Medical Handset

Abstract

Provided is a handset for medical use that has a novel structure and that can achieve, inter alia, an improvement in operability when an attachment for medical use such as a mounted shaft drill is turned in a direction substantially plumb downward.　This handset 14 for medical use comprises a housing 45 having an intermediate portion A that accommodates an electric motor 46, a frontward portion B that constitutes a tip grip section in a style that allows for holding in the same manner as a pen, and a rearward portion C that has a battery built-in, the handset 14 for medical use being such that a rotating output shaft 52 is provided on an input axis Z of an attachment 10 for medical use that is provided with an input shaft driven so as to rotate about one axis, the rotating output shaft 52 extending toward the frontward side from the rotational driving shaft of the electric motor 46, and the input shaft of the attachment 10 for medical use being coupled with the rotating output shaft 52.

Description

[Technical Field]

[0001] The present invention relates to a medical handset that applies a rotational driving force about one axis to a medical attachment that is actuated by the rotational driving force. [Background technology]

[0002] As a type of medical instrument, there are various medical attachments that are actuated by applying a rotational driving force about one axis. For example, during endoscopic spinal surgery, bones such as vertebrae are cut using a medical shaft drill that is inserted into a through-hole in the barrel of a rigid endoscope. Such a shaft drill has a long shaft that is inserted into the through-hole in the barrel of the endoscope, and a drill head at the tip of the shaft protrudes from the barrel.

[0003] Incidentally, medical handsets that exert a rotational driving force around one axis on medical attachments such as shaft drills are known to use electric motors as their driving source, as shown in, for example, Patent Publication No. 2020-81282 (Patent Document 1).

[0004] Furthermore, JP 2019-520860 A (Patent Document 2) proposes a medical handset that has a built-in battery that drives an electric motor, eliminating the need for a power supply cord. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2020-81282 [Patent Document 2] Special Publication No. 2019-520860 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the conventional medical handsets described in Patent Documents 1 and 2 both have a problem in that it is difficult for a practitioner holding the handpiece to apply a pushing force in the direction of the rotation axis.

[0007] In other words, in the handset described in Patent Document 1, a shaft drill is attached as a medical attachment and driven to rotate, but because the rotation output shaft to which the shaft drill is attached is approximately perpendicular to the handpiece that houses the motor's rotation drive shaft, when an external force is applied by the hand holding the handpiece to push (push-cut) or pull (pull-cut) the shaft drill in the direction of the rotation axis, such external force and reaction force are likely to generate a rotation moment in a direction that tilts the shaft drill. As a result, it has been difficult to efficiently apply a sufficient amount of pushing force or pulling force in the direction of the drill's rotation axis to the shaft drill.

[0008] The handset described in Patent Document 2 is also a gun type with a grip that protrudes in a direction substantially perpendicular to the rotation output shaft direction. Therefore, similar to the handset described in Patent Document 1, the operating force and reaction force of the handpiece are likely to generate a rotation moment in a direction that tilts the shaft drill, making it difficult to apply a pushing force or pulling force in the direction of the drill rotation shaft to the shaft drill attached as a medical attachment.

[0009] In particular, in the case of long shaft drills that are inserted into the tube of a rigid endoscope, in conventional handset devices such as those described in Patent Documents 1 and 2, in which the operator's central axis of grip is approximately perpendicular to the rotation axis of the shaft drill, small oscillations in the gripping portion located at the base end of the shaft drill are greatly amplified at the tip portion (drill head) of the shaft drill, and it has become clear that it is difficult to accurately position the drill head when performing cutting operations, for example, while applying a pushing force or pulling force to the shaft drill.

[0010] Furthermore, the conventional handsets described in Patent Documents 1 and 2 have handpieces and gun-type grips that protrude in a direction substantially perpendicular to the rotation axis and house the rotary drive shaft of the motor. Therefore, when operating the medical attachment in a substantially vertically downward position, such as during endoscopic spinal surgery, gravity acts on the handpiece and grips themselves as a rotational moment that tilts the medical attachment. Therefore, to eliminate this rotational moment, the practitioner must also adjust the operating force, which makes operation even more difficult.

[0011] In addition, the conventional handsets described in Patent Documents 1 and 2 grip the part that protrudes in a direction approximately perpendicular to the rotation axis, so the rotational reaction force of the medical attachment during cutting is received by only one gripping part that is off the driving rotation axis. This raises the risk of the medical attachment shaking, especially when the rotational reaction force fluctuates, making it difficult to hold the medical attachment stably during cutting and other operations.

[0012] The object of the present invention is to solve or mitigate at least one of the problems inherent in conventional medical handsets that apply a rotational driving force around one axis to a medical attachment that is actuated by the rotational driving force. [Means for solving the problem]

[0013] The following describes preferred embodiments for understanding the present invention, but the embodiments described below are merely examples and may be appropriately combined with one another. Multiple components described in each embodiment may be recognized and employed independently to the greatest extent possible, and may also be appropriately combined with any of the components described in other embodiments. Accordingly, the present invention is not limited to the embodiments described below, and various other embodiments may be realized.

[0014] In a first aspect, there is provided a medical handset for applying a rotational driving force about one axis to a medical attachment attached thereto, the handset comprising an electric motor as a driving source, the electric motor being arranged coaxially with a rotary drive shaft of the electric motor and extending towards the distal end, the rotary drive shaft being connected to the rear end, and a rotary output shaft being provided at the distal end to which the input shaft of the medical attachment is connected, the electric motor having a battery arranged coaxially with the rotary drive shaft of the electric motor and at the rear end, the electric motor having a housing incorporating the electric motor, the rotary output shaft and the battery, the distal end portion of the housing accommodating the rotary output shaft having an outer circumferential length equal to or smaller than that of the intermediate portion accommodating the electric motor, and the distal end portion of the housing having an outer circumferential surface that forms a fingertip grip that an operator can hold in a pen-like style with their fingers. The outer peripheral surface constituting the fingertip grip portion at the tip portion has a rounded rectangular outer peripheral cross section. There is something.

[0015] The handset of this aspect can achieve the following effects (1) to (8), for example. (1) The rotary drive shaft of the electric motor and the central axis of rotation of the shaft drill are arranged on the same axis, which prevents shaking of the handset and therefore the medical attachment caused by the rotary drive reaction force of the medical attachment due to the electric motor, particularly compared to the conventional structure in which the rotary drive shaft of the motor and the rotary input shaft of the medical attachment are approximately perpendicular, as in Patent Document 1. (2) By placing the electric motor and battery, which are particularly heavy parts of the handset, on the rotation input shaft of the medical attachment, the center of inertia in the rotation direction is brought closer to the rotation input shaft of the medical attachment, which reduces axial wobble caused by the rotation drive reaction force of the medical attachment, thereby improving rotation stability. (3) By locating the battery, which is a heavy object, at a position away from the fingertip grip (support point) provided at the tip of the housing toward the rear end of the housing, the moment of inertia against tilting around the support point can be increased. Therefore, even with a medical attachment such as a relatively long shaft drill, the resistance to tilting exerted as an operational reaction force for cutting and the like can be efficiently generated by cleverly utilizing the battery, thereby improving the positional stability of the treatment head portion (drill head, etc.) of the medical attachment during treatment such as cutting, and therefore the cutting accuracy. (4) By connecting the rotary output shaft to the rotary drive shaft of the electric motor, the housing extends forward from the electric motor, and the outer periphery length is reduced by the extending portion, thereby realizing a shape suitable for holding in a pen-like style. (5) The tip of the housing can be held in a pen-like style, making it easier to hold the housing when operating a medical attachment pointing approximately vertically downward, such as in endoscopic spinal surgery, and improving the stability and accuracy of operation. (6) By holding the housing in a pen-like style and locating the heavy electric motor and battery on the rotation input shaft of the medical attachment, when operating a medical attachment such as a shaft drill in an approximately vertically downward direction, such as in endoscopic spinal surgery, the weight of the handset itself can be used as a pushing force or a compressing force in the direction of the rotation drive shaft of the medical attachment, thereby improving operability. (7) The distal end portion where the fingertip grip is provided for a pen-style grip has portions with outer perimeters equal to or greater than those of the distal end portion (the intermediate portion that houses the electric motor and the rear portion that houses the battery). This prevents the hand from slipping backward when gripping the housing in a pen-style grip. Therefore, even in situations where the weight of the heavy electric motor or battery is exerted downward, such as when operating a medical attachment pointing approximately vertically downward, the housing can be held firmly, stably, and easily in a pen-style grip. (8) When the medical attachment attached to the handset is long, such as a shaft drill inserted into the tube of a rigid endoscope, the fingertip grip is provided at the tip of the handset where the medical attachment is attached, allowing the medical attachment to be held as close as possible to the tip. This makes it possible to efficiently apply a force at the fingertip grip that is effective in suppressing the swinging or tilting of the medical attachment itself. The effects of the invention are subjective, and requirements vary depending on factors such as the conditions of use, circumstances, and purpose of use of the handset. Therefore, the present invention requires that at least one of the effects (1) to (8) above be achieved. In addition, it is desirable that the medical handset according to the present invention be capable of detachably mounting a medical attachment such as a shaft drill to the rotary output shaft, allowing for replacement with a necessary or appropriate medical attachment as needed. However, the present invention is also applicable to medical handsets in which a specific medical attachment is mounted to the rotary output shaft in a fixed or nearly fixed state. Furthermore, in the handset of this embodiment, the rounded rectangular outer cross section shape makes it easier to grip with the fingertips and makes it easier to specify the grip direction.

[0016] A second aspect is the medical handset according to the first aspect, wherein a speed control switch for adjusting the rotation speed of the electric motor is provided on the outer peripheral surface of the fingertip grip portion.

[0017] In this handset, the speed control switch is located on the outer periphery of the fingertip grip for a pen-style grip set at the tip of the housing, making it possible to easily control the speed with the tip of a single finger, such as the index finger, without moving the finger significantly, especially while holding the handset in a pen-style grip. This makes it possible to easily control the rotation speed while suppressing unstable movements such as shaft wobble and tilting in medical attachments such as shaft drills.

[0018] A third aspect is a medical handset according to the second aspect, in which the outer peripheral surface constituting the fingertip grip portion at the tip portion has a rounded rectangular outer cross-sectional shape, and the speed control switch is arranged on the short side so as to be operated in the axial direction.

[0019] The handset of this embodiment has a rounded rectangular cross-sectional outer periphery, which allows for a more comfortable grip with the fingertips and facilitates specific gripping directions. For example, the user can grip the handset with the thumb on one of the long sides and operate the speed control switch located on the short side with the index finger. This allows for stable holding with the thumb and easy, highly accurate speed control with the index finger.

[0020] A fourth aspect is a medical handset according to any one of the first to third aspects, wherein the outer peripheral surface of the intermediate portion housing the electric motor forms a palm-side grip portion to which the palm-side base ends of the thumb and index finger of an operator holding the fingertip grip portion in a pen-like grip style are placed, and the rear portion housing the battery extends rearward from the intermediate portion with a larger outer peripheral length than the intermediate portion housing the electric motor.

[0021] In this handset, the palm-side gripping portion has a larger outer perimeter than the fingertip gripping portion, allowing for a more stable grip. Furthermore, the rear portion is larger than the middle portion, ensuring storage space for the battery, circuit board, etc., and more effectively preventing the handset from unintentionally slipping off the gripping portion, particularly when operating a medical attachment such as a shaft drill with its head pointed substantially vertically downward due to gravity.

[0022] A fifth aspect is a medical handset according to any one of the first to fourth aspects, wherein the tip portion where the fingertip grip portion is formed is further provided with a tubular portion extending toward the tip side.

[0023] In this handset, a cylindrical portion extending from the fingertip grip portion toward the distal end allows the proximal end of a medical attachment to be inserted into the cylindrical portion. This facilitates secure attachment of an outer sleeve (outer shaft) to the cylindrical portion, even when the shaft drill, a type of medical attachment, has a rotary shaft and an outer sleeve (outer shaft), as described in the following embodiment. Furthermore, by covering the proximal end of the shaft drill with the cylindrical portion, it is possible to reduce or prevent direct contact of the fingers gripping the fingertip grip portion with the shaft drill. It is desirable that the cylindrical portion in this embodiment be formed with a smaller outer circumference than the distal end.

[0024] A sixth aspect is a medical handset according to any one of the first to fifth aspects, wherein the connecting portion of the rotary output shaft to which the rear end of the shaft drill is connected is a tubular structure made of synthetic resin, and the input shaft of the medical attachment is inserted from the rear end to connect.

[0025] In the handset of this aspect, a synthetic resin rotary output shaft is interposed between the tip of the rotary drive shaft of the electric motor and the input shaft of the medical attachment, thereby absorbing and reducing vibrations and shocks at the drive connection, improving operability and reducing the operator's effort, and also suppressing heat generation in components. Furthermore, the synthetic resin rotary output shaft achieves low friction at the connection with the medical attachment, allowing relative axial movement between the rotary drive shaft of the electric motor and the medical attachment while stably transmitting the rotary drive force.

[0026] A seventh aspect is a medical handset according to any one of the first to sixth aspects, wherein the medical attachment is a medical shaft drill that is inserted into a through-hole in the barrel of a rigid endoscope, and the electric motor is arranged so that the rotation drive shaft is located on an extension of the rotation center axis of the shaft drill.

[0027] The shaft drill used as a medical attachment in this type of handset is relatively long, making stable treatment operations difficult. However, by applying the handset of the present invention to this shaft drill, it is possible to stabilize cutting procedures using the drill head and facilitate operation.

[0028] An eighth aspect is a medical handset according to the seventh aspect, wherein the shaft drill includes a rotating shaft having a drill head at its tip and a sleeve-shaped outer shaft fitted onto the rotating shaft so as to be rotatable relative to the rotating shaft, and the base end of the rotating shaft is detachably connected to the rotation output shaft, and the base end of the outer shaft is detachably fixed to the tip portion of the housing.

[0029] In the handset of this embodiment, when the rotating shaft is inserted into the through-hole in the lens barrel of the rigid endoscope, direct contact of the rotating shaft with the lens barrel is avoided, thereby realizing protection of the lens barrel. Furthermore, the outer shaft can suppress vibration of the rotating shaft in a long shaft drill, improving the rotational stability of the rotating shaft. Furthermore, by attaching the base end of the outer shaft to the distal end of the housing, the base end portion of the rotating shaft is prevented from being exposed from the handset, making it possible to prevent inadvertent contact with the rotating shaft by fingers, etc. [Effects of the Invention]

[0030] The present invention can solve at least one of the problems inherent in conventional handsets for driving medical attachments that are operated by a rotational driving force about one axis, such as a shaft drill, and can provide a medical handset with a novel structure that improves operability when operating a medical attachment such as a shaft drill in a substantially vertically downward direction. [Brief explanation of the drawings]

[0031] [Figure 1]FIG. 1 is a perspective view showing a handset according to a first embodiment of the present invention with a shaft drill, which is a type of medical attachment, attached thereto; [Figure 2] FIG. 2 is a perspective view of the handset and detachable shaft drill shown in FIG. 1; [Figure 3] FIG. 2 is a plan view of the handset and detachable shaft drill shown in FIG. 1; [Figure 4] FIG. 2 is a front view of the handset shown in FIG. 1 as seen in the axial direction from the tip end side; [Figure 5] A longitudinal section of the shaft drill shown in Figure 1 [Figure 6] FIG. 2 is an exploded perspective view of the handset shown in FIG. 1; [Figure 7] A photograph to explain an example of how the handset shown in Figure 1 is used. DETAILED DESCRIPTION OF THE INVENTION

[0032] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0033] 1 to 4 show an example of a medical drill instrument 12, which is a medical hand instrument equipped with a medical shaft drill 10, which is a type of medical attachment. The medical drill instrument 12 has a structure in which a handpiece (handset) 14, which is a first embodiment of the present invention, is attached to the proximal end of the shaft drill 10. In the following description, the distal end generally refers to the left side in FIG. 3 , which is the side of the drill head 16 having a bit, and the proximal end generally refers to the right side in FIG. 3 , which is the side of the handpiece 14. Furthermore, the left-right direction generally refers to the left-right direction in FIG. 4 , which is the width direction of the handpiece 14, and the up-down direction generally refers to the up-down direction in FIG. 4 , which is the height direction of the handpiece 14. Furthermore, the axial direction generally refers to the direction of the central axis of the shaft drill 10 in the medical drill instrument 12.

[0034] As shown in Figures 2 and 3, the shaft drill 10 has an elongated (long, thin) shape overall and includes a drill head 16 at its tip. The drill head 16 in this embodiment is substantially spherical, has cutting particles such as diamonds fixed to its outer periphery, and is capable of cutting bones or the like by being rotated about the central axis of the shank 18. However, the specific shape, size, structure, etc. of the drill head 16 are not limited, and any drill head that can achieve the intended medical cutting procedure may be used, such as a drill that includes a cutting blade instead of a structure with fixed cutting particles, as disclosed in, for example, JP2018-526175A and Japanese Patent No. 6129955A.

[0035] As shown in Fig. 5, the drill head 16 of this embodiment has a rod-shaped shank 18 protruding toward its base end. The shank 18 of this embodiment has a smaller diameter than the outer diameter of the drill head 16, allowing for push cutting forward along the rotation axis as well as pull cutting backward along the axis. The drill head 16 and shank 18 are integrally formed from a metal such as medical stainless steel or titanium alloy.

[0036] The shank 18 is fixed to the distal end of the elongated, rod-shaped shaft body 20. In this embodiment, the shaft body 20 is a hollow cylinder with a circular cross section that extends straight, achieving a good balance between high strength and weight. The shaft body 20 is formed from a metal such as medical-grade stainless steel or a titanium alloy, and a low-friction coating layer is preferably provided on the outer surface. Such a low-friction coating layer is a coating layer that enhances the slipperiness of the surface, and various well-known materials can be appropriately used, such as fluororesins such as polytetrafluoroethylene (PTFE), polyether ether ketone (PEEK), silicone, and ceramic. The outer diameter of the shaft body 20 is not particularly limited as long as it can be inserted into the outer shaft 36 described below, but is, for example, 2.75 mm.

[0037] The hollow portion of the shaft body 20 is desirably filled with a filler 22. The filler 22 is not particularly limited and may be a solid, liquid, gel, or the like, and may be filled partially or over the entire length of the hollow portion of the shaft body 20. In this embodiment, the filler 22 is a solid such as a synthetic resin, and is housed within the shaft body 20. The entire filler 22 may be made of a single material, or, for example, the distal and proximal portions may be made of different materials. In this case, the distal and proximal portions made of different materials may be independent of each other, and the entire filler 22 does not necessarily have to be continuous. Housed within the hollow shaft body 20, the filler 22 stabilizes the posture by increasing inertia during rotation, suppressing wobble during rotation of the shaft body 20, and improving the strength of the shaft body 20.

[0038] The filler 22 is not disposed at the tip portion of the shaft body 20, and the shank 18 is inserted and fixed into the tip portion of the hollow shaft body 20, with the shank 18 and shaft body 20 constituting a rotary shaft 24. The rotary shaft 24 has a structure in which the solid shank 18 is inserted and fixed into the hollow shaft body 20, which efficiently ensures strength in the tip portion of the shaft body 20 close to the drill head 16 where force is particularly applied.

[0039] The fixing structure between the shank 18 and the shaft body 20 is not limited, and any structure capable of withstanding the axial force and rotational force around the axis exerted during cutting may be used, and in addition to a fixing structure using press fitting or fitting, the shank 18 may be fixed in an inserted state into the shaft body 20 by various means such as welding, adhesive bonding, pinning, caulking, or screwing, or by a fixing structure combining these. Alternatively, the shank 18 may have a hollow structure, and the tip end of the shaft body 20 may be inserted and fixed from the base end side of the shank 18, or the shank 18 may be detachable from the shaft body 20.

[0040] 5, a step 26 is formed at the tip of the rotary shaft 24 due to the difference in outer diameter between the shaft body 20 and the shank 18. The outer diameter of the drill head 16 is larger than the outer diameter of the shaft body 20.

[0041] An engaging member 28 is fixed to the base end of the rotary shaft 24. The engaging member 28 is cylindrical with a bottom, and the base end of the shaft body 20 is inserted and fixed to the engaging member 28. The engaging member 28 is preferably made of a material that can achieve low surface friction and low heat transfer coefficient.

[0042] The engaging member 28 in this embodiment is made of a synthetic resin, such as PEEK, which has a low surface friction coefficient, low heat transfer coefficient, and excellent heat resistance. The engaging member 28 includes engaging ribs 30 that protrude from the outer periphery and extend axially. The engaging ribs 30 may be formed with projections and recesses in the circumferential direction to achieve a recess-projection or recess-projection engagement that restricts or prevents relative rotation about the central axis of the rotary output shaft 52 of the handpiece 14 (described later). In this embodiment, the engaging ribs 30 are provided at multiple locations (e.g., four locations) spaced apart from one another around the circumferential direction of the engaging member 28, each extending linearly in the axial direction. However, the number and arrangement of the engaging ribs are not particularly limited as long as they are compatible with the rotary output shaft 52. The engaging ribs 30 in this embodiment have a substantially semicircular cross section extending axially, but may have other cross-sectional shapes, such as a substantially rectangular cross section.

[0043] The engaging member 28 may have a polygonal cross-sectional outer periphery shape, such as a hexagon, corresponding to the rotary output shaft 52 of the handpiece 14, eliminating the need for a special engaging rib 30. To improve the relative fixing strength of the engaging member 28 to the rotary shaft 24 in the circumferential and axial directions, it is also possible to employ, for example, a concave-convex locking structure on the mating surface or a connecting shaft structure that penetrates radially, or a resin plug 22 protruding from the base end of the rotary shaft 24 may be welded to the engaging member 28.

[0044] A gap ring 32 is fitted onto the rotating shaft 24. The gap ring 32 is made of synthetic resin, like the engaging member 28, such as PEEK. The gap ring 32 is fitted onto the rotating shaft 24 so as to be rotatable relative to the rotating shaft 24. The gap ring 32 has lightening recesses 34 that open onto its outer circumferential surface, which increase the surface area and thereby improve heat dissipation performance and reduce weight. The gap ring 32 is fitted onto the rotating shaft 24 on the tip side of the engaging member 28. The outer circumferential surface of the gap ring 32 has a larger diameter than the engaging member 28, and the outer circumferential surface is located further outward than the tip of the engaging rib 30 of the engaging member 28.

[0045] An outer shaft 36 is fitted onto the rotating shaft 24. The outer shaft 36 is sleeve-shaped with an inner diameter slightly larger than the outer diameter of the shaft body 20. The outer shaft 36 is made of a metal such as medical-grade stainless steel or titanium alloy. The outer shaft 36 is fitted onto the shaft body 20, allowing the rotating shaft 24 to rotate within the outer shaft 36. It is desirable that a low-friction coating layer be provided on the inner and outer circumferential surfaces of the outer shaft 36, similar to the outer circumferential surface of the shaft body 20. The inner diameter of the outer shaft 36 is not particularly limited as long as it allows the rotating shaft 24 to be inserted therethrough, but it is, for example, 2.8 mm.

[0046] A connector 38 is fixedly attached to the base end portion of the outer shaft 36. The connector 38 is made of a synthetic resin material such as polycarbonate. The connector 38 is hollow cylindrical as a whole, and the outer shaft 36 is fixed to its inner peripheral surface. The connector 38 is provided with an operating piece 40 that protrudes from the outer peripheral surface at its tip portion. In this embodiment, the operating piece 40 is in the shape of a roughly flange-shaped elliptical plate, but it may also be in the shape of a circular plate. However, in order to prevent the shaft drill 10 from rolling, it is desirable that the outer peripheral surface shape of the operating piece 40 be other than circular, and a shape in which the outer diameter dimension varies circumferentially, such as an elliptical or polygonal shape, is preferred.

[0047] The connector 38 also has a connecting protrusion 42 that protrudes partially from the outer periphery of the base end portion. The connecting protrusion 42 is a protruding strip that extends in a generally C- or U-shape with an open tip end when viewed from above, and a pair of locking portions 44, 44 that protrude outward to the left and right at a middle portion in the axial direction of the shaft are formed on both linear portions that are positioned opposite each other in the circumferential direction. Furthermore, a flange-like protrusion 43 that protrudes onto the outer periphery of the connector 38 is formed on the tip side of the connecting protrusion 42.

[0048] The base end of the connector 38 is approximately the same as the base end of the outer shaft 36 and protrudes axially rearward by a predetermined length. Furthermore, the base end side of the rotating shaft 24, which is inserted through the outer shaft 36, protrudes from the connector 38. The gap ring 32 fitted onto the rotating shaft 24 is disposed axially between the connector 38 provided at the base end of the outer shaft 36 and the engaging member 28 provided at the base end of the rotating shaft 24. The gap ring 32 has a larger diameter than the outer shaft 36 and cannot be inserted into the outer shaft 36. The outer diameter of the gap ring 32 is larger than the opening diameter on the base end side of the connector 38.

[0049] The rotating shaft 24 is movable axially relative to the outer shaft 36 by a predetermined distance, and the limit of movement of the rotating shaft 24 toward the tip side relative to the outer shaft 36 is determined by the engagement member 28 abutting against the connector 38 via the gap ring 32. Furthermore, withdrawal of the rotating shaft 24 toward the rear end side relative to the outer shaft 36 is determined by the abutment of the drill head 16, whose outer diameter is larger than the inner diameter of the outer shaft 36, against the tip opening of the outer shaft 36. If the drill head 16 has a small diameter, a projection for preventing withdrawal or a ring member may be fitted and fixed to the tip portion of the shank 18 or shaft body 20 protruding from the outer shaft 36.

[0050] The handpiece 14, to which the shaft drill 10 is detachably attached and which applies a rotational driving force about one axis to the shaft body 20, is a device that is held and operated by a practitioner. As shown in an exploded view in Fig. 6, the handpiece 14 of this embodiment incorporates, within a hollow housing 45, an electric motor 46 that generates the rotational driving force, a power supply device 48 such as a battery pack that supplies power to the electric motor 46, and a control board 50 that controls the power supply from the power supply device 48 to the electric motor 46. In other words, the handpiece 14 incorporates an energy source and a driving device, and does not require a cable or the like for connection to an external energy source.

[0051] The housing 45 is composed of a pair of roughly symmetrical housing halves 45a and 45b. Each housing halve 45a and 45b has a boat-like, bottomed shape with a roughly uniform overall thickness, and the peripheral walls of the halves 45a and 45b are butted together with their opening edges overlapping, and are positioned and fastened to each other with appropriate positioning pins, fixing bolts, etc., to form the housing 45 as a case having an interior that is roughly closed off from the outside space.

[0052] The housing 45 extends long in the axial direction, which coincides with the central axis of rotation Z of the attached shaft drill 10 (the central axis of the engaging member 28, which is the input shaft of the shaft drill 10), and has different outer perimeters, with the front portion B located at the axial tip end having a smaller outer perimeter than the axial intermediate portion A, and the rear portion C located at the axial base end having a larger outer perimeter. In particular, in this embodiment, the middle portion A, the front portion B, and the rear portion C each have a hollow cylindrical portion extending with a substantially constant outer perimeter, and between the middle portion A, the front portion B, and the rear portion C in the axial direction, there is provided an inclined surface region whose outer perimeter gradually changes in the axial direction, smoothly connecting the portions A, B, and C.

[0053] In addition, in this embodiment, the middle portion A, the front portion B, and the rear portion C all have an approximately rectangular outer cross-sectional shape with rounded corners, and a pair of short sides are located above and below, while a pair of long sides are located to the left and right.

[0054] In particular, the axially intermediate portion A has an outer peripheral surface that is roughly square or circular, and the electric motor 46 is accommodated within this intermediate portion A and is fixedly positioned within the housing 45. The rotary drive shaft 51 of the electric motor 46 extends in line with the central axis of rotation Z of the shaft drill 10 to which it is attached.

[0055] A rotary output shaft 52, to which the engaging member 28 of the rotary shaft 24 constituting the shaft drill 10 is connected, is attached to the tip of the rotary drive shaft 51 so as not to rotate relative to the shaft. The rotary output shaft 52 extends from the intermediate portion A toward the tip in the axial direction and is disposed within the front portion B of the housing 45.

[0056] The front portion B of the housing 45 is slightly smaller than the intermediate portion A, and as shown in Fig. 4, has a height dimension Y slightly larger than a width dimension X, giving it a generally rectangular outer peripheral shape with rounded corners. In this embodiment, the width dimension X of the front portion B is smaller than the outer diameter dimension φD of the motor main body of the electric motor 46 housed in the intermediate portion A.

[0057] The outer peripheral surface of the tip portion B, which has such a small outer periphery and extends toward the axial tip, constitutes a fingertip grip for gripping the housing 45 and holding the entire shaft drill 10 in the hand during a procedure such as human bone cutting. The outer peripheral surface of the tip portion B, which is the fingertip grip, desirably has an outer peripheral length set within a range of 100 mm to 150 mm. This allows for a size that is particularly suitable for an operator to grip the housing 45 with their fingers in a pen-like style, with the central axis of the housing 45 approximately vertical and the tip of the housing 45 pointing approximately vertically downward, as exemplified in Fig. 7.

[0058] However, the outer perimeter lengths of the middle portion A, distal portion B, and rear portion C are not limited and may be appropriately set depending on the intended use of the handpiece 14, the attachments to be attached, and the like. Preferably, the outer perimeter length of the middle portion A is set within a range of 100 mm to 150 mm. Considering typical usage conditions, it is desirable to make the outer perimeter length of the distal portion B smaller than that of the middle portion A. However, it is also possible to make the outer perimeter lengths of the middle portion A and the distal portion B equal, for example. By making the outer perimeter lengths of both portions approximately equal, it is possible to facilitate holding the middle portion A in a pen grip style, as well as the distal portion B, depending on the situation. In short, by setting at least the outer perimeter length of the middle portion A equal to the outer perimeter length of the distal portion B, the handpiece 14 can be easily gripped in a pen grip style.

[0059] The rotary output shaft 52, housed within the distal end portion B, has a connecting hole opening at its distal end. The engaging member 28, which constitutes the proximal end of the rotary shaft 24, is inserted into this connecting hole from the rear end, providing a detachable connection in a circumferentially non-rotatable state. While the rotary drive shaft 51 of the electric motor 46 is typically a solid metal rod, the rotary output shaft 52 is preferably made of synthetic resin, which has lower heat transfer properties and a lower coefficient of friction than metal. Using a synthetic resin rotary output shaft allows for greater design freedom, including the selection of materials and the thickness of components, while ensuring good mass productivity. This facilitates flexible response to various requirements and facilitates adjustment of the weight balance of the handpiece 14 while taking operability into consideration. The rotary output shaft 52 is preferably rotatably supported at its distal end, etc., relative to the housing 45 via a bearing 53.

[0060] Further, a speed control switch 58 for adjusting the rotation speed of the electric motor 46 is provided in the front portion B of the housing 45. The speed control switch 58 is preferably located on the surface of the narrower short side of the front portion B and is provided so as to be operable to control the speed in the axial direction of the housing 45. This makes it easier to change and adjust the rotation speed of the electric motor 46 using the speed control switch 58 only with, for example, the index finger of the hand gripping the front portion B (while ensuring a stable grip of the housing 45 with the other fingers). Note that the speed control switch 58 generally converts the amount of movement (operation amount) of an operating portion thereof by a finger into an electric signal and transmits the signal to the control board 50 (described later). The mechanism for converting the amount of movement into an electric signal can be disposed in the space around the rotation output shaft 52 in the front portion B, as shown in FIG. 6, for example.

[0061] Furthermore, the housing 45 of this embodiment is provided with a small-diameter cylindrical connecting tube portion 60 that protrudes forward from the tip end portion of one of the housing segments 45a, and this connecting tube portion 60 is located axially forward of the rotation output shaft 52 and extends on the central axis of the housing 45. When the shaft drill 10 is installed, the base end portion of the connector 38 of the outer shaft 36 is inserted into this connecting tube portion 60 to be locked and connected.

[0062] The connecting tube portion 60 has a notched connecting recess 62 formed in its upper portion. The connecting recess 62 opens forward in the top view shown in FIG. 3 , allowing the connecting protrusion 42 of the connector 38 to be inserted axially. Locking recesses 64, 64 corresponding to the locking portions 44, 44 of the connecting protrusion 42 are formed on the inner surfaces of the connecting recess 62 on both circumferentially opposing left and right sides. When the connecting protrusion 42 of the connector 38 is inserted into the connecting recess 62 of the handpiece 14, the locking portions 44, 44 of the connecting protrusion 42 engage with the locking recesses 64, 64 of the connecting recess 62, thereby preventing the connector 38 from coming out of the connecting tube portion 60 in the axial direction. This maintains the shaft drill 10 attached to the handpiece 14 (housing 45).

[0063] The shaft drill 10 thus mounted is stably maintained in an mounted state in which the central axis of rotation of the electric motor 46 and the central axis of rotation of the shaft drill 10 are aligned, thanks to the holding action of the rotary shaft 24 (engagement member 28) by the rotary output shaft 52 and the holding action of the outer shaft 36 (connector 38) by the connecting tube portion 60. The rotational driving force of the electric motor 46 is applied to the rotary shaft 24 via the rotary output shaft 52, thereby driving the rotary shaft 24 to rotate about its central axis within the outer shaft 36 fixedly attached to the handpiece 14, thereby rotating the drill head 16. To remove the shaft drill 10 from the handpiece 14, for example, the shaft drill 10 can be pulled out axially from the handpiece 14 by hooking a finger on the operating piece 40 of the connector 38.

[0064] The structure for connecting the shaft drill 10 to the handpiece 14 is not limited. For example, positioning irregularities can be appropriately provided between the inner circumferential surface of the connecting tube portion 60 and the outer circumferential surface of the outer shaft 36 (connector 38), or a bearing member can be used to rotatably support the rotating shaft 24 relative to the handpiece 14. Furthermore, a known chuck structure can be used at the attachment portion of the rotating shaft 24 to the rotation output shaft 52 and at the attachment portion of the outer shaft 36 to the connecting tube portion 60.

[0065] As described above, the shaft drill 10 is detachable from the handpiece 14 of this embodiment, which allows for a compact size and allows various shaft drills with different lengths and bits to be selected and attached as appropriate depending on the treatment, and as will be described later, various medical attachments other than the shaft drill can also be attached as needed. Furthermore, because the shaft drill 10 and the handpiece 14 are separable, for example, the shaft drill 10 can be used once and the handpiece 14 can be used multiple times. This single use allows the shaft drill 10 to be kept clean, and multiple use of the expensive handpiece 14 reduces costs.

[0066] On the other hand, the rear portion C of the housing 45 is slightly larger than the middle portion A, and as shown in FIG. 4, has a substantially rectangular outer cross-sectional shape that is larger than the middle portion A in both width dimension X and height dimension Y.

[0067] As shown in Fig. 6, a power supply device 48 consisting of a battery pack is accommodated and positioned in the rear portion C having the enlarged internal space. In this embodiment, a control board 50 that controls the power supply from the power supply device 48 to the electric motor 46 is positioned between the electric motor 46 and the power supply device 48 and is arranged so as to extend in the direction perpendicular to the axis, and the power supply device 48 is arranged close to the rear end within the housing 45. As shown in Fig. 6, in this embodiment, by arranging multiple (two) battery packs on an extension of the central axis of rotation Z, the outer perimeter of the rear portion C is prevented from becoming longer than necessary, and the power supply device 48 has a sufficient storage capacity.

[0068] Furthermore, in this embodiment, the upper part of the rear portion C (upward in Fig. 4) protrudes in a generally mountain-like shape, and as shown in Fig. 6, a main switch 56 is disposed in this mountain-like protruding portion with its operation button exposed on the surface of the housing 45. The main switch 56 is an operation unit that controls the power supply to the electric motor 46 housed in the middle portion A to turn the rotation of the drill head 16 ON / OFF.

[0069] By positioning the main switch 56 far away from the tip part B constituting the fingertip grip in the axial direction of the housing 45, the risk of the fingers holding the fingertip grip accidentally touching the main switch 56 and stopping or starting the drill operation can be reduced.

[0070] In addition, by arranging the electric motor 46, power supply 48, and control board 50 in a position in the housing 45 that is offset axially rearward from the tip portion B that constitutes the fingertip grip, the risk of these electric operating mechanisms generating heat and causing discomfort to the gripping fingers can be reduced. Furthermore, by providing the middle portion A with a large outer perimeter axially rearward of the tip portion B that constitutes the fingertip grip, as shown in Figure 7, when the tip portion B is held in a pen-like style, the palm area corresponding to the base of the thumb and index finger can be placed against the outer periphery of the middle portion A, thereby improving the stability of holding the housing 45 in a pen-like style. Furthermore, when held in a pen-like grip as shown in FIG. 7, the middle portion A, which has a larger outer perimeter, is located above the tip portion B that constitutes the fingertip grip, and the rear portion C, which has an even larger outer perimeter, is located further above the middle portion A. This reduces the risk that the gripping position at the fingertips will shift upward due to the weight of the electric motor 46 or the power supply unit 48, etc.

[0071] Furthermore, by connecting the rotary output shaft 52 to the rotary drive shaft 51 of the electric motor 46, the tip end portion B of the fingertip grip portion extends forward from the intermediate portion A where the electric motor 46 is disposed, with a smaller outer periphery than the intermediate portion A (particularly in this embodiment, with a width dimension X smaller than the outer diameter of the electric motor 46). This reduces the outer periphery, allowing for a shape and size suitable for holding in a pen-style grip to be realized without being limited by the contents, such as the electric motor 46. Particularly in this embodiment, the tip end portion B has a rounded rectangular outer cross-sectional shape, making it easier to hold in a pen-style grip and enabling directional awareness. In addition, a speed control switch 58 operable in the axial direction is disposed in the substantially flat area on the short side of the upper surface of the tip end portion B, making it easier to adjust the motor rotation speed with an index finger when holding the pen-style grip with a fingertip.

[0072] Furthermore, by allowing the distal end portion B of the housing 45 to be held in a pen-like style, the housing 45 can be easily held when the drill head 16 of the shaft drill 10 is operated in a substantially vertically downward direction, such as in endoscopic spinal surgery, thereby reducing the operator's labor and improving the stability and accuracy of operations such as cutting. In particular, by holding the housing 45 in a pen-like style and by locating the centers of gravity (M1, M2 in FIG. 2 ) of the heavy electric motor 46 and power supply 48 on a substantially extended line of the rotational axis Z of the shaft drill 10, the weight of the handpiece 14 itself can be used as a pushing force in the direction of the rotational axis Z of the shaft drill 10 when the shaft drill 10 is operated in a substantially vertically downward direction, such as in endoscopic spinal surgery, thereby further reducing the operator's labor and improving operability. In addition, a fingertip grip is provided at the tip end (tip portion B) of the handpiece 14, where the long shaft drill 10 is attached to the handpiece 14, so that the shaft drill 10 can be supported at a position as close as possible to the handpiece 14. In other words, the distance between the drill head 16, where the cutting reaction force is input, and the support point of the handpiece 14 (O in FIG. 2) can be made as short as possible, so that the fingertip grip can efficiently apply a force that is effective in suppressing the swinging or tilting of the shaft drill 10 itself due to the cutting reaction force.

[0073] 2, the support center O of the fingers gripping the outer peripheral surface of the front portion B is located approximately on an extension of the rotation center axis Z, which extends axially through approximately the center of the housing 45. The center of gravity M1 of the electric motor 46 is located rearward from the support center O at approximately the axial center of the intermediate portion A and on the extension of this rotation center axis Z. Furthermore, the center of gravity M2 of the power supply device 48, which has a larger mass than the electric motor 46 and is located even further rearward from the support center O, is located approximately on the extension of the rotation center axis Z at approximately the axial center of the rear portion C.

[0074] In this way, the centers of gravity M1, M2 of the electric motor 46 and the power supply 48, which are heavy objects, are set relatively far away on the central axis rearward from the support center O of the handpiece 14 by the fingers, thereby ensuring a large moment of inertia in the tilting direction about the support center O. Therefore, when using the handpiece 14 to perform a human bone drilling procedure with the shaft drill 10 attached to the distal end, even if a resistance reaction force is applied from the drill head 16, tilting is suppressed, and stable drilling operation can be achieved.

[0075] Furthermore, since the rotary drive shaft 51 of the electric motor 46 and the central axis Z of rotation of the shaft drill 10 (rotating shaft 24) are arranged on the same axis, wobble caused by the reaction force of the rotary drive of the shaft drill 10 by the electric motor 46 is prevented. Moreover, by positioning the centers of gravity M1, M2 of the electric motor 46 and the power supply 48, which are particularly heavy parts of the handpiece 14, approximately on the central axis Z of rotation of the shaft drill 10, the central axis of inertia in the rotational direction of the handpiece 14 is brought closer to an extension of the central axis Z of rotation of the shaft drill 10 (rotating shaft 24), which can suppress axial wobble caused by the reaction force of the rotary drive of the shaft drill 10 and improve rotational stability.

[0076] The medical drill instrument 12 of this embodiment, constructed as described above, is used, for example, during endoscopic surgery to drill bone, by being inserted into a rigid endoscope 66, which is supported in a substantially vertical direction (including a slightly tilted position) and inserted into the human body with its distal end facing downward, as shown in FIG. 7 . The rigid endoscope 66 includes a rigid lens barrel 68, as shown imaginarily in FIG. 3 , through which a shaft drill 10 is inserted. The drill head 16 of the shaft drill 10 can be positioned to protrude distally from the lens barrel 68. The rigid endoscope 66 is equipped with a camera, a light, and the like (not shown) at its distal end, allowing the drill head 16 protruding distally from the lens barrel 68 to be visualized through the endoscope. The proximal end of the shaft drill 10 protrudes proximally from the lens barrel 68, and the handpiece 14 is positioned proximally of the lens barrel 68. It is desirable that the outer peripheral surface of the outer shaft 36 be in contact with the inner peripheral surface of the through-hole 70 of the rigid endoscope 66 or be in close proximity to it with a slight gap therebetween.

[0077] The outer shaft 36 is made of metal, which provides high strength and sufficient pushability when inserted into the through-hole 70 of the rigid endoscope 66. The outer peripheral surface of the outer shaft 36 is desirably provided with a low-friction coating layer, which reduces frictional resistance and snagging when inserting the shaft drill 10 into the through-hole 70 of the rigid endoscope 66, thereby facilitating insertion. Furthermore, even when supplying or discharging liquids such as blood or saline, or small pieces of cut bone (cuttings) through the through-hole 70, resistance when moving between the inner peripheral surface of the through-hole 70 and the outer peripheral surface of the outer shaft 36 is reduced, which ensures a clear field of view through the endoscope by discharging saline, and efficiently discharges the cuttings by suction.

[0078] 7, when a practitioner holds and uses the handpiece 14 and the lens barrel 68, the outer shaft 36 is integrally connected to the handpiece 14 and therefore does not rotate relative to the rigid endoscope 66 unless the practitioner intentionally rotates it. The rotating shaft 24 inserted into the outer shaft 36 is rotated about its central axis by the driving force of the electric motor 46 within the outer shaft 36 inserted into a through-hole 70 of the lens barrel 68. When the shaft drill 10 is inserted into the through-hole 70, the outer shaft 36 is interposed between the rotating shaft 24 and the rigid endoscope 66, preventing contact between the rotating shaft 24 and the rigid endoscope 66. Note that FIG. 3 shows a cross section of the rigid endoscope 66 passing through the through-hole 70.

[0079] The medical drill instrument 12 can drill bone by bringing the rotating drill head 16 into contact with the bone to be drilled under an endoscope. At least one of the outer peripheral surface of the rotating shaft 24, which is continuous with the drill head 16, and the inner peripheral surface of the outer shaft 36, which is inserted through the through-hole 70 of the rigid endoscope 66, has a low-friction coating layer, allowing the rotating shaft 24 to rotate efficiently within the outer shaft 36 and reducing heat generation due to friction. The rotating shaft 24 is made of metal and therefore has high strength, and is supported by the metal outer shaft 36. This allows the drill head 16 to abut against the bone with sufficient force and prevents vibration or damage caused by bending of the rotating shaft 24 due to the reaction force generated when the drill head 16 abuts against the bone.

[0080] Furthermore, contact of the rotating shaft 24 with the rigid endoscope 66 is avoided, which also prevents damage and heating of the rigid endoscope 66 due to contact with the rotating shaft 24. Furthermore, by adjusting the thickness and diameter of the outer shaft 36 according to the difference between the outer diameter of the rotating shaft 24 and the inner dimensions of the through-hole 70 of the rigid endoscope 66, the rotating shaft 24 can be appropriately guided by the outer shaft 36, and wobble of the rotating shaft 24 during rotation can also be more efficiently suppressed.

[0081] Furthermore, the rotating shaft 24 is movable axially relative to the rotary output shaft 52 of the handpiece 14 and the outer shaft 36 by a predetermined distance. When the rotating shaft 24 moves toward the distal end, the gap ring 32 reduces or prevents heat generation and damage caused by contact between the engaging member 28 of the rotating shaft 24 and the outer shaft 36 (connector 38). Because the gap ring 32 is rotatable relative to both the rotating shaft 24 and the outer shaft 36, it may rotate as the rotating shaft 24 rotates. However, the rotation speed of the gap ring 32 is lower than that of the rotating shaft 24. Therefore, frictional heat and resistance are reduced compared to when the engaging member 28, which rotates at high speed, is in direct contact with the outer shaft 36. In particular, in this embodiment, a resin connector 38 is provided on the proximal end of the outer shaft 36, and the gap ring 32 contacts the connector 38. This more effectively suppresses frictional heat generation due to contact with the gap ring 32.

[0082] Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the specific description. For example, the specific structure of the shaft drill 10 is not limited, and various conventionally known shaft drills 10 can be attached. Furthermore, the structures of the rotary output shaft 52, connecting tube portion 60, etc. of the handpiece 14 can be appropriately modified depending on the structure of the attachment portion of the shaft drill 10.

[0083] Furthermore, the medical attachment that can be attached to the medical handset according to the present invention is not limited to the shaft drill described above, and various medical attachments that are connected to the rotary output shaft of the medical attachment and are actuated by the rotational driving force applied about one axis from the rotary output shaft can be used. For example, an attachment that has a rotary input shaft that is driven to rotate about one axis and a cutting blade such as a saw or cutter that is reciprocated via a motion conversion mechanism that converts the rotational motion of the rotary input shaft into reciprocating motion or the like can also be attached to the medical handset according to the present invention.

[0084] Furthermore, the electric motor 46, power supply 48, and electrical control system including the control board 50 employed in the handpiece 14 are not limited. The location of the main switch 56 is also not limited; for example, it may be located on the rear end face of the handpiece 14, or a toggle switch other than a push switch may be employed. The specific structure, shape, and location of the speed control switch 58 are also not limited; for example, a rotary or dial-type control unit that controls the speed continuously or in steps may be employed. However, the provision of the speed control switch 58 is not essential to the present invention; for example, it is also possible to drive the electric motor 46 with a constant supply of power, or to employ a control circuit that adjusts the power supply (torque) to the electric motor 46 in accordance with the rotational reaction force (cutting resistance). Furthermore, the present invention originally includes each of the inventions described below in (i) to (viii), and the configurations and effects thereof will be described below. The present invention provides (i) A medical handset to which a medical attachment is attached and which exerts a rotational driving force about one axis on the medical attachment, the medical handset comprising an electric motor as a driving source, the electric motor being arranged coaxially with a rotary drive shaft of the electric motor and extending towards the distal end, the rotary drive shaft being connected to the rear end, and a rotary output shaft being provided at the distal end to which the input shaft of the medical attachment is connected, a battery being arranged coaxially with the rotary drive shaft of the electric motor and on the rear side, the electric motor, the rotary output shaft and the battery being housed in a housing, the distal portion of the housing housing the electric motor and the rotary output shaft extending from the intermediate portion towards the distal end with an outer circumferential length equal to or smaller than that of the intermediate portion, and the outer circumferential surface of the distal portion forming a fingertip grip that an operator holds in a pen-like style. (ii) The medical handset according to (i), wherein a speed control switch for adjusting the rotation speed of the electric motor is provided on the outer peripheral surface of the fingertip grip portion. (iii) The medical handset according to (ii), wherein the outer peripheral surface constituting the fingertip grip portion at the tip portion has a rounded rectangular outer cross-sectional shape, and the speed control switch is disposed on a short side thereof so as to be operated in the axial direction. (iv) The medical handset according to any one of (i) to (iii), wherein the outer peripheral surface of the intermediate portion that houses the electric motor forms a palm-side grip portion to which the palm-side base ends of the thumb and index finger of an operator who holds the fingertip grip portion in a pen-hold style are placed, and wherein the rear portion that houses the battery has a larger outer peripheral length and extends rearward from the intermediate portion that houses the electric motor. (v) The medical handset according to any one of (i) to (iv), wherein the tip portion where the fingertip grip portion is formed is provided with a cylindrical portion extending further toward the tip side. (vi) The medical handset according to any one of (i) to (v), wherein the rotary output shaft has a coupling portion to which the input shaft of the medical attachment is coupled, the coupling portion having a tubular structure made of synthetic resin, and the input shaft of the medical attachment is inserted and coupled from the rear end thereof; (vii) A medical handset according to any one of (i) to (vi), wherein the medical attachment is a medical shaft drill that is inserted into a through-hole in a lens barrel of a rigid endoscope, and the electric motor is disposed so that the rotation drive shaft is positioned on an extension line of the rotation center axis of the shaft drill. (viii) The medical handset according to (vii), wherein the shaft drill includes a rotary shaft having a drill head at its tip and a sleeve-shaped outer shaft fitted onto the rotary shaft so as to be rotatable relative to the rotary shaft, and the base end of the rotary shaft is detachably connected to the rotary output shaft, and the base end of the outer shaft is detachably fixed to the tip portion of the housing. This includes inventions relating to: The invention described in (i) above can exhibit the following effects (1) to (8), for example. (1) The rotary drive shaft of the electric motor and the central axis of rotation of the shaft drill are arranged on the same axis, which prevents shaking of the handset and therefore the medical attachment caused by the rotary drive reaction force of the medical attachment due to the electric motor, particularly compared to the conventional structure in which the rotary drive shaft of the motor and the rotary input shaft of the medical attachment are approximately perpendicular, as in Patent Document 1. (2) By placing the electric motor and battery, which are particularly heavy parts of the handset, on the rotation input shaft of the medical attachment, the center of inertia in the rotation direction is brought closer to the rotation input shaft of the medical attachment, which reduces axial wobble caused by the rotation drive reaction force of the medical attachment, thereby improving rotation stability. (3) By locating the battery, which is a heavy object, at a position away from the fingertip grip (support point) provided at the tip of the housing toward the rear end of the housing, the moment of inertia against tilting around the support point can be increased. Therefore, even with a medical attachment such as a relatively long shaft drill, the resistance to tilting exerted as an operational reaction force for cutting and the like can be efficiently generated by cleverly utilizing the battery, thereby improving the positional stability of the treatment head portion (drill head, etc.) of the medical attachment during treatment such as cutting, and therefore the cutting accuracy. (4) By connecting the rotary output shaft to the rotary drive shaft of the electric motor, the housing extends forward from the electric motor, and the outer periphery length is reduced by the extending portion, thereby realizing a shape suitable for holding in a pen-like style. (5) The tip of the housing can be held in a pen-like style, making it easier to hold the housing when operating a medical attachment pointing approximately vertically downward, such as in endoscopic spinal surgery, and improving the stability and accuracy of operation. (6) By holding the housing in a pen-like style and locating the heavy electric motor and battery on the rotation input shaft of the medical attachment, when operating a medical attachment such as a shaft drill in an approximately vertically downward direction, such as in endoscopic spinal surgery, the weight of the handset itself can be used as a pushing force or a compressing force in the direction of the rotation drive shaft of the medical attachment, thereby improving operability. (7) The distal end portion where the fingertip grip is provided for a pen-style grip has portions with outer perimeters equal to or greater than those of the distal end portion (the intermediate portion that houses the electric motor and the rear portion that houses the battery). This prevents the hand from slipping backward when gripping the housing in a pen-style grip. Therefore, even in situations where the weight of the heavy electric motor or battery is exerted downward, such as when operating a medical attachment pointing approximately vertically downward, the housing can be held firmly, stably, and easily in a pen-style grip. (8) When the medical attachment attached to the handset is long, such as a shaft drill inserted into the tube of a rigid endoscope, the fingertip grip is provided at the tip of the handset where the medical attachment is attached, allowing the medical attachment to be held as close as possible to the tip. This makes it possible to efficiently apply a force at the fingertip grip that is effective in suppressing the swinging or tilting of the medical attachment itself. The effects of the invention are subjective, and requirements vary depending on factors such as the conditions of use, circumstances, and purpose of use of the handset. Therefore, the present invention requires that at least one of the effects (1) to (8) above be achieved. In addition, it is desirable that the medical handset according to the present invention be capable of detachably mounting a medical attachment such as a shaft drill to the rotary output shaft, allowing for replacement with a necessary or appropriate medical attachment as needed. However, the present invention is also applicable to medical handsets in which a specific medical attachment is mounted to the rotary output shaft in a fixed or nearly fixed state. In the invention described in (ii) above, the speed control switch is located on the outer peripheral surface of the fingertip grip section for holding the tool in a pen-like style, which is set at the tip of the housing. This makes it possible to easily control the speed with the tip of one finger, such as the index finger, without moving the fingertip significantly, especially while holding the tool in a pen-like style. This makes it possible to easily control the rotation speed while suppressing unstable movements such as shaft wobble and tilting in medical attachments such as shaft drills. In the invention described in (iii) above, the rounded rectangular cross-sectional shape of the outer periphery improves gripping with the fingertips and makes it easier to specify the gripping direction. For example, the user can grip the device with the thumb on one of the long sides and operate the speed control switch located on the short side with the index finger. This allows for stable holding with the thumb and easy, highly accurate speed control with the index finger. In the invention described in (iv) above, by making the middle portion of the handset gripping section larger in outer perimeter than the fingertip gripping section, a more stable grip can be achieved. Also, by making the rear portion even larger than the middle portion, it is possible to secure storage space for the battery, circuit board, etc., and more effectively prevent the handset from unintentionally slipping off the gripping section, particularly downward slippage due to gravity when operating a medical attachment such as a shaft drill with its head pointed substantially vertically downward. In the invention described in (v) above, a tubular portion extending further distally from the fingertip grip portion is provided, allowing the proximal end of a medical attachment to be inserted into the tubular portion. This facilitates securely attaching the outer sleeve to the tubular portion, even when a shaft drill, a type of medical attachment, has a rotary shaft and an outer sleeve (outer shaft), as described in the embodiment described below. Furthermore, by covering the proximal end of the shaft drill with the tubular portion, it is possible to reduce or prevent direct contact of the fingertips gripping the fingertip grip portion with the shaft drill. It is desirable that the tubular portion in this embodiment be formed with a smaller outer perimeter than the distal end. In the invention described in (vi) above, a synthetic resin rotary output shaft is interposed between the tip of the rotary drive shaft of the electric motor and the input shaft of the medical attachment, thereby absorbing and reducing vibrations and shocks at the drive connection, improving operability and reducing the operator's effort, and also suppressing heat generation in components. Furthermore, the synthetic resin rotary output shaft achieves low friction at the connection with the medical attachment, making it possible to stably transmit the rotary drive force while allowing relative axial movement between the rotary drive shaft of the electric motor and the medical attachment. In the invention described in (vii) above, the shaft drill used as a medical attachment in the handset is relatively long, making stable treatment operation difficult. However, by applying the handset of the present invention to this, it becomes possible to stabilize cutting treatment using the drill head and facilitate operation. In the invention described in (viii) above, when the rotating shaft is inserted into the through-hole in the lens barrel of the rigid endoscope, direct contact of the rotating shaft with the lens barrel is avoided, thereby realizing protection of the lens barrel. Furthermore, the outer shaft can suppress vibration of the rotating shaft in a long shaft drill, improving the rotational stability of the rotating shaft. Furthermore, by attaching the base end of the outer shaft to the distal end of the housing, the base end portion of the rotating shaft is prevented from being exposed from the handset, making it possible to prevent inadvertent contact with the rotating shaft by fingers, etc. [Explanation of symbols]

[0085] 10 Shaft Drill (Medical Attachment) 12 Medical drilling equipment 14 Handpiece (Handset) 16 Drill Head 18 Shank 20 Shaft body 22 Filling 24 Rotating shaft 26 Step 28 Engagement member 30 Engagement ridge 32 Gap ring 34 Recessed hole 36 outer shaft 38 Connectors 40 Operation piece 42 Connecting protrusion 43 Flange-shaped protrusion 44 Locking part 45 Housing 46 Electric Motor 48 Power Supply (Battery) 50 Control board 51 Rotating drive shaft 52 Rotating output shaft 53 Bearing 54 Connection recess 56 Main switch 58 Speed ​​control switch 60 Connecting tube part (tubular part) 62 Connection recess 64 Locking recess 66 Rigid endoscope 68 Telescope 70 through holes A middle part B Tip part (fingertip grip part) C rear part Z rotation axis

Claims

1. A medical handset to which a medical attachment is attached and which exerts a rotational driving force around one axis on the medical attachment, It is equipped with an electric motor as a driving source, a rotary output shaft that is disposed coaxially with the rotary drive shaft of the electric motor and extends forward, the rotary drive shaft is connected to the rear end thereof, and the rotary output shaft is provided at the front end thereof to which the input shaft of the medical attachment is connected; A battery is disposed coaxially with the rotary drive shaft of the electric motor on the rear side thereof, a housing that houses the electric motor, the rotary output shaft, and the battery; The housing has a front portion that houses the rotary output shaft and has an outer circumferential length that is equal to or smaller than that of an intermediate portion that houses the electric motor, and extends from the intermediate portion toward the front end, The outer peripheral surface of the tip portion forms a fingertip grip portion that an operator holds in a pen-hold style with their fingertips, The medical handset has an outer peripheral surface that forms the fingertip grip portion at the tip portion and has a rounded rectangular outer cross-sectional shape.

2. 2. The medical handset according to claim 1, wherein a speed control switch for adjusting the rotation speed of the electric motor is provided on the outer peripheral surface of the fingertip grip portion.

3. 3. The medical handset according to claim 2, wherein the outer peripheral surface constituting the fingertip grip portion at the tip portion has a rounded rectangular outer cross-sectional shape, and the speed control switch is disposed on a short side thereof so as to be operated in the axial direction.

4. an outer peripheral surface of the intermediate portion that houses the electric motor forms a palm-side grip portion to which base ends of the thumb and index finger of an operator who holds the fingertip grip portion in a pen-holding style are placed; and 4. The medical handset of claim 1, wherein the rear portion that houses the battery has a larger outer perimeter than the intermediate portion that houses the electric motor, and extends rearward from the intermediate portion.

5. 5. The medical handset according to claim 1, wherein the tip portion where the fingertip grip is formed is provided with a cylindrical portion extending further toward the tip side.

6. The medical handset according to any one of claims 1 to 5, wherein the rotary output shaft has a connecting portion to which the input shaft of the medical attachment is connected that has a tubular structure made of synthetic resin, and the input shaft of the medical attachment is inserted and connected from a rear end thereof.

7. 7. The medical handset according to claim 1, wherein the medical attachment is a medical shaft drill that is inserted into a through-hole in a lens barrel of a rigid endoscope, and the electric motor is disposed so that the rotation drive shaft is located on an extension of a rotation center axis of the shaft drill.

8. The shaft drill includes a rotary shaft having a drill head at its tip, and a sleeve-shaped outer shaft that is fitted onto the rotary shaft so as to be rotatable relative to the rotary shaft, The base end of the rotary shaft is detachably connected to the rotary output shaft, 8. The medical handset of claim 7, wherein the proximal end of the outer shaft is removably secured to the distal end portion of the housing.

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