JP4018327B2 - Osteosynthesis device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an osteosynthesis device, and more particularly, to an osteosynthesis device including a bone screw suitable for repairing a fracture near the head of a femur.
[0002]
[Prior art]
Conventionally, an osteosynthesis device for repairing and fixing a fracture near the head of the femur is known. As such an osteosynthesis device, for example, called a waist compression screw (CHS), a lag screw having a screw portion on the distal end side and a shaft portion on the proximal end side, and an attachment body engaged with the lag screw, There is a device consisting of
[0003]
The attachment body includes a plate portion arranged along the surface of the femur and fixed by a bone screw or the like, and a cylindrical sleeve portion joined to one end of the plate portion. The sleeve portion is configured to accommodate the shaft portion of the lag screw.
[0004]
In this type of device, the first type is configured so that the end of the lag screw can be freely inserted into the tip of the sleeve portion, and the lag screw is already inserted into the sleeve portion, and the lag screw is connected to the sleeve portion. However, the head of the lag screw whose diameter is enlarged is engaged with the engagement part at the tip of the sleeve, and the lag screw is prevented from coming off from the sleeve. There is a second type.
[0005]
In the first type of device, only the lag screw is screwed into the femur first, and then the base end of the shaft portion of the lag screw screwed into the femur is inserted into the distal end of the sleeve portion. Finally, the plate part of the mounting body is fixed on the surface of the femur with bone screws or the like. In this case, the inner surface of the sleeve and the outer surface of the shaft portion of the lag screw are provided with a structure that engages with each other in the rotational direction, such as a key and a groove, or a square hole and a prism. It is considered that the lag screw rotates after the attachment of the screw is completed, and as a result, the femoral head rotates and the fracture portion is damaged.
[0006]
On the other hand, in the second type device, the lag screw inserted into the sleeve portion is screwed into the femur, the mounting body is positioned as it is, and the plate portion of the mounting body is fixed on the surface of the femur with bone screws or the like. To do. In this case, in order to enable screwing of the lag screw accommodated in the sleeve portion, the shaft portion and the sleeve portion of the lag screw are configured to be rotatable with respect to each other.
[0007]
[Problems to be solved by the invention]
Of the conventional osteosynthesis devices, in the first type device, the lag screw is configured not to rotate with respect to the attachment body after the attachment to the femur is completed. In this case, when the sleeve part of the attachment body is inserted, the longitudinal direction of the plate part of the attachment body may not be aligned with the longitudinal direction of the femur, depending on the rotation posture of the attachment body. It is necessary to remove the attachment body once and finely adjust the rotation posture of the lag screw, and then reinsert the sleeve portion of the attachment body into the lag screw, which requires skill in the operation and is often complicated. There is a problem.
[0008]
On the other hand, in the second type device, since the lag screw is inserted in the sleeve in advance, the handling is somewhat easy, but the shaft portion of the lag screw is not configured to be rotatable with respect to the sleeve portion. Since the lag screw cannot be screwed into the femur, the lag screw will rotate relative to the mounting body even after the installation is completed, so the head of the femur will rotate with the lag screw and damage the fractured part. There was a fear.
[0009]
In order to eliminate the second type of drawbacks described above, it is conceivable to engage the lag screw and the attachment body by some rotation stopping means after the screwing of the lag screw into the femur is completed. However, such a structure has a problem that the apparatus is complicated and the manufacturing cost is increased.
[0010]
Accordingly, the present invention solves the above-mentioned problems, and the problem is that an osteosynthesis device that can easily be attached during surgery and can prevent rotation of the lag screw after surgery is realized with a simple structure. There is to do.
[0011]
[Means for Solving the Problems]
The osteosynthesis device of the present invention includes a screw portion screwed into the femur on the distal side, a lag screw having a shaft portion on the proximal end side of the screw portion, and a slide of the shaft portion of the lag screw And an attachment body having a plate attached to the surface of the femur. The lag screw is rotatable with respect to the sleeve when the shaft portion is pulled out from the sleeve by a predetermined length, and the lag screw is moved into the sleeve when the shaft portion is pulled into the sleeve. It is comprised so that it may be controlled by the rotation direction by. According to the present invention, when the shaft portion is pulled out, the lag screw is rotated and screwed into the bone, and then, when the sleeve is pushed into the bone and the plate is fixed to the bone, the shaft portion is pulled into the sleeve. Thus, the lag screw is restricted in the rotational direction with respect to the sleeve.
[0012]
In the osteosynthesis device of the present invention, the shaft portion includes a first outer surface portion configured to be regulated in a rotational direction with respect to an engagement portion provided in the sleeve, and the engagement portion. On the other hand, the second outer surface portion configured to be rotatable is provided in a portion having a different axial direction. According to this invention, depending on the insertion depth of the shaft portion of the lag screw with respect to the sleeve, either the state in which the first outer surface portion is disposed inside the engaging portion of the sleeve or the state in which the second outer surface portion is disposed. Can be set to Therefore, when the first outer surface portion is arranged inside the engaging portion, the lag screw can be regulated in the rotational direction with respect to the sleeve, and the second outer surface portion is arranged inside the engaging portion. The lag screw can be made rotatable relative to the sleeve.
[0013]
In this invention, it is preferable that the said 1st outer surface part is provided in the terminal side of the said lag screw rather than the said 2nd outer surface part. In this case, the lag screw can be screwed into the bone with the lag screw being pulled out of the sleeve and the first outer surface portion is disposed inside the engaging portion, and then the sleeve is pushed into the bone. This makes it possible to regulate the lag screw in the rotational direction with respect to the sleeve.
[0014]
In the present invention, it is preferable that the engaging portion is provided at a distal end portion of the sleeve. Since the engagement portion is provided at the distal end portion of the sleeve, it is easy to process the sleeve for forming the engagement portion, and a large effective sliding range of the lag screw with respect to the sleeve can be taken. .
[0015]
In the present invention, it is preferable that a base having an enlarged diameter is provided at a base end of the lag screw, and the lag screw is prevented from coming off by the head coming into contact with the engaging portion. Accordingly, the engaging portion can be used as a portion for preventing the lag screw from coming off.
[0016]
Next, another osteosynthesis device of the present invention includes a screw portion screwed into the femur on the distal side, a lag screw having a shaft portion on the proximal end side of the screw portion, and the shaft of the lag screw. An osteosynthesis device having a sleeve for slidably receiving a portion and an attachment body having a plate attached to the surface of the femur, wherein the sleeve includes a cover provided on the shaft portion of the lag screw. A first inner surface portion configured to be rotationally stopped with respect to the engaging portion and a second inner surface portion configured to be rotatable with respect to the engaged portion are provided at different portions in the axial direction. It is characterized by being.
[0017]
In the present invention, it is preferable that the first inner surface portion is provided on the rear end side of the sleeve from the second inner surface portion.
[0018]
In this invention, it is preferable that the said to-be-engaged part is provided in the base end part of the said axial part. Thereby, the processing of the lag screw for forming the engaged portion is facilitated, and an effective sliding range with respect to the sleeve of the lag screw can be taken large.
[0019]
In the present invention, it is preferable that a locking portion having a reduced diameter is provided at the tip of the sleeve, and the locking portion is brought into contact with the engaged portion to prevent the lag screw from coming off. As a result, the engaged portion can be used as a portion for preventing the lag screw from coming into contact with the locking portion of the sleeve.
[0020]
In the present invention, it is preferable that the shaft portion of the lag screw is prevented from coming off so as not to separate from the sleeve.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
Next, an embodiment of an osteosynthesis device according to the present invention will be described with reference to the accompanying drawings. 1 and 2 are partial cross-sectional views showing the overall structure of the osteosynthesis device of this embodiment, and FIG. 3 is an exploded perspective view showing the assembly structure of the sleeve and lag screw of this embodiment.
[0022]
In the present embodiment, a lag screw 10 provided with a screw part 11 provided at a distal end and a shaft part 12 provided on the base end side from the screw part 11, and a sleeve 13 that accommodates the shaft part 12 of the lag screw 10. And an attachment body comprising a plate 14 configured to connect the sleeve 13.
[0023]
The lag screw 10 is screwed obliquely upward from the outer surface of the femur toward the femoral head. A shaft hole for inserting a guide pin (guide wire) is provided at the center.
[0024]
The screw portion 11 of the lag screw 10 is configured to be firmly bonded to the bone while tapping in the bone. The shaft portion 12 of the lag screw 10 includes a head portion 12a that is slightly larger in diameter than other portions, a slightly reduced diameter cylindrical outer surface portion 12b that is formed adjacent to the distal end side of the head portion 12a, And a deformed outer surface portion 12c formed adjacent to the distal end side of the cylindrical outer surface portion 12b. As shown in FIG. 3, the deformed outer surface portion 12c has an outer surface shape in which a pair of flat surfaces 12c1 are formed in mutually opposing portions of the cylindrical surface, and its cross-sectional shape is 12s in the figure. It is shown.
[0025]
On the other hand, the sleeve 13 is formed in a cylindrical shape as a whole, and includes a front end portion 13 a having an inner edge with a slightly reduced diameter, and a rear end portion 13 b formed obliquely so as to fit the outer surface of the plate 14. The inner edge of the distal end portion 13a constitutes the engagement portion protrudes inwardly over the entire circumference. That is, it is formed in an inner edge shape that can be engaged in the rotational direction with respect to the deformed outer surface portion 12c of the lag screw 10, that is, an opening shape in which a pair of circular opposing portions are formed substantially flat.
[0026]
The plate 14 is provided with an inclined mounting hole 14a for accommodating the rear end portion 13b of the sleeve 13 on one end side thereof, and a bone screw (not shown) for fixing the plate 14 on the outer surface of the femur. A plurality of fixing holes 14b configured to be inserted and engaged are provided. Here, as shown in the figure, the sleeve 13 and the plate 14 may be configured to be detachable by, for example, a method in which a rib 14c that engages with a lateral groove 13c formed on the outer surface of the sleeve 13 is configured to be freely retractable. Well (for example, the structure described in Japanese Patent Publication No. 5-81254 and Utility Model Registration No. 2504411 may be adopted, for example, the rib may be configured so as to be able to move in and out), or the sleeve 13 and The plate 14 may be integrated with the plate 14 by welding or the like.
[0027]
As shown in FIG. 3, the base end portion 12 d of the lag screw 10 is formed to have an outer diameter that can pass through the tip end portion 13 a of the sleeve 13, and after the shaft portion 12 is inserted into the sleeve 13, the base end portion 12 d The above-mentioned head 12a is formed by fixing the cylindrical annular member 12e by welding, bonding or the like. Since the head portion 12a is configured so as not to pass through the distal end portion 13a, the lag screw 10 and the sleeve 13 are prevented from coming off from each other.
[0028]
As shown in FIGS. 1 and 2, the base end portion 12d of the lag screw 10 is provided with a base end side hole communicating with the shaft hole, and the shallow portion of the base end side hole is a rotating tool. A rectangular hole 12f for engaging (not shown) is formed, and a female screw portion 12g is formed in a deep portion of the hole. The lag screw 10 can be pulled to reduce the fractured portion of the femoral head by a pulling device (not shown) having a male screw portion that is screwed into the female screw portion 12g.
[0029]
FIG. 4A shows an engaged state between the distal end portion 13a of the sleeve 13 and the deformed outer surface portion 12c. The cylindrical outer surface portion 12b indicated by the dotted line in the figure is configured to be rotatable inside the tip portion 13a, while the deformed outer surface portion 12c is configured to be fixed in the rotational direction within the tip portion 13a.
[0030]
FIG. 4B shows an engagement state between the sleeve distal end portion 23a and the lag screw deformed outer surface portion 22c in an embodiment different from the above embodiment. The inner edge of the tip 23a is formed in a square hole shape (hexagonal hole in the illustrated example), and the outer surface of the deformed outer surface part 22c is formed in a rectangular shape (hexagonal in the illustrated example) corresponding to the rectangular hole shape. Yes. In this case, the outer surface of the cylindrical outer surface portion 22b has a cross-sectional shape substantially equal to the square inscribed circle of the deformed outer surface portion 22c.
[0031]
FIG. 4C shows an engagement state between the distal end portion 33a of the sleeve and the deformed outer surface portion 32c of the lag screw in another embodiment different from the above embodiment. A plurality of curved convex portions or concave portions are formed in the rotation direction on the inner edge of the tip portion 33a, and the outer surface of the deformed outer surface portion 32c is formed in a shape having concave grooves or convex ribs corresponding to the convex portions or concave portions. Has been. The cylindrical outer surface portion 32b in this case also has a cross-sectional shape substantially equal to the inscribed circular shape of the cross section of the deformed outer surface portion 32c.
[0032]
Next, a method for repairing a fracture near the head of the femur using the osteosynthesis device of the present embodiment will be described. For example, in the case of a femoral neck fracture, first, a guide pin is inserted from the outer surface of the femur and is set so that the tip of the guide pin reaches the head of the femur. Next, a piercing device such as a reamer is introduced along the guide pin, and piercing is performed from the outer surface of the femur into the head of the femur. At this time, in order to accommodate the sleeve of the attachment body, a shallow portion near the outer surface of the drilled hole is formed to have a slightly larger inner diameter than the deep portion.
[0033]
Next, the lag screw 10 is screwed into the femur along the guide pin. Here, the lag screw 10 is connected to the mounting body as described above. However, by setting the lag screw 10 to the state shown in FIG. The outer surface portion 12 b is disposed inside the distal end portion 13 a of the sleeve 13, and as a result, the lag screw 10 can be rotated with respect to the sleeve 13. In this state, the tip of the driver tool is inserted into a square hole 12f drilled in the end face of the head 12a of the lag screw 10 and rotated to screw the lag screw 10 into the bone.
[0034]
When the screw portion 11 of the lag screw 10 is introduced into the femoral head and reaches a sufficient depth, the sleeve 13 is drilled on the outer surface of the femur so as to press the plate 14 against the outer surface of the femur. Push it into the hole. This state is shown in FIG. In this state, the distal end portion 13 a of the sleeve 13 is engaged with the deformed outer surface portion 12 c of the shaft portion 12 of the lag screw 10, and the lag screw 10 is restricted in the rotational direction with respect to the sleeve 13.
[0035]
Finally, a bone screw (not shown) is screwed from the outer surface of the femur through the fixing hole 14b of the plate 14 to fix the plate 14 on the outer surface of the femur.
[0036]
As described above, in the present embodiment, the sleeve 13 is screwed into the bone by rotating the lag screw 10 with the distal end portion 13a of the sleeve 13 and the cylindrical outer surface portion 12b of the lag screw 10 facing each other, and after the screwing is completed, the sleeve By pushing 13 in, the front-end | tip part 13a can be comprised so that it may engage with the deformed outer surface part 12c of the lag screw 10 in a rotation direction, and the plate 14 can be fixed on the surface of a bone in this state. Therefore, it is possible to restrict the lag screw 10 from rotating with respect to the plate 14 in a state where the attachment to the bone is completed. Therefore, it is possible to avoid the occurrence of a situation in which the fracture portion fixed to the screw portion 11 together with the lag screw 10 rotates after the operation and causes damage to the fracture portion.
[0037]
Further, in the state where the lag screw 10 is screwed into the bone, if the postures in the rotational direction of the deformed outer surface portion 12c of the shaft portion 12 and the distal end portion 13a of the sleeve 13 do not match, the sleeve 13 and the plate 14 are pulled out as they are. Then, fine adjustment of the rotational posture of the lag screw 10 is performed with the cylindrical outer surface portion 12b facing the tip portion 13a of the sleeve 13, and the sleeve 13 and the plate 14 are pushed again to engage the tip portion 13a of the sleeve 13 with the deformed outer surface portion 12c. Therefore, even if it is not an expert, surgery can be easily performed without taking time and effort.
[0038]
The distal end portion 13a of the sleeve corresponds to the engagement portion that acts on the cylindrical outer surface portion 12b corresponding to the second outer surface portion of the lag screw and the deformed outer surface portion 12c corresponding to the first outer surface portion. Monodea Ru.
[0039]
FIG. 5 shows the structure of another embodiment different from the above embodiment. In this embodiment, the plate 14 is the same as the above embodiment, and the description thereof is omitted.
[0040]
In this embodiment, the lag screw 40 has the screw part 41 and the axial part 42 similarly to the above. In this lag screw 40, a base portion 42a having a square shape (hexagonal shape in the illustrated example) is provided at the base end of the shaft portion 42, and the shaft portions other than the head portion 42a are equal to or less than the inscribed circle of the head portion 42a. A cylindrical portion 42b having an outer diameter is formed.
[0041]
The sleeve 43 can be inserted through the cylindrical portion 42b of the lag screw 40, but the front end portion 43a that prevents the head portion 42a from slipping out, and closer to the rear end portion 43b than the front end portion 43a. A cylindrical inner surface portion 43d having an inner diameter equal to or larger than the circumscribed circle of the head portion 42a of the lag screw 40 is formed closer to the rear end portion 43b than the cylindrical inner surface portion 43d. And a deformed inner surface portion 43e having a square shape (hexagonal hole shape in the illustrated example) that can be engaged in the rotation direction.
[0042]
In this embodiment, when the lag screw 40 protrudes from the sleeve 43 (the state shown in FIG. 5), the head 42 a of the lag screw 40 is disposed within the cylindrical inner surface portion 43 d of the sleeve 43. Can rotate freely with respect to the sleeve 43 and the plate. Further, in a state where the lag screw 40 is drawn into the sleeve 43 rather than the state shown in FIG. 5, the head portions 42a of the lag screw 40 are disposed in the deformed inner surface portion 43e and engage with each other in the rotational direction. Accordingly, the lag screw 40 is fixed (restricted) in the rotational direction with respect to the sleeve 43 and the plate.
[0043]
Also in this embodiment, the same operational effects as in the embodiment shown in FIGS. The outer surface shape of the head portion 42a and the deformed inner surface portion 43e can take various rotation restricting modes as in the above embodiment (as shown in FIG. 4). Also, the head 42a is Ru der corresponds to the engaged portion of the acting respectively profiled inner surface portion 43e which corresponds to the cylindrical inner surface portion 43d and the first inner surface portion corresponding to the second inner surface of the sleeve.
[0044]
【The invention's effect】
As described above, according to the present invention, when the lag screw is screwed into the bone, the lag screw can be rotated with respect to the sleeve, and when the osteosynthesis apparatus is attached to the bone, the lag screw is rotated with respect to the sleeve. The direction can be regulated.
[Brief description of the drawings]
FIG. 1 is a partial cross-sectional view showing a state when a lag screw is screwed into bone in an embodiment of an osteosynthesis device of the present invention.
FIG. 2 is a partial cross-sectional view showing a state of completion of attachment in the same embodiment.
FIG. 3 is an exploded perspective view of a lag screw and a sleeve in the same embodiment.
4 is a partial cross-sectional view (a) to (c) showing a restricting mode in a rotational direction of a lag screw and a sleeve in the same embodiment. FIG.
FIG. 5 is a partial cross-sectional view of an embodiment different from the above embodiment.
[Explanation of symbols]
10, 40 Lag screw 11, 41 Screw portion 12, 42 Shaft portion 12a, 42a Head portion 12b Cylindrical outer surface portion 12c Deformed outer surface portion 13, 43 Sleeve 13a, 43a Tip portion 14 Plate 43d Cylindrical inner surface portion 43e Deformed inner surface portion

Claims (5)

A screw portion screwed into the femur on the distal side, a lag screw having a shaft portion on the proximal end side of the screw portion, a sleeve for slidably housing the shaft portion of the lag screw, and a femur An osteosynthesis device having an attachment body with a plate attached to the surface,
The base end of the shaft portion of the lag screw is prevented from coming off from the sleeve by having a head that cannot pass through the distal end portion of the sleeve,
The shaft portion includes a first outer surface portion configured to be regulated in a rotational direction with respect to the tip portion of the sleeve, and a second outer surface portion configured to be rotatable with respect to the tip portion . Provided in different parts of the axial direction ,
The osteosynthesis apparatus , wherein the first outer surface portion is formed adjacent to a distal end side of the second outer surface portion, and the second outer surface portion is formed adjacent to a distal end side of the head . The osteosynthesis apparatus according to claim 1, wherein the first outer surface portion is a deformed outer surface portion, and the second outer surface portion is a cylindrical outer surface portion . A screw portion screwed into the femur on the distal side, a lag screw having a shaft portion on the proximal end side of the screw portion, a sleeve for slidably housing the shaft portion of the lag screw, and a femur An osteosynthesis device having an attachment body with a plate attached to the surface,
The base end of the shaft portion of the lag screw is prevented from coming off from the sleeve by having a head that cannot pass through the distal end portion of the sleeve,
The sleeve has a first inner surface portion configured to be rotationally stopped with respect to the head portion of the lag screw, and a second inner surface portion configured to be rotatable with respect to the head portion in the axial direction. Provided in different parts of
The first inner surface portion is formed adjacent to the rear end side of the second inner surface portion, and the second inner surface portion is formed adjacent to the rear end side of the distal end portion. apparatus. The osteosynthesis apparatus according to claim 3, wherein the first inner surface portion is a deformed inner surface portion, and the second inner surface portion is a cylindrical inner surface portion . The osteosynthesis device according to any one of claims 1 to 4, wherein the sleeve and the plate are configured to be detachable .

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