Powder-printed thighbone cushion block

Abstract

According to the powder printed thighbone cushion block and the thighbone condyle prosthesis, the tubular reinforcing part is creatively introduced into the thighbone cushion block, and the problem that the inherent mechanical property of a 3D printed porous structure is poor is solved; the porous structures of the reinforcing part and the peripheral part are formed into an integrated structure through a 3D printing technology, the reinforcing part mainly bears force, and the overall mechanical performance is improved; in addition, the reinforcing part further serves as a limiting assembly of the bone cement, the action range of the bone cement between the cushion block and the tibia support is limited, and damage to the medullary cavity wall in the bone cement pumping stage is avoided.

Description

Technical Field

[0001] The present application belongs to the field of metal powder products, and specifically relates to a powder-printed femoral pad. Background Art

[0002] Traditional knee prostheses mainly include a femoral condyle prosthesis, a tibial base for combining with the tibia, and a pad arranged on the tibial base. The combination of the three realizes the joint function. The femoral condyle prosthesis is provided with a positioning rod that can be inserted into the medullary cavity to ensure the stability of the connection. However, after long-term use, it was found that the contact area between the positioning rod and the medullary cavity was too small, resulting in local pressure concentration and wear, and eventually leading to aseptic loosening of the femoral condyle prosthesis, requiring surgical revision again.

[0003] To this end, the existing technology proposes to increase the contact area with the tibia by adding a porous pad. The porous pad is a porous structure formed by 3D printing, and its shape can be customized to greatly increase the contact area with the medullary cavity. After being combined with the tibial base, it can improve the stability of the positioning rod; but in fact, since the porous pad is a fully porous structure, the actual mechanical properties of the porous pad are relatively poor locally, and the shape of the medullary cavity is not a standard cylinder, which makes it difficult to achieve absolute uniform contact between the porous pad and the medullary cavity. The force will definitely be concentrated locally, especially the instantaneous stress generated during implantation is greater, which can easily cause damage or falling off of the porous structure, seriously affecting safety of use. Utility Model Content

[0004] The purpose of this utility model is to provide a powder-printed femoral spacer that creatively incorporates a tubular reinforcement. This reinforcement and the porous structure of the peripheral portion form an integrated structure, with the reinforcement primarily bearing the load, thereby improving overall mechanical performance and overcoming the problem of poor mechanical properties. Furthermore, the reinforcement acts as a bone cement limiter, restricting the range of bone cement application between the spacer and the tibial tray, thereby preventing damage to the medullary cavity wall during the cement injection phase.

[0005] In order to achieve the above purpose, the following technical solutions are adopted:

[0006] A powder-printed femoral pad comprises: a reinforcement portion and a peripheral portion, wherein the peripheral portion surrounds the outer surface of the reinforcement portion and is fixedly connected to the outer surface of the reinforcement portion; the reinforcement portion is provided with a through channel, and the peripheral portion is a porous structure formed by additive manufacturing technology, and the porous structure of the peripheral portion is constructed with the outer surface of the reinforcement portion as a reference surface.

[0007] Furthermore, the reinforcement portion is a solid structure, which is integrally formed with the peripheral portion through additive manufacturing technology, wherein the porous structure is a three-dimensional mesh structure constructed by wire or thread; the three-dimensional mesh structure is formed by repeated stacking of polygonal units.

[0008] Furthermore, the projection shape of the outer contour of the reinforcement portion is one of a circle, an ellipse, and a regular polygon.

[0009] The utility model has at least the following beneficial effects:

[0010] Significantly improve the stability of the connection between the femoral condyle prosthesis and the femur. The femoral spacer increases the contact area between the positioning rod and the medullary cavity, greatly enhancing the stability of the femoral prosthesis. At the same time, a reinforced part is provided inside the spacer to replace the porous structure as the main load-bearing component. At the same time, it can optimize the force performance and avoid the risk of failure of the peripheral porous structure due to pressure concentration.

[0011] Additionally, the reinforcement portion is located exactly at the filling position of the bone cement, forming a limiting structure to block the bone cement. When the bone cement is pumped in under pressure, the pumping pressure can be effectively limited to prevent excessive pressure from damaging the medullary cavity wall.

[0012] In addition, one-piece molding based on 3D printing technology can realize the molding of complex porous structures and directly connect them with the reinforcement part. The structural stability of the two is stronger. At the same time, porous structures with smaller porosity can be formed, thereby improving the effect of bone ingrowth in the later stage. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 Schematically shows the use status diagram of this application;

[0014] Figure 2 The structural diagram of Example 1 is schematically shown;

[0015] Figure 3 The structural diagram of Example 2 is schematically shown;

[0016] Figure 4 The stress-strain curve of the experimental example is schematically shown.

[0017] in:

[0018] 1-femoral spacer, 11-reinforcement part, 12-peripheral part;

[0019] 2-femoral condyle, 3-extension rod. DETAILED DESCRIPTION

[0020] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, the specific embodiments of the present invention are now described in detail with reference to the accompanying drawings. In the following description, it should be understood that the directions or positional relationships indicated by "front", "back", "up", "down", "left", "right", "longitudinal", "horizontal", "vertical", "horizontal", "top", "bottom", "inside", "outside", "head", "tail", etc. are based on the directions or positional relationships shown in the accompanying drawings and are constructed and operated in specific directions. They are only for the convenience of describing the present technical solution and do not indicate that the devices or components referred to must have specific directions. Therefore, they should not be understood as limiting the present invention.

[0021] It should also be noted that, unless otherwise expressly specified or limited, terms such as "installed," "connected," "connect," "fixed," and "set" should be understood broadly. For example, they can refer to fixed connections, detachable connections, or integration; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; they can refer to internal connectivity between two elements or interactions between two elements. When an element is referred to as being "on" or "under" another element, the element can be "directly" or "indirectly" located above the other element, or one or more intervening elements may be present. Those skilled in the art will understand the specific meanings of the above terms in this utility model based on the specific circumstances. Example 1

[0022] like Figure 1 As shown, the femoral condyle prosthesis includes a femoral condyle 2 and an extension rod 3, which are formed in one piece through 3D printing technology. The shape of the femoral condyle 2 is the same as the original femoral condyle 2, which can achieve a customized effect and cooperate with the tibial tray to realize the joint function. The extension rod 3 is inserted into the medullary cavity through an intraoperative incision to stabilize the femoral condyle 2. The extension rod 3 is connected to the dorsal side of the femoral condyle 2, and the femoral pad passes through the extension rod 3 and is located at the connection part between the two. The femoral pad is fixed by injecting bone cement. The femoral pad increases the contact area with the medullary cavity, which solves the problem of pressure concentration in the prior art due to the complex structure of the joint part, the non-fixed force direction, and the limited contact area between the extension rod 3 and the femoral medullary cavity.

[0023] In this application, a pad structure is used in conjunction with the extension rod 3. The outer wall contour of the pad is formed by 3D printing to match the patient's physiological shape, increase the contact area, disperse the force points, avoid wear under long-term use, and maintain long-term stability.

[0024] The structure of the femoral spacer is as follows Figure 2As shown, it includes: a reinforcement part 11 and a peripheral part 12, wherein the reinforcement part 11 is provided with a channel for the extension rod 3 to pass through in the axial direction, the inner wall of the channel is the inner surface of the reinforcement part 11, and correspondingly, the outer side of the reinforcement part 11 is the outer surface, and the femoral pad is fixed at the position where the extension rod 3 contacts the femoral condyle 2, and the shape of the peripheral part 12 is the same as the shape of the opening reserved on the tibial surface during surgery, thereby increasing the contact area.

[0025] Furthermore, the projected shape of the outer contour of the reinforcement portion 11 is not limited and can be a circle, an ellipse, or a regular polygon. This application uses a tubular structure with a circular projected shape as an example for illustration. Of course, the projected shape of its outer contour can also be a square or a partially thickened irregular shape.

[0026] In order to improve bone ingrowth of the medullary cavity pad, the peripheral part 12 is formed by additive manufacturing, and a fully porous structure is constructed with the surface of the peripheral part 12 as a reference surface. This structure can improve bone ingrowth and fully integrate with the femur, but the mechanical properties of the porous structure itself are poor.

[0027] It should be noted that the above-mentioned porous structure is not a dense through hole as commonly understood, but a three-dimensional network structure constructed by filaments or threads of hard materials. The structure can be formed by repeated stacking of multiple polygonal units, and the polygonal units can be regular dodecahedral unit cells, rutile unit cells and other structures. The porosity of the porous structure is very small, and it appears macroscopically similar to dense pores, so it is usually called a porous structure.

[0028] This application combines the peripheral part 12 of the porous structure with the reinforcement part 11 of the solid structure. The reinforcement part 11 serves as the main load-bearing member, sharing the force of the porous structure, effectively maintaining the stability of the porous structure, overcoming the problem of poor mechanical properties of the porous structure, and giving full play to the bone inductivity of the porous structure.

[0029] In addition, since the bone cement is located exactly between the reinforcement part 11 and the femoral condyle 2 prosthesis and is restricted by the reinforcement part 11, the bone cement is relatively isolated from the internal environment of the body. In particular, after the femoral stem is inserted, the addition of bone cement will cause the pressure in the medullary cavity to increase rapidly, causing the thin-walled intramedullary blood vessels to rupture, resulting in air, fat and bone marrow tissue entering the blood circulation, and then causing serious adverse reactions such as diffuse pulmonary embolism. After the bone cement is restricted by the reinforcement part 11, the occurrence of the above situation is effectively avoided. Example 2

[0030] like Figure 3 As shown, the femoral pad of this embodiment is provided with a groove on the side in contact with the femoral condyle 2 prosthesis, for avoiding the protrusion on the contact surface of the femoral condyle 2, so as to adapt to the plethora of models on the market. The reinforcement portion extends and covers the inner side of the groove.

[0031] Experimental example

[0032] Experimental samples:

[0033] Sample 1: fully porous femoral spacer;

[0034] Sample 2: femoral spacer of Example 1;

[0035] Experimental instruments and equipment: universal mechanical testing machine;

[0036] The experimental example compares the mechanical properties of the fully porous pad in the prior art and the pad of the present application. The mechanical properties are an important reference indicator for the use of the product. The results are shown in the following table.

[0037] Table 1 Experimental results

[0038]

[0039] Note: >50000N means it has exceeded the measurement range of the universal mechanical testing machine.

[0040] Through experimental design, it is determined that the main difference between the two samples is that sample 1 does not have the reinforcement part 11, and this simple structure improves the mechanical properties far beyond expectations, such as Figure 4 As shown in the figure, the compressive load and stiffness of sample 1 are much smaller than those of sample 2.

[0041] After the technology of the present application is implanted in the body, due to the complex stress conditions, a large instantaneous impact force will often be generated in the part where the stress is concentrated, which is more likely to cause the porous structure to break. The reinforced part 11 in the present application greatly enhances the overall mechanical properties, maintains the structural stability of the porous structure after implantation, and is obviously safer to use.

[0042] In the following description, for purposes of illustration and not limitation, specific details such as particular system structures and techniques are provided to provide a thorough understanding of the embodiments of the present invention. However, those skilled in the art will appreciate that the present invention can be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, and methods are omitted to avoid obscuring the description of the present invention with unnecessary detail.

Claims

1. A powder-printed femoral spacer, characterized in that: include: A reinforcement portion and a peripheral portion, wherein the peripheral portion surrounds the outer surface of the reinforcement portion and is fixedly connected to the outer surface of the reinforcement portion; a through channel is provided on the reinforcement portion, and the peripheral portion is a porous structure formed by additive manufacturing technology, and the porous structure of the peripheral portion is constructed with the outer surface of the reinforcement portion as a reference surface.

2. The powder-printed femoral spacer according to claim 1, characterized in that: The reinforcement portion is a solid structure and is integrally formed with the peripheral portion through additive manufacturing technology.

3. The powder-printed femoral spacer according to claim 1, characterized in that: The porous structure is a three-dimensional network structure constructed by silk or thread.

4. The powder-printed femoral spacer according to claim 3, characterized in that: The three-dimensional network structure is formed by repeatedly stacking polygonal units.

5. A powder-printed femoral pad according to any one of claims 1 or 2, characterized in that: The projection shape of the outer contour of the reinforcement portion is one of a circle, an ellipse, and a regular polygon.

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