JPH0466582B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an endoprosthetic member, and more particularly to an endoprosthetic member used for prosthesis of a hip joint and fixed within a medullary canal.

(Prior art) This type of endoprosthetic component is McBride (Mc
Bride) in 1948. This publication states that the diameter of the threaded mandrel must be as large as possible, since the core of the threaded mandrel has to transmit extreme forces. For this reason, Matsukubride makes a hole in the medullary canal,
It is proposed to have a threaded neck for the head of the prosthesis and screw in the threaded mandrel. The screw of the threaded mandrel must be fixed in the bone structure that has been removed for fixation of this mandrel.

(Problems to be Solved by the Invention) However, it is recognized that this arthroplasty technique has many drawbacks. The medullary canal is already curved rather than straight, and the bone is necessarily weakened in some areas by drilling a straight hole. It is precisely in this weakened region of the bone that the best fixing effect of the screwed mandrel cannot be achieved. Also, due to the curvature of the medullary canal, a wide canal surface is left unengaged by the threads of the threaded mandrel. Due to the bell-shaped proximal femoral section, the screw mandrel will float in this region. The screw enters the cortex at the end of the threaded mandrel, and because the cortical structure is much stronger than the bone marrow, the prosthetic element is supported approximately at this end. This results in loosening and weakening of the proximal load-bearing structure, and biomechanical degeneration of the bone structure that extends from the proximal end to the distal end. Another drawback is that in order not to weaken the core of the threaded mandrel, the height of the threaded side surface is extremely low, so the threaded engagement must be small.
Also important is that the threaded mandrel cannot be held rigidly against rotation.

Another type of endoprosthetic component known as the "Spotorno prosthesis" in use today is
It consists of a strut with an oblong cross section that slopes towards the end and somewhat conforms to the shape of the medullary canal. The strut is driven axially into the medullary canal and wedges itself therein. A plurality of longitudinal support surfaces are provided on the wide sides of the base of the column to prevent rotation of the column. However, with this type of endoprosthetic component, the press-fit fixation is only at the end of the medullary canal;
This is unsatisfactory as the result is the same as above.

The present invention was made in view of the current state of this type of endoprosthetic member as described above, and its first purpose is to provide a cement material that can transmit load to the proximal femoral region near the body center. An object of the present invention is to provide an endoprosthetic member that does not require any.

A second object of the present invention is to provide a cementless endoprosthetic component that can be secured into the femoral structure proximal to the body without the use of a wedge.

A third object of the present invention is to provide an endoprosthetic component that is inserted axially into the medullary canal without the use of cement, the prosthetic component being inserted into the cancellous bone structure near the center of the body, The object of the present invention is to provide an endoprosthetic member having a wide support surface that does not damage or break the mesh structure when inserted into the body.

A fourth object of the present invention is to provide a multi-component endoprosthetic component, wherein a first component is non-rotatably fixed within the medullary canal and a second component is fixed to said inserted endoprosthetic component. fixed by part 1,
The second component consists in providing an endoprosthetic element having a lateral bearing surface that cuts into the cancellous structure of the proximal femur.

A fifth object of the invention is to provide an axially insertable post with an integral neck for fixing the head;
An object of the present invention is to provide a novel endoprosthetic member having a helical member guided by the strut.

(Means for Solving the Problems) In order to solve the above object, the present invention provides an intracorporeal prosthesis member that is used for bone prosthesis and is fixed in the body, which is tapered from the base in the axial direction and has a substantially plate shape. A neck is formed on the side of the base to protrude in a direction tilted with respect to the axis, and a helical screw is formed around the opening formed at the axis and inserted into the medullary canal. A flange-like spiral wing is formed around the shaft and protrudes outward from a pair of mutually opposing plate surfaces of the strut, and is inserted through the opening and screwed into the helical screw, and the spiral wing is inserted into the medullary canal. The structure includes a threaded mandrel that bites into the strut and fixes the strut within the medullary canal, and a rotation prevention pin that prevents the threaded mandrel from rotating within the strut.

(Function) With such a configuration, in the present invention, when the strut is inserted into the medullary canal and the screwed mandrel is screwed through the aperture formed in the strut, the flange-like spiral wings of the screwed mandrel move around the aperture. Screwed into the helical thread of the column being formed. Then, the spiral wings protruding outward from a pair of mutually opposing plate surfaces of the strut bite into the medullary canal and are fixed within the medullary canal. The threaded mandrel prevents relative rotation between the column and the threaded mandrel.

According to one embodiment of the invention, the helical wings of the threaded mandrel are frusto-conical, such that the self-cutting wing surfaces cut increasingly deeper into the cancellous bone structure of the proximal femoral portion. In the structure according to the invention, the threaded mandrel is strengthened by the struts to form a rigid device as a whole, the core of the threaded mandrel is formed with a small diameter, while the helical wings of the threaded mandrel are formed at their ends with the core It has an outer diameter that is more than three times the diameter of the The lateral bearing surfaces from the wide flanged wings of the threaded mandrel thus cut deeply into the cancellous bone structure and even into the cortex around the proximal femoral portion.
Since the present invention does not require drilling a hole in the medullary canal,
There is no loss of bone matrix.

The threaded mandrel only needs to be half of the base if the strut is of normal length, and no axial supporting force is applied to the end of the strut, allowing the end of the strut to be shortened.

In an embodiment of the invention, the column is also provided with at least one window through which the threaded mandrel passes longitudinally. A cavity is created on each side of the window between the core of the threaded mandrel and the leg of the post, so that the bone mesh can grow into the cavity and increase the fixation result of the endoprosthetic component.

(Example) An example of the present invention will be described below with reference to FIGS. 1 to 3. Here, FIG. 1 is a front view showing the structure of the embodiment, FIG. 2 is a side view showing the structure of the embodiment, and FIG. 3 is a sectional view taken along line 3-3 in FIG.

The endoprosthetic member 10 of the embodiment has a titanium alloy strut 12, the pair of wide plate surfaces 14 of which taper from the base to the distal end. Pillar 1
The thickness of the strut, measured at the pair of narrow side surfaces 16 of 2, becomes slightly thinner toward the tip. A cylindrical neck 17 is integrally formed at the upper right end (FIG. 1) of the column 12, and the neck 17 is attached to a head (not shown) as usual.

Two windows 18, 20 are provided in the base region of the column 12, passing through the column at right angles to the plate surface 14. The web 22 remaining between the windows 18, 20 strengthens the strut 12 and strengthens the endoprosthetic component 10.
It has the function of stably fixing the entire body within the body.
A pair of legs 24 and 26 extend between the side surface 16 and the windows 18 and 20, respectively, with the center of the body facing the pair of legs.
These legs 24, 26 are joined together at their ends to form a bridge portion 28, which is slightly bulged relative to the plate surface 14. Leg 2 on the opposite side of the neck 17
6 is enlarged on both sides so that the cross section of the strut 12 substantially matches the cross section of the medullary canal.

The aperture 30 passes through the bridge section 28 along an axis 32 that makes an angle a of approximately 5 DEG with the longitudinal axis 34 of the column 12. The angle of the shaft 32 with respect to the axis of the neck 17 is smaller than that of the axis 34. and window 1
8 and 20 are located at the center of the support column 12. Further, the web 22 is provided with a hole concentric with the aperture 30 and having the same diameter. A helical groove 36 is formed in the bridge portion 28, communicates with the aperture 30, and extends concentrically with the aperture 30 in the direction of the axis 32 of the strut 12. This spiral groove 36 is open to the upper and lower end surfaces of the bridge 28 and both wide side surfaces thereof.

Both legs 24 and 26 have grooves 46 on their inner surfaces facing each other that form part of a spiral groove that is continuous with the spiral groove 36.
is cut. The helical groove 36, the arcuate or ring-shaped groove 46, and the groove in the web 22 lie on the same helical path, the external contour of which is a virtual truncated cone.

The threaded mandrel 38, which is screwed into the strut 12 along the axis 32, consists of a cylindrical core 40 of circular cross-section and a wide flange-like thread forming a helical wing 42, the outer diameter of the end of the helical wing 42 being , is set to be more than three times the diameter of the core 40, and its blade surface is conical toward the end, with a conical angle of 20 degrees.
The thickness of the helical wing 42 tapers slightly radially outward from a constant leg width of approximately 2 mm, with the pitch of the wing surface being absolutely constant and equal to 10 DEG. Groove 36 in bridge 28 and in web 22
The dimensions of the groove, that is, the height of the groove and the pitch of the spiral path, are the same as those of the spiral groove formed in the support column 12. The maximum dimension of the end of the spiral wing 42 is 32 mm, while the minimum diameter is 13 mm. The diameter of the core portion 40 is 5 mm. The length along the axis of the screwed mandrel 38 is approximately 52 mm
It is. Recesses 48 are provided on the outer periphery of the spiral blade 42, and the intervals between the recesses 48 are set at 90 degrees. Each recess 48
The trailing edge is shaped like cutting teeth.

The strut 12 has the following dimensions: total length (excluding neck 17) 155 mm, side width 16 approximately 10 mm, end width 8 mm.
mm, width of wide plate surface 14 is approximately 50mm, edge width is 8mm
It is.

The threaded mandrel 38 inserts its protruding core 40 into the aperture 30 and is then rotated to release the helical wing 42
The bridge section enters the entrance of the groove 36 on the upper side of the bridge section 28.
From this point the threaded mandrel 38 is actively guided to be threaded into a predetermined helical path. After one complete rotation, the end of the spiral wing 42 is connected to the bridge section 28.
When the screw-in shaft 38 is further screwed in,
Its ends pass through window 18, web 22, and window 20, and the end of the core enters tap hole 44 in post 12. During this threading movement of the threaded mandrel 38, the peripheral self-cutting edges of the helical wings 42 cut into the mesh-like bone structure close to the wide plate faces 14 of the strut 12. During the final rotation, the periphery of the helical wing 42 further engages the groove 46 provided in the legs 24, 26, thereby stabilizing this wide flange-like helical wing 42 and the core 40 of the threaded mandrel 38. do.

The bridge portion 28 and the reinforcing web 22 are designed so that their upper and lower sides are adjacent to the adjacent portions of the helical wing 42, respectively.
I'm trying not to make it weak.

When the threaded mandrel 38 is fully screwed, the helical wing 42 is inserted into the groove 36 in the bridge 28 and the web 22.
The multiple bow-shaped wing surfaces are screwed into the strut 1.
It protrudes laterally from the wide plate surface 14 of 2. These wing sections form a wide flange-like lateral support surface, the radial dimensions of which are taken to be sufficient to cut into the cancellous bone structure as well as into the surrounding cortex. In this example, the radial dimension of the support surface is taken equal to 11 mm.

A hole 50 is provided in the bridge portion 28, and a rotation prevention pin 5 is provided in the bridge portion 28.
2 is screwed into the hole 50 and the anti-rotation pin 52 passes through one of the recesses 48 in the helical wing 42, by means of which the anti-rotation pin 52 fixes the strut 12 to the screwed axle 38.

The windows 18, 20 can in principle be omitted, but they are provided in such a way that the cancellous bone structure is inwardly formed in the recess formed between the core 40 of the threaded mandrel 38 and the legs 24, 26 of the strut, respectively. Favorable for growth.
In the illustrated embodiment, the windows 18, 20 are generally trapezoidal;
The angle between the wide sides is approximately equal to the cone angle of the helical wing 42 of the threaded mandrel 38. The arcuate or ring-shaped grooves 46 have the same depth.

(Effects of the Invention) According to the present invention, the bone network structure can be damaged or broken by a simple operation of screwing the mandrel into the strut inserted into the medullary canal, without using cement or wedges. It is possible to provide an endoprosthetic member that can be stably fixed in the body without any problems.

[Brief explanation of the drawing]

FIG. 1 is a front view showing the structure of an embodiment of the present invention, FIG. 2 is a side view showing the structure of an embodiment of the invention, and FIG. 3 is a sectional view taken along line 3-3 in FIG. DESCRIPTION OF SYMBOLS 10... Internal prosthesis member, 12... Support column, 14... Plate surface, 16... Side surface, 17... Neck, 18, 19... Window,
22...web, 24, 26...leg, 28...bridge, 3
0...Open hole, 32...Shaft, 34...Axis core, 38...Screwed mandrel, 42...Spiral blade, 52...Rotation prevention pin.

Claims (1)

[Scope of Claims] 1. An intracorporeal prosthesis member used for bone prosthesis and fixed in the body, which is tapered in the axial direction from the base and formed into a substantially plate shape, and has a wall on the side of the base relative to the axis. a strut having a neck protruding in an inclined direction, a helical screw formed around an aperture formed at the axial center position, and inserted into the medullary canal; and a pair of struts facing each other around the axis. a threaded mandrel having a flange-like helical wing protruding outward from the plate surface thereof, which is inserted through the opening and screwed into the helical screw, so that the helical wing bites into the medullary canal and fixes the strut within the medullary canal; , and an anti-rotation pin for preventing rotation of the threaded mandrel within the strut. 2. In the endoprosthetic member according to claim 1, at least one window is formed that penetrates the plate surface, and a helical screw into which the helical wing is screwed is formed on the circumferential surface of this window. An endoprosthetic member characterized by: 3. The endoprosthetic member according to claim 1, wherein the axis of the threaded mandrel is inclined at approximately 5 degrees in the cervical direction with respect to the axis of the strut. 4. An endoprosthetic component according to claim 1, characterized in that the external contour of the threaded mandrel is substantially frustoconical. 5. The endoprosthetic member according to claim 1, characterized in that the post has a tap hole into which the tip of the threaded mandrel is inserted when the threaded mandrel is screwed and fixed to the post. Endoprosthetic components. 6. The endoprosthetic member according to claim 1, wherein the diameter of the threaded mandrel is 30% or less of the maximum diameter of the helical wing. 7. The endoprosthetic member according to claim 1, wherein a rotation prevention pin that prevents rotation of the threaded mandrel from the upper surface of the base of the strut is inserted into the threaded mandrel.