Surgical instrument

Abstract

A surgical instrument (1) for dressing a prosthesis, comprising: a handpiece (2) in which a cylinder (3) is arranged with a piston element (4) associated with the cylinder (3); the invention relates to a mobile phone (2) comprising a cylinder (3), a piston element (4), and a switching element (5) and a chisel (6), the chisel (6) being mounted and arranged in an axially movable manner at one end of the mobile phone (2), the chisel (6) being fastened to the mobile phone (2) in a loss-proof manner, the piston element (4) being arranged in an axially movable manner in the cylinder (3), the piston element (4) being arranged to be moved by means of a fluid, wherein the piston element (4) is configured to generate a pulse oriented in the direction of the chisel (6) to drive the chisel (6) into a prosthetic handle gap (8) associated with the prosthesis (7), and wherein the piston element (4) is configured to generate a pulse oriented opposite the chisel (6) to drive the chisel (6) out of the prosthetic handle gap (8).

Description

Technical Field

[0001] The invention relates to a surgical instrument for trimming a prosthesis, comprising: a handpiece in which a cylinder is arranged, wherein a piston element is associated with the cylinder; and a switching element and a chisel, wherein the chisel is axially movably mounted and arranged at one end of the handpiece, wherein the chisel is fastened to the handpiece in a loss-proof manner, wherein the piston element is axially movably arranged in the cylinder, wherein the piston element can be set to move by means of a fluid. Background Art

[0002] From EP 0 910 317 B1, a surgical instrument for trimming a prosthesis is known, in which a piston element is pneumatically moved back and forth in a cylinder, wherein the piston element exerts an impact on a chisel mounted axially in a housing. Such a surgical instrument can be used to drive the chisel into the gap between a prosthesis stem associated with the prosthesis and a groove made in the bone. This gap is also called the prosthesis stem gap.

[0003] Chisels are usually elongated and flexible in shape. Such a design enables the chisel to penetrate very deeply into the gap of the prosthesis stem. However, a disadvantage of this design is that the chisel may get stuck in the gap of the prosthesis stem. The chisel can then only be loosened after extensive manual labor. For example, it is known to place a slotted hammer on the chisel on the underside of the handpiece and to loosen the chisel by controlled hammering with a second hammer. However, there is a risk of injury to the bone adjacent to the prosthesis and this procedure is time-consuming and ergonomic for the surgeon. Summary of the invention

[0004] An object of the present invention is to provide a surgical instrument for modifying a prosthesis with improved operability.

[0005] This object is achieved with the features of claim 1. The dependent claims mention advantageous embodiments.

[0006] The surgical instrument for trimming a prosthesis according to the present invention comprises: a handpiece in which a cylinder is arranged, wherein a piston element is associated with the cylinder; and a switching element and a chisel, wherein the chisel is axially movably mounted and arranged at one end of the handpiece, wherein the chisel is fastened to the handpiece in a loss-proof manner, wherein the piston element is axially movably arranged in the cylinder, wherein the piston element can be configured to move by means of a fluid, wherein the piston element is configured to generate a pulse directed in the direction of the chisel to drive the chisel into a prosthesis stem gap associated with the prosthesis, wherein the piston element is configured to generate a pulse directed in the opposite direction to the chisel to drive the chisel out of the prosthesis stem gap.

[0007] The repeatability of the pulses can be achieved by driving the chisel into and out of the gap of the prosthesis shaft associated with the prosthesis by means of pulses that can be generated in a controlled manner by means of a fluid and a piston element. Gases and liquids are referred to as fluids. In particular, the piston element can be set to move pneumatically or hydraulically. For example, possible fluids that can be used include compressed air or nitrogen. In principle, it is conceivable that the fluid is a hydraulic fluid.

[0008] For example, in the event that a chisel is stuck in a prosthesis stem gap and is no longer freely movable, the generated pulses can be used to drive the chisel back out. With the aid of pulses that can be generated in a controlled manner (also used to drive the back out), the work process is standardized and simplified, process safety and work safety are improved, and the quality of the entire work process can be kept consistent. The time required for trimming the prosthesis is shortened, and at the same time, the durability of the surgical instrument is increased by reducing possible misuse. Moreover, patient safety is increased because damage to the prosthesis stem gap and surrounding body parts is reduced.

[0009] According to an advantageous embodiment of the present invention, the piston element can be selectively configured to drive the chisel in or out by means of the switching element. With this measure, the user can conveniently select the operation mode, further improving the operability of the surgical instrument.

[0010] A pulse transmitter can be associated with the cylinder, wherein the pulse transmitter is associated with an end face associated with the chisel, so that the pulse transmitter is arranged between the piston element and the chisel, wherein the pulse transmitter is configured to transmit pulses from the piston element to the chisel, wherein the pulse transmitter seals the end face of the cylinder facing the chisel. The pulse transmitter is usually a high-quality component and has good guiding properties for precise movement relative to the cylinder. In addition, the pulse transmitter provides a receiving element for the chisel, so that different chisels can be inserted without each chisel having high-quality guiding properties. This reduces the costs when replacing chisels while maintaining quality standards.

[0011] The cylinder may be a tubular element inserted into the mobile phone. The dimensions of the cylinder are preferably set so that the piston element is arranged inside the cylinder so that it can move along the longitudinal axis of the cylinder. The gap between the piston element and the cylinder sleeve is preferably designed so that the piston element can be moved by the fluid.

[0012] A first and a second dynamic pressure chamber can be associated with the cylinder body, wherein both dynamic pressure chambers can be connected to the cylinder body in a fluid-conducting manner, wherein a fluid source is associated with the cylinder body. Depending on the direction of movement of the piston element, the first dynamic pressure chamber or the second dynamic pressure chamber is used, among other things, to accommodate a fluid moved by the piston element, wherein the moved fluid is compressed in the corresponding dynamic pressure chamber. Preferably, the first and / or second dynamic pressure chamber at least partially surrounds the cylinder body in a coaxial ring along the longitudinal axis of the cylinder body. The fluid source can be used to convey the fluid and serve as a drive device for the piston element. With the help of this measure, it is possible to avoid using hazardous liquids as drive devices, for example, which can further increase process safety and work safety. The embodiment using a dynamic pressure chamber is particularly suitable for using a compressible gaseous fluid as a working medium. When using an incompressible fluid, the dynamic pressure chamber must have a variable volume.

[0013] The cylinder can comprise a first channel on the side facing away from the chisel, wherein the cylinder can preferably be fluidically connected to the fluid source via the first channel. In the sense of the invention, on the side facing away from the chisel means that the channel can be arranged on the end face of the cylinder facing away from the chisel and / or in the jacket surface of the cylinder. Fluid can flow into the cylinder via the first channel in order to move the piston element in the direction of the chisel. This measure also serves to further increase process safety and work safety.

[0014] The cylinder can comprise a second channel on the side facing the chisel, wherein the cylinder can preferably be fluidically connected to the first dynamic pressure chamber via the second channel. In the sense of the invention, on the side facing the chisel means that the channel can be arranged on the end face of the cylinder facing the chisel and / or in the cylinder liner surface of the cylinder. Through the second channel, a fluid exchange can take place between the cylinder and the first dynamic pressure chamber.

[0015] The first dynamic pressure chamber may comprise a third channel, wherein the first dynamic pressure chamber can be fluidically connected to the fluid source preferably via the third channel. Fluid can flow from the fluid source into the first dynamic pressure chamber via the third channel. The third channel is preferably arranged on the side of the first dynamic pressure chamber facing away from the chisel. This allows a shorter or more compact fluid channel structure to be achieved.

[0016] The cylinder body may comprise a fourth channel on a side facing the chisel, wherein the cylinder body can be preferably fluidically connected to the second dynamic pressure chamber via the fourth channel. Through the fourth channel, fluid exchange can be performed between the cylinder body and the second dynamic pressure chamber.

[0017] The first, third and fourth passages can be optionally closable. The first, third and fourth passages can be opened or closed independently of each other. In the sense of the present invention, closable means that the passage is closed in a fluid-tight manner. This at least means that fluid-tight is in such a way that an expected sealing function can be achieved. If the function is not adversely affected, leakage can be tolerated.

[0018] In order to drive the chisel into the gap of the prosthesis handle, the first and second channels can be in an open state, and the third and fourth channels can be in a closed state. In order to drive the entry, the piston element applies a pulse to the pulse transmitter, and the pulse is transmitted to the chisel. The movement of the piston element driving the chisel into the gap of the prosthesis handle can be divided into two stages. During the first stage, the fluid is delivered to the cylinder body from the fluid source through the first channel, and thus the piston element is accelerated in the direction toward the side of the chisel until the pulse is transmitted to the pulse transmitter. Thus, the fluid in the cylinder body between the piston element and the side toward the chisel is delivered to the first dynamic pressure chamber by the piston element moved by the second channel and is compressed. During the second stage, the fluid delivery from the fluid source is interrupted. In addition, the fluid compressed in the first dynamic pressure chamber expands and flows back into the cylinder body through the second channel, and according to the initial position of the movement driving the chisel into, the piston element is driven to the side of the cylinder body facing away from the chisel.

[0019] In order to drive the chisel to exit the gap of the prosthesis handle, the first channel can be in a closed state, and the second, third and fourth channels can be in an open state. In order to drive the exit, the piston element applies a pulse in the opposite direction to the chisel. The movement of the piston element to drive the chisel to exit the gap of the prosthesis handle can also be divided into two stages. During the first stage, the fluid enters the first dynamic pressure chamber from the fluid source through the third channel and further enters the cylinder through the second channel. The fluid accelerates the piston element in the direction of the side facing away from the chisel until the pulse is transmitted to the cylinder. The cylinder fluid between the piston element and the side facing away from the chisel in the cylinder is transported to the second dynamic pressure chamber by the piston element moved through the fourth channel and compressed there. Preferably, the fourth channel is arranged so that no fluid buffer, in particular a gas pressure buffer, is formed between the piston element and the side of the cylinder facing away from the chisel. This can further improve the pulse transmission from the piston element to the cylinder. During the second stage, the fluid delivery from the fluid source is interrupted. The fluid compressed in the second dynamic pressure chamber expands and flows back into the cylinder through the fourth passage, and drives the piston element to the side of the cylinder toward the chisel according to the initial position of the movement for driving the chisel to withdraw.

[0020] The fluid source can generate pressure fluctuation pulses, wherein the repetition frequency is preferably in the range between 1 Hz and 40 Hz. It is particularly preferred if the repetition frequency is in the range between 2 Hz and 20 Hz. These pressure fluctuation pulses enable targeted repetition of pulses within a small time window. Compared to manual release of the surgical instrument, higher repetition frequencies can be achieved. With the aid of these measures, process safety and work safety as well as operability are further increased.

[0021] The switching element can be designed as a rotary handle, wherein the switching element has a channel structure, which establishes a fluid connection between the fluid source and the cylinder body by means of the first channel, or the channel structure establishes a fluid connection between the fluid source and the first dynamic pressure chamber by means of the third channel. The rotary handle improves operability because the operator can choose between driving in and driving out by means of the rotary handle. Advantageously, the switching position of the rotary handle can be selected with only a small amount of rotation. There is no need for complicated grip replacement or re-gripping of the surgical instrument or changing the viewing angle. In addition, an engaging means can be provided to assign the limited positions of the rotary handle to the various switching positions.

[0022] The chisel can be arranged on the mobile phone in a tool-free interchangeable manner. The chisel is preferably fastened using a snap-on fastener. In addition to tool-free interchangeability, it is also advantageous that the processing time for establishing and releasing the mechanical connection is shortened.

[0023] A magnetic holder can be arranged on the side facing away from the chisel, wherein the piston element comprises a ferromagnetic material. The magnetic holder is designed such that the piston element can be held in its end position facing away from the chisel. This counteracts any unwanted movement of the piston element in the cylinder. By supplying fluid from a fluid source, the holding force of the magnetic holder can be overcome and the piston element can be moved. By means of this measure, the initial position of the piston element is fixed, thereby increasing process reliability.

[0024] According to an advantageous embodiment of the invention, the surgical instrument comprises a display element. The display element is preferably digital. The information that can be displayed preferably includes the applied fluid pressure, the set repetition frequency and possible error message information. With the aid of this measure, the user receives feedback information about the settings made or other useful information, thus, this measure serves to further improve the operability. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] An embodiment of the surgical instrument according to the invention is described in more detail with reference to the accompanying drawings. In each case, these drawings schematically show:

[0026] Figure 1It is a surgical instrument used to trim prostheses;

[0027] Figure 2 is a surgical instrument having a fluid source;

[0028] Figure 3 It is a cross-sectional view of the surgical instrument when the chisel is driven into the surgical instrument;

[0029] Figure 4 is a first cross-sectional view of the surgical instrument in a state where the driving chisel is withdrawn;

[0030] Figure 5 is a second cross-sectional view of the surgical instrument in a state where the driving chisel is withdrawn;

[0031] Figure 6 It is the third cross-sectional view of the surgical instrument when the driving chisel is withdrawn. DETAILED DESCRIPTION

[0032] Figure 1 A surgical instrument 1 for trimming a prosthesis, in particular a hip endoprosthesis, is shown. The surgical instrument 1 comprises a handpiece 2 and a chisel 6. The chisel 6 is mounted axially movably at one end of the handpiece 2 and is fastened to the handpiece 2 in a loss-proof manner. The chisel 6 is fastened by means of a snap fastener and can be replaced without tools.

[0033] For trimming, the chisel is driven into the prosthesis stem gap 8 associated with the prosthesis 7. This can loosen the fixation of the prosthesis 7 to the bone. However, the surgical instrument 1 according to the invention also makes it possible to drive the chisel 6 out of the prosthesis stem gap 8 associated with the prosthesis 7. This is particularly advantageous in the event that the chisel 6 penetrates too deeply into the prosthesis stem gap 8 and gets stuck there. Figure 1 A finishing procedure is shown, wherein the chisel 6 is driven partially into the prosthesis stem gap 8 .

[0034] Figure 2 Shown according to Figure 1 A surgical instrument 1 for trimming a prosthesis has a fluid source 13. In this example, the fluid source 13 is a compressed air source. The compressed air can be provided by a compressor. Alternatively, it is also conceivable to obtain a compressed gaseous medium, such as nitrogen, from a pressure accumulator.

[0035] The surgical instrument 1 comprises a handpiece 2, a switching element 5 and a chisel 6. Via the switching element 5, the setting can be selectively set so that the surgical instrument 1 can be used to drive the chisel 6 into or out of the prosthesis stem gap 8. The driving means for generating the pulses is a gaseous fluid in the form of compressed air, which is provided via a fluid source 13. The fluid source 13 generates bursts of compressed air with a repetition frequency in the range between 1 Hz and 40 Hz. The compressed air is transmitted from the fluid source 13 to the handpiece 2 via a compressed air hose.

[0036] Figure 3 Shown according to Figure 2 The surgical instrument 1 is a cross-sectional view of a state in which the chisel 6 is driven to enter. The surgical instrument 1 comprises a handpiece 2, a switching element 5 and a chisel 6.

[0037] A cylinder 3 is arranged in the handpiece 2, wherein the cylinder 3 is a tubular element inserted into the handpiece 2. A piston element 4 is associated with the cylinder 3, wherein the piston element 4 is arranged in the cylinder 3 in an axially movable manner and can be set to move by means of compressed air. The piston element 4 is configured to generate a pulse in the direction of the chisel 6 to drive the chisel 6 into the prosthesis shaft gap 8 associated with the prosthesis 7. In addition, the piston element 4 is configured to generate a pulse in the opposite direction to the chisel 6 to drive the chisel 6 out of the prosthesis shaft gap 8.

[0038] The pulse transmitter 9 is associated with the cylinder 3. The pulse transmitter 9 is associated with the end face associated with the chisel 6 and is arranged between the piston element 4 and the chisel 6. The pulse transmitter 9 is configured to transmit pulses from the piston element 4 to the chisel 6, wherein the pulse transmitter 9 seals the end face of the cylinder 3 facing the chisel 6.

[0039] The cylinder 3 comprises a first channel 12 on the side facing away from the chisel 6. The cylinder 3 is fluidically connected to a fluid source 13 via the first channel 12.

[0040] A first dynamic pressure chamber 10 and a second dynamic pressure chamber 11 are associated with the cylinder 3. Both dynamic pressure chambers 10 and 11 can be connected in a fluid-conducting manner to the cylinder 3. The cylinder 3 comprises a second channel 14 on the side facing the chisel 6 and is fluidically connected to the first dynamic pressure chamber 10 via the second channel 14.

[0041] The first dynamic pressure chamber 10 includes a third passage 15, and is fluidically connectable to the fluid source 13 through the third passage 15. In the illustrated state, the third passage 15 is closed, and the first dynamic pressure chamber 10 is not fluidically connected to the fluid source 13.

[0042] The piston element 4 can be selectively configured to drive the chisel 6 to enter or exit via the switching element 5. To this end, the switching element 5 is designed as a rotary handle and has a channel structure. Through the channel structure, the fluid connection between the fluid source 13 and the cylinder body 3 using the first channel 12 can be selectively set or interrupted, the fluid connection between the fluid source 13 and the first dynamic pressure chamber 10 using the third channel 15 can be selectively set or interrupted, and the fluid connection between the cylinder body 3 and the second dynamic pressure chamber 11 using the fourth channel can be selectively set or interrupted. Therefore, the first channel 12, the third channel 15 and the fourth channel 16 (not depicted here) can be selectively closed.

[0043] The first channel 12 is open so that a fluid connection is made between the fluid source 13 and the cylinder 3 by means of the first channel 12. The third channel 15 is closed. The fourth channel 16 is also closed and is not depicted in this figure due to the complex geometry of the rotary handle channel structure.

[0044] In order to drive the chisel 6 in, the first channel 12 and the second channel 14 are in an open state. The third channel 15 and the fourth channel are in a closed state. In order to drive in, the piston element 4 is accelerated by a burst of compressed air in the direction of the pulse transmitter 9, and finally a pulse is applied to the pulse transmitter 9, which is then transmitted to the chisel 6. In order to move the piston element 4 to drive the chisel 6 in, compressed air is delivered from the fluid source 13 to the cylinder 3 through the first channel 12, thereby accelerating the piston element 4 in the direction of the side facing the chisel 6 until the pulse is transmitted to the pulse transmitter 9. At the same time, the compressed air in the cylinder 3 is delivered to the first dynamic pressure chamber 10 by the piston element 4 moved between the piston element 4 and the side facing the chisel 6 through the second channel 14 and compressed. Once the burst of compressed air generated from the fluid source 13 ends, the compressed air compressed in the first dynamic pressure chamber 10 will expand and flow back into the cylinder 3 through the second channel 14, and drive the piston element 4 back to the side of the cylinder 3 facing away from the chisel 6, corresponding to the initial position of the movement for driving the chisel 6 in.

[0045] Figure 4 , Figure 5 and Figure 6 Shows Figure 3 The cross-sectional view of the surgical instrument 1 depicted in FIG. 1 is a state in which the driven chisel 6 is withdrawn.

[0046] To drive the chisel 6 out, the first channel 12 is closed and the second channel 14, the third channel 15 and the fourth channel 16 are opened. Due to the complex geometry of the rotary handle channel structure, the first channel 12 is not depicted in these figures.

[0047] The third channel 15 is open, so that a fluid connection is established between the fluid source 13 and the dynamic pressure chamber 10 by means of the third channel 15 .

[0048] To drive the withdrawal, the piston element applies a pulse in the opposite direction to the chisel 6. To move the piston element 4 to drive the chisel withdrawal, a burst of compressed air is delivered from the fluid source 13 through the third channel 15 into the first dynamic pressure chamber 10 and further delivered into the cylinder 3 through the second channel 14. The compressed air accelerates the piston element 4 in the direction of the side facing away from the chisel 6 until the pulse is transmitted to the cylinder 3. The compressed air in the cylinder 3 between the piston element 4 and the side facing away from the chisel 6 is delivered by the moved piston element 4 through the fourth channel 16 into the second dynamic pressure chamber 11 and compressed there.

[0049] When the piston element 4 closes the opening of the fourth channel 16, the compressed air between the opening in the cylinder 3 leading to the fourth channel 16 and the side of the cylinder 3 facing away from the chisel 6 is delivered to the dynamic pressure chamber 11 through the fifth channel 17. When the piston element 4 is driven out, the fifth channel 17 opens, so that a fluid connection is established between the cylinder 3 and the dynamic pressure chamber 11 by means of the fifth channel 17. Due to the complex geometry, the fifth channel 17 is only Figure 6 . When the piston element 4 is driven to withdraw, the fifth channel 17 advantageously prevents the formation of an air cushion between the piston element 4 and the side of the cylinder 3 facing away from the chisel 6. With this measure, pulse transmission can be improved. Subsequently, the compressed air compressed in the second dynamic pressure chamber 11 expands and flows back into the cylinder 3 through the fourth channel 16, and drives the piston element 4 to the side of the cylinder 3 facing the chisel 6, corresponding to the initial position of the movement for driving the chisel 6 to withdraw.

[0050] Figure 5 Shows Figure 3 and Figure 4 A second cross-sectional view of the surgical instrument 1 is depicted in FIG. Figure 4 , the surgical instrument 1 is in a state of driving the chisel 6 to withdraw. Figure 5 is a cross-section view along another cross-section.

[0051] Figure 6 Shows Figure 3 , Figure 4 and Figure 5 The third cross-sectional view of the surgical instrument 1 depicted in Figure 5 In comparison, the section is rotated 90°. Figure 4 and Figure 5 , the surgical instrument 1 is in a state of driving the chisel 6 to withdraw.

[0052] exist Figure 5 and Figure 6 In the views of FIG. 1 , the fluid connection between the cylinder body 3 and the second dynamic pressure chamber 11 through the fourth channel 16 is depicted respectively.

Claims

1. A surgical instrument (1) for trimming a prosthesis, comprising: A mobile phone (2) having a cylinder (3) arranged therein, wherein a piston element (4) is associated with the cylinder (3); and a switching element (5) and a chisel (6), wherein the chisel (6) is axially movably mounted and arranged at one end of the mobile phone (2), wherein the chisel (6) is fastened to the mobile phone (2) in an anti-lost manner, wherein the piston element (4) is axially movably arranged in the cylinder (3), wherein the piston element (4) can be set to move with the aid of a fluid, wherein the piston element (4) is configured to generate a pulse oriented in the direction of the chisel (6) to drive the chisel (6) into a prosthesis handle gap (8) associated with the prosthesis (7), characterized in that the piston element (4) is configured to generate a pulse oriented in the opposite direction to the chisel (6) to drive the chisel (6) out of the prosthesis handle gap (8).

2. The surgical instrument (1) according to claim 1, characterized in that: By means of the switching element (5), the piston element (4) can be selectively configured to drive the chisel (6) inward or outward.

3. The surgical instrument (1) according to claim 1 or 2, characterized in that: A pulse transmitter (9) is associated with the cylinder (3), wherein the pulse transmitter (9) is associated with an end face associated with the chisel (6), such that the pulse transmitter (9) is arranged between the piston element (4) and the chisel (6), wherein the pulse transmitter (9) is configured to transmit pulses from the piston element (4) to the chisel (6), wherein the pulse transmitter (9) seals the end face of the cylinder (3) on the side facing the chisel (6).

4. The surgical instrument (1) according to any one of claims 1 to 3, characterized in that: The cylinder (3) is a tubular element inserted into the mobile phone (2).

5. The surgical instrument (1) according to any one of claims 1 to 4, characterized in that: A first dynamic pressure chamber (10) and a second dynamic pressure chamber (11) are associated with the cylinder (3), wherein the dynamic pressure chambers (10, 11) can be connected to the cylinder (3) in a fluid-conducting manner, wherein a fluid source (13) is associated with the cylinder (3).

6. The surgical instrument (1) according to claim 5, characterized in that: The cylinder (3) comprises a first channel (12) on a side facing away from the chisel (6), wherein the cylinder (3) can be fluidically connected to the fluid source (13) via the first channel (12).

7. The surgical instrument (1) according to claim 5 or 6, characterized in that: The cylinder (3) comprises a second passage (14) on a side facing the chisel (6), wherein the cylinder (3) can be fluidically connected to the first dynamic pressure chamber (10) via the second passage (14).

8. The surgical instrument (1) according to any one of claims 5 to 7, characterized in that: The first dynamic pressure chamber (10) comprises a third passage (15), wherein the first dynamic pressure chamber (10) can be fluidically connected to the fluid source (13) through the third passage (15).

9. The surgical instrument (1) according to any one of claims 5 to 8, characterized in that: The cylinder body (3) comprises a fourth channel (16) on the side facing away from the chisel (6), wherein the cylinder body (3) is fluidically connected to the second dynamic pressure chamber (11) via the fourth channel (16).

10. The surgical instrument (1) according to claim 9, characterized in that The first, third and fourth passages (12, 15, 16) are selectively closable.

11. The surgical instrument (1) according to claim 10, characterized in that: In order to drive the chisel (6) into the prosthesis stem gap (8), the first and second channels (12, 14) are in an open state, and the third and fourth channels (15, 16) are in a closed state.

12. The surgical instrument (1) according to claim 11, characterized in that In order to drive the chisel (6) out of the prosthesis stem gap (8), the first channel (12) is in a closed state, and the second, third and fourth channels (14, 15, 16) are in an open state.

13. The surgical instrument (1) according to any one of claims 5 to 12, characterized in that: The fluid source (13) generates bursts of compressed air with a repetition frequency in the range between 1 Hz and 40 Hz.

14. The surgical instrument (1) according to any one of claims 1 to 13, characterized in that: The switching element (5) is designed as a rotary handle, wherein the switching element (5) has a channel structure. In a first position, the channel structure establishes a fluid connection between the fluid source (13) and the cylinder body (3) by means of the first channel (12), and interrupts the fluid connection between the fluid source (13) and the first dynamic pressure chamber (10) by means of the third channel (15), and interrupts the fluid connection between the cylinder body (3) and the second dynamic pressure chamber (11) by means of the fourth channel (16); or, in a second position, the channel structure interrupts the fluid connection between the fluid source (13) and the cylinder body (3) by means of the first channel (12), and establishes a fluid connection between the fluid source (13) and the first dynamic pressure chamber (10) by means of the third channel (15), and establishes a fluid connection between the cylinder body (3) and the second dynamic pressure chamber (11) by means of the fourth channel (16).

Images