KR20100110157A - Tibial component having locking system - Google Patents

Abstract

PURPOSE: A tibial component having a locking system is provided, which can prevent micromovement between the tibia bone base part and articular surface insertion part. CONSTITUTION: A tibial component having a locking system comprises: a stem(320); a base plate(310) which slopes rearward on the stem; a tibia bone base part(300) equipped with a rib spread between the stem and base plate; and an articular surface insertion part(400) which fits in the base plate of the tibia bone base part. The angle of inclination of the base plate is 5-10 degrees. The thickness of the rib is 1.5-3 mm. The base plate comprises grooves in the central side and lateral face side.

Description

Tibial component having locking system for artificial knee joint with fastening system

The present invention relates generally to medical prosthetic prostheses, and more particularly, to the fastening system of tibial components for artificial knee joints. The present invention also relates to an orthopedic prosthetic joint insertion part used in connection with Total Knee Arthroplasty (TKA). In total knee arthroplasty using a modular fixed support, the weak fastening mechanism causes a movement between the articular joint insert in polyethylene and the tibial base in the metal, resulting in floor wear and loosening along with osteolysis. It is known to cause. Accordingly, the present invention is to provide a tibial component having a fastening system configured to prevent micromovement between the tibial base and the articular surface insert, and the tibial component has the advantage of being easily fastened and easily manufactured. .

In general, it is known to construct a modular tibial component having a joint plate member separate from the base plate. Preferably, a separate member for the articulation surface can be made of a different material than the base plate. In particular, because the base plate is inserted directly into the cavernous bone at the proximal end of the tibia, the base plate is usually made of a titanium alloy because titanium is strong, relatively light and biocompatible as is known to those skilled in the art. However, titanium is not suitable as a friction surface, so that a separate member, typically made of a polymeric material, is attached to the base plate, which acts as a joint surface that engages with the distal femur by sliding friction. At this time, the distal femur is provided with a femur side component having a pair of joints.

Modular tibial components using articulation members that are attachable separately from the baseplate require reliable means for attaching the articular surface member to the baseplate. Among the members, it is important to achieve stable fixation without excessively weakening one or both of them. These requirements are difficult to achieve due to the significant load exerted on the articular surface member by the distal femur, especially in the case of posteriorly stable knee joints. Here, the posteriorly stable knee joint is an artificial knee joint with a cam member that limits the maximum flexion point of the knee to compensate for the removal of the posterior cruciate ligament and a spinous protruding member extending upward from the base plate where the movement is forcibly guided by the joint of the femur. Say In contrast, the posterior cruciate ligament conserving knee joint refers to an artificial knee joint without a cam member and a spinous protruding member because the knee movement is sufficiently forcibly guided due to the presence of an acting posterior cruciate ligament.

In addition to the material and geometrical requirements of the tibial component, there are significant assembly conditions, that is, the joint surface member made of polymer material must be stably attached to the base of the tibial side made of metal, and in particular, the joint surface member is also sheared in use. It should be attached to resist stress. This assembly condition is deeply related to the "modular tibial component".

Currently, modular prosthetics are widely used by orthopedic surgeons. These modular prostheses allow doctors to order prostheses to fit the anatomy of an individual patient. Accordingly, these modular prostheses typically have tibial bases of various and different types and sizes, and articular face members or articulation inserts of polymeric materials of various different types and sizes. Since the prosthesis is to be assembled by the doctor just before insertion, it is important that the prosthesis be easily assembled without any modification in terms of its size and mechanical aspects.

Other detachable tibial components are known and used in the art, some of which do not require a separate tibial base. US Pat. No. 4,016,606 to Murry et al., Secured in the insertable tibial base by sliding the inclined, notched bottom of the articular insert into the correspondingly inclined and notched area of the tibial base. It describes a flat articular insert inserted into the tibial base by pins that penetrate the articular surface insert and the metal tibial base. This may omit the fastening pin, but has the disadvantage of requiring a separate pin for fastening the joint surface insert in place.

In addition, attempts have been made to provide a modular tibial component with an effective mechanism for attaching articulation inserts to the base plate. U.S. Patent Nos. 5,405,396 to Heldreth et al. And 4,822,362 to Walker et al. Each disclose an attachment system for attaching separate articular inserts to the base plate. U.S. Patents of Heldres et al. Utilize dovetail structures for members for retaining joint inserts, while U.S. Patents of Walker et al. Use lingual joints to retain joint inserts.

US Patent No. 4,963,152 to Hofmann et al. Describes asymmetric tibial components. Here the plastic articulation insert is joined to the metal tibial base via a pair of posterior lingual joints and a central central snap fixation. This form gives a much lower bond strength.

US Pat. No. 4,714,474 to Brooks et al. Shows a tibial component of the knee joint with a removable articular insert. The inclined portions are used here to easily assemble the articular insert at the tibial base and have surfaces at the rear for fastening the articular insert, the surfaces at the rear of the tibial base and the articular insert. And cause problems during separation. In addition, the tibial base includes nails for seating the tibial base, another problem with this fastening system is mainly in nails attached to the tibial base. In other words, these nails cause problems for the doctor to remove bones and cause instability in the tibia, and in recent years doctors have avoided this type of articular insertion, while the tibia has an easy-to-operate fastening system. The situation is demanding side parts.

None of these other patents known in the patent document or application satisfy the requirement of very effectively resisting the movement of the joint surface insert in all directions while keeping the thickness of the joint surface insert to a minimum.

Accordingly, the present invention is conceived to solve the above problems, the present invention can minimize and eliminate some of the above-mentioned or other problems by using the method and structural features described below.

It is an object of the present invention to provide a tibial component with a fastening system.

Another object of the present invention is to provide a tibial component that is simple in structure and manufacturing method and easier to use.

It is a further object of the present invention to provide a tibial component with a fastening system that provides improved resistance to at least four directions of movement of the articulation insert, ie forward and backward translation, lateral translation, vertical movement and rotational movement. .

It is another object of the present invention to provide a tibial component with a fastening system in which the thickness of the articular insert can be kept to a minimum.

The above objects and other objects not specifically described may be embodied in a particular embodiment of the tibial component according to the invention, in order to achieve the above objects, the present invention relates to a stem and a rear on the stem. A tibial side base having an inclined base plate and ribs extending between these stems and the base plate; It characterized in that it comprises a; joint surface insertion portion to be fitted to the base plate of the tibial side base.

As described above, according to the present invention, it is possible to prevent the micromovement between the tibial base and the articular surface insertion portion, to reduce the wear of the bottom surface of the articular surface insertion portion, and to provide the minimum thickness of the articular surface insertion portion. In addition, the tibial component according to the present invention has the advantage of being easily fastened and simply manufactured.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. First of all, in adding reference numerals to the components of each drawing, it should be noted that the same reference numerals are used as much as possible even if displayed on different drawings. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention unclear.

Here, the term defining the directionality below is used. Anterior and posterior mean the front or the back of the human body, respectively. In addition, the intermediate | middle side and the side surface mean a place near a sagittal plane, and a place far from a sagittal plane, respectively. The sagittal plane is an imaginary vertical plane that passes through the middle of the body, dividing it into left and right halves.

The present invention relates to a structure of a unique and modular tibial component that provides improved resistance to at least four directions of movement of the articulation member. This structure includes a number of key members that provide a unique fastening between the base plate and the articular surface insert without the need to increase the thickness of the articular surface insert. In addition, the structure of this fastening system provides high bending and prevents collision with the tibia.

Referring now to FIG. 1, this is a schematic exploded view showing the tibial component according to the present invention together with the distal femur and proximal tibia, which includes a femur side component 100; Tibial component (200) consisting of a joint surface insertion portion 400 and the tibial side base portion 300; Femur 10 and; Tibia 20 is shown. The present invention relates to the tibial component 200 having the articular surface insertion portion 400 and the tibial side base 300 among them.

The joint surface insertion portion 400 snaps to the tibial side base part 300, whereby the joint surface insertion part and the tibial side base part are assembled, and their assembly is shown in FIG. 2. FIG. 2 is a perspective view of the tibia component including the articular surface insertion portion and the tibial base portion viewed from the rear, and when assembled, the articular surface insertion portion 400 snaps to the tibial base portion 300 along the arrow shown in FIG. 3. It will be fixed. 3 shows a fastening method of the present invention.

The tibial base 300 is one of the components in the tibial component 200 according to the present invention. As shown in FIG. 2, the base plate 310 and the stem 320 and the base plate 310 and the stem are shown. It has two ribs 330 extending in a similar shape between the 320. Here, the thickness of the rib is preferably in the range of 1.5mm to 3mm.

4 is a side view of the tibial base and, as shown, the base plate 310 is inclined by the inclination angle θ on the stem 320. In the posterior cruciate ligament conserving knee, a careful assessment of the posterior cruciate ligament's tension is essential, because the excess posterior cruciate ligament's tension can adversely affect the range of motion and long-term success. To avoid this problem, a sufficient tibial posterior tilt angle is an important factor for proper tension of the posterior cruciate ligament. This structure is one of the major considerations in the present invention. The inclination angle θ is 5 to 10 degrees, but is preferably about 7 degrees.

5 is a plan view of the tibial base and shows a fastening system on the tibial base 300. Referring to this figure, the base plate 310 of the tibial base 300 includes a middle side 301, a side face 302, a rear part 303, and a front part 304. The intermediate side 301 and the side surface 302 has a straight tip 311 of the base plate 310, adjacent to the tip 311, the groove 312 having an approximately c-shaped cross section on the base plate upper portion Is formed. Each of these recesses starts at the middle of both sides of the base plate and extends to the rear of the base plate as shown. The end portion 313 of the recess portion protrudes toward the center of the base plate 310 due to the shape of the recess portion 312, and is fitted into the slot of the joint surface insertion portion described later. The tip 314 of each recess 312 extending to the rear of the base plate extends straight and is parallel to the outer tip 311, respectively. Reference numeral 315 denotes a wall portion in which no recess is formed in the rear portion 303 of the base plate 310. On the other hand, the front portion 304 of the base plate 310 is formed with a convex portion 316 protruding upward.

FIG. 6 is a cross-sectional view taken along the line A-A of FIG. 5, and reference numeral α denotes the subtraction inclination angle at the bottom surface 317 of the end portion 313 of the groove portion.

7 is a bottom view of the articular insert, showing a fastening system on articulation insert 400. Referring to this figure, the articulation surface inserting portion 400 includes a lateral side 401, a middle side 402, a rear portion 403, and a front portion 404. The lateral side 401 and the intermediate side 402 has a straight tip 411 of the articulation insert 400, and a cross-section having a substantially c-shape on the side of the bottom surface adjacent to the tip 411. Slot 412 is formed. These slots each start at both midpoints of the articular insert and extend to the rear of the articular insert as shown. Due to the shape of the slot 412, the protrusion 413 of the slot which protrudes toward the outer circumferential side of the joint surface inserting part 400 is inserted into the recess 312 of the base plate 310 described above. The tip 414 of each slot 412 extending to the rear of the articular insertion portion extends straight and is parallel to the outer tip 411, respectively. Reference numeral 415 is a step in which no slot is formed in the rear portion 403 of the articulation insert 400, which extends to the center of the articulation insert, and because of this structure, the articulation insert 400 is minimized. It will have a thickness. Meanwhile, a stepped and curved recess 416 is formed in the front portion 404 of the joint surface inserting portion 400.

FIG. 8 is a cross-sectional view taken along the line B-B of FIG. 7, and a reference numeral β denotes a subtraction inclination angle at the upper surface 417 of the protrusion 413 of the slot.

On the other hand, the tibial base 300 may be composed of, for example, cobalt-chromium alloy, etc., the articular surface insert 400 may be a medically acceptable grade of polymeric material, in particular ultra high molecular weight polyethylene resin (UHMWPE) or polyetheretherel. It is preferable to be made of ketone resin (PEEK).

Now, a method of fastening the fastening system of the tibial component according to the present invention will be described.

FIG. 9 is a front sectional view showing the assembly of the tibial base and the articular surface insert, and FIG. 10 is a side cross-sectional view showing the assembly of the tibial base and the articular insert.

First, the tibial side base 300 is fixed to the tibia 20 (see FIG. 1), and then the joint surface inserting portion 400 is assembled to the tibial side base 300. The fastening of the tibial component according to the present invention is made by press-fitting between the base plate 310 and the articular surface inserting portion 400 of the tibial base 300, the method being performed as shown in FIG. . That is, the protrusion 413 of the articular surface inserting portion 400 and the groove 312 in the base plate 310 of the tibial base 300 are fitted at the rear portion, and the end of the groove in the base plate 310 is fitted. 313 is easily inserted into slot 412 in articulation insert 400. Here, the contact surfaces are the top surface 417 of the protrusion 413 of the articular insertion portion and the bottom surface 317 of the end portion 313 of the base plate, and these surfaces move smoothly with respect to each other. Next, the straight end ends 314 and 414 guide the articulation insert 400 on the base plate 310 without being inclined or distorted, the straight end tip 414 of the articulation insert being the straight end on the base plate. Aligned with 314, the alignment between the joining surfaces of these two tip ends will guide the correct direction of the fastening. In addition, when these joint surfaces are aligned, the outer surface of the protruding portion 413 of the joint surface inserting portion 400 is joined to the inner surface of the recess 312 of the base plate 310.

In the front portion, the curved convex portion 316 of the base plate 310 is fitted into the curved concave portion 416 of the articulation insert 400.

This fastening method may require an auxiliary device not included in the present invention.

Engagement by the fastening system as described above prevents forward and backward translation, lateral translation, vertical movement and rotational movement of the tibial component. In more detail, the forward and backward translation of the articulation insert 400 is prevented by the curved convex portion 316 of the base plate 310 as shown in FIG. 10. In addition, the vertical movement of the joint surface inserting portion 400 is prevented by the end 313 of the base plate 310, in particular the bottom surface 317, as shown in Figure 10, the rotation of the joint surface inserting portion 400 Is prevented due to indentation as shown in FIG. 10. The rotation of the tibial base 300 and the articulation insert 400, ie the tibial component 200, is prevented by the inclined rib 330 shown in detail in FIG. The additional pins for preventing rotation can be eliminated, which has advantages over the prior art.

The main advantage of the present invention is the rear slope of the base plate 310 as shown in FIG. Many factors affect the performance to achieve maximum range of motion (ROM) after total knee arthroplasty. Some of these factors can be controlled by the doctor, but factors such as preoperatively moving joint range cannot be controlled by the doctor. The inclination of the tibia affects the postoperative range of motion of the joint. In the tibial component of the present invention, the base plate 310 provides a posterior inclination angle θ. This is an excellent advantage of the fastening system of the present invention over the prior art.

Another advantage of the present invention is that it can be easily separated, the joint surface insertion portion 400 is easily separated from the base plate 310 of the tibial side base 300. Since the end or surface of the convex portion 316 in the base plate 310 is a flat surface, the articulation insert 400 is moved away from the base plate 310 by simply lifting the front end of the articulation insert 400. Just slide forward and you're off. In particular, the articulation insert 400 is easily pulled out due to the bottom surface 317 and the top surface 417 having a minus inclination angle as shown in FIGS. 6 and 8 and 10. The subtilt angle α of the bottom surface 317 is preferably 1 degree to 1.5 degrees, and this inclination extends to the straight end 314. Similarly, the subtraction inclination angle β of the upper surface 417 is 1 degree to 1.5 degrees, and this inclination extends to the straight end end 414.

Tibial component according to the present invention can be made in a variety of sizes and thickness, preferably the thickness of the assembly portion of the base plate 310 of the joint surface inserting portion 400 and the tibial side base 300 may be 9mm. At this time, the joint surface insertion portion 400 has a minimum thickness of 6mm.

The overall tolerance can be selected such that the play between all the ends joined by the fastening system described above is up to 0.05 mm. This provides an articular surface insert that is fastened in a tight press, but allows the articulation insert to be inserted into or separated from the base plate.

The foregoing description is merely illustrative of the technical idea of the present invention, and various changes and modifications may be made by those skilled in the art without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are not intended to limit the technical idea of the present invention but to describe the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The protection scope of the present invention should be interpreted by the following claims, and all technical ideas within the equivalent scope should be interpreted as being included in the scope of the present invention.

1 is a schematic diagram illustrating an exploded view of the tibial component made in accordance with the present invention, together with the distal femur and the proximal tibia.

Figure 2 is a perspective view from behind of the tibial component including the articular surface insert and the tibial base.

Figure 3 is a side view showing a fastening method of the tibia component.

4 is a side view of the tibial base.

5 is a plan view of the tibial base.

6 is a cross-sectional view taken along the line A-A of FIG.

7 is a bottom view of the joint surface inserting portion.

8 is a cross-sectional view taken along the line B-B in FIG.

9 is a front sectional view showing the assembly of the tibial base and the articular surface insertion portion.

10 is a side cross-sectional view showing the assembly of the tibial base and the articular surface insertion portion.

Claims (11)

A tibial side base having a stem, a base plate inclined rearwardly on the stem, and ribs extending between these stems and the base plate; Tibial component including a; joint surface insertion portion to be fitted to the base plate of the tibial base. The tibial component according to claim 1, wherein the base plate has an inclination angle of 5 degrees to 10 degrees. The tibial component according to claim 1, wherein the rib has a thickness of between 1.5 mm and 3 mm. The tibial component according to claim 1, wherein the base plate has recesses on the intermediate and side surfaces, respectively, and these recesses extend from the middle of the base plate to the rear portion of the base plate. The tibial component according to claim 4, wherein the inclination angle of the bottom surface of the recessed portion is 1 to 1.5 degrees. 5. The tibial component according to claim 4, wherein the recessed portion at the rear portion of the base plate has a straight end end, and these end ends are parallel to the outer end of the base plate. The tibial component according to claim 1, wherein the front portion of the base plate is provided with a curved and flat convex portion. 2. The tibial side according to claim 1, wherein the articular surface inserting portion has slots on the side and middle sides, respectively, and these slots extend from the middle portion of the articular surface inserting portion to the rear portion of the articular surface inserting portion. part. The tibial component according to claim 8, wherein the inclination angle of the upper surface of the slot protrusion is 1 to 1.5 degrees. 9. The tibial component according to claim 8, wherein the slot at the rear of the articular insert has a straight tip, and the tip is parallel to the outer tip of the articular insert. The tibial component according to claim 1, wherein the front portion of the articular surface inserting portion has a curved and flat recess.

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