Drill sleeve and medical instrument

Abstract

A tubular drill sleeve (1) is provided with a through-hole (1a) through which a drill is insertable. The drill sleeve (1) is provided with: an external thread (1b) formed at one end in the longitudinal direction and configured to be screwed into an internal thread; and a handle (2) formed on the exterior surface at any position in the longitudinal direction and configured for an operator to grip with the fingers and apply a rotational force around the center axis. The handle (2) has an outer contour that allows a rotational force in a second direction around the center axis to be more easily transmitted to the handle (2) than that in a first direction around the center axis, wherein the first direction is a direction in which the external thread (1b) is to be screwed into the internal thread, and wherein the second direction is opposite to the first direction.

Description

Drill sleeves and medical devices

[0001] The present invention relates to a drill sleeve and a medical instrument, and more particularly to a drill sleeve and a medical instrument used when forming pilot holes in bones for screws that secure bone plates used in orthopedic surgery.

[0002] Conventionally, osteotomy has been performed to treat osteoarthritis of the knee, for example, when the articular cartilage of the patella and femur is damaged. In osteotomy, an incision is made in the bone to correct the curvature of the bone, and then the bone is fixed with a bone-setting material such as a bone plate until the bone heals (see, for example, Patent Document 1).

[0003] The bone plate is provided with a plurality of screw holes each having an internal thread for fastening an external thread provided on the head of a bolt, and a drill sleeve is fastened to the screw hole to guide the drill when forming a pilot hole for the bolt to be fastened to each screw hole in the bone.

[0004] The drill sleeve includes a cylindrical body with a central hole through which a drill passes, a male thread at the tip of the body for fastening to a screw hole in a bone plate, and a handle at the base end of the body that is larger in diameter than the body. The outer surface of the handle is knurled to improve friction when gripped by an operator, and has a flat surface for clamping with a tool such as a wrench (see, for example, Patent Document 2).

[0005] International Publication No. WO 2018 / 021134 Republished No. WO 2020 / 059405

[0006] When fixing or removing a drill sleeve in or from a screw hole, an operator such as a surgeon rarely uses a tool, and the operation is usually performed with the fingers of a gloved hand. In order to fasten multiple drill sleeves into multiple screw holes densely formed in a bone plate, it is necessary to reduce the diameter of the drill sleeve, especially the diameter of the large-diameter operating portion.

[0007] However, the large-diameter operating portion is provided to facilitate the transmission of torque from the fingers to the drill sleeve, and a smaller diameter requires the operator to apply a large force. In particular, while a nurse or other professional whose gloves are clean with blood and grease fastens the drill sleeve to the bone plate and hands it over to the operator, during orthopedic surgery, blood and grease adhere to the operator's gloves, making it difficult to transmit the operator's force to the drill sleeve and making it difficult to remove the drill sleeve from the bone plate without a tool. The present invention aims to provide a drill sleeve that can be easily removed from the bone plate with the operator's fingers, even when the diameter is reduced.

[0008] One aspect of the present invention is a cylindrical drill sleeve having a through hole through which a drill can be inserted, the drill sleeve comprising: a male thread formed at one longitudinal end and fastened to a female thread; and a handle portion formed on the outer surface at any position in the longitudinal direction and which an operator can grasp with their fingers to apply a rotational force around a central axis, the handle portion having an outer surface shape that makes it easier to transmit the rotational force in a second direction around the central axis, opposite to the first direction, to the handle portion than in a first direction around the central axis that fastens the male thread to the female thread.

[0009] According to this aspect, by inserting a drill into a through-hole of a drill sleeve fixed by fastening an external thread provided at one end to an internal thread and driving the drill, the drill sleeve can guide the drilling. When fastening the external thread of the drill sleeve to the internal thread, an operator grips a handle provided on the cylindrical drill sleeve with his / her fingers and applies a rotational force in a first direction around the central axis. On the other hand, when loosening the fastening between the external thread and the internal thread of the drill sleeve, the operator grips a handle provided on the cylindrical drill sleeve with his / her fingers and applies a rotational force in a second direction around the central axis.

[0010] The handle portion has an outer surface shape that makes it easier to transmit a rotational force to the handle portion in the second direction than in the first direction, so when the same operator who fastened the fastener loosens it, it is difficult to tighten it too much, but it is easy to loosen it. During surgery, even with gloved and bloody fingers, it is easy to apply a rotational force to loosen the fastening, so the drill sleeve can be removed without using tools.

[0011] 1 is a perspective view showing a drill sleeve according to an embodiment of the present invention;

[0023] FIG. 1 is a front view of the drill sleeve of FIG. 1 as viewed in the longitudinal direction from the handle portion side;

[0024] FIG. 2 is a partially enlarged view showing an enlargement of portion A of FIG. 2;

[0025] FIG. 3 is a longitudinal sectional view illustrating an operation of attaching the drill sleeve of FIG. 1 to a bone plate and forming a pilot hole with a drill;

[0026] FIG. 4 is a view showing an operation of fastening the male thread of the drill sleeve of FIG. 1 to the female thread;

[0027] FIG. 5 is a view showing an operation of loosening the fastening of the male thread and the female thread of the drill sleeve of FIG. 1;

[0028] FIG. 6 is a view showing a contour shape connecting the outermost positions of the cross section of the handle portion of the drill sleeve of FIG. 1;

[0029] FIG. 7 is a partially enlarged view showing an enlargement of portion A of FIG. 2 from a different perspective than FIG. 3;

[0029] FIG. 8 is a front view showing a first modified example of the drill sleeve of FIG. 1;

[0029] FIG. 9 is a front view showing a second modified example of the drill sleeve of FIG. 1;

[0029] FIG. 10 is a front view showing a third modified example of the drill sleeve of FIG. 1;

[0029] FIG. 11 is a front view showing a fourth modified example of the drill sleeve of FIG. 1;

[0029] FIG. 12 is a partially enlarged view similar to FIG. 3 showing a sixth modified example of the drill sleeve of FIG. 1;

[0029] FIG. 13 is a front view showing a seventh modified example of the drill sleeve of FIG. 1;

[0012] A drill sleeve 1 according to one embodiment of the present invention will be described below with reference to the drawings. As shown in Fig. 1, the drill sleeve (medical device) 1 according to this embodiment is formed in a cylindrical shape with a through hole 1a penetrating in the longitudinal direction, and includes a male thread 1b formed at one longitudinal end and a handle portion 2 formed on the outer surface of the other longitudinal end. The through hole 1a has a diameter that allows insertion of a drill D for forming a pilot hole, as will be described later.

[0013] The handle portion 2 comprises a cylindrical surface portion 3 formed to have a larger diameter than the other portions over a predetermined length in the longitudinal direction, and a flat surface portion 4 formed by cutting out a part of the cylindrical surface portion 3 by a flat surface extending in the longitudinal direction. As shown in Figure 2, the flat surface portions 4 are arranged at two positions 180° apart around the central axis of the cylindrical surface portion 3 and extend parallel to each other.

[0014] As shown in Figure 2, a plurality of grooves 5 are formed at intervals in the circumferential direction in the cylindrical surface portion 3 and the flat surface portion 4 of the handle portion 2. Each groove 5 extends linearly over the entire longitudinal length of the handle portion 2. Figure 3 shows a detail of portion A in Figure 2. In the example shown in Figure 3, each groove 5 is a V-shaped groove in which a first groove wall 5a and a second groove wall 5b, which are flat and adjacent to each other in the circumferential direction, intersect at the groove bottom.

[0015] In each groove 5, the first groove wall 5a is disposed forward in the first direction A1 about the central axis O, and the second groove wall 5b is disposed rearward in the first direction A1 about the central axis O. At the radially outermost position P2 of the second groove wall 5b, the inclination angle θ2 of the second groove wall 5b with respect to the tangent T2 to the circle C centered on the central axis O is larger than the inclination angle θ1 of the first groove wall 5a with respect to the tangent T1 to the circle C centered on the central axis O at the radially outermost position P1 of the first groove wall 5a. In particular, in this embodiment, the inclination angle θ2 of the second groove wall 5b is 90°.

[0016] As shown in FIG. 4, the male thread 1b is a tapered thread that can be fastened to a screw hole (female thread) 10a, which is a tapered thread hole formed in the bone plate 10. In this embodiment, the male thread 1b is a right-handed thread. In FIG. 1, reference numeral 6 denotes a transverse hole drilled at a midpoint in the longitudinal direction of the drill sleeve 1 so as to penetrate the drill sleeve 1 in a direction perpendicular to the longitudinal direction. The transverse hole 6 has a diameter that allows a tool such as a screwdriver (not shown) to be inserted. In this embodiment, the transverse hole 6 is optional and may be provided in one or more locations, or may not be provided at all.

[0017] The operation of the drill sleeve 1 according to this embodiment configured as described above will be described below. To form a pilot hole in the bone R for a bolt (bone screw) for fixing the bone plate 10 using the drill sleeve 1, the bone plate 10 is placed at an attachment position on the outer surface of the bone R, and the male thread 1b of the drill sleeve 1 is fastened to the screw hole 10a of the bone plate 10, as shown in Figure 4. This positions the longitudinal direction of the drill sleeve 1 in the direction that matches the desired pilot hole direction, and serves as a guide when drilling a pilot hole using a drill D. After drilling the pilot hole in the desired direction, the drill sleeve 1 is removed, and the operation of fastening the bone screw (bolt) begins.

[0018] When the male thread 1b of the drill sleeve 1 is to be fastened to the screw hole 10a, the operator grasps the cylindrical surface portion 3 of the handle portion 2 provided on the drill sleeve 1 with the fingers F, and applies a rotational force in a first direction (clockwise) A1 around the central axis O while pressing the handle portion 2 radially inward, as shown in Figure 5. This causes the male thread 1b of the drill sleeve 1 to be fastened to the screw hole 10a of the bone plate 10.

[0019] In this case, the fingers F of the operator gripping the handle portion 2 are pressed radially inward and enter the multiple grooves 5 formed in the handle portion 2. Then, when a rotational force is applied in the first direction A1 in this state, the fingers F mainly press the first groove walls 5a in the grooves 5 in the first direction A1.

[0020] On the other hand, when loosening the external thread 1b of the drill sleeve 1 that is fastened to the screw hole 10a, the operator grasps the cylindrical surface portion 3 of the handle portion 2 provided on the drill sleeve 1 with the fingers F, and applies a rotational force in the second direction (counterclockwise) A2 around the central axis O while pressing the cylindrical surface portion 3 radially inward, as shown in Figure 6. This causes the external thread 1b of the drill sleeve 1 to be released from the screw hole 10a of the bone plate 10.

[0021] In this case, the fingers F of the operator gripping the handle portion 2 are pressed radially inward and enter the multiple grooves 5 formed in the handle portion 2. Then, when a rotational force is applied in the second direction A2 in this state, the fingers F mainly press against the second groove walls 5b in the grooves 5 in the second direction A2.

[0022] In this embodiment, as described above, the inclination angle θ2 of the second groove wall 5b relative to the tangent T2 of the circle C at the outermost position P2 in the radial direction is larger than the inclination angle θ1 of the first groove wall 5a relative to the tangent T1 of the circle C at the outermost position P1 in the radial direction. Therefore, when the first groove wall 5a, which is inclined at a relatively small inclination angle θ1 relative to the tangent T1, is pressed in the first direction A1 during tightening of the male screw 1b, the component of the force in the tangent T1 direction of the rotational force applied by the finger F becomes relatively small. Therefore, unless the operator applies a relatively large rotational force, the operator cannot generate the tightening force required to tighten the male screw 1b into the screw hole 10a.

[0023] On the other hand, when loosening the male screw 1b, the second groove wall 5b, which is inclined at a relatively large inclination angle θ2 with respect to the tangent line T2, is pushed in the second direction A2. In this case, the component of the rotational force applied by the fingers F in the direction of the tangent line T2 becomes relatively large. In particular, when the inclination angle θ2 is 90°, the rotational force applied by the fingers F is transmitted directly to the handle portion 2 as a force in the direction of the tangent line T2. Furthermore, by increasing the inclination angle θ2, the edge formed between the outer peripheral surface of the handle portion 2 and the second groove wall 5b becomes sharper. This makes it easier for the fingers F entering the groove 5 to be caught by the edge.

[0024] That is, according to this embodiment, the groove 5 provided on the outer surface of the handle portion 2 has the advantage that the rotational force applied from the fingers F in the second direction A2, which is opposite to the first direction A1, can be more easily transmitted to the handle portion 2 than in the first direction A1 around the central axis O for fastening the male thread 1b. When fastening the male thread 1b, the rotational force required for fastening gradually increases from the start of fastening, so a large rotational force is not required to proceed with fastening. If a large rotational force is transmitted to the handle portion 2 during fastening, the male thread 1b will be tightly fastened in the screw hole 10a, making it difficult to remove the drill sleeve 1 from the bone plate 10. Therefore, by making it difficult for the rotational force to be transmitted to the handle portion 2 during fastening, it is possible to prevent the male thread 1b from being unnecessarily tightly fastened in the screw hole 10a.

[0025] On the other hand, when loosening the male screw 1b, a large rotational force is required at the beginning of the loosening operation. According to this embodiment, when loosening, the rotational force applied by the operator's fingers F can be efficiently transmitted to the handle portion 2, and the reduction in rotational force can be suppressed, allowing the male screw 1b and the screw hole 10a to be loosened.

[0026] In particular, the operation of removing the drill sleeve 1 from the bone plate 10 is performed during surgery in which the patient's skin and tissue are incised, so the operator, such as a surgeon, wears gloves on his or her fingers F, and blood and grease often adhere to the tips of the fingers F. Wearing gloves makes it more difficult for the operator to generate a large rotational force than when not wearing gloves. Furthermore, the presence of blood and grease reduces the coefficient of friction between the gloves and the handle portion 2, making them slippery, making it more difficult to transmit the rotational force.

[0027] According to this embodiment, even when performed under such circumstances, the rotational force applied by the fingers F can be efficiently transmitted to the handle portion 2, so that the drill sleeve 1 can be easily removed from the bone plate 10 by generating a relatively small rotational force. Furthermore, because the drill sleeve 1 can be removed from the bone plate 10 with a relatively small rotational force, the outer diameter of the handle portion 2 can be kept small. As shown in Figure 4, even when drill sleeves 1 are attached to multiple screw holes 10a formed at relatively small intervals in the bone plate 10, the narrow diameter of the handle portion 2 ensures sufficient spacing between adjacent drill sleeves 1, improving operability.

[0028] Furthermore, according to this embodiment, by providing the handle portion 2 with two parallel flat surfaces 4, it is possible to apply a large rotational force by clamping the flat surfaces 4 with a tool such as a wrench. Furthermore, by providing the handle portion 2 with the flat surfaces 4, it is possible to make the envelope E passing through the outermost positions P1, P2 of all the grooves 5 non-circular in cross section, as shown in Figure 7. This prevents the drill sleeve 1 from rolling off the instrument table when placed on a flat instrument table.

[0029] In this embodiment, a plurality of grooves 5 is provided on the outer surface of the handle portion 2. From another perspective, this can be rephrased as a plurality of protrusions 7 being provided on the outer surface of the handle portion 2.

[0030] 8, each protrusion 7 is a convex ridge extending in the longitudinal direction, and includes a first side surface 7a disposed forward in the first direction A1 and a second side surface 7b disposed rearward in the first direction A1. The inclination angle θ1 of the second side surface 7b with respect to the tangent T1 to the circle C at the outermost position P1 in the radial direction is smaller than the inclination angle θ2 of the first side surface 7a with respect to the tangent T2 to the circle C at the outermost position P2 in the radial direction.

[0031] In addition, in this embodiment, the protrusions 7, which are made up of ridges extending continuously in the longitudinal direction, are arranged at intervals in the circumferential direction. However, instead of this, a structure may be adopted in which the protrusions 7 are made up of a plurality of protrusions arranged at intervals in the longitudinal and circumferential directions, and each protrusion has the first side surface 7a and the second side surface 7b described above. The shape of the protrusions is arbitrary, and they may be arranged in a straight line in the longitudinal and circumferential directions, or may be arranged in a staggered pattern. Furthermore, the size and intervals of the protrusions may also be arbitrary.

[0032] Furthermore, in this embodiment, the grooves 5 or protrusions 7 are also provided on the flat surface portion 4 provided on the handle portion 2, but instead, as shown in Figure 9, the grooves 5 may not be provided on the flat surface portion 4. This is because the flat surface portion 4 is located closer to the central axis O than the cylindrical surface portion 3, and therefore a greater rotational force needs to be applied to the grooves 5 on the flat surface portion 4 when fastening and loosening.

[0033] Furthermore, although two parallel flat surfaces 4 are provided on the handle portion 2, a single flat surface 4 may be provided instead to prevent rotation, as shown in Fig. 10. Furthermore, in the example shown in Fig. 2, a large number of relatively narrow grooves 5 are arranged at a relatively small pitch on the handle portion 2, but the size and number of grooves 5 may be arbitrary. For example, as shown in Fig. 11, four relatively wide grooves 5 may be provided at 90° intervals in the circumferential direction. In the example shown in Fig. 11, the first groove wall 5a and the second groove wall 5b are perpendicular to each other.

[0034] Reducing the number of grooves 5 can reduce the amount of work required for processing. Providing a large number of grooves 5 at a small pitch can distribute the force applied to each groove 5 from the fingers F, allowing for more effective transmission of rotational force. When reducing the number of grooves 5, grooves 5 having a shape having a first groove wall 5a, a second groove wall 5b, and a groove bottom 5c, as shown in Figure 12, may be used instead of V-grooves.

[0035] Furthermore, it is preferable to provide an even number of grooves 5 at equal intervals so that a rotational force can be applied on both sides of the central axis O, but this is not limitative, and the grooves 5 may be spaced at uneven intervals or the number of grooves 5 may be an odd number. Furthermore, one or more flat portions 4 may be provided as shown in FIG.

[0036] In this embodiment, the inclination angle θ2 of the second groove wall 5b relative to the tangent T2 is set to 90°, but this is not limited thereto. For example, as shown in FIG. 14 , the inclination angle θ2 may be set to an angle smaller than 90° but greater than the inclination angle θ1 of the first groove wall 5a, or may be set to an angle larger than 90°. Furthermore, although the first groove wall 5a and the second groove wall 5b are configured as flat surfaces, they may also be configured as curved surfaces. For example, if the first groove wall 5a is configured as a convex surface and the second groove wall 5b is configured as a concave surface, a further difference in the rotational force that can be transmitted in the first direction A1 and the second direction A2 can be achieved.

[0037] 15, the inner surface of the through hole 1a seen from the other end of the drill sleeve 1 may be formed into a hexagonal hole 1c into which a hexagonal wrench can be fitted. When multiple drill sleeves 1 are tightly fixed to the bone plate 10, or when the handle portion 2 or the through hole for a tool cannot be accessed, the drill sleeve 1 can be removed by fitting a hexagonal wrench into the inner surface of the hexagonal hole 1c.

[0038] In addition, in this embodiment, the handle portion 2 is provided at the longitudinal end of the drill sleeve 1, but it may be provided at any intermediate position in the longitudinal direction, or may be provided at two or more positions spaced apart in the longitudinal direction.

[0039] Furthermore, in this embodiment, the drill sleeve 1 attached to the bone plate 10 is exemplified as the structure of the medical instrument, but the present invention is not limited to this and can be used for a long medical instrument having a fastening structure (e.g., screw fastening) in which the operator wears gloves and the fastening operation is performed by the medical staff with their own fingers in an environment where the friction coefficient of the surface of the gloves is reduced by the patient's body fluids.

[0040] REFERENCE SIGNS LIST 1 Drill sleeve 1a Through hole 1b Male thread 2 Handle portion 4 Flat portion 5 Groove 5a First groove wall 5b Second groove wall 7 Projection 7a First side surface 7b Second side surface 10a Screw hole (female thread) A1 First direction A2 Second direction C Circle D Drill E Envelope O Central axis T1, T2 Tangent P1 Outermost position θ1, θ2 Inclination angle

Claims

1. A cylindrical drill sleeve having a through hole through which a drill can be inserted, the drill sleeve comprising: a male thread formed at one longitudinal end and fastened to a female thread; and a handle portion formed on the outer surface at any position in the longitudinal direction and which an operator can grasp with their fingers to apply a rotational force around a central axis, wherein the handle portion has an outer surface shape that makes it easier to transmit the rotational force in a second direction around the central axis opposite to the first direction to the handle portion than in a first direction around the central axis for fastening the male thread to the female thread.

2. A drill sleeve as claimed in claim 1, wherein the outer surface of the handle portion is provided with a plurality of grooves extending in a direction intersecting the circumferential direction, each of the grooves having a first groove wall disposed in the front in the first direction and a second groove wall disposed in the rear in the first direction, and the angle of inclination of the second groove wall with respect to a tangent to a circle centered on the central axis at the outermost position in the radial direction is greater than the angle of inclination of the first groove wall with respect to a tangent to the circle at the outermost position in the radial direction.

3. A drill sleeve according to claim 1, wherein the handle portion is provided with a plurality of protrusions protruding in the radial direction, each of the protrusions having a first side surface disposed forward in the first direction and a second side surface disposed rearward in the first direction, and the angle of inclination of the second side surface with respect to the tangent to a circle centered on the central axis at the outermost position in the radial direction is smaller than the angle of inclination of the first side surface with respect to the tangent to the circle at the outermost position in the radial direction.

4. A drill sleeve according to claim 3, wherein each of said projections is a circumferentially spaced ridge extending in said longitudinal direction.

5. A drill sleeve according to claim 3, wherein each of said projections is a convex portion spaced apart in the circumferential direction and in said longitudinal direction.

6. A drill sleeve as described in any one of claims 1 to 5, wherein the handle portion is formed with a larger diameter than the other portions in the longitudinal direction and has a flat portion perpendicular to the radial direction in at least a portion of the circumferential direction.

7. A drill sleeve as claimed in any one of claims 2 to 5, wherein the handle portion is formed with a larger diameter than the other portions in the longitudinal direction, and in cross section, the envelope line connecting the outermost positions is non-circular.

8. A long medical instrument comprising: a male screw formed at one end in the longitudinal direction and fastened to a female screw; and a handle portion formed on the outer surface at any position in the longitudinal direction and for an operator to grasp with their fingers and apply a rotational force around a central axis, wherein the handle portion has an outer surface shape that makes it easier to transmit the rotational force in a second direction around the central axis opposite to the first direction to the handle portion than in a first direction around the central axis for fastening the male screw to the female screw.

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