Surgical instrument

Abstract

A surgical instrument (1) for the replacement of a prosthesis (7), comprising a handpiece (2) in which a cylinder (3) is arranged, with a switching element (5) and a chisel tool (6), a piston element (4) being associated with the cylinder, the chisel tool being arranged axially movably attached to one end of the handpiece, the chisel tool being fastened to the handpiece in a loss-preventing manner, the piston element being arranged axially movably in the cylinder, the piston element being movable by a fluid, the piston element being configured to induce a pulse directed in the direction of the chisel tool for driving the chisel tool into a prosthesis stem gap (8) associated with the prosthesis, the piston element being configured to induce a pulse directed in the direction opposite to the chisel tool for removing the chisel tool from the prosthesis stem gap.

Description

Technical Field

[0001] The present invention relates to a surgical instrument for the replacement of a prosthesis, comprising a handpiece in which a cylinder is arranged. With a switching element and a chisel tool, a piston element is associated with the cylinder, the chisel tool is axially movably mounted and arranged at one end of the handpiece, the chisel tool is fastened to the handpiece in a loss-preventing manner, the piston element is axially movably arranged in the cylinder, and the piston element can be moved by a fluid.

Background Art

[0002] In European Patent EP0910317B1, a surgical instrument for the replacement of a prosthesis is known. This reciprocates a piston element pneumatically in a cylinder, and the piston element imparts an impact to a chisel tool axially attached to a housing. Such a surgical instrument can be used to drive a chisel tool into a gap between a prosthetic stem associated with a prosthesis and a recess formed in a bone. This gap is further referred to as a prosthetic stem gap.

Summary of the Invention

[0003] The chisel tool usually has an elongated and flexible shape. With such a configuration, the chisel tool can penetrate deep into the prosthetic stem gap. However, this drawback is that the chisel tool may get stuck in the stem gap. In this case, the chisel tool can only be released by manual labor with considerable effort. For example, it is known to place a grooved hammer under the handpiece on the chisel tool and loosen the chisel tool by a controlled hammer blow with a second hammer. However, there is a risk of damaging the bone adjacent to the prosthesis, and this method is time-consuming and not ergonomic for the surgeon.

[0004] The object of the present invention is to provide a surgical instrument for the replacement of a prosthesis that gives improved operability.

[0005] This object is achieved by using the features of claim 1. The dependent claims indicate advantageous embodiments.

[0006] According to the present invention, there is provided a surgical instrument for the replacement of a prosthesis, comprising a handpiece in which a cylinder is arranged, accompanied by a switching element and a chisel tool, a piston element is associated with the cylinder, the chisel tool is axially movably mounted and arranged at one end of the handpiece, and the chisel tool is fastened to the handpiece in a loss-preventing manner, the piston element is axially movably arranged in the cylinder, the piston element can be moved by a fluid, and in order to drive the chisel tool into the prosthesis stem gap associated with the prosthesis, the piston element is configured to induce a pulse directed in the direction of the chisel tool, the piston element is configured to induce a pulse directed in the direction opposite to the chisel tool in order to drive the chisel tool out of the prosthesis stem gap.

[0007] According to a pulse that can be generated in a manner controlled by a fluid and a piston element for driving the chisel tool into or out of the stem gap associated with the prosthesis, the repeatability of the pulse can be achieved. Gases and liquids are referred to as fluids. In particular, the piston element can be moved pneumatically or hydraulically. Usable fluids include, for example, compressed air and nitrogen. In principle, it is also possible to consider that the fluid is a hydraulic fluid.

[0008] Pulses that can be generated to remove the chisel tool may be used, for example, when the chisel tool jams in the prosthesis stem gap and becomes immovable. By pulses that can be generated in a controlled manner, the work process is standardized and simplified for removal, the safety of the process and the work is improved, and consistent quality of the entire work process is achieved. At the same time, the time required for prosthesis replacement is shortened, and the durability of the surgical instrument is improved by reducing the possibility of misuse. Furthermore, since damage to the prosthesis stem gap and surrounding body parts is reduced, patient safety is improved.

[0009] In an advantageous embodiment of the invention, the piston element can be selectively configured by the switching element to drive in or remove the chisel tool. By this means, the user can easily select the operating mode, and the operability of the surgical instrument is further improved.

[0010] The pulse transmitter may be associated with the cylinder. The pulse transmitter is associated with the end face associated with the chisel tool such that the pulse transmitter is disposed between the piston element and the chisel tool. The pulse transmitter is configured to transmit the pulse from the piston element to the chisel tool, and the pulse transmitter seals the end face of the cylinder on the side facing the chisel tool. The pulse transmitter is typically a high-quality component and has good guiding characteristics for accurate movement relative to the cylinder. Furthermore, the pulse transmitter provides a receiving element for the chisel tool, eliminating the need to equip each chisel tool with high-quality guiding characteristics and allowing different chisel tools to be inserted. Thereby, the cost of replacing the chisel tool can be reduced while maintaining quality standards.

[0011] The cylinder may be a tubular element inserted into the handpiece. The cylinder is preferably dimensioned to be disposed within the cylinder such that the piston element can move along the longitudinal axis of the cylinder. The gap between the piston element and the cylinder jacket is preferably configured such that the piston element can be moved by the fluid.

[0012] The first and second hydrodynamic chambers may be associated with the cylinder, and both hydrodynamic chambers may be connected to the cylinder in a fluid-conducting manner. A fluid source is associated with the cylinder. Depending on the direction of movement of the piston element, the first or second hydrodynamic chamber, in particular, serves to receive the fluid displaced by the piston element, and the displaced fluid is compressed within the respective hydrodynamic chamber. Preferably, the first and / or second hydrodynamic chambers at least partially surround the cylinder in a coaxial ring shape along the longitudinal axis of the cylinder. The fluid source may be used to convey the fluid and functions as a driving means for the piston element. By this means, for example, dangerous liquids as driving means can be avoided, and the safety of the process and the operation can be further enhanced. The embodiment with hydrodynamic chambers is particularly suitable when using a compressible gaseous fluid as the working medium. When using an incompressible fluid, the hydrodynamic chamber needs to have a variable volume.

[0013] The cylinder may include a first channel on the side facing away from the chisel tool, and the cylinder is preferably fluidly connectable to the fluid source via the first channel. The side facing away from the chisel tool means, in the context of the present invention, that the channel can be arranged on the end face of the cylinder on the side opposite to the chisel tool and / or on the jacket surface of the cylinder. The fluid can flow into the cylinder through this first channel to move the piston element in the direction of the chisel tool. This means also helps to further enhance the safety of the process and the operation.

[0014] The cylinder may include a second channel on the side facing the chisel tool, and the cylinder is preferably fluidly connectable to the first hydrodynamic chamber via the second channel. The side facing the chisel tool means that in the context of the present invention, a channel can be arranged on the end face of the cylinder facing the chisel tool and / or on the jacket face of the cylinder. Through this second channel, fluid exchange may take place between the cylinder and the first hydrodynamic chamber.

[0015] The first hydrodynamic chamber may include a third channel, and preferably via the third channel, the first hydrodynamic chamber is fluidly connectable to a fluid source. Fluid can flow into the first hydrodynamic chamber from the fluid source via the third channel. The third channel is preferably arranged on the side of the first hydrodynamic chamber opposite to the chisel tool. Thereby, it is possible to achieve a shorter or more compact channel structure for the fluid.

[0016] The cylinder may include a fourth channel on the side opposite to the chisel tool, and the cylinder is preferably fluidly connectable to the second hydrodynamic chamber via the fourth channel. Through this fourth channel, fluid exchange may take place between the cylinder and the second hydrodynamic chamber.

[0017] The first channel and the third and fourth channels can optionally be closed. The first channel and the third and fourth channels can be opened and closed independently of each other. Being closable in the context of the present invention means that the flow path is fluid-tightly closed. That is, it means fluid tightness in this way, whereby the intended sealing function can be achieved. Leakage may be tolerated if there is no adverse effect on the function.

[0018] To drive the chisel tool into the prosthesis system gap, the first and second channels can be opened and the third and fourth channels can be closed. To drive, the piston element acts a pulse on the pulse transmitter, and the pulse is transmitted to the chisel tool. The movement of the piston element for driving the chisel tool into the prosthesis system gap can be divided into two stages. During the first stage, the fluid is conveyed from the fluid source through the first channel into the cylinder and accelerates the piston element in the direction of the side facing the chisel tool until a pulse is transmitted to the pulse transmitter. Thereby, the fluid in the cylinder between the piston element and the side facing the chisel tool is conveyed through the second channel into the first dynamic pressure chamber and compressed by the moving piston element. During the second stage, the conveyance of the fluid from the fluid source is interrupted. Further, the fluid compressed in the first dynamic pressure chamber expands, flows back into the cylinder through the second channel, and drives the piston element to the side of the cylinder opposite to the chisel tool according to the initial position of the movement for driving into the chisel tool.

[0019] To remove the chisel tool from the prosthesis system gap, the first channel can be closed and the second, third, and fourth channels can be opened. For removal, the piston element applies a pulse in a direction opposite to that of the chisel tool. Further, the movement of the piston element for removing the chisel tool from the prosthesis system gap may be divided into two stages. During the first stage, the fluid is conveyed from the fluid source through the third channel to the first dynamic pressure chamber and further through the second channel to the cylinder. The fluid accelerates the piston element in the direction of the side opposite to the chisel tool until a pulse is transmitted to the cylinder. The fluid in the cylinder between the piston element and the side opposite to the chisel tool is conveyed through the fourth channel to the second dynamic pressure chamber by the moving piston element and compressed there. Preferably, the fourth channel is arranged so that a fluid cushion, especially a gas pressure cushion, cannot be provided between the piston element and the side of the cylinder opposite to the chisel tool. Thereby, the pulse transmission from the piston element to the cylinder can be further improved. During the second stage, the conveyance of the fluid 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 channel, driving the piston element to the side of the cylinder facing the chisel tool according to the initial position of the operation for removing the chisel tool.

[0020] The fluid source can generate a pulsed pressure surge, and the repetition frequency is preferably in the range of 1 to 40 Hz. In particular, the repetition frequency is preferably in the range of 2 to 20 Hz. Such a pulsed pressure surge enables the repetition of pulses with a narrow target in a small time window. A higher repetition frequency is possible compared to the manual release operation of the surgical instrument. By these means, the safety and operability of the process and the operation are further improved.

[0021] The switching element may be configured as a rotary handle. The switching element has a channel structure that establishes either a flow path connection between the fluid source and the cylinder by way of the first channel or between the fluid source and the first dynamic pressure chamber by way of the third channel. Since the operator can select to drive in and to withdraw by means of the rotary handle, the operability of the rotary handle is improved. Advantageously, only a small rotation is required to select the switch position of the rotary handle. Sophisticated grip exchanges or regrasps of the surgical instrument or changes in the viewing angle are unnecessary. Furthermore, engagement means may be provided for assigning defined positions of the rotary handle to the individual switch positions.

[0022] The chisel tool may be arranged on the handpiece in an exchangeable manner without a tool. The chisel tool is preferably fastened using a bayonet catch. In addition to the exchangeability without a tool, it is also advantageous that the processing time for establishing and releasing the mechanical connection is short.

[0023] The magnet holder may be arranged on the side opposite the chisel tool, and the piston element is made of a ferromagnetic material. The magnet holder is configured such that the piston element can be held at an end position opposite the chisel tool. Thereby, unnecessary movement of the piston element in the cylinder is suppressed. By supplying fluid from the fluid source, the holding force of the magnet 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 and an increased reliability of the process can be achieved.

[0024] In 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 rate, and possible error messages. By means of this measure, the user receives feedback regarding the settings made or other useful information, and this measure serves to further improve the operability.

[0025] An embodiment of a surgical instrument according to the present invention will be described in more detail with reference to the drawings. These schematically show the following in each case.

Brief Description of the Drawings

[0026]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Mode for Carrying Out the Invention

[0027] FIG. 1 shows a surgical instrument 1 for the replacement of a prosthesis, in particular an endoprosthesis within the hip joint. The surgical instrument 1 comprises a handpiece 2 and a chisel tool 6. The chisel tool 6 is axially movably attached to one end of the handpiece 2 and is fastened to the handpiece 2 in a loss-preventing manner. The chisel tool 6 is fastened by a bayonet catch and is exchangeable without tools.

[0028] For replacement, the chisel tool is driven into the prosthesis stem gap 8 associated with the prosthesis 7. Thereby, the prosthesis 7 fastened to the bone is loosened. However, the surgical instrument 1 according to the present invention further enables the removal of the chisel tool 6 from the prosthesis stem gap 8 associated with the prosthesis 7. This is particularly advantageous when the chisel tool 6 has become stuck too deep in the prosthesis stem gap 8 and cannot be removed. FIG. 1 shows a replacement procedure in which the chisel tool 6 is partially driven into the prosthesis stem gap 8.

[0029] Figure 2 shows the surgical instrument 1 of FIG. 1 for prosthesis replacement, with a fluid source 13. In this example, the fluid source 13 is a compressed air source. The compressed air may be supplied by a compressor. Alternatively, it is also conceivable to take out a compressed gas medium such as nitrogen from an accumulator.

[0030] The surgical instrument 1 includes a handpiece 2, a switching element 5, and a chisel tool 6. The settings may be selectively set via the switching element 5 so that the surgical instrument 1 can be used to drive the chisel tool 6 in or remove it from the prosthesis stem gap 8. The driving means for generating the pulse is a gaseous fluid in the form of compressed air and is supplied via the fluid source 13. The fluid source 13 generates a pulsed compressed air burst, and its repetition frequency is in the range of 1 to 40 Hz. The compressed air is transmitted from the fluid source 13 to the handpiece 2 via a compressed air hose.

[0031] Figure 3 is a cross-sectional view of the surgical instrument 1 of FIG. 2 in a state where the chisel tool 6 is being driven in. The surgical instrument 1 includes a handpiece 2, a switching element 5, and a chisel tool 6.

[0032] A cylinder 3 is disposed within the handpiece 2. The cylinder 3 is a tubular element inserted into the handpiece 2. A piston element 4 is associated with the cylinder 3. The piston element 4 is disposed within the cylinder 3 so as to be axially movable and can be moved by compressed air. The piston element 4 is configured to induce a pulse directed in the direction of the chisel tool 6 for driving the chisel tool 6 into the prosthesis stem gap 8 associated with the prosthesis 7. Further, the piston element 4 is configured to induce a pulse in a direction opposite to the chisel tool 6 for removing the chisel tool 6 from the prosthesis stem gap 8.

[0033] The pulse transmitter 9 is associated with the cylinder 3. The pulse transmitter 9 is associated with the end face associated with the chisel tool 6 and is arranged between the piston element 4 and the chisel tool 6. The pulse transmitter 9 is configured to transmit a pulse from the piston element 4 to the chisel tool 6, and the pulse transmitter 9 seals the end face of the cylinder 3 on the side facing the chisel tool 6.

[0034] The cylinder 3 includes a first channel 12 on the side opposite to the chisel tool 6. The cylinder 3 is fluidly connected to the fluid source 13 via the first channel 12.

[0035] The first dynamic pressure chamber 10 and the second dynamic pressure chamber 11 are associated with the cylinder 3. Both dynamic pressure chambers 10, 11 can be connected to the cylinder 3 in a fluid-conducting manner (so as to communicate). The cylinder 3 has a second channel 14 on the side facing the chisel tool 6 and is fluidly connected to the first dynamic pressure chamber 10 via the second channel 14. The first dynamic pressure chamber 10 includes a third channel 15 and can be fluidly connected to the fluid source 13 via the third channel 15. In the depicted state, the third channel 15 is closed and the first dynamic pressure chamber 10 is not fluidly connected to the fluid source 13.

[0036] Via the switching element 5, the piston element 4 can be selectively configured to drive in or remove the chisel tool 6. For this purpose, the switching element 5 is configured as a rotary handle and has a channel structure. Between the fluid source 13 and the cylinder 3, the first channel 12, between the fluid source 13 and the first dynamic pressure chamber 10, the third channel 15, and between the cylinder 3 and the second dynamic pressure chamber 11, the fourth channel, this channel structure can selectively set or cut off the fluid connection. Therefore, the first channel 12, the third channel 15, and the fourth channel 16 (not shown here) can be selectively closed.

[0037] The first channel 12 is open, and there is communication between the fluid source 13 and the cylinder 3 through the first channel 12. The third channel 15 is closed. Further, although the fourth channel 16 is closed, it is not depicted in this figure because the channel structure of the rotary handle has a complex shape.

[0038] To drive the chisel tool 6, 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. For driving, the piston element 4 is accelerated in the direction of the pulse transmitter 9 by a compressed air burst, and finally a pulse is applied to the pulse transmitter 9, and that pulse is transmitted to the chisel tool 6. To move the piston element 4 to drive the chisel tool 6, compressed air is conveyed from the fluid source 13 through the first channel 12 into the cylinder 3, and as a result, the piston element 4 is accelerated in the direction of the side facing the chisel tool 6 until a pulse is transmitted to the pulse transmitter 9. At the same time, the compressed air in the cylinder 3 is conveyed by the moving piston element 4 through the second channel 14 into the first dynamic pressure chamber 10 between the piston element 4 and the side facing the chisel tool 6 and is compressed. As soon as the compressed air burst released from the fluid source 13 ends, the compressed air compressed in the first dynamic pressure chamber 10 expands and flows back into the cylinder 3 through the second channel 14, driving the piston element 4 in the opposite direction to the side of the cylinder 3 opposite the chisel tool 6 corresponding to the initial position of the movement for driving the chisel tool 6.

[0039] Figures 4, 5, and 6 are cross-sectional views of the surgical instrument 1 depicted in Figure 3 with the chisel tool 6 removed.

[0040] To remove the chisel tool 6, the first channel 12 is in a closed state, and the second channel 14, the third channel 15, and the fourth channel 16 are in an open state. Since the channel structure of the rotary handle has a complex shape, the first channel 12 is not depicted in these figures.

[0041] The third channel 15 opens such that there is a flow path connection between the fluid source 13 and the first dynamic pressure chamber 10 via the third channel 15.

[0042] To remove the chisel tool 6, the piston element 4 acts on a pulse directed in the opposite direction to the chisel tool 6. To move the piston element 4 to remove the chisel tool, a compressed air burst is conveyed from the fluid source 13 through the third channel 15 to the first dynamic pressure chamber 10 and further through the second channel 14 to the cylinder 3. Until the pulse is transmitted to the cylinder 3, the compressed air accelerates the piston element 4 in the direction of the side opposite to the chisel tool 6. The compressed air in the cylinder 3 between the piston element 4 and the side opposite to the chisel tool 6 is conveyed through the fourth channel 16 by the moving piston element 4 to the second dynamic pressure chamber 11 where it is compressed.

[0043] The compressed air located between the opening to the fourth channel 16 in the cylinder 3 and the side of the cylinder 3 opposite to the chisel tool 6 is conveyed through the fifth channel 17 to the second dynamic pressure chamber 11 when the piston element 4 closes the opening to the fourth channel 16. Since the fifth channel 17 opens when the piston element 4 is driven in the extraction direction (driven out), the fifth channel 17 provides a flow path connection between the cylinder 3 and the second dynamic pressure chamber 11. Due to its complex shape, the fifth channel 17 is only visible in FIG. 6. Advantageously, the fifth channel 17 prevents the formation of an air cushion between the piston element 4 and the side of the cylinder 3 opposite to the chisel tool 6 when the piston element 4 is driven in the extraction direction. By this means, the pulse transmission can be improved. Thereafter, the compressed air compressed in the second dynamic pressure chamber 11 expands and flows back into the cylinder 3 through the fourth channel 16, driving the piston element 4 towards the side of the cylinder 3 facing the chisel tool 6, corresponding to the initial position of the operation of removing the chisel tool 6.

[0044] Figure 5 is a second cross-sectional view of the surgical instrument 1 depicted in FIGS. 3 and 4. The surgical instrument 1 pertains to FIG. 4 and is in a state where the chisel tool 6 has been removed. In FIG. 5, the cross-sectional view is in a different plane.

[0045] Figure 6 is a third cross-sectional view of the surgical instrument 1 depicted in FIGS. 3, 4, and 5, and the cross-sectional plane is rotated 90 degrees compared to FIG. 5. The surgical instrument 1 pertains to FIGS. 4 and 5 and is in a state where the chisel tool 6 has been removed.

[0046] From the viewpoints of FIGS. 5 and 6, the flow path connections between the cylinder 3 and the second dynamic pressure chamber 11 via the fourth channel 16 are respectively depicted.

Claims

1. A surgical instrument for the replacement of a prosthesis, comprising a handpiece with a cylinder arranged therein, accompanied by a switching element and a chisel tool, a piston element is associated with the cylinder, the chisel tool is axially movably attached and arranged at one end of the handpiece, and the chisel tool is fastened to the handpiece in a loss-preventing manner, the piston element is axially movably arranged in the cylinder, the piston element can be moved by a fluid, and in order to drive the chisel tool into the prosthesis stem gap associated with the prosthesis, the piston element is configured to induce a pulse directed in the direction of the chisel tool, the piston element is configured to induce a pulse directed in a direction opposite to the chisel tool in order to remove the chisel tool from the prosthesis stem gap. A surgical instrument.

2. The surgical instrument according to claim 1, wherein the piston element is selectively configurable by the switching element in order to drive or remove the chisel tool.

3. A pulse transmitter is associated with the cylinder, and the pulse transmitter is associated with an end face associated with the chisel tool, whereby the pulse transmitter is arranged between the piston element and the chisel tool, the pulse transmitter is configured to transmit a pulse from the piston element to the chisel tool, and the pulse transmitter is configured to seal an end face of the cylinder on the side facing the chisel tool. The surgical instrument according to claim 1 or 2.

4. The surgical instrument according to claim 1 or 2, wherein the cylinder is a tubular element inserted into the handpiece.

5. A first dynamic pressure chamber and a second dynamic pressure chamber are associated with the cylinder, the first dynamic pressure chamber and the second dynamic pressure chamber can be connected to the cylinder in a fluid-conducting manner, and a fluid source is associated with the cylinder. The surgical instrument according to claim 1.

6. The surgical instrument according to claim 5, wherein the cylinder includes a first channel on a side opposite to the chisel tool, and the cylinder can be fluidly connected to the fluid source via the first channel.

7. The cylinder includes a second channel on a side facing the chisel tool, and the cylinder is fluidly connectable to the first dynamic pressure chamber via the second channel. The surgical instrument according to claim 5 or 6.

8. The first dynamic pressure chamber includes a third channel, and the first dynamic pressure chamber is fluidly connectable to the fluid source via the third channel. The surgical instrument according to claim 5 or 6.

9. The cylinder includes a fourth channel on a side opposite to the chisel tool, and the cylinder is fluidly connectable to the second dynamic pressure chamber via the fourth channel. The surgical instrument according to claim 5 or 6.

10. The first channel, the third channel, and the fourth channel are selectively closable. The surgical instrument according to claim 9.

11. For driving the chisel tool into the prosthesis system gap, the first and second channels are open, and the third and fourth channels are closed. The surgical instrument according to claim 10.

12. For removing the chisel tool from the prosthesis system gap, the first channel is closed, and the second, third, and fourth channels are open. The surgical instrument according to claim 11.

13. The fluid source generates a pulsed compressed air burst, and the repetition frequency is in the range of 1 to 40 Hz. The surgical instrument according to claim 5 or 6.

14. The switching element is configured as a rotary handle, and the switching element has a channel structure. In the first position, the channel structure establishes a fluid connection between the fluid source and the cylinder through the first channel, blocks the fluid connection between the fluid source and the first dynamic pressure chamber through the third channel, and blocks the fluid connection between the cylinder and the second dynamic pressure chamber through the fourth channel. Alternatively, in the second position, the channel structure blocks the fluid connection between the fluid source and the cylinder through the first channel, establishes a fluid connection between the fluid source and the first dynamic pressure chamber through the third channel, and establishes a fluid connection between the cylinder and the second dynamic pressure chamber through the fourth channel. The surgical instrument according to claim 1, 2, 5, or 6.

Images