CN111938876A

CN111938876A - Combined femoral stem

Info

Publication number: CN111938876A
Application number: CN202010790271.7A
Authority: CN
Inventors: 李超宁
Original assignee: Wuhan United Imaging Zhirong Medical Technology Co Ltd
Current assignee: Wuhan United Imaging Zhirong Medical Technology Co Ltd
Priority date: 2020-08-07
Filing date: 2020-08-07
Publication date: 2020-11-17

Abstract

The invention relates to the technical field of medical prostheses, in particular to a combined femoral stem. This combination formula femoral stem includes: the handle body is provided with a mounting groove; one end of the femoral neck extends into the mounting groove; and the filling layer is filled between the femoral neck and the inner wall of the mounting groove, and is fixedly connected with the handle body and the femoral neck. In the combined femoral stem, the stem body and the femoral neck are of a split structure, the femoral neck with different anteverted angles can be prepared, the wider anteverted angle change can be adapted, the choice of a patient is increased, and meanwhile, compared with the existing integral femoral stem structure, the production cost can be reduced; the femoral neck and the handle body are connected through the filling layer, so that the connection firmness of the femoral neck and the handle body is ensured, and the problem of fretting wear of the existing press-fit femoral handle is solved, thereby solving the problem of loosening and failure of the prosthesis caused by bone dissolution.

Description

Combined femoral stem

Technical Field

The invention relates to the technical field of medical prostheses, in particular to a combined femoral stem.

Background

The femoral stem is a medical prosthesis which can replace diseased bones in human bodies.

The existing femoral stem is generally divided into an integral structure and a split structure. The integral femoral stem is integrally formed, and is generally only manufactured into a 0-degree anteversion angle due to the limitation of manufacturing cost, so that the difference between the physiological anteversion angle of the integral femoral stem and the physiological anteversion angle of a patient can be caused after the integral femoral stem is installed, and the patient can hardly reach a normal walking posture.

In split type femoral stem, the femoral neck inserts that the handle is internal and through press fit, has fretting wear among the in-service use process, and the piece of production will lead to the bone to dissolve to lead to the not hard up inefficacy of false body.

Therefore, there is a need for a combination femoral stem that can avoid fretting wear and reduce manufacturing costs to solve the above problems.

Disclosure of Invention

The invention aims to provide a combined femoral stem which can avoid fretting wear and reduce the manufacturing cost.

In order to achieve the purpose, the invention adopts the following technical scheme:

a modular femoral stem comprising:

the handle body is provided with a mounting groove;

one end of the femoral neck extends into the mounting groove; and

the filling layer is filled between the femoral neck and the inner wall of the mounting groove, and the filling layer is fixedly connected with the handle body and the femoral neck.

Wherein the filling layer has a modulus of elasticity less than the modulus of elasticity of the stem or the femoral neck;

the filling layer is formed by a fluid material through an injection molding or pouring process, or the filling layer is formed by a solid material through pressure filling.

Wherein, the depth of mounting groove is greater than the degree of depth that the thighbone neck stretched into the mounting groove.

Wherein the cross-sectional area of the end of the stem body distal to the femoral neck decreases progressively in a direction away from the femoral neck.

Wherein an end of the stem body distal to the femoral neck includes first and second oppositely disposed surfaces and third and fourth oppositely disposed surfaces, the first, second, third and fourth surfaces being beveled or curved.

Wherein the cross-sectional area of the end of the femoral neck extending into the mounting groove gradually decreases along the direction extending into the mounting groove.

The end, extending into the mounting groove, of the femoral neck comprises a fifth surface and a sixth surface which are arranged oppositely and a seventh surface and an eighth surface which are arranged oppositely, and the fifth surface, the sixth surface, the seventh surface and the eighth surface are inclined planes or curved surfaces.

Wherein the femoral neck comprises:

the neck root part extends into the mounting groove;

the neck top is formed by upwards extending the neck root, and the included angle between the extending direction of the neck top and the extending direction of the neck root is 0-20 degrees.

Wherein, a plurality of concave pits or bulges are arranged on the surface of one end of the femoral neck extending into the mounting groove.

Wherein, the surface of the one end of the thighbone neck stretching into the mounting groove is a rough surface.

Has the advantages that: the invention provides a combined femoral stem. In the combined femoral stem, the stem body and the femoral neck are of a split structure, the femoral neck with different anteverted angles can be prepared, the wider anteverted angle change can be adapted, the choice of a patient is increased, and meanwhile, compared with the existing integral femoral stem structure, the production cost can be reduced; the femoral neck and the handle body are connected through the filling layer, so that the connection firmness of the femoral neck and the handle body is ensured, and the problem of fretting wear of the existing press-fit femoral handle is solved, thereby solving the problem of loosening and failure of the prosthesis caused by bone dissolution.

Drawings

FIG. 1 is a front view of a modular femoral stem provided in the present invention;

FIG. 2 is a side view of the modular femoral stem provided by the present invention;

FIG. 3 is a schematic view of a femoral neck according to the present invention;

fig. 4 is a side view of another modular femoral stem provided in the present invention;

fig. 5 is an exploded view of a combined femoral stem provided by the present invention;

fig. 6 is a sectional view of a combined femoral stem provided in the present invention;

FIG. 7 is a side view of a femoral neck provided in the present invention;

FIG. 8 is a front view of a femoral neck provided in accordance with the present invention;

FIG. 9 is a schematic structural view of another femoral neck provided in accordance with the present invention;

fig. 10 is a schematic structural view of a further femoral neck provided in accordance with the present invention.

Wherein:

1. a handle body; 11. a first surface; 12. a second surface; 13. a third surface; 14. a fourth surface;

2. a femoral neck; 21. the root of the neck; 211. a fifth surface; 212. a sixth surface; 213. a seventh surface; 214. an eighth surface; 215. a dot-shaped bulge; 216. a strip-shaped bulge; 22. a neck top;

3. and (5) filling the layer.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are illustrative and intended to be illustrative of the invention and are not to be construed as limiting the invention.

In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance. Wherein the terms "first position" and "second position" are two different positions.

Unless expressly stated or limited otherwise, the terms "mounted," "connected," and "secured" are to be construed broadly and encompass, for example, both fixed and removable connections; can be mechanically or electrically connected; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

Unless expressly stated or limited otherwise, the first feature "on" or "under" the second feature may include the first feature being in direct contact with the second feature, or may include the first feature being in direct contact with the second feature but being in contact with the second feature by another feature therebetween. Also, the first feature being "on," "above" and "over" the second feature includes the first feature being directly on and obliquely above the second feature, or merely indicating that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature includes the first feature being directly under and obliquely below the second feature, or simply meaning that the first feature is at a lesser elevation than the second feature.

The technical scheme of the invention is further explained by the specific implementation mode in combination with the attached drawings.

As shown in fig. 1, the present embodiment provides a combined femoral stem, which comprises a stem body 1 and a femoral neck 2. The lower end of the handle 1 can be inserted into the human medullary cavity, the femoral neck 2 is arranged at the upper end of the handle 1, the femoral neck 2 is used for connecting the femoral ball, and the femoral ball can be inserted into the cup-shaped 'socket' in the pelvis and jointed with the cup-shaped 'socket' so as to replace the diseased hip joint.

In order to improve the stability of the connection of the stem body 1 with the human skeleton, the cross-sectional area of the lower end of the stem body 1 may be gradually reduced in a direction away from the femoral neck 2. When the lower extreme of the handle body 1 inserts human marrow cavity, along with the increase of depth of insertion, the chucking effect of handle body 1 and human marrow cavity is better, and along with the femoral stem bears load, can further improve the fixed effect of handle body 1 and human marrow cavity.

Further, the lower end of the shank 1 may be of a prismoid structure. In this embodiment, as shown in fig. 1 and 2, the lower end of the shank 1 has a quadrangular frustum structure with two sets of oppositely disposed inclined surfaces, namely a first surface 11 and a second surface 12 which are oppositely disposed and a third surface 13 and a fourth surface 14 which are oppositely disposed.

The lower end of the handle body 1 is provided with the quadrangular frustum pyramid structure, so that the lower end of the handle body 1 is of a double-taper structure, the surfaces of the lower end of the handle body 1 can be better matched with the inner wall of a marrow cavity of a human body, and the handle body 1 is more stable in connection with the human skeleton.

Optionally, two adjacent slopes of the handle body 1 may be smoothly transitioned, so as to avoid pain and discomfort of a patient in the using process due to small contact area between the edge angle of the handle body 1 and the marrow cavity of the human body.

Alternatively, the respective surfaces of the lower end of the shank 1 may also be curved to better match the inner wall of the marrow cavity.

In other embodiments, the lower end of the shank 1 may be a truncated cone structure, other polygonal frustum or other irregular structure capable of satisfying the gradually decreasing cross-sectional area.

Because the anteversion angles of the acetabulum and the femur of different patients are different, in order to enable the femoral stem implanted after the operation of the patient to be matched with the physiological anteversion angle of the patient, the femoral stem needs to be designed with the matched anteversion angle according to the actual condition of the patient.

Therefore, in the combined femoral stem in the embodiment, the femoral neck 2 and the stem body 1 are in a split structure. As shown in fig. 3, the femoral neck 2 includes a neck base 21 and a neck top 22, and the upper end of the shank 1 is provided with a mounting groove. Neck root 21 is used for with mounting groove fixed connection, and neck top 22 sets up in the upper end of neck root 21 for be connected with the thighbone ball.

In the combined femoral stem, the stem body 1 and the femoral neck 2 are of a split structure, and the femoral neck 2 with different anteverted angles can be prepared to adapt to the anteverted angle difference between the acetabulum and the femur of a human body of different patients, so that the choice of patients is increased, and better adaptation and movement of the patients after operation are facilitated; compared with the integral femoral stem structure in the prior art, the femoral neck 2 can be replaced only, which is beneficial to reducing the production cost.

Illustratively, as shown in FIG. 2, the neck crown 22 and neck heel 21 may extend in the same direction, such that the anteversion angle of the femoral neck 2 is 0 °.

Illustratively, as shown in fig. 4, the extending directions of the neck top portion 22 and the neck bottom portion 21 may be set at an angle, the extending direction of the neck bottom portion 21 extending into the shank 1 is shown as a direction in fig. 4, and the neck top portion 22 extends from the upper end of the neck bottom portion 21 along a direction b in fig. 4 to form a non-zero rake angle.

Optionally, the angle between the extending direction of the neck top 22 and the extending direction of the neck root 21 is 0-20 °, for example, 5 °, 10 °, 15 ° or 20 °, and the specific angle can be set according to actual needs.

As shown in fig. 5 and 6, the combined femoral stem further comprises a filling layer 3, and the lower end of the femoral neck 2 extends into the mounting groove and is connected with the stem body 1 through the filling layer 3. Connect handle body 1 and femoral neck 2 through filling layer 3, can improve handle body 1 and 2 joint strength of femoral neck, avoid because of the fretting wear between handle body 1 and femoral neck 2 to avoid leading to the osteolysis and the not hard up inefficacy of combination formula femoral handle.

Optionally, the filling material forming the filling layer 3 may be a fluid material or a solid material, and has a certain filling pressure when being filled in the installation groove, so that on one hand, the filling material can be ensured to fill the gap between the installation groove and the femoral neck 2, and dead angles in the installation groove are avoided; on the other hand, the connection strength of the filling material with the stem body and the femoral neck 2 can be improved.

In for making things convenient for filling material to pour into the mounting groove into, during shaping filling layer 3, can be through the fixed handle body 1 of frock and femoral neck 2, can avoid leading to handle body 1 or femoral neck 2 position to remove because of injection pressure to guarantee the position precision of the two.

In this embodiment, behind the neck root 21 inserts in the mounting groove, through the filler material to the mounting groove intussuseption fluid, filler material solidifies the back and forms filling layer 3, and it is fixed with handle body 1 and femoral neck 2, the connection of femoral neck 2 and handle body 1 is more firm, can avoid the relative movement between femoral neck 2 and the handle body 1, press-fit type femoral stem fretting wear's problem among the prior art has been solved, thereby avoid the false body that leads to because of the bone dissolves not hard up inefficacy.

Exemplarily, the filling material can be pressed into the mounting groove in an injection molding mode, and the gap between the mounting groove and the femoral neck 2 can be filled with the filling material under certain injection molding pressure, so that the connection firmness of the femoral neck 2 and the handle body 1 is improved.

When the filling layer 3 is injection molded, the stem body 1 and the femoral neck 2 are fitted and placed in a mold to fix the stem body 1 and the femoral neck 2. A molding cavity is formed among the mold, the handle body 1 and the femoral neck 2, wherein the inner wall of the mounting groove and part of the outer wall of the femoral neck 2 are used as a part of the mold cavity. The molding cavity is provided with an injection gate and an exhaust port, the injection molding machine injects fluid filling materials with certain pressure into the molding cavity through the injection gate, and gas in the molding cavity flows out of the exhaust port so that the filling materials can fill the molding cavity. Wherein, the pressure and the flow rate of the injected fluid can be set according to actual needs.

When the filling material overflows from the exhaust port, the molding cavity is filled with the filling material, the injection is stopped, and the pressure of the mold is maintained for a certain time so that the filling material is solidified and molded.

After that, the stem 1 and the femoral neck 2 fixed by the filling layer 3 are removed from the mold.

Illustratively, the filling material can be filled into the mounting groove by means of pouring, and the filling material, the inner wall of the mounting groove and the femoral neck 2 are fully contacted by the pouring pressure of the pouring glue.

In other embodiments, the filler material may also be a solid material. Solid material can be through pressure filling between mounting groove and thighbone neck 2, and after pressure filling, solid material is connected with handle body 1 and thighbone neck 2 respectively and is an organic whole, and fixed effect is firm.

Alternatively, the solid material may be a powdered material or a bulk particulate material.

Optionally, the fixing material may also have a certain elasticity so as to be able to better fill the gap between the mounting groove and the femoral neck 2 after pressure injection into the mounting groove.

In order to improve the service life and strength of the femoral stem, the femoral neck 2 and the stem body 1 can be made of metal materials, such as cobalt-chromium master alloy or titanium alloy.

Alternatively, due to the smaller size of the femoral neck 2 and the relatively higher load bearing capacity, the material of the femoral neck 2 may be stiffer than the stem 1 to avoid deformation of the femoral neck 2 leading to failure of the prosthesis.

Because the elastic modulus of the metal material is larger than that of the human skeleton and the difference value is larger, stress shielding can be formed, namely, the combined femoral stem with the larger elastic modulus bears larger load, and the human skeleton which is in contact with the combined femoral stem bears smaller load. The human skeleton shielded by stress is easy to dissolve due to the stimulation of insufficient force, so that the human skeleton around the combined femoral stem forms severe osteoporosis, the osteoporosis can cause the reduction of the bone strength, the reduction of the bone strength can cause the reduction of the bonding force of the human femur and the combined femoral stem, and finally the combined femoral stem is loosened and fails.

In order to solve the above problems, the elastic modulus of the filling layer 3 can be smaller than that of the stem body 1 or the femoral neck 2, so as to reduce the elastic modulus of the combined femoral stem, and make the combined femoral stem close to that of human skeleton, thereby reducing stress shielding and avoiding osteoporosis.

In addition, the filling layer 3 with a smaller elastic modulus can also reduce the density of the combined femoral stem so as to reduce the weight of the combined femoral stem under the condition of unchanged volume.

Alternatively, the filler material may be a polymeric material, such as Polyetheretherketone (PEEK). PEEK is a special engineering plastic with excellent performance, has the advantages of good self-lubricating property, good wear resistance, good glass core resistance and the like, and is beneficial to improving the connection strength of the femoral neck 2 and the handle body 1.

The filling material may also be bone cement. The bone cement is a bone cement, has an adhesion effect, and can further improve the fixing effect of the handle body 1 and the femoral neck 2.

The thickness of the filling layer 3 is related to the gap between the outer wall of the femoral neck 2 and the inner wall of the mounting groove on the stem 1. Optionally, the thickness of the filling layer 3 may be uniform or non-uniform, and the specific situation may be set according to actual needs.

Alternatively, the thickness distribution of the filling layer 3 can be optimally designed according to finite element analysis. And carrying out finite element analysis according to the actual stress condition of the combined femoral stem, the elastic modulus of the combined femoral stem and the elastic modulus of human skeleton, and calculating the thickness of the filling layer 3 so as to enable the elastic modulus of the combined femoral stem to be closer to the elastic modulus of the human skeleton, thereby obtaining better use effect and prolonging the service life.

In order to further reduce the difference of the elastic modulus between the combined femoral stem and the human skeleton, the depth of the mounting groove can be larger than the depth of the femoral neck 2 extending into the mounting groove, so that on one hand, the using amount of the filling material in the mounting groove can be increased, and the elastic modulus of the combined femoral stem can be further reduced; on the other hand, the fixation between the femoral neck 2 and the stem body 1 can be enhanced.

Alternatively, the mounting groove may have a certain bending angle along the length direction of the stem body 1, which can increase the contact area between the neck root 21 and the filling material without changing the volume of the neck root 21, thereby increasing the firmness of the fixation between the femoral neck 2 and the stem body 1. The mounting groove has a certain bending angle, that is, at least two opposite side walls of the mounting groove are curved surfaces with a certain bending angle, so that the whole mounting groove extends along a curve. For ease of understanding, taking FIG. 6 as an example, the top of the mounting groove is curved to the right as shown in FIG. 6.

To improve the stability of the connection of the stem 1 to the femoral neck 2, the cross-sectional area of the neck root 21 may be gradually reduced in the direction of extending into the mounting groove.

In the present embodiment, as shown in fig. 7 and 8, the neck base portion 21 has two sets of oppositely disposed surfaces, i.e., oppositely disposed fifth and

sixth surfaces

211 and 212 and oppositely disposed seventh and

eighth surfaces

213 and 214, respectively. Since the neck base 21 has a certain bending angle as a whole, the fifth surface 211, the sixth surface 212, the seventh surface 213, and the eighth surface 214 may be curved surfaces, which can increase a contact area with the filling material compared to a slope, thereby improving stability of the connection of the stem 1 and the femoral neck 2.

The neck root 21 has two sets of curved surfaces which are oppositely arranged, so that the neck root 21 is of a double-taper structure, and the neck root 21 and the handle body 1 can be connected more stably.

Optionally, the two adjacent surfaces of the neck root 21 may be smoothly transited, so as to avoid dead corners formed at the positions corresponding to the edges when filling or injecting the filling material.

In other embodiments, the lower end of the neck root 21 may be a frustum or pyramid structure.

Further improving the stability of the connection between the shank 1 and the neck root 21, the neck root 21 may be provided with a plurality of pits or protrusions on the surface thereof to increase the contact area between the neck root 21 and the filling material.

It will be appreciated that the inner wall of the mounting groove may be provided with a plurality of dimples or protrusions which increase the contact area of the shank 1 with the filling material.

In other embodiments, the inner wall of the mounting groove is provided with a concave pit or a convex, the surface of the neck root 21 is provided with a convex pit or a concave pit corresponding to the structure on the inner wall of the mounting groove, and the concave pits and the convex pits on the inner wall of the mounting groove and the surface of the neck root 21 correspond to each other, so as to improve the firmness of the filling layer 3 connecting the stem body 1 and the femoral neck 2.

Taking the case of providing the protrusion on the surface of the neck root 21 as an example, as shown in fig. 9 and 10, the protrusion may be a dot-shaped protrusion 215 or a strip-shaped protrusion 216, and the shape of the protrusion may be circular or polygonal.

Optionally, the distribution density and/or size of the protrusions may be gradually reduced along the insertion direction of the neck root portion 21, so that the neck root portion 21 is more uniformly contacted with the filling material everywhere along the insertion direction on the basis of increasing the total contact area of the neck root portion 21 and the filling material, which is beneficial to improving the uniformity of the distribution of the connection force applied by the filling layer 3 to the neck root portion 21.

In other embodiments, the surface of the neck root 21 and/or the inner wall of the mounting groove may be roughened, which may also increase the contact area of the neck root 21 and/or the shank 1 with the filler material, thereby increasing the degree of fastening.

In other embodiments, both the femoral neck 21 and the mounting groove may be provided with dimples or protrusions on one and a roughened surface on the other.

The above description is only a preferred embodiment of the present invention, and for those skilled in the art, the present invention should not be limited by the description of the present invention, which should be interpreted as a limitation.

Claims

1. A modular femoral stem, comprising:

the handle comprises a handle body (1), wherein a mounting groove is formed in the handle body (1);

the femoral neck (2), one end of the femoral neck (2) extends into the mounting groove; and

and the filling layer (3) is filled between the femoral neck (2) and the inner wall of the mounting groove, and the filling layer (3) is fixedly connected with the handle body (1) and the femoral neck (2).

2. The modular femoral stem according to claim 1, characterized in that the modulus of elasticity of the filling layer (3) is smaller than the modulus of elasticity of the stem body (1) or the femoral neck (2);

the filling layer (3) is formed by a fluid material through an injection molding or pouring process, or the filling layer (3) is formed by a solid material through pressure filling.

3. The modular femoral stem according to claim 1, characterized in that the depth of said mounting groove is greater than the depth of said femoral neck (2) extending into said mounting groove.

4. The modular femoral stem according to any one of claims 1 to 3, characterized in that the cross-sectional area of the end of the stem body (1) distal to the femoral neck (2) gradually decreases in a direction away from the femoral neck (2).

5. The modular femoral stem according to claim 4, characterized in that the end of the stem body (1) remote from the femoral neck (2) comprises a first (11) and a second (12) oppositely disposed surface and a third (13) and a fourth (14) oppositely disposed surface, the first (11), the second (12), the third (13) and the fourth (14) surfaces being beveled or curved.

6. The modular femoral stem according to any one of claims 1 to 4, wherein the cross-sectional area of the end of the femoral neck (2) protruding into the mounting groove is gradually reduced in the direction of protruding into the mounting groove.

7. The modular femoral stem according to claim 6, wherein the end of the femoral neck (2) protruding into the mounting groove comprises oppositely disposed fifth (211) and sixth (212) surfaces and oppositely disposed seventh (213) and eighth (214) surfaces, the fifth (211), sixth (212), seventh (213) and eighth (214) surfaces being beveled or curved.

8. The modular femoral stem according to any one of claims 1 to 3, characterized in that said femoral neck (2) comprises:

the neck root part (21), the neck root part (21) stretches into the mounting groove;

the neck top part (22) is formed by extending the neck root part (21) upwards, and the included angle between the extending direction of the neck top part (22) and the extending direction of the neck root part (21) is 0-20 degrees.

9. The modular femoral stem according to any one of claims 1 to 3, wherein the surface of the femoral neck (2) at the end extending into the mounting groove is provided with a plurality of depressions or protrusions.

10. The modular femoral stem according to any one of claims 1 to 3, wherein the surface of the end of the femoral neck (2) protruding into the mounting groove is a rough surface.