MEDICAL HAND INSTRUMENT

Description

[0001] The invention relates to a medical hand instrument, in particular a disposable bone planer, with a handpiece and a planing blade and chip chamber arranged distally of the handpiece.

[0002] Such hand instruments are used, for example, as bone scrapers in dentistry to obtain bone material for autologous bone transplantation. Autologous bone transplantation is used, for example, to create a stable bone structure for dental implants.

[0003] The planer blade of the hand instrument is designed for scraping bones in particular and is arranged so that shavings scraped by the planer blade reach the shaving chamber and are collected there for further use. In known hand instruments, the planer blade runs in a plane inclined relative to a longitudinal axis of the handpiece. Such a hand instrument is known, for example, from EP 1 829 486 A1.

[0004] The use of such a hand instrument requires the user, e.g. a dentist or oral surgeon, to have great stamina and precision in handling.

[0005] The inventor has recognized that known medical hand instruments are deficient in this regard and do not facilitate the user's work to the desired extent.

[0006] Therefore, the aim of the invention is to create a medical hand instrument that relieves the user.

[0007] According to the invention, this aim is achieved by a hand instrument of the type mentioned at the outset, in which the handpiece is designed as a handle with three finger rests and a proximal support rest, wherein the three finger rests are inclined to one another in such a way that the three finger rests run in pairs at an angle of less than 90° to one another in a cross-section through the handpiece.

[0008] The invention incorporates the recognition that a currently available instrument on the dental market for obtaining bone chips from the jaw has the following deficiencies: The handpiece is a straight rod. This leads to fatigue in the dentist's fingers. The inventor recognized that an adequate shape and grip for the fingers and hand guidance are lacking to efficiently perform fine motor movements during removal. Removal requires more of a physical effort. - Due to the lack of ergonomics, the effectiveness of the instrument is hampered in terms of removal angle, holding angle, and guidance angle. The surrounding tissue can and often is injured.

[0009] The instrument is based on the principle of scraping, which requires greater force for removal with less yield. The scraping angle here is 160°. The cutting angle of the cutting edge is not optimal and forces the dentist to use the instrument at a single, defined angle. This is sometimes anatomically difficult and also leads to soft tissue injury during scraping.

[0010] The plane blade isn't made of spring-hard steel and is far from being sharp. It also blunts quickly.

[0011] The instrument is designed for right-handed people only.

[0012] The chip chamber for collecting the chips can only hold a volume of 2.5 - 3 cm3.

[0013] The working area is too large, requiring a larger surgical incision to work into the donor area.

[0014] To solve the aforementioned problems, the ergonomic disposable bone planer was developed based on the inventor's practical experience. Aspects of this medical handheld instrument include the following: The shape of the instrument is based on ergonomic principles. The shape of the instrument allows for fine motor movements of the user's fingers. The ergonomic shape makes the instrument comfortable to hold and therefore suitable for fine motor control.

[0015] Preferably, the finger rests are designed as curved recesses at least along the length of the instrument. The recesses for the fingers, and preferably additional nubs for grip, provide the necessary stability and support in the hand. The recess on the underside is designed to rest between the thumb and index finger. Both right- and left-handed users enjoy controlled guidance while working. This leads to significantly less trauma to the soft tissue.

[0016] A preferred removal angle of the plane blade of 50° to 75° is derived from an imaginary line drawn through the handpiece in relation to the cutting edge at 18° to 25°. The plane blade lies in the receiving area of ​​the plane blade and chip receiving gap, which is inclined at approximately 40° to the rest of the handpiece. This allows for better fine motor control. However, these angles can also be easily adapted to the anatomical situation through ergonomics by changing the finger position in the recesses. The planing principle enables qualitatively and quantitatively better removal. The removal angle is the same as with planing and is between 50° and 75°. This also requires significantly less force, which relieves strain on the surgeon's fingers and allows for more fine motor control.

[0017] The plane blade is made of spring-hardened steel and is noticeably sharper. This plane blade hardly loses its sharpness during use.

[0018] In a preferred embodiment, the chip chamber can have a volume of more than 3.5 cm³, preferably more than 4 cm³. If the chip chamber can accommodate a volume of 4 cm³, for example, this also means fewer work interruptions to empty the chip chamber compared to the prior art.

[0019] The working surface at the tip of the instrument is narrow—preferably 0.5 mm to 0.8 mm, e.g., 0.7 mm—and only 16 mm to 20 mm, e.g., 18.9 mm long. This allows for greater visibility during removal, thus greater control and guidance, and no soft tissue injury. Another advantage is that the surgeon requires a smaller operating area, meaning fewer cuts, less swelling, and less pain. The attached figures and explanations illustrate the descriptions.

[0020] Preferably, the three finger rests are designed as depressions and have a concave shape in the longitudinal direction of the handpiece.

[0021] The support surface is preferably formed by a spherical surface at the proximal end of the handpiece, which is oriented in the radial direction of the handpiece in which an outer flat side of the plane blade is oriented. It is particularly preferred if the support surface extends in the longitudinal direction of the hand instrument at an obtuse angle of between 0° and 10° with respect to the outer flat side of the plane blade.

[0022] Preferably, the width of the handpiece in the area of ​​the finger rests is between 11 mm and 16 mm. It is also preferred if the width of the handpiece in the area of ​​the support rest is between 20 mm and 25 mm, initially decreasing in the distal direction and increasing again in the area of ​​the finger rests.

[0023] The plane blade preferably runs essentially, in particular with the exception of the cutting edge, in a blade plane which is inclined by at least 50° with respect to the longitudinal axis of the handpiece.

[0024] The handpiece is preferably made of thermoplastic material, preferably medically approved polycarbonate or polyamide, for example the polycarbonate Makrolon 2458 or the polyamide ixef 1022.

[0025] Preferably, the chip chamber and the handpiece are formed in one piece and are part of a one-piece base body to which the planing blade and a chip chamber closure in the form of a removable cover are attached.

[0026] According to one variant of the hand-held instrument, the plane blade is designed as a conical disc and attached to a shaft that is longitudinally movable within the handpiece. The peripheral edge of the conical disc forms the cutting edge of the plane blade. The conical shape of the plane blade also defines the cutting angle of the plane blade.

[0027] In this embodiment, the chip chamber is preferably formed as a cylindrical cavity concentrically surrounding the shaft, which is open at the distal end of the handpiece. By means of a preferably provided ejector, wood shavings can be ejected distally from the chip chamber. For this purpose, the ejector, together with the planer blade and the shaft, is arranged in the handpiece for longitudinal displacement. The ejector is axially spaced from the planer blade, and the chip chamber extends axially between the planer blade and an end wall of the ejector.

[0028] Preferably, the shaft with the plane blade can be locked in such a way that the shaft and the plane blade (in the locked state) are no longer longitudinally displaceable with respect to the handpiece and the plane blade is locked in a working position used for scraping in such a way that tensile forces can be introduced into the shaft by means of the handpiece and transferred to the plane blade.

[0029] The shaft is preferably at least indirectly connected to a handle, which serves to longitudinally displace the shaft and the plane blade relative to the handpiece. The handpiece preferably has a longitudinal groove for guiding the handle. Furthermore, the handpiece preferably has a recess at the proximal end of the longitudinal groove, into which the handle can be pivoted by means of a rotational movement around the longitudinal axis of the shaft to lock the shaft and the plane blade in the working position.

[0030] In a hand instrument with a plane blade in the form of a conical disc or a blunt cone, the distal end of the handpiece, in particular of the base body of the handpiece, is designed in a stepped manner. A distally projecting projection of the base body encloses a first partial circumference of the plane blade, while an end wall of the base body, which is recessed in the longitudinal direction of the base body, longitudinally delimits the gap leading to the chip chamber. The gap is thus located between the cutting edge of the plane blade and the axially recessed end wall of the base body of the hand instrument.In the area of ​​the first partial circumference of the plane blade, a support and contact surface for the plane blade is preferably provided at the distal end of the base body. This support and contact surface lies in a plane extending perpendicular to the longitudinal axis of the plane blade shaft and is offset distally by the width of the gap relative to the plane in which the end face delimiting the gap extends. The support and contact surface is preferably enclosed by the forwardly projecting projection of the base body.

[0031] When scraping, tensile forces act on the shaft of the plane blade which are transferred to the plane blade. The material being scraped exerts forces on the plane blade which oppose the tensile force and which lead to a torque. The support and contact surface at the distal end of the base body absorbs this torque and supports the plane blade. The forward-projecting projection of the base body absorbs forces which act on the plane blade perpendicular to the longitudinal axis of the shaft. The shaft, the support and contact surface and the forward-projecting projection of the base body optimally stabilize the plane blade in its working position for scraping and hold it in such a way that the forces acting during scraping are transferred into the base body without the shaft and plane blade being able to deform significantly under the influence of the acting forces.The projection at the distal end of the base body, which encompasses the first part of the cutting edge in the working position of the planer blade, also reduces the risk of injury.

[0032] The ergonomic shape of the handpiece and the design of the planer blade and the distal end of the base body have a synergistic effect and, in combination, allow particularly precise and effective handling of the instrument because the gripping surfaces on the base body enable precise introduction of hand and finger forces into the instrument and the structure of the planer blade in combination with the design of the distal end of the base body allows precise implementation of the introduced forces.

[0033] The invention will now be explained in more detail using an exemplary embodiment with reference to the figures. The figures show: Fig. 1: a perspective overall view of the medical hand instrument; Fig. 2: a longitudinal section through the medical hand instrument; Fig. 3: a view of the medical hand instrument from the front and diagonally above; Fig. 4: a top view of the medical hand instrument; Fig. 5: a left side view of the medical hand instrument; Fig. 6: a right side view of the medical hand instrument; Fig. 7: a front view of the medical hand instrument; and Fig. 8: a cross-section through the medical hand instrument in the area of ​​the finger rests. Fig. 9: details of the instrument tip in a partially sectioned side view. Figs. 10a - c: various perspective views illustrating the chip chamber of the hand instrument. Fig. 11: a longitudinal section through a distal end section of the medical hand instrument illustrating the arrangement of the planing blade and chip chamber. Fig. 12: an enlarged section of the longitudinal section. Figure 11; Fig. 13: a grid model of a distal longitudinal section of the hand instrument to illustrate the spatial arrangement of the planer blade and a fastening screw for the planer blade; Fig. 14: an alternative embodiment of a medical hand device similar to the one shown above, but with a larger angle between the blade plane and the longitudinal axis of the handpiece; Fig. 15: another alternative embodiment of a medical hand device similar to the one shown above, but with an even larger angle between the blade plane and the longitudinal axis of the handpiece; Fig. 16: a perspective view of the planer blade; Fig. 17: a schematic longitudinal section through the planer blade; Fig. 18: various views of the fastening screw for attaching the planer blade to the hand instrument; Fig. 19: an alternative embodiment of a medical hand device similar to the one shown above, but with a narrower distal end; and Fig.20: another alternative embodiment of the medical hand instrument with a round blade that is attached to a chip chamber that can be removed from the rest of the hand instrument; Fig. 21: a perspective overall view of a second variant of the medical hand instrument, obliquely from above; Fig. 22: a perspective overall view of the second variant of the medical hand instrument, obliquely from the side; Fig. 23: a perspective overall view of the second variant of the medical hand instrument, obliquely from below; Fig. 24: a perspective detailed view of the distal end of the second variant of the medical hand instrument; Fig. 25: a longitudinal section through the distal end of the second variant of the medical hand instrument; Fig. 26: views of the four long sides of the medical hand instrument a) from the left, b) from above, c) from the right, and d) from below; Fig. 27: a perspective exploded view of the medical hand instrument; Fig.Fig. 28: a perspective overall view of the second variant of the medical hand instrument, viewed diagonally from the front; Fig. 29: a perspective overall view of the second variant of the medical hand instrument with the plane blade and shaft in the extended ejection position; and Fig. 30: an alternative design of the assembly comprising the handle, shaft, ejector, and plane blade of the medical hand instrument.

[0034] A medical hand instrument 10 according to the invention has a preferably one-piece base body 12 that extends from a distal end 14 of the medical hand instrument 10 to a proximal end 16 of the medical hand instrument. Near its distal end 14, the medical hand instrument has a planing blade 18. A longitudinal section of the one-piece base body 12 extending proximal to the planing blade 18 is designed as a handle 20. The handle 20 serves to grip the medical hand instrument 10 with one hand.

[0035] Two variants of the medical hand instrument 10 are presented. Figures 1 to 20 show a first variant as well as sub-variants of the first variant of the medical hand instrument 10 and details thereof, while Figures 21 to 29 show a second variant of the medical hand instrument 10 and details thereof.

[0036] The differences concern in particular the planing blade, while the longitudinal section of the one-piece base body 12 designed as a handpiece 20 is at least similar in both embodiments.

[0037] First, the first variant of the medical hand instrument 10 is described in more detail: The handpiece 20 extends along a longitudinal axis 22 and the planing blade 18 runs in a blade plane 24. The cutting edge 26 of the planing blade 18 protrudes from the blade plane 24, resulting in a cutting angle 28 between the cutting edge 26 and the blade plane 24.

[0038] Preferably, the cutting angle of the planer blade is between 50° and 75°, and the guide angle is preferably approximately 40°. The cutting angle α + β of the planer blade is between 50° and 75°, resulting from the position of the cutting edge 26 with the cutting angle α of 18° and a horizontal line drawn through the entire handpiece 20. The guide angle β, which should be approximately 40°, results from the inclination of the planer blade and the gap for collecting the chips surrounding it (corresponding to the blade plane 24) in relation to the handpiece 20. The guide angle β is thus the inclination of the instrument tip relative to the rest of the instrument 10.

[0039] Adjacent to the plane blade 18 is a chip chamber 30, so that bone chips scraped off by the cutting edge 26 of the plane blade 18 enter the chip chamber 30. The chip chamber 30 has a volume of approximately 4 cm 3 . The chip chamber 30 is provided with a removable cover 40; see Figures 9 and 10 .

[0040] The handpiece 20 has three finger rests 32, 34, and 36 formed as recesses. A finger rest 32 for the user's middle finger is located on the same side of the medical hand instrument 10 as the planer blade 18. A finger rest 34 for the user's thumb and a finger rest 36 for the user's index finger are arranged on the side of the handpiece 20 of the medical hand instrument 10. In the cross-section of the handpiece 20 (see Figure 8 ) it can be seen that the finger rests are arranged in cross-section in such a way that they enclose an angle of less than 90° between them.

[0041] In the longitudinal direction 22 of the handpiece 20, the finger rests 32, 34 and 36 are trough-shaped, i.e., concavely curved. As a result, the finger rests 32, 34 and 36 each offer good support for the user's respective finger. At the proximal end 16 of the hand instrument 10, the handpiece 20 is flat and relatively wide, thus forming a proximal support rest 38 which, when the medical hand instrument 10 is in use, can rest on the user's hand over the area of ​​the finger root between the thumb and index finger, so that the user can easily apply the pressure required for planing, and the corresponding counterforce is transferred to the user's hand via the relatively large surface area of ​​the support rest.

[0042] Figures 1 and 2show the base body 12 with the planing blade 18 attached to it of a first embodiment of the medical hand instrument 10. The one-piece base body 12 of this embodiment is shown in the Figures 3 to 7 shown again in various views. The base body 12 is preferably injection-molded from a plastic, in particular a polyamide or a polycarbonate.

[0043] In Figure 9 , details of the tip of the instrument 10 with the planing blade 18 and the chip chamber 30 as well as the cover 40 can be seen. Immediately adjacent to the cutting edge 26 of the planing blade 18 there is a gap 42 through which the bone chips scraped off by the planing blade 18 can enter the chip chamber 30. The planing blade 18 can be Figure 9As shown, it can be embedded at an angle in, for example, plastic. In particular, a planer blade 18 made of stainless steel can be overmolded with thermoplastic. Alternatively, the cutting edge 26 of the planer blade 18 can also be bent out of a larger piece of sheet metal, in which case the sheet metal then forms the blade plane 24 (see. Figure 2 ).

[0044] Figures 10a to 10c illustrate in partially sectioned and perspective views how the chip chamber 30 can be closed with the lid and how the planing blade 18 can be formed from a piece of sheet metal from which the actual cutting edge 26 is bent out, similar to what is known, for example, from kitchen graters.

[0045] Figure 11shows a longitudinal section through a distal end section of the base body 12 of a further embodiment of the hand instrument 10. The chip chamber 30 is located in the distal longitudinal section shown. In addition, the plane blade 18 is fastened to the base body 12 by means of a screw 44 near the distal end of the hand instrument 10. Also visible is the gap 42, through which bone chips separated from the cutting edge 26 of the plane blade 18 can reach the chip chamber 30. The Figure 11 The illustrated variant for fastening the planing blade 18 to the base body 12 differs from the one shown in Figure 9 illustrated variant in particular in that the planing blade 18 is fastened to the base body 12 of the hand instrument 10 by means of the screw 44.

[0046] This is even more precisely shown in the enlarged image in Figure 12 to recognize.

[0047] Figure 13shows a grid model of the base body 12 of the hand instrument 10 and the planing blade 18 as well as the screw 44 in a perspective view, which illustrates the spatial arrangement of the planing blade 18 and the screw 44 with respect to the distal end of the base body 12 of the hand instrument 10.

[0048] In Figure 16 the planing blade 18 is shown in a perspective view and Figure 17 shows a longitudinal section through the plane blade 18.

[0049] Like the Figures 11 to 13As can be seen, in the embodiment shown there, the planer blade 18 is fastened to the base body 12 of the hand instrument 10 by means of the screw 44. As a result, the planer blade 18 is essentially detachably connected to the rest of the hand instrument 10. An important aspect, however, is that the fastening of the planer blade 18 by means of the screw 44 ensures that the planer blade 18 is fastened firmly enough to the base body 12 of the hand instrument 10.

[0050] Different design variants of the hand instrument 10 can differ in the angle at which the blade plane 24 extends to the longitudinal axis 22 of the handpiece 20. Figures 14 and 15 illustrate two examples in which the angle between the blade plane 24 and the longitudinal axis 22 of the handpiece 20 is larger than in the examples shown in the Figures 1 to 13 are shown, namely up to 90° (see Figure 15 ).

[0051] This also depends on the geometry of the screw 44, which is Figure 16is shown in detail. As can be seen, the screw 44 has a self-tapping thread 46 and a countersunk head 48. A recess 50 with a driver profile in the shape of a hexalobular socket is provided in the countersunk head 48 in order to be able to turn the screw 44 using an appropriate tool of size T6. The outer diameter of the countersunk head 48 is dimensioned such that it extends almost over the entire width of the planer blade 18 in order to ensure the largest possible contact surface between the bevels of the countersunk head 48, the screw 44 and the corresponding bevels of the associated fastening opening 52 in the planer blade 18. The fastening opening 52 is designed in such a way that the countersunk head (screw head) 48 of the screw 44 does not protrude beyond the contour of the planing blade 18 when the planing blade 18 is screwed to the base body 12 of the hand instrument 10 by means of the screw 44. This is the case, for example, in Figure 12 shown.

[0052] The illustrated fastening of the plane blade 18 by means of the screw 44 offers two advantages. Due to the advantageous design of the plane blade 18 and screw 44, the fastening of the plane blade 18 to the base body 12 by means of the screw 44 is particularly strong. Since the screw 44 has a self-tapping thread 46, the base body 12 of the hand instrument 10 can be easily manufactured from a thermoplastic material by injection molding without also having to create a thread for the screw 44. A further advantage is that it is theoretically possible to replace a possibly blunt plane blade 18 with a new plane blade 18 during the treatment of a patient.Basically, however, the hand instrument 10 is intended for single use, in which the planing blade 18 remains permanently connected to the base body 12 and is disposed of together with the rest of the hand instrument 10 after use of the hand instrument on a patient.

[0053] Depending on the patient, a medical hand instrument such as that shown in Figures 1 to 13 may be too large. Therefore, the medical hand instrument 10' may alternatively be designed such that its entire distal area, including the planing blade 26' and the chip chamber 30', is significantly narrower. Such a medical hand instrument 10' is Figure 19 shown.

[0054] According to a sub-variant of the first variant of the medical hand instrument 10", the medical hand instrument 10‴ has at its distal end a ring blade 54 which is attached to a distal end of a sleeve-shaped chip chamber 30"; see Figure 20 The annular planing blade 54 encloses a central opening 56 through which scraped bone chips can enter the chip chamber 30".

[0055] The sleeve-shaped chip chamber 30", together with the ring blade 54 attached to it, can be separated from the rest of the medical hand instrument 10". For example, the sleeve-shaped chip chamber 30" can be plugged or screwed onto the rest of the hand instrument. With such a medical hand instrument 10", an even narrower distal area can be realized in order to scrape bone even in otherwise inaccessible places. The disadvantage in this case is the small capacity of the chip chamber 30".

[0056] Now to the second variant of the medical hand instrument 10: In the second variant of the medical hand instrument 10, the handpiece 20 also extends along a longitudinal axis 22 and is shaped similarly to the handpiece of the Figures 1 to shown variant. This is shown in the perspective views in the Figures 21 , 22 , 23 and 28 as well as the side views in the Figures 26a to 26d A difference to the previously mentioned Figures 1 to 20 The variants and sub-variants of the medical hand instrument 10 shown differ in terms of the type and arrangement of the planing blade and the chip chamber.

[0057] In the second variant of the medical hand instrument 10, the planer blade 60 is formed by a conical disc whose peripheral edge forms the cutting edge 62 and which has a diameter between 4 mm and 6 mm, e.g., 5 mm. In alternative embodiments, the planer blade 60 can also have a larger diameter, e.g., 8 mm, 10 mm, or 12 mm. The planer blade 60 is connected to a shaft 64, which is connected to the center of the planer blade 60 on the inner side in the region of the tip 66 of the conical disc forming the planer blade 60.

[0058] The chip chamber 30‴ is shaped like a hollow cylinder, with the shaft 64 extending through its center. The diameter of the shaft 64 is smaller than the inner diameter of the chip chamber 30', so that a hollow space is created between the outer surface of the shaft 64 and the inner wall of the chip chamber 30‴, which serves to collect chips.

[0059] The medical hand instrument 10 is shaped in the region of the distal end of the chip chamber 30‴ such that a projection 78 at the distal end of the base body 12‴ encloses the planing blade 60 in a first partial circumference of the planing blade 60, while a second partial circumference of the planing blade 60 is free when the planing blade 60 is in its working position; see Figure 24. In the region of the second, free-standing partial circumference of the planing blade 60, the distal end of the base body 12 is shortened such that a partial annular gap 42‴ is formed through which bone chips can reach the chip chamber 30‴. The distal end of the base body 12‴ of the medical hand instrument 10 is thus designed in a stepped manner, with the distally forwardly projecting projection 78 of the base body 12‴ enclosing the first partial circumference of the planing blade 60, while an end wall 80 of the base body 12‴, which recesses in the longitudinal direction of the base body 12, delimits the gap 42‴, which leads to the chip chamber 30‴, in the longitudinal direction. The gap 42‴ is thus located between the cutting edge 62 of the planing blade 60 and the end wall 80 of the base body 12‴ of the hand instrument 10, which front wall 80 is set back in the axial direction.

[0060] During scraping, tensile forces act in the shaft 64 and are transferred to the plane blade 60. The material to be scraped exerts forces on the plane blade 60 that oppose the tensile force, resulting in a torque. In order to absorb this torque and support the plane blade 60, a support and bearing surface 84 is provided at the distal end of the base body 12‴. This support and bearing surface 84 lies in a plane running perpendicular to the longitudinal axis of the shaft 64 and is offset distally from the plane in which the end face 80 runs by the width of the resulting gap 42‴. The support and bearing surface 84 is bordered by the forwardly projecting projection 78 of the base body 12‴. The forwardly projecting projection 78 of the base body 12‴ absorbs forces that act on the plane blade transversely to the longitudinal axis of the shaft 64.By means of the shaft 64 and the projection 78 of the base body 12‴ projecting forwards, the planer blade is optimally stabilized in its working position for scraping and is held in such a way that the forces acting during scraping are introduced into the base body 12‴ without the shaft 64 and planer blade 60 being able to deform to a greater extent under the influence of the acting forces.

[0061] This allows the forces applied by a user to the planer blade 60 via the ergonomically shaped handpiece 20 to be transferred in a highly controlled manner for precise and effective scraping. The ergonomic shape of the handpiece 20 and the design of the planer blade 60 and the distal end of the base body 12‴ thus have a synergistic effect that allows for particularly precise and effective handling of the instrument 10.

[0062] The planing blade 60 is designed as a conical disc and can be used as in Figure 25shown in the figure have the shape of a truncated cone with an apex angle γ of approximately 110°. Unlike in Figure 25 As shown, the tip 66 of the planer blade 60 is preferably rounded. The tip angle of 110° results in a cutting angle δ of the circumferential cutting edge 62 of 35°, provided the planer blade is not hollow but has a flat back as shown.

[0063] The outer diameter of the ejector 68 corresponds approximately to an inner diameter of the chip chamber 30"', so that an end wall 70 of the ejector 68 limits the chip chamber 30" in its longitudinal direction when the planer blade 60 is in the working position, but the ejector 68 can be moved in the chip chamber 30"'.

[0064] To eject bone chips, the ejector 68 together with the shaft 64 in the planing blade 60 can be pushed axially forward out of the base body 12‴, as shown in Figure 29is shown. For this purpose, a handle 72 is provided, which is attached to the proximal end of the ejector 68 and guided in a longitudinal groove 74 in the base body 12‴ of the hand instrument 10. With the aid of the handle 72, the planing blade 60, the shaft 64 and the ejector 68 can be axially displaced from a working position to the ejection position and back. In doing so, the handle 72 moves in the longitudinal groove 74. The handle 72 can be an integral component of the ejector 68 or it can be attached to the ejector 68 as a separate part. For this purpose, the ejector 68 can have a recess 82 at its proximal end, into which a radially inwardly facing end of the handle 72 can be inserted, see Figure 27 .

[0065] In order to fix the planing blade 60 with the shaft 64 in the ejector 68 in the working position of the planing blade 60, the handle 72 can be pivoted around the longitudinal axis of the shaft 64 and the ejector 68 into a locking recess 76 when the planing blade 60 is in the working position; see Figure 23 . When the handle 72 is pivoted into the recess 76, the handle 72 can no longer be moved back and forth along the longitudinal groove 74.

[0066] In order to use the medical hand instrument 10 according to the second variant for scraping, the planing blade 60 together with the shaft 64 and the ejector 68 must be in the working position in which the planing blade is partially enclosed by the distal end of the base body 12‴ of the hand instrument 10. The handle 72 must be pivoted into the locking recess 76 so that tensile forces can be transmitted from the base body 12‴ of the hand instrument 10 via a distal wall of the locking recess 76 to the handle 72 and from there via the ejector 68 and the shaft 64 to the planing blade 60. This state is in Figures 21 to 25 and 27 shown.

[0067] In order to empty the chip chamber 30‴ of the medical hand instrument 10 after use, the handle 72 must be pivoted out of the locking recess 76 and positioned so that the handle 72 can be pushed forward in the longitudinal groove 74. In doing so, the ejector 68, the shaft 64, and the planing blade 60 are also moved forward—i.e., in the distal direction. The end wall 70 of the ejector 68 pushes material located in the chip chamber 30‴ out of the chip chamber 30‴ in the distal direction.

[0068] In the illustrated embodiment, the ejector 68 is designed as an elongated cylindrical body, the outer diameter of which approximately corresponds to the inner diameter of the chip chamber 30‴ and to which the shaft 64 is attached distally. This design of the ejector 68 has the advantage that the peripheral surface of the ejector 68 and the inner wall of the chip chamber 30‴ ensure secure longitudinal guidance. In the exploded view in Figure 27 all components of this embodiment of the medical hand instrument are shown, including the elongated ejector 68 with its end face 70.

[0069] In an alternative, in Figure 30In the embodiment shown, the ejector 68 can also be designed as a type of disc that is attached to the shaft 64. In this embodiment, the shaft 64 extends through the disc-shaped ejector 68 as far as the handle 72. Adequate longitudinal guidance can be ensured by designing the handle 72 such that it is securely guided along the longitudinal groove 64 not only laterally, but also in all radial directions. A corresponding design of the base body 12 and the handle 72 is shown in cross-section in Figure 30a.

[0070] In another design variant (not shown), the shaft is continuous and angled at its proximal end, so that the angled end of the shaft forms the handle for advancing and retracting the planer blade and ejector. Because the shaft in this embodiment is continuous and integral from the planer blade to its angled end forming the handle, it can transmit large tensile forces.

[0071] The planer blade 60 is preferably made of stainless medical steel, for example 316L. The shaft 64 is also preferably made of stainless steel. The ejector 68 and the handle 72 are preferably made of plastic. In one embodiment, the ejector 68 and the handle 72 can be formed as a single piece, i.e., the handle 72 is formed as a lateral projection at the distal end of the ejector 68. In the other embodiment, particularly the embodiment in which the ejector is in the shape of a disc or a short cylinder that is attached to the shaft 64, the ejector 68 and the handle 72 are separately connected to the shaft 64. Reference symbol

[0072] 10Hand instrument 12Base body 14Distal end 16Proximal end 18Planer blade 20Handpiece 22Longitudinal axis 24Blade plane 26Cutting edge 28Cutting angle 30Chip chamber 32Finger rest for middle finger 34Finger rest for thumb or index finger 36Finger rest for thumb or index finger 38Support rest 40Chip chamber cover 42Gap 44Screw 46Thread 48Countersunk head 50Recess 52Mounting opening 54Ring blade 56Central opening in the ring blade 60Disc-shaped plane blade (conical disc) 62Cutting edge of the plane blade 64Shaft, to whose distal end the plane blade is attached 66Tip of the conical disc forming the plane blade 68Ejector for ejecting chips from the chip chamber 70End wall of the ejector 72Handle for pushing the shaft forward and backward,Ejector and planing blade 74Longitudinal groove for the handle 76Recess for locking the handle 78Protrusion at the distal end of the base body 80End wall of the base body 82Recess at the proximal end of the ejector for fastening the handle 84Support and contact surface for the planing blade αCutting angle βGuide angle γTip angle δCutting angle,

Claims

1. Hand instrument (10) having a handpiece (20) and a scraping blade (18; 60) arranged distally of the handpiece and a chip chamber (30), of which the scraping blade (18; 60) is designed for scraping bones and is arranged in such a way that chips scraped by means of the scraping blade enter the chip chamber (30) and that the scraping blade (18; 60) extends in a plane inclined with respect to a longitudinal axis (22) of the handpiece (20), characterized in that the handpiece (20) is designed as a handle with three finger rests (32, 34, 36) and a proximal support rest (38), the three finger rests (32, 34, 36) being inclined to one another in such a way that the three finger rests (32, 34, 36) extend in pairs at an angle of less than 90° to one another in a cross-section through the handpiece (20).

2. Hand instrument according to claim 1, characterized in that the three finger rests (32, 34, 36) are designed as depressions having a concave shape in the longitudinal direction of the handpiece (20).

3. Hand instrument according to claim 1 or 2, characterized in that the support rest (38) is formed by a spherical surface at the proximal end of the handpiece (20), which is oriented in the radial direction of the handpiece (20) in which an outer flat side of the scraping blade (18) is oriented.

4. Hand instrument according to claim 3, characterized in that the support rest (38) extends in the longitudinal direction of the hand instrument (10) at an obtuse angle of between 0° and 10° with respect to the outer flat side of the scraping blade (18).

5. Hand instrument according to at least one of claims 1 to 4, characterized in that the chip chamber (30) has a volume of more than 3.5 cm3, preferably more than 4 cm.

36. Hand instrument according to at least one of claims 1 to 5, characterized in that the scraping blade (18) extends substantially, in particular with the exception of the cutting edge (26), in a blade plane (24) which is inclined by at least 50° with respect to the longitudinal axis (22) of the handpiece.

7. Hand instrument according to at least one of claims 1 to 6, characterized in that the handpiece (20) is made of thermoplastic material, preferably of polycarbonate Makrolon 2458 or polyamide ixef 1022 approved for medical use.

8. Hand instrument according to at least one of claims 1 to 7, characterized in that the chip chamber (30) and the handpiece (20) are formed in one piece and are part of a one-piece base body (12) to which the scraping blade (18) and a chip chamber closure in the form of a removable cover (40) are attached.

9. Hand instrument according to at least one of claims 1, 2 and 5 to 8, characterized in that the scraping blade (60) is designed as a conical disc and is attached to a shaft (64) which is arranged in the handpiece (20) so as to be longitudinally displaceable.

10. Hand instrument according to claim 9, characterized in that the chip chamber (30"') is formed as a cylindrical cavity concentrically surrounding the shaft (64), which is open at the distal end of the handpiece (20).

11. Hand instrument according to claim 9 or 10, characterized by an ejector (68), which is longitudinally displaceable together with the scraping blade (60) and the shaft (64) and has an axial distance from the scraping blade (60), the chip chamber extending in the axial direction between the scraping blade (60) and an end wall (70) of the ejector (68).

12. Hand instrument according to at least one of claims 9 to 11, characterized in that the shaft (64) can be locked with the scraping blade (60) in such a way that the shaft (64) and the scraping blade (60) can no longer be longitudinally displaced with respect to the handpiece (20) in the locked state and the scraping blade is locked in a working position serving for scraping in such a way that tensile forces can be introduced into the shaft (64) by means of the handpiece (20) and transmitted to the scraping blade (60).

13. The hand instrument according to at least one of claims 9 to 11, characterized in that the shaft (64) is at least indirectly connected to a handle (72) which serves for longitudinally displacing the shaft (64) and the scraping blade (60) with respect to the handpiece (20).

14. Hand instrument according to claim 13, characterized in that the handpiece (20) has a longitudinal groove (74) for guiding the handle (72).

15. The hand instrument according to claim 14, characterized in that the handle (72) of the handpiece (20) has a recess at the proximal end of the longitudinal groove into which the handle (72) can be pivoted by means of a rotary movement around the longitudinal axis of the shaft (64) in order to lock the shaft (64) and the scraping blade (60) in the working position.