Patent Application
20080133026
1. Field of the Invention
The invention relates to an artificial bone, more particularly to an artificial bone having a porous structure. The invention also relates a method for making the artificial bone.
2. Description of the Related Art
Referring to
The artificial bone 3 used presently in the art is solid, and includes a bone body 31 inserted into the femur 1, and a neck portion 32 connected to the bone body 31 and bent relative to the bone body 31.
The method for making the artificial bone 3 includes the steps of: preparing a solid cylindrical rod of titanium alloy having a proper length; lubricating the surface of the rod; bending the rod by forging to form a preformed blank; cleaning and lubricating the surface of the preformed blank; forging the preformed blank at least two more times at a constant temperature to form a semi-product; and trimming the semi-product to obtain the artificial bone 3. It should be noted that the artificial bone 3 is required to be further processed, such as by rubbing, turning and localized-coarsening before being used in a human body.
In view of the aforesaid, the artificial bone 3 used presently in the art has the following disadvantages:
1. Since the raw material used for making the artificial bone 3 is a solid titanium alloy rod, it is necessary to use a relatively large-sized forging machine to produce a relatively large mechanical force for the forging process.
2. Since the artificial bone 3 is made of a solid titanium alloy rod, it is necessary to use a relatively large amount of raw material, and a relatively large amount of waste material is produced. Therefore, the production cost is relatively high.
3. Since the conventional method for making the artificial bone 3 involves various processing steps, such as lubricating, bending, cleaning, forging, etc., it is relatively complicated and time-wasting.
One object of the present invention is to provide an artificial bone which is lightweight, and which can simulate the porous structure of a real bone.
Another object of the present invention is to provide a method for making the artificial bone, which reduces the amount of waste material, which is simple, and which does not require a large-sized processing machine.
Accordingly, in one aspect of this invention, an artificial bone includes a bone-shaped hollow metal body confining a sealed space and having two opposite closed ends, and a porous structure disposed in the sealed space.
In another aspect of this invention, a method for making an artificial bone includes the steps of: positioning a metal tube in a bone-shaped mold cavity of a mold, hydro-forming the metal tube into a bone-shaped hollow tube in the bone-shaped mold cavity by injecting a high pressure fluid into the metal tube, disposing a crumple of metal wire into the bone-shaped hollow tube, depositing a metal coating on the metal wire and an inner surface of the bone-shaped hollow tube to form a porous structure in the bone-shaped hollow tube, and sealing the bone-shaped hollow tube.
Other features and advantages of the present invention will become apparent in the following detailed description of the preferred embodiments with reference to the accompanying drawings, of which:
Referring to
The porous structure 42 is disposed and fixed in the sealed space 43 of the bone-shaped hollow metal body 41, and includes a crumple of metal wire 421 and a metal coating 422 deposited on the metal wire 421 and an inner surface of the bone-shaped hollow metal body 41. In this preferred embodiment, the metal wire 421 is made of a titanium alloy. Alternatively, the metal wire 421 can be made of other suitable metals, such as a nickel alloy, a copper alloy, a gold alloy, a silver alloy, or the like. Furthermore, the crumple of metal wire 421 can be composed of one or more metal segments.
The metal coating 422 is deposited on the metal wire 421 and the inner surface of the bone-shaped hollow metal body 41 so as to form the porous structure 42 which simulates the sponge structure of a real bone, and which is fixed in the bone-shaped hollow metal body 41. In this preferred embodiment, the metal coating 422 is made of a titanium alloy. Alternatively, the metal coating 422 can be made of other suitable metals, such as a nickel alloy, a copper alloy, a gold alloy, a silver alloy, or the like.
It should be noted that since the bone-shaped hollow metal body 41 will come into contact with human cells, the material for the bone-shaped hollow metal body 41 should have superior human affinity. However, since the metal wire 421 and the metal coating 422 are disposed in the bone-shaped hollow metal body 41, various materials can be used therefor.
Referring to
A) Positioning:
Referring to
B) Hydro-Forming:
The mold 7 is closed by disposing the upper mold part 71 on the lower mold part 72 after the metal tube 6 is positioned in the lower mold cavity portion 721. The first sealing block 73 is sleeved on one of the open ends 61 of the metal tube 6 so as to close said one of the open ends 61. The second sealing block 74 is sleeved on the other one of the open ends 61 of the metal tube 6. The metal tube 6 is hydro-formed into a bone-shaped hollow tube 82 in the bone-shaped mold cavity 70 by injecting a high pressure fluid into the metal tube 6 via the fluid passage 741 of the second sealing block 74. The mold 7 is opened after releasing the fluid, and the bone-shaped hollow tube 82 is taken out of the mold 7.
C) Disposing:
Referring to
D) Depositing:
Referring to
In this preferred embodiment, the bone-shaped hollow tube 82 is connected electrically to a cathode, and a titanium alloy plate 9 is connected electrically to an anode. When an electric current is applied, the titanium alloy plate 9 dissociates to form metal ions, which migrate into the bone-shaped hollow tube 82 via the electroforming medium and form the metal coating 86 deposited on the metal wire 84 and the inner surface of the bone-shaped hollow tube 82.
E) Sealing:
Referring again to
In addition to electroforming, other suitable methods can be used to form the porous structure. For example, sintered metal particles can be used to form the porous structure. Additionally, a removable material, such as a material having a low melting point, is disposed in the bone-shaped hollow tube 82, and a desirable metal is deposited on the removable material. The porous structure is formed after melting and removing the molten removable material from the bone-shaped hollow tube 82.
In view of the aforesaid, this invention has the following advantages:
1. Since the metal tube 6 used for forming the bone-shaped hollow tube 82 is hollow, the mechanical force required to perform the hydro-forming process is relatively small as compared to the prior art, and the raw material requirement in this invention is reduced significantly. Therefore, the production cost is lowered.
2. The processing step, such as forging, trimming, etc., required in the prior art can be omitted in this invention, and the method of this invention can be performed at ambient temperature. Therefore, the method of this invention is relatively simple.
3. The porous structure 42 formed in the artificial bone 4 of this invention can reduce the overall weight of the artificial bone 4 while providing a satisfactory mechanical strength.
While the present invention has been described in connection with what are considered the most practical and preferred embodiments, it is understood that this invention is not limited to the disclosed embodiments but is intended to cover various arrangements included within the spirit and scope of the broadest interpretation so as to encompass all such modifications and equivalent arrangements.
