvis-contacting element, the indented portions are biased radially inward so that the spaces created between the flexible joint member and the head are removed, to thereby appropriately support the head while preventing the head from being unintentionally released from the flexible joint member.

The flexible joint member has an inner diameter which corresponds to the diameter of the head, to minimize abrasion and wear of the component parts due to collision.

Meanwhile, a plurality of through-holes may be defined through the depressed part in a manner such that they are spaced apart one from another by a predetermined interval. In another embodiment of the present invention, the through-hole may not be defined in the form of a slot so long as a space for ensuring resilient deformation of the resilient part is provided in the flexible joint member and a dummy portion for additionally supporting the head inserted into the flexible joint member is produced in the depressed part.

In still another embodiment of the present invention, it can be envisaged that the projecting ribs project radially inward adjacent to the entrance of and from the inner surface of the pelvis-contacting element and have the preselected depth, and the engaging grooves are defined on the outer surface of the resilient part and extend in the circumferential direction.

DESCRIPTION OF THE INVENTION

Reference should now be made to the drawings, in which the same reference numerals are used throughout the different drawings to designate the same or similar component parts. Hereafter, a first embodiment representative of the present invention will be described in detail, and as for the other embodiments, only the features which are different from those of the first embodiment will be described.

As shown inFIG. 1, an artificial hip joint prosthesis1in accordance with a first embodiment of the present invention is installed between a pelvis8and a femur9to connect the femur9to the pelvis8so that the femur9can be rotated relative to the pelvis8.

As can be readily seen fromFIGS. 2 through 4, the artificial hip joint prosthesis1comprises a pelvis-contacting element10and a stem50which are respectively fixed to the pelvis8and the femur9, and a flexible joint member30which is interposed between the pelvis-contacting element10and the stem50to rotatably connect the pelvis-contacting element10and the stem50with each other.

The pelvis-contacting element10may be formed of a metallic material, for example, stainless steel, alloyed steel, etc. The pelvis-contacting element10is formed to have a configuration of a truncated hollow sphere which has a volume slightly greater than that of a hollow hemisphere. The pelvis-contacting element10is inserted into the pelvis8in a manner such that an entrance10athereof faces the femur9.

Engaging grooves10b(seeFIG. 7) in which projecting ribs44of the flexible joint member30are to be engaged, as will be described later in detail, are defined on an inner surface of the pelvis-contacting element10to have a preselected depth. The engaging grooves10bare positioned adjacent to the entrance10abetween the entrance10aand a center of the pelvis-contacting element10.

The entrance10aof the pelvis-contacting element10is formed to have an inner diameter which is less than a diameter of the flexible joint member30, so that the flexible joint member30accommodated in the pelvis-contacting element can be prevented from being unintentionally released. Due to the fact that a height of the pelvis-contacting element10which is measured from the entrance10ais less than a diameter of the pelvis-contacting element10, it is possible to decrease a relative height of the flexible joint member30. As a consequence, it is possible to manufacture an artificial hip joint prosthesis which can be adapted even to Orientals having relatively small physiques and bone sizes, install the artificial hip joint prosthesis in an easy and convenient manner, and shorten an installation time. Further, as will be described later in detail, since smooth rotation of the head20is ensured and interference between the pelvis-contacting element10and the head20is minimized, it is possible to prevent the pelvis including a cartilage and the femur of the human body from being injured.

The stem50has a long rod-shaped configuration and is fixed to the femur9along a lengthwise direction thereof. The stem50is integrally coupled at a distal end thereof with the head20which is to be inserted into the flexible joint member30. The head20has a truncated sphere-shaped configuration to be freely rotated in the flexible joint member30. The head20is defined with a hole21in which the distal end of the stem50is press-fitted.

The flexible joint member30can be resiliently deformed in radial inward and outward directions. As a consequence, the flexible joint member30can accommodate therein and support the head20so that the head20can be freely rotated, and can be coupled to and decoupled from the pelvis-contacting element10along with the head20.

An outer surface of the flexible joint member30is contoured in conformity with the inner surface of the pelvis-contacting element10to be in surface contact therewith. The flexible joint member30has a resilient part40formed at an entrance thereof. The resilient part40has a diameter which is greater than the inner diameter of the entrance10aof the pelvis-contacting element10. By this fact, after the flexible joint member30is accommodated in the pelvis-contacting element10with the resilient part40resiliently contracted radially inward, the resilient part40can be resiliently expanded again radially outward to prevent the flexible joint member30from being unintentionally released from the pelvis-contacting element10.

As can be readily seen fromFIGS. 5 through 10, the flexible joint member30comprises a body part35, the resilient part40, and the depressed part38(also known hereinafter as a middle part). The body part35has a configuration of a hollow hemisphere. The resilient part40is formed at the entrance30aof the body part35to have a predetermined thickness and possesses a ring-shaped configuration. The depressed part38is depressed radially inward on the outer surface of the flexible joint member30by a predetermined depth to extend at least partially in a circumferential direction between the body part35and the resilient part40.

In this first embodiment of the present invention, the depressed part38is formed on the outer surface of the flexible joint member30in such a way as to continuously extend along the circumferential direction of the flexible joint member30. At this time, it is preferable to determine a depth of the depressed part38so that the resilient part40can be reliably supported by the body part35and the flexible joint member30does not lose its resiliency even though it is repeatedly contracted and expanded.

A pair of through-holes38aand38bare defined through the depressed part38each to extend at least partially in the circumferential direction. Each of the through-holes38aand38bis defined in the form of a slot which is rounded at both ends thereof so that cracks are not formed in the depressed part38due to repeated contraction and expansion. The pair of through-holes38aand38bare defined through the depressed part38such that they are opposite to each other. The through-holes38aand38bare not necessarily defined in the depressed part38.

In order to ensure that the flexible joint member30is resiliently deformed in an easy manner while the flexible joint member30accommodates the head20or is inserted by itself into the pelvis-contacting element10, the resilient part40is divided into a pair of unit resilient portions40aand40bwhich are separated by a predetermined distance H and symmetrical with each other. The pair of unit resilient portions40aand40bare formed by the fact that a pair of slits41aand41bare defined in the resilient part40at regions where the through-holes38aand38bare respectively defined.

A pair of flattened portions42aand42bare formed on an outer surface of the resilient part40at regions where the slits41aand41bare respectively defined, so that each of the flattened portions42aand42bextends through a predetermined angle in the circumferential direction. The flattened portions42aand42bare formed to ensure that the pair of unit resilient portions40aand40bcan be biased toward each other by a small level of force.

In cooperation with the material used for forming the flexible joint member30which may be, for example, silicon, ceramic and thermoplastic synthetic resin, the depressed part38, the through-holes38aand38band the slits41aand41bplay an important role of determining a flexibility of the flexible joint member30which repeatedly undergoes contraction and expansion. If the flexible joint member30has excessive flexibility, coupling of the flexible joint member30with the head20and the pelvis-contacting element10can be easily effected, but the likelihood of the flexible joint member30to be released therefrom is increased. On the contrary, if the flexible joint member30has insufficient flexibility, coupling of the flexible joint member30with the head20and the pelvis-contacting element10cannot be easily effected. Accordingly, the depressed part38, the through-holes38aand38band the slits41aand41bmust be defined to have appropriate contours and sizes.

With the flexible joint member30coupled to the pelvis-contacting element10, in order to allow the flexible joint member30to be decoupled from the pelvis-contacting element10, a pair of decoupling grooves43aand43bare defined on the outer surface of the resilient part40.

The pair of decoupling grooves43aand43bare defined on the outer surface of the resilient part40in a manner such that they are aligned on a line which is orthogonal to another line connecting the slits41aand41bwith each other and thereby are spaced apart from the slits41aand41bby 90° in the circumferential direction. The pair of decoupling grooves43aand43bserve as tool passage openings so that a tool can be placed between the pelvis-contacting element10and the flexible joint member30when the flexible joint member30is coupled to the pelvis-contacting element10. Actually, when performing an operation, as occasion demands, decoupling of the head20formed at the distal end of the stem50from the flexible joint member30or decoupling of the flexible joint member30having the head20inserted therein from the pelvis-contacting element10may be needed or not. In consideration of this fact, in a fifth embodiment of the present invention, the pair of decoupling grooves43aand43bmay be or may not be defined on the outer surface of the resilient part40.

If the flexible joint member30can be easily decoupled from the pelvis-contacting element10, when performing an operation, convenience can be improved and a required time can be shortened. Therefore, it is preferred that the decoupling grooves43aand43bare normally defined on the outer surface of the resilient part40.

Here, the tool for decoupling the flexible joint member30from the pelvis-contacting element10may have a configuration such as of a pair of long-nose pliers. In this case, after placing the respective actuating arms of the pliers into the pair of decoupling grooves43aand43b, by pressing grip portions of the pliers toward each other, the flexible joint member30can be easily decoupled from the pelvis-contacting element10. If a tool is not separately prepared, the flexible joint member30can be decoupled from the pelvis-contacting element10using two screwdrivers.

The projecting ribs44are formed in a manner such that they project radially outward from the outer surface of the resilient part40and extend in the circumferential direction of the resilient part40. When the flexible joint member30is accommodated in the pelvis-contacting element10, the projecting ribs44are engaged into the engaging grooves10bwhich are defined on the inner surface of the pelvis-contacting element10.

When it is necessary to decouple the flexible joint member30from the pelvis-contacting element10, by pressing the resilient part40radially inward in the decoupling grooves43aand43busing a separate tool, the resilient part40is contracted along the circumferential direction. At this time, in the regions where the slits41aand41bare defined to divide the resilient part40into the pair of unit resilient portions40aand40b, since contraction occurs to a slight extent, it is not easy to decouple the flexible joint member30from the pelvis-contacting element10.

To cope with this problem, as shown inFIG. 11, the projecting ribs44are formed in a manner such that their height is gradually decreased from the decoupling grooves43aand43btoward the slits41aand41b. Due to this fact, in the regions where the slits41aand41bare defined in the resilient part40and contraction occurs to a slight extent, the projecting ribs44can be easily disengaged from the engaging grooves10b.

Each projecting rib44has a first inclined surface44awhich is inclined downward by a preselected angle when the surface44ais viewed in a direction along which the flexible joint member30is inserted into the pelvis-contacting element10. Thus, when the flexible joint member30is inserted into the pelvis-contacting element10, due to the presence of the first inclined surface44a, the flexible joint member30can be slidingly guided at the entrance10aof the pelvis-contacting element10. Thereafter, the projecting ribs44are respectively engaged into the engaging grooves10b. At this time, after the engagement is effected between the projecting ribs44and the engaging grooves10b, the projecting ribs44are respectively brought into contact with bottom surfaces of the engaging grooves10bin a vertical direction, whereby the flexible joint member10is prevented from being unintentionally released in a direction opposite to the direction along which the flexible joint member30is inserted into the pelvis-contacting element10(see the enlarged part inFIG. 8).

The resilient part40which is divided into the pair of unit resilient portions40aand40bis formed to have an outer diameter which is greater than a diameter of the entrance10aof the pelvis-contacting element10. By this fact, when the flexible joint member30is accommodated in the pelvis-contacting element10, the pair of unit resilient portions40aand40bare contracted radially inward, and the projecting ribs44are inserted and engaged into the engaging grooves10b, respectively. When the insertion of the projecting ribs44into the engaging grooves10bis completed, the pair of unit resilient portions40aand40bare expanded radially outward so that the projecting ribs44can be held securely engaged in the engaging grooves110b.

Further, the resilient part40, which is divided into the pair of unit resilient portions40aand40b, is formed to have an inner diameter which is less than a diameter of the head20. By this fact, when the head20is accommodated in the flexible joint member30, the pair of unit resilient portions40aand40bare expanded radially outward. When the insertion of the head20into the flexible joint member30is completed, the pair of unit resilient portions40aand40bare contracted radially inward to properly support the head20. At this time, an inner edge of each unit resilient portion40aand40bis formed with a second inclined surface45, which has an inclination substantially corresponding to a surface curvature of the head20to allow easy insertion and removal of the head into and out of the flexible joint member30.

While the flexible joint member30is formed to have the diameter which is substantially the same as the diameter of the head20so that collision does not occur between the component parts and abrasion and wear are not caused, a pair of indented portions46aand46bare defined on an inner surface of the flexible joint member30in a manner such that they define a diameter which is greater than the diameter of the head20, to ensure smooth insertion and removal of the head20into and out of the flexible joint member30. The pair of indented portions46aand46bare defined to be diametrically opposite to each other.

The indented portions46aand46b(seeFIG. 8, where the dotted lines show the indented portions when the flexible joint member30is not placed in the pelvis-contacting element10) create spaces of a predetermined size between the flexible joint member30and the head20when the head20is inserted into the flexible joint member30. When the flexible joint member30is inserted into the pelvis-contacting element10along with the head20accommodated therein, the indented portions46aand46bare biased radially inward. In this way, as the contraction is effected in the flexible joint member30having accommodated therein the head20, the spaces created between the head20and the flexible joint member30due to the presence of the indented portions46aand46bare removed, whereby collision does not occur and the head20can be securely supported in the flexible joint member30.

Hereinafter, a procedure for installing the artificial hip joint prosthesis1according to the present invention, constructed as mentioned above, will be described.

First, a position and a status of the pelvis8into which the pelvis-contacting element10is to be inserted are checked. Then, after fixing the stem150to the femur9, the head20is coupled to the distal end of the stem50.

Next, the head20coupled with the stem50is inserted through the entrance30aof the flexible joint member30. By doing this, as the head20is guided along the second inclined surface45which is formed on the inner edge of each unit resilient portion40aand40b, the head20is inserted into the flexible joint member30which is resiliently expanded outward in the radial direction.

That is to say, the pair of unit resilient portions40aand40bare expanded radially outward due to the presence of the depressed part38, through-holes38aand38band slits41aand41bwhich are formed on or defined in the flexible joint member30. When the head20is completely inserted into the flexible joint member30, the pair of unit resilient portions40aand40bare contracted radially inward.

By the fact that the pair of indented portions46aand46bare defined on the inner surface of the flexible joint member30in a manner such that they define the diameter which is greater than the diameter of the head20, if the head20is completely inserted into the flexible joint member30, the spaces of the predetermined size are created between the inner surface of the flexible joint member30and the outer surface of the head20.

If the coupling of the head20with the flexible joint member30is completed, the flexible joint member30having accommodated therein the head is inserted into the pelvis-contacting element10. Thereupon, due to the presence of the depressed part38, through-holes38aand38band slits41aand41b, the pair of unit resilient portions40aand40bare resiliently contracted radially inward, by which the flexible joint member30is inserted into the pelvis-contacting element10. After the insertion of the flexible joint member30into the pelvis-contacting element10is completed, the pair of unit resilient portions40aand40bare expanded radially outward again.

At this time, the projecting ribs44are respectively engaged into the engaging grooves10b. Since an expansion degree of the flexible joint member is less than a contraction degree thereof, if the flexible joint member30is completely inserted into the pelvis-contacting element10, the spaces created between the outer surface of the head20and the inner surface of the flexible joint member30are removed. Consequently, the head20can be held securely supported in the flexible joint member30, and at the same time, the flexible joint member30can be securely supported in the pelvis-contacting element10. Thereafter, the combination of the head20, flexible joint member30and pelvis-contacting element10which are coupled one with another is positioned in place on the pelvis8.

As apparent from the above description, in the present invention, since it is possible to operatively connect the head20and the pelvis-contacting element with each other by virtue of resiliency of the flexible joint member30which comprises a single component which allows a user to easily and simply manipulate the joint member30, it is possible to conveniently install the artificial hip joint prosthesis and shorten an installation time.

Further, in the present invention, because it is possible to decrease relative heights of the pelvis-contacting element10and the flexible joint member30, the artificial hip joint prosthesis can be easily and conveniently adapted even to Orientals having relatively small physiques and bone sizes. Also, since smooth rotation of the head20is ensured and interference between the pelvis-contacting element10and the head20is minimized, it is possible to prevent the pelvis including a cartilage and the femur of the human body from being injured.

Moreover, in the present invention, the pelvis-contacting element10, the head20and the flexible joint member30can be easily coupled to and decoupled from one another, and collision and interference between component parts are minimized. In addition, it is possible to prevent the respective component parts from being unintentionally released from one another. Because the flexible joint member30comprises a single component, manufacture of the artificial hip joint prosthesis can be conveniently implemented and a manufacturing cost can be reduced.

In the above-described embodiment, it was explained that the through-holes38aand38bof the flexible joint member30are defined in the form of a slot. However, as shown inFIG. 12, instead of defining the through-holes38aand38bin the form of a slot, the through-hole38bcan be defined in a manner such that a space for ensuring resilient deformation of the resilient part40is sufficiently provided in the flexible joint member30and a dummy portion47for additionally supporting the head20inserted into the flexible joint member30is formed on the depressed part38.

Also, as shown inFIG. 13, the configuration of the flexible joint member30′ can be partially changed. In other words, the unit resilient portions40a′ and40b′ can be formed to have a polygonal configuration, and the associated parts such as the slits41a′ and41b′, the projecting ribs44′, the flattened portions42a′ and42b′ and the through-holes38a′ and38b′ can be defined or formed to have a corresponding contour or configuration.

Furthermore, in the above-described embodiment, it was explained that the projecting ribs44are formed on the resilient part40and the engaging grooves10bare defined in the pelvis-contacting element10. However, in another embodiment of the present invention as shown inFIG. 14, the projecting ribs44″ can project radially inward adjacent to the entrance of and from the inner surface of the pelvis-contacting element10″ and have the preselected depth, and the engaging grooves10b″ can be defined on the outer surface of the resilient part40″ of the flexible joint member30″ and extend in the circumferential direction.

When selectively decoupling the head20and the stem50from their corresponding component elements, it is not always necessary to decouple the flexible joint member30from the pelvis-contacting element10. Accordingly, as shown inFIG. 15, within the scope of the present invention, the decoupling grooves may not be defined in the unit resilient portions40a′″ and40b′″ of the flexible joint member30.

INDUSTRIAL APPLICABILITY

As described above, the present invention provides an artificial hip joint prosthesis in which interference and collision are minimized between component parts and which ensures smooth rotation of a head and is constructed in such a way as to be easily installed and shorten an installation time.

The artificial hip joint prosthesis according to the present invention can be optimally adapted even to Orientals having relatively small physiques and bone sizes, and can minimize the interference and collision between the component parts to thereby prevent the pelvis including a cartilage and the femur of the human body from being injured.

The artificial hip joint prosthesis according to the present invention allows assembly and disassembly of component parts to be easily performed and minimizes radial movement of the head so that collision does not occur between the component parts, while release of the head is properly prevented. As the present artificial hip joint prosthesis is constructed to render partial structural integration, it is possible to simplify a manufacturing procedure and reduce a manufacturing cost.