JPH0593412U - Bone head remover - Google Patents

Abstract

(57) [Summary] [Structure] A U-shaped notch is provided at the tip of the arm whose tip is bent downward in a stepwise manner, a through hole 13 is provided from the surface at the rear end, and further from the surface toward the tip. A through hole 14 is provided, an upper arm 1 having a female spherical surface formed on the back side of the through hole, a U-shaped notch having a convex curved side surface at the tip of the arm, and a female screw cut from the surface at the rear end, Further, a lower head 2 having a female screw cut from the surface toward the tip, a support bolt 3 having a male spherical surface formed on the upper portion of the bolt, and a tightening bolt 4 for removing the head of the bone. [Effect] The action point P and the fulcrum O are located on the extension line of the contact surface between the upper arm and the lower surface of the femoral head, and the force acting on the action point P can be effectively used to remove the femoral head from the stem.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a femoral head remover for an artificial hip joint used in orthopedics.

[0002]

[Prior Art]

 As shown in Fig. 3, an artificial hip joint is composed of a head 11 and a stem 12. Generally, the head and the stem are made of different materials. For example, the material of the head 11 is mostly ceramic, and the stem 12 is There are many titanium alloys. (b) shows the state in which the head 11 is inserted into the stem 12, and the fitting part of the head 11 and the stem 12 consists of a pair of male and female tapered parts, and the head 11 has a tapered hole. The tapered portion 15 of the stem 12 is inserted into the stem 12 and is attached to the stem 12.

In an artificial hip joint, at the time of surgery, the stem is first fixed to the femur of the patient, and then the femoral head is inserted into the tapered portion of the stem. At this time, the femoral head is placed at the proper position on the pelvis side. It is checked if it is fitted, and if it is not fitted in the proper position, the head is removed again. In addition, there is a case where the head of the head is to be removed again for another reason, or only the head of the head is removed by re-operation. In this case, it is necessary to surely remove the head from the stem in a short time without damaging the head, and a head remover is used at this time.

FIG. 4 shows an example of a conventional bone head remover. 4A is a plan view, FIG. 4B is a sectional view taken along the arrow B, and FIG. 4C is a sectional view taken along the arrow A. In the figure, 1 is an upper arm, and the tip of the upper arm 1 is cut out so that it can be inserted into the lower surface of the bone head 11. Further, there is a through hole 13 at the rear end of the upper arm 1 through which the tightening bolt 4 is inserted, and a female screw is cut near the tip, and the support bolt 3 is screwed to this female screw.

Similarly to the upper arm 1, the tip of the lower arm 2 is also cut out, and the side surface of the cutout portion is formed into a spherical shape so as to match the tapered surface of the tapered portion 15 of the stem 12. Further, a female screw is cut at the rear end portion of the lower arm 2 and a tightening bolt 4 is screwed therein. Further, a support bolt receiver 16 having a female spherical surface is provided near the tip.

[0006] The tip of the support bolt 3 is a male spherical surface, and when the bone head remover is used, the center of the male spherical surface serves as a fulcrum O to open the tips of the upper arm 1 and the lower arm 2. A handle 7 is attached to the tightening bolt 4 through a through hole of the tightening bolt 4, and a pin 9 for retaining the handle 7 is attached to the handle 7. In addition, 5 shows a male spherical washer and 6 shows a female spherical washer.

When removing the head 11 from the stem 12 with the head remover, the notch of the upper arm 1 is inserted into the lower surface of the head 11, and the notch of the lower arm 2 is inserted into the tapered portion 15 of the stem 12, The support bolt 3 adjusts the mutual gap so that the upper arm 1 and the lower arm 2 are parallel to each other. At this time, the upper arm 1 and the lower surface of the bone head 11 are brought into contact with each other. Next, by rotating the tightening bolt 4 with the handle 7 and tightening the upper arm 1 and the lower arm 2, the tips of the upper arm 1 and the lower arm 2 are opened with the center of the male spherical surface of the support bolt 3 as the fulcrum O. , The head 11 is removed from the stem 12.

[0008]

[Problems to be solved by the device]

 The method of removing the head using the head remover shown in FIG. 4 utilizes the principle of leverage, and the direction of the force acting on the point of action is perpendicular to the straight line connecting the point of action P and the fulcrum O. However, in the femoral head remover shown in FIG. 4, since the straight line connecting the action point P and the fulcrum O does not coincide with the extension line of the contact surface between the upper arm 1 and the lower surface of the femoral head 11, the direction of the force acting on the action point P is changed. Does not coincide with the axial direction of the tapered portion 15 of the stem 12, and the force that acts on the lower surface of the head 11 (the force that removes the head 11) is reduced. Therefore, the force acting on the point of action cannot be effectively used, and the head cannot be easily removed.

The present invention was made in order to solve the above-mentioned problems, and the fulcrum of the femoral head remover is made to coincide with the extension line of the lower surface of the femoral head, and the straight line connecting the action point and the fulcrum and the upper arm 1 are provided. An object of the present invention is to provide a head head remover that can easily remove the head from the stem by matching the extension line of the contact surface with the lower surface of the head 11.

[0010]

[Means for Solving the Problems]

 In a femoral head remover in which an upper arm and a lower arm can swing via a fulcrum, a U-shaped notch is formed at the tip of the arm whose tip is bent downward in a stepwise manner, and a through hole is formed from the surface to the rear end. In addition, a through hole is provided from the surface near the tip, and the back side of this through hole has a female spherical surface processed upper arm, and the tip of the arm has a U-shaped notch with a convex curved side surface. It is a bone head remover that consists of a lower arm with a female thread cut from the surface at the end and a female thread from the surface toward the tip, a support bolt with the male spherical surface of the upper part of the bolt, and a tightening bolt.

[0011]

[Action]

 The femoral head remover of the present invention is composed of an upper arm, a lower arm, a support bolt and a tightening bolt, and the tip of the upper arm is notched in a U shape for inserting the upper arm into the lower surface of the femoral head. By bending the tip of the upper arm downward in a stepwise manner, the fulcrum can be aligned with the extension line of the contact surface between the upper arm and the lower surface of the head, and the force of withdrawal can be effectively applied to the lower surface of the head. ..

The through hole at the rear end of the upper arm is a hole for passing the tightening bolt. The through hole near the tip of the upper arm is a support bolt receiver. The female spherical surface on the back side of the through hole contacts the male spherical surface above the support bolt, and the upper arm swings about the male spherical center of the support bolt.

In order to insert the lower arm into the tapered portion of the stem, the tip of the lower arm is notched in a U shape. The side surface of the notch is in contact with the tapered portion of the stem, and has a convex curved surface shape so that the lower arm can be stably fixed to the tapered portion of the stem.

A female screw at the rear end of the lower arm is screwed into a tightening bolt that passes through a through hole at the rear end of the upper arm to tighten the upper and lower arms, and the bone head is removed at the tip of the upper arm. It is for generating the force to do. Further, the female screw near the tip of the lower arm is for screwing a support bolt to form a fulcrum.

As described above, the support bolt is formed by processing the upper portion of the bolt with a male spherical surface, and is screwed into a female screw near the tip of the lower arm to form a fulcrum. The tightening bolt is to tighten the upper arm and the lower arm by screwing them into the female screw at the rear end of the lower arm through the through hole at the rear end of the upper arm.

[0016]

【Example】

 An essential requirement of the femoral head remover of the present invention is that the working point and the fulcrum are located on the extension line of the contact surface between the upper arm and the lower surface of the femoral head. An embodiment of the present invention will be described below with reference to the drawings. 1A and 1B are explanatory views of the bone head remover. FIG. 1A is a plan view, FIG. 1B is a sectional view taken along arrow B, and FIG. 1C is a sectional view taken along arrow A. In the figure, reference numeral 1 is an upper arm, and the tip end of the upper arm 1 is bent downward in a stepwise manner, and the tip is notched so that it can be inserted into the lower surface of the head 11. Also, there is a through hole 13 through which the tightening bolt 4 passes at the rear end of the upper arm 1, and a through hole 14 through which the shaft of the support bolt 3 passes near the tip, and the back surface of the through hole 14 is the male side of the support bolt 3. A female spherical surface that contacts the spherical surface 10 is processed. When processing the female spherical surface, it is important to perform processing so that the center of the male spherical surface 10 lies on the extension line of the contact surface between the upper arm 1 and the lower surface of the head 11.

Reference numeral 2 denotes a lower arm, and a tip of the lower arm 2 is cut out similarly to the upper arm 1, and a side surface of the cutout is spherically shaped so as to fit the tapered portion 15 of the stem 12. Further, a female screw with which the tightening bolt 4 is screwed is cut at the rear end of the lower arm 2, and a female screw with which the support bolt 3 is screwed is further cut toward the tip. The tip of the lower arm 2 is reduced in thickness according to the stepwise bending of the upper arm 1.

The intermediate portion of the support bolt 3 has a male spherical surface 10, and a rotary knob 8 is attached to a shaft extending from the upper portion of the male spherical surface 10. When the bone head remover is used, the upper arm swings with the male spherical center of the support bolt 3 as the fulcrum O. A handle 7 is attached to the tightening bolt 4 through a through hole of the tightening bolt 4, and a pin 9 for preventing the handle 7 from coming off is attached to the handle 7. In addition, 5 shows a male spherical washer and 6 shows a female spherical washer.

When removing the head 11 from the stem 12 with the head remover, the notch of the upper arm 1 is inserted into the lower surface of the head 11, and the notch of the lower arm 2 is inserted into the tapered portion 15 of the stem 12, The mutual gap is adjusted by the rotating knob 8 of the support bolt 3 so that the upper arm 1 and the lower arm 2 are parallel to each other. At this time, the upper arm 1 is brought into contact with the lower surface of the bone head 11. Next, by rotating the tightening bolt 4 with the handle 7 and tightening the upper arm 1 and the lower arm 2, the center of the male spherical surface of the support bolt 3 is set as the fulcrum O, and the tips of the upper arm 1 and the lower arm 2 are fixed. When the head is opened, a force for removing the head 11 is applied to the lower surface of the head 11, and the head 11 is removed from the stem 12.

A modified embodiment is shown in FIG. In the decapsulator of Fig. 2, the tip of the support bolt 3 is finished as a male sphere, a female screw is cut on the upper arm 1, the support bolt 3 is screwed to this female screw, and the lower arm 2 is aligned with the male sphere of the support bolt 3. The support bolt receiver 16 in which the female spherical surface is processed is provided. Also in this case, the center of the male spherical surface of the support bolt 3 is the fulcrum O, and the action point P and the fulcrum O are on the extension line of the contact surface between the upper arm and the lower surface of the condyle, and the force acting on the action point P is 11 Can be effectively used to remove the stem from the stem 12.

The decapsulator of the present invention has an action point P and a fulcrum O on the extension line of the contact surface between the upper arm and the lower surface of the femoral head, and is used to remove the force acting on the action point P from the stem. It can be used effectively. Therefore, the head of the bone can be easily removed from the stem.

[0022]

[Effect of the device]

 The present invention is a femoral head remover in which an upper arm and a lower arm can be swung via a fulcrum, and a U-shaped notch is formed at the tip of the arm whose tip portion is bent downward in a stepwise manner, and a rear end. A through hole is formed in the surface of the through hole, and a through hole is formed in the vicinity of the tip from the surface. The back side of the through hole is a female spherical surface processed upper arm, and the tip of the arm is a U-shaped cut with a convex curved side surface. A lower head with a notch, a female thread cut from the surface at the rear end, and a female thread cut from the surface toward the tip, a support bolt with the male spherical surface of the upper part of the bolt, and a bone head remover consisting of a tightening bolt. In the femoral head remover of the present invention, the action point P and the fulcrum O are located on the extension line of the contact surface between the upper arm and the lower surface of the femoral head, and the force acting on the action point P is removed from the stem. Can be used effectively. Therefore, the bone head can be easily removed from the stem.

[Brief description of drawings]

1A and 1B are explanatory views of a femoral head remover of the present invention, in which FIG. 1A is a plan view, FIG. 1B is a side view taken along arrow B, and FIG.

FIG. 2 is an explanatory view of a modified embodiment of the femoral head remover of the present invention.

FIG. 3 is an explanatory diagram of an artificial hip joint.

FIG. 4 is an explanatory view of a conventional bone head remover.

[Explanation of symbols]

1 ... Upper arm, 2 ... Lower arm, 3 ... Support bolt, 4
… Tightening bolts, 5… Male spherical washer, 6… Female spherical washer,
7 ... Handle, 8 ... Rotating knob, 9 ... Pin, 10 ... Male spherical surface, 11 ... Bone head, 12 ... Stem, 13 ... Through hole, 14 ... Through hole,
15 ... taper part, 16 ... support bolt receiver, P ... point of action,
O ... fulcrum.

Claims (1)

[Scope of utility model registration request] 1. A femoral head remover in which an upper arm and a lower arm can swing through a fulcrum, and a U-shaped notch is formed at the tip of the arm whose tip is bent downward in a stepwise manner, and a rear end. A through-hole is provided on the surface of the arm, a through-hole is provided on the surface near the tip, and the back side of the through-hole is a female spherical surface processed upper arm and a U-shaped notch with a convex curved side surface at the tip of the arm. , Female thread is cut from the surface at the rear end,
A femoral head remover characterized by a lower arm with a female thread cut from the surface toward the tip, a support bolt with a male spherical surface on the top of the bolt, and a tightening bolt.