JPH05309129A - Prosthetic means and its manufacture - Google Patents

Abstract

PURPOSE:To increase the break strength of a surface layer itself, and to increase the joining strength of the surface layer to bone cement by providing a surface layer on which a silane coupling agent has been coated to the portion called as bone of the base body that constitutes a prosthetic means consisting of an inorganic material such as a metal ceramics. CONSTITUTION:As the medical treatment in the orthopedics for the disease of bone, such a treatment as the damaged part is substituted by a prosthetic means such as an artificial joint is carried out. In a case where an artificial knee joint, for instance, is applied to a thighbone member 1 as the prosthetic means, the base body 2 of the thighbone member 1 is made up of the metal such as pure titanium, titanium alloy, and cobalt chromium alloy, or ceramics such as alumina and zirconia; and on the inside surface 2a of the baszed body 2 facing the far end part F of the thighbone, a surface layer 3 of a silane coupling agent whose thickness has been minimized is formed. The thighbone member 1 is fixed to the far end part F of the thighbone with bone cement 4 making the main component with polymethyl methacrylate. Thereby, a prosthetic means having a high bonding strength can be obtained.

Description

Detailed Description of the Invention

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a prosthesis for repairing a function lost in a human body due to a disease, a disaster or the like, and a method for producing the same, more specifically, a prosthesis suitable for being fixed to bone by bone cement. The present invention relates to an ingredient and a manufacturing method thereof.

[0002]

2. Description of the Related Art When bone function such as osteoarthritis or rheumatoid arthritis impairs the joint function of the limbs, replacement of the affected part with a prosthetic device such as an artificial joint is performed as a treatment in orthopedics. ing. Then, as a means for binding such a prosthesis to bone, a bone containing a mixture of polymetal methyl methacrylate (hereinafter abbreviated as PMMA) and a methyl methacrylate monomer or a copolymer of PMMA and styrene. Cement is commonly used.

However, the bond between the prosthesis and the bone cement is not strong at all, and the boundary surface is ruptured under repeated loading, and especially the surface of the prosthesis is rough or uneven. When the stress in the bone cement is non-uniform due to the presence of cracks, there is a problem that a crack is generated in the bone cement, the crack spreads over the entire bone cement, and finally the bone cement breaks.

In order to solve such a problem, Japanese Patent Publication No. 63-40550 discloses that a PMMA film is formed on at least the surface of a base body made of a metal, ceramics or plastics material which constitutes a prosthesis and is in contact with bone. The base is metal,
When made of an inorganic material such as ceramics, the surface of the substrate is chemically bonded to both the organic PMMA and the inorganic metal or ceramic substrate, if necessary, to firmly bond the both. The invention describes a prosthesis in which a silane coupling agent layer having an action is formed, a PMMA film is formed thereon, and the PMMA film is further annealed and then cured and cooled.

In this prosthesis, the residual stress in the PMMA film is uniformly dispersed by the above-mentioned annealing treatment, and the PMMA film and the bone cement molecules are chemically bonded to each other to form the bone cement. It was said that the joint strength of the prosthesis would increase significantly.

[0006]

However, in the above-mentioned conventional prosthesis, the bonding strength between the prosthesis and the bone cement is remarkably larger than that of the prosthesis in which the PMMA film is not formed on the surface of the substrate. However, the joint strength was not clinically sufficient.

This is because the annealing process is troublesome and it is very difficult to actually disperse the residual stress in the PMMA film evenly. In addition, the silane coupling agent layer is used as a PMMA film. The prosthesis to be interposed between the bases did not take any special measures to make the silane coupling agent layer as thin as possible, so the silane coupling agent layer becomes thicker, and the silane coupling agent layer becomes thicker. This is because the breaking strength of the agent layer itself was not sufficient.

[0008]

In order to solve the above-mentioned problems, the present invention comprises coating a silane coupling agent on at least a portion of a base body made of an inorganic material such as metal or ceramics which constitutes a prosthesis and in contact with bone. A prosthesis provided with a surface layer, and as a method for producing the prosthesis, distilled water or pure water and an acetic acid solution are used as solvents, and a silane coupling agent is added in an amount of 0.01 to 1
PH 2.5 with alcohol added to a mixture containing 0 wt%
~ 5.5 alcohol added liquid at 20 ~ 30 ℃ 1 ~ 24
The silane coupling agent solution, which has been stirred for a period of time, is applied to at least the bone-contacting portion of the base body of the prosthesis that is made of an inorganic material such as metal or ceramics, and then air-dried to form the surface layer of the silane coupling agent. A method of manufacturing a prosthesis including the step of forming

[0009]

The present invention will be described in detail below with reference to the drawings. The prosthesis of the present invention forms a surface layer formed by coating a silane coupling agent on at least a portion of a base body which is made of an inorganic material such as metal or ceramics and which constitutes the prosthesis, and is in contact with bone, and this portion is formed by bone cement. FIG. 1 shows a femoral member 1 of an artificial knee joint as an example of a prosthesis according to the present invention, which is made of pure titanium, a titanium alloy, a cobalt chromium alloy, or the like, which is biohazardous. The inner surface 2a facing the distal end portion F of the femur of the base body 2 made of a non-metal or an inorganic material of ceramics such as alumina and zirconia has a silane whose thickness is reduced as much as possible by the method for manufacturing a prosthesis described later. Surface layer 3 of coupling agent
Is formed. The femoral member 1 is fixed to the distal end portion F of the femur using a bone cement 4 containing PMMA as a main component.

The silane coupling agent forming the surface layer 3 has a property of chemically bonding to both the organic material and the inorganic material and firmly bonding the both. First, the bone cement 4, which is an organic material, and the silane coupling agent are
It has several kinds of functional devices corresponding to each, and chemically bonds with them. Further, in the chemical bond between the silane coupling agent and the substrate 2 made of an inorganic material,
When water is added to the silane coupling agent, the methoxy group and the ethoxy group bonded to the silicon element are hydrolyzed to produce silanol (SiOH), which is then adsorbed on the silanol and the oxide layer on the surface of the substrate 2. Reacting water molecules react with each other, and the chemical bond strongly bonds the surface layer 3 and the substrate 2 together. At this time, if the surface of the substrate is cleaned to a state where no contaminant is present, more water molecules are adsorbed on the surface of the substrate 2 instead of the contaminant.

FIG. 2 is an enlarged view showing the joint between the femoral member 1 and the distal end F of the femur shown in FIG. 1. The surface layer 3 formed on the inner surface 2a of the base 2 is As described above, the base 2 and the bone cement 4 are strongly bonded by a chemical bond, but since the molecules of the silane coupling agent in the surface layer 3 are not chemically bonded, the smaller the thickness T is, The breaking strength of the surface layer 3 itself is large. Needless to say, the most ideal state is a monatomic adsorption state. The thickness T of the surface layer 3 is several to several hundred Å, and the thickness T could not be measured accurately. However, by changing some conditions in the manufacturing method described below, the thickness T Can be made as small as possible.

Next, a method of manufacturing the prosthesis according to the present invention will be described. A method for manufacturing a prosthesis according to the present invention includes: Preparation of substrate 2, B. Preparation of silane coupling agent solution, C.I. The step of forming the surface layer is included.

Among these, A. The method of preparing the base 2 is different when the base 2 is a metal and when it is a ceramic.

First, when the substrate 2 is made of metal, at least a portion in contact with bone is surface-ground and mirror-polished, and then,
Glass beads blasting is performed on that portion, Ra = 0.25
The surface is roughened to about 0.35 μm. Finally, ultrasonic cleaning is performed in toluene for about 5 minutes to degrease the surface. On the other hand, in the case of a ceramic material, after firing the substrate 2, the substrate 2 is dipped in concentrated hydrochloric acid for about 30 minutes to wash it, and the substrate 2 is removed for the purpose of removing excess hydrocarbons.
Heat treatment at ~ 1300 ° C.

Next, B. In the preparation of the silane coupling agent solution of, for example, N.beta.aminoethyl.gamma.aminopropyltrimethoxysilane, gamma.aminopropyltriethoxysilane, bis (beta.hydroxyethyl) .gamma. Aminopropyltriethoxysilane, beta- (3,4-epoxycyclooxyethyl) -ethyltrimethoxysilane, gamma-glycidoxytrimethoxysilane, gamma-methacryloxypropyltrimethoxysilane, sulfonylazidosilane, vinyltrichlorosilane, vinyltri Commercially available products such as ethoxysilane can be used.

The work also includes the steps of preparing a mixed solution, adding alcohol to the mixed solution, and stirring the alcohol-added solution.

In the preparation of the mixed solution, the silane coupling agent as described above is contained in an amount of 0.01 to 10 wt%.
Distilled water or pure water is mixed with acetic acid solution to obtain a mixed solution. The breaking strength of the surface layer 3 itself does not change regardless of whether distilled water or pure water is used. Further, alcohol is added to the above mixed solution so as to have a pH of 2.5 to 5.5 to obtain an alcohol-added solution.

Thus, the purpose of adding alcohol to the above-mentioned mixed solution is to prolong the life of the alcohol-added solution, that is, to prevent excessive condensation of the alcohol-added solution at the time of stirring described below, and to increase the amount of the silane coupling agent. It is to prevent it from becoming a molecule.

Further, the pH of the alcohol-added liquid is 2.5 to
If it is 5.5, the joint strength between the prosthesis and the bone cement 4 becomes very large. The adjustment of this pH is controlled by the amount of alcohol and acetic acid solution added. Further, it is preferable to use ethanol as the alcohol to be added.

Next, the above alcohol-added liquid is added at a temperature of 20 to 30 ° C. for 1 to 2
The solution is stirred for 4 hours to obtain a silane coupling agent solution (hereinafter, abbreviated as solution).

If the stirring time is less than 1 hour, the alcohol-added liquid does not react sufficiently, and if it exceeds 24 hours, the reaction proceeds too much to polymerize the silane coupling agent and the surface layer 3 itself. The breaking strength becomes small.

As described above, a silane coupling agent is prepared to obtain a solution.

Finally, C.I. Regarding the formation of the surface layer of the silane coupling agent, the method is as follows:
At least the part in contact with bone is immersed in the solution for about 10 seconds, or the solution is sprayed onto at least the part in contact with the bone of the substrate 2, or is applied with a brush or the like and then air-dried. The surface layer 3 is formed.

The prosthesis of the present invention is manufactured as described above. In the prosthesis of the present invention manufactured by the above-described method, the surface layer 3 is formed on at least the portion of the base body 2 in contact with the bone, and the thickness T of the surface layer 3 is made as small as possible by the manufacturing method described above. The fracture strength of the surface layer 3 itself is very large, so that the joint strength with the bone cement is very large, and the joint strength is clinically sufficient.

Further, according to the above manufacturing method, the surface layer 3 having the smallest possible thickness can be formed relatively easily.

Example 1 A lower surface of a test piece made of a titanium alloy was prepared by the above-mentioned method so that Ra = 0.25 μm.

The concentration of the silane coupling agent is 5.
The mixed solution using distilled water and an acetic acid solution as a solvent was prepared so that the concentration was 0 wt%, and this was divided into two, but one was mixed with butanol and the other with ethanol in an appropriate amount so as to have a pH of 3.5. Alcohol-added liquids were prepared, and each of these alcohol-added liquids was stirred at 25 ° C. for 1 hour to obtain the solution.

Next, the prepared lower surface of the test piece was dipped in each of these two kinds of solutions for 10 seconds and air-dried to form the surface layer 3.

The lower surface of these test pieces and the lower surface of the test piece whose lower surface was not adjusted were joined to a bone cement of Surgical Simplex (registered trademark) manufactured by Howmedica Co., so that the effective area was φ15 (mm), and the instrument was installed. Using a Ron type tester, a simple tensile test was performed at a speed of 1 (mm / min). The results are shown in Table 1. The same experiment was performed 5 times for each experimental system, and the bonding strength shown in the table is the average value.

[0030]

[Table 1]

As is clear from Table 1, it was found that the bonding strength of the test piece having the surface layer 3 formed on the lower surface increased dramatically.

Further, it has been found that ethanol is preferable as the alcohol to be added.

Example 2 The bottom surface of a test piece made of pure titanium was rounded by the above method.
It was prepared so that a = 0.3 μm.

Further, using distilled water and an acetic acid solution as a solvent, four kinds of the above mixed liquids having the concentrations of the silane coupling agents as shown in Table 2 were prepared, and these had the pH values shown in Table 2. Mix the appropriate amount of ethanol with each of the 4
Alcohol-added liquids of various kinds were prepared, and these alcohol-added liquids were stirred at 28 ° C. for 1 hour to obtain the above solution.

[0035]

[Table 2]

Next, the prepared lower surface of the test piece was immersed in each of these four kinds of solutions for 10 seconds, and this was air-dried to form the surface layer.

The lower surface of these test pieces and the lower surface of the test piece whose lower surface was not adjusted were joined to a bone cement of Surgical Simplex (registered trademark) manufactured by Howmedica Co., so that the effective area was φ15 (mm), and the instrument was installed. Using a Ron type tester, a simple tensile test was performed at a speed of 1 (mm / min). The results are shown in Table 2. The same experiment was performed 5 times for each experimental system, but the bonding strength shown in the table is the average value thereof.

As is clear from Table 2, it was found that the bonding strength between the test piece and the bone cement was dramatically increased when the pH of the alcohol-added liquid was 2.5 to 5.5.

Example 3 A lower surface of a test piece made of a cobalt chromium alloy was prepared by the above-described method so that Ra = 0.35 μm.

Further, using pure water and an acetic acid solution as a solvent, 6 kinds of the above-mentioned mixed solutions having the concentrations of the silane coupling agent as shown in Table 3 were prepared, and these were as shown in Table 3.
Ethanol was mixed in an appropriate amount so as to be H to prepare 6 kinds of alcohol addition liquids, and these alcohol addition liquids were respectively stirred at 24 ° C. for 3 hours to obtain the above solution.

[0041]

[Table 3]

Next, the lower surface of the test piece was dipped in each of these six kinds of solutions for 10 seconds and air-dried to form the surface layer 3.

The lower surface of these test pieces and the lower surface of the test piece whose lower surface was not adjusted were joined to a bone cement of Surgical Simplex (registered trademark) manufactured by Howmedica Co., so that the effective area was φ15 (mm), and the instrument was installed. Using a Ron type tester, a simple tensile test was performed at a speed of 1 (mm / min). The results are shown in Table 3. The same experiment was performed 5 times for each experimental system, and the bonding strength shown in the table is the average value.

As is clear from Table 3, the joint strength between the test piece and the bone cement was dramatically increased when the concentration of the silane coupling agent in the mixed solution was 0.01 to 10 wt%. It was

Example 4 The lower surface of a test piece made of a titanium alloy and a test piece made of a cobalt chrome alloy were subjected to Ra = 0.
It was adjusted to 3 μm.

Further, the lower surface of the test piece made of alumina ceramics and the lower surface of the test piece made of zirconia ceramics was adjusted to Ra = 0.7 μm by the above-mentioned method.

Further, using pure water and an acetic acid solution as a solvent, the above-mentioned mixed solution having a concentration of the silane coupling agent of 5 wt% was prepared, and an appropriate amount of ethanol was mixed with these so as to have a pH of 3.9, and alcohol was added. A liquid was prepared, and this alcohol-added liquid was stirred at 25 ° C. for 3 hours to obtain the above solution.

Next, titanium alloy, cobalt chrome alloy,
This solution was applied to the lower surface of the test piece made of alumina ceramics and zirconia ceramics using a brush, and this was air-dried to form the surface layer 3.

The lower surfaces of these test pieces and the lower surfaces of the test pieces made of titanium alloy, cobalt chrome, alumina ceramics, and zirconia ceramics whose lower surfaces have not been adjusted are the bone cements of Surgical Simplex (registered trademark) manufactured by Howmedica. Effective area is φ
It joined so that it might become 15 (mm), and the simple tension test was done at a speed of 1 (mm / min) using the Instron type tester. The results are shown in Table 4. The same experiment was performed 5 times for each experimental system, but the bonding strength shown in the table is the average value thereof.

[0050]

[Table 4]

As is clear from Table 4, the test piece provided with the surface layer 3 has a dramatically increased bonding strength regardless of whether it is made of metal or ceramics. understood.

Example 5 The lower surface of a test piece made of a titanium alloy was prepared to have the surface roughness (Ra) shown in Table 5 by the method described above.

[0053]

[Table 5]

Further, using pure water and an acetic acid solution as a solvent, a mixed solution having a concentration of the silane coupling agent of 5 wt% was prepared, and an appropriate amount of ethanol was mixed with these so as to have a pH of 3.9, and alcohol was added. A liquid was prepared, and this alcohol-added liquid was stirred at 25 ° C. for 2 hours to obtain the above solution.

Next, this solution was sprayed on the lower surface of the test piece and air-dried to form the surface layer 3.

The lower surface of these test pieces and the lower surface of the test piece made of a titanium alloy whose lower surface has not been adjusted are used as bone cement of Surgical Simplex (registered trademark) manufactured by Howmedica Co., so that the effective area becomes φ15 (mm). And using an Instron type tester, 1 (mm /
The simple tensile test was performed at a speed of (min). The results are shown in Table 5. The same experiment was performed 5 times for each experimental system, but the bonding strength shown in the table is the average value thereof.

As is apparent from Table 5, it was found that the above-mentioned test piece made of metal had a higher bonding strength when Ra = 0.25 to 0.35.

Example 6 The lower surface of a test piece made of a titanium alloy was prepared to have Ra = 0.30 by the method described above.

Further, using pure water and an acetic acid solution as a solvent, the above mixed solution having a concentration of the silane coupling agent of 5 wt% was prepared, and an appropriate amount of ethanol was mixed with these so that the pH was 3.9, and alcohol was added. A liquid was prepared, and this alcohol-added liquid was stirred at 25 ° C. for 1 hour to obtain the above solution.

Next, this solution was sprayed on the lower surface of the test piece and air-dried to form the surface layer 3.

Further, as a comparative example, an annealed PMMA film was formed on the lower surface of a group of test pieces according to the method for manufacturing a prosthesis of the invention of Japanese Patent Publication No. 63-40550.

The lower surface of the test piece on which only the surface layer 3 was formed and the lower surface of the test piece on which the PMMA film was formed on the surface layer 3 were used as an effective area for bone cement of Surgical Simplex (registered trademark) manufactured by Howmedica. Was bonded to be φ15 (mm), and a simple tensile test was performed at a speed of 1 (mm / min) using an Instron type tester. As a result, the surface layer 3 alone had a bonding strength of 150.2 kgf / cm ² and showed a clinically sufficient bonding strength, but the test piece of the comparative example had a bonding strength of 72.0.
It was kgf / cm ² and could not be said to have clinically sufficient joint strength.

[0063]

In the prosthesis of the present invention, the surface layer is formed on at least the surface of the substrate that contacts the bone, and the thickness of the surface layer is made as small as possible by the manufacturing method described above. The fracture strength is also very large, and therefore the joint strength with bone cement is very large, and the joint strength is clinically sufficient. Furthermore, according to the above manufacturing method, the surface layer having the smallest possible thickness can be formed relatively easily.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a femoral member of an artificial knee joint as an embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view showing a surface portion of the femoral member of FIG. 1 and a femur joined using bone cement.

[Explanation of symbols]

 1 Femur Member 2 Base 2a Inner Surface 3 Surface Layer 4 Bone Cement F Femur Far End

Claims (2)

[Claims] 1. A prosthesis having a surface layer made of an inorganic material such as metal or ceramics and having a silane coupling agent coated on at least a portion of a base constituting the prosthesis, which is in contact with bone. 2. Distilled water or pure water and acetic acid solution as a solvent,
A silane coupling agent solution prepared by stirring an alcohol-added solution having a pH of 2.5 to 5.5, which is obtained by adding alcohol to a mixed solution containing 0.01 to 10 wt% of a silane coupling agent, at 20 to 30 ° C for 1 to 24 hours A prosthesis including a step of forming a surface layer of a silane coupling agent by applying air-drying to a base made of an inorganic material such as metal or ceramics and at least a portion of the base constituting the prosthesis, which is in contact with bone. Method.