WO2025149249A1 - Shockwave appliance with improved guide tube - Google Patents

Abstract

The invention relates to device for treating a human or animal body with mechanical shockwaves, the device having: a dimensionally stable guide tube, a projectile movable in the guide tube, a means of accelerating the projectile in the guide tube for the movement, and an applicator at one end of the guide tube for the impact of the accelerated projectile thereon in order to generate the shockwaves and to couple the shockwaves into the body, characterized in that the guide tube is made, at least on the inside, of a material having a hardness of at most 150HV0.1 according to the Vickers scale.

Description

Pressure wave device with improved guide tube

The invention relates to a device for treating the human or animal body by means of mechanical pressure waves.

Such devices are already known, particularly in the field of lithotripsy. Here, focused mechanical pressure waves are used to break up body concretions, particularly stones in body tissue. Furthermore, devices have been developed that generate mechanical pressure waves through the collision of an accelerated projectile and an applicator that acts as an anvil, and couple them into the body tissue to be treated via the applicator. Such devices are primarily designed to couple non-focused pressure waves and are used, for example, to treat muscle disorders and disorders in the transition area between muscles and bones, as well as many other indications.

The device type just described can be referred to as a "ballistic pressure wave device" and typically generates somewhat less energetic pressure waves with a not quite as steep initial pressure rise as actual lithotripsy devices. Furthermore, two mechanisms can be distinguished when coupling the pressure waves. On the one hand, the applicator, which is typically elastically suspended in the pressure wave device, is displaced "macroscopically" as a result of the collision, i.e., in the sense of a center of gravity movement. Therefore, a part of the applicator resting directly or indirectly on the body to be treated generates a corresponding pressure wave. On the other hand, the collision creates a significantly higher-frequency sound wave (typically 75-200 kHz) in the applicator, which propagates through the applicator and is coupled by it into the body tissue. Both pressure waves can have therapeutic effects. The literature generally focuses on the high-frequency wave, i.e., the second mechanism described.

As an example of the state of the art, reference is made to the applicant's patent EP 2 213 273 B1, which shows a typical device and deals with details of a pneumatic device for accelerating the projectile (referred to therein as the striking part).

On this basis, the invention is based on the task of technically developing such a pressure wave device.

The guide tube used to guide the projectile in relevant state-of-the-art devices is made of stainless steel (VA steel). The same applies to the projectile itself, although in practice, a hard carbide coating has been used to improve the service life of the projectile. Furthermore, the guide tube, with an inner diameter of typically 6 mm, has been precision-machined on its inside, with a tolerance of approximately 0.01 mm.

According to the invention, a significantly softer guide tube material is used, at least on the inside of the guide tube, with which the projectile comes into contact. Specifically, the material used here should have a hardness according to the Vickers scale of no more than 150HV0.1, preferably no more than 120HV0.1 or no more than 100HV0.1. Other preferred upper limits are 80HV0.1, 60HV0.1, and 40HV0.1. This allows for various advantages.

The current EN ISO 6507-1:2023 is relevant here.

Firstly, the projectile can be dispensed with without a hard coating. This reduces technical effort and costs. It also offers advantages for operational reliability and durability, because coated A coated projectile could result in flaking of the coating after extended running times, and flaked pieces could increase wear or even lead to blockages. With a softer material for the inner wall of the guide tube, an uncoated projectile, particularly made of metal, preferably stainless steel, is also possible.

Additionally or alternatively, simple and cost-effective guide tubes made of polymer materials, especially thermoplastic polymers, can be used. Preferred options are PTFE (polytetrafluoroethylene), PET (polyethylene terephthalate), POM (polyoxymethylene), and especially polyamides, especially PA6. Fiber-reinforced plastics, especially glass-fiber-reinforced plastics, are also possible.

In principle, it is sufficient if the inner walls of the guide tube are made of this or another soft material. The guide tubes can also be made of solid material; thus, no coating is necessary, e.g., for stability reasons (although this is of course possible). This allows the use of extruded tube material, which is considerably cheaper than precision-machined stainless steel tubes. However, suitable tubes can also be drilled and subsequently punched with a sharp punch to a suitable internal dimension and used according to the invention.

The change in material does not necessarily result in differences in the geometric dimensions. For the tests underlying this example, polyamide pipes with dimensions corresponding to the previously used stainless steel pipe were used. Typical wall thicknesses range from 0.5 mm to 2.5 mm, with 0.6 mm, 0.7 mm, and 0.8 mm as the lower limit and 2.0 mm, 1.7 mm, and 1.4 mm as the upper limit being increasingly preferred.

In any case, it has been found that the comparatively very soft guide tube provides very good running properties and a surprisingly good durability. durability could be achieved. It is apparently not a priority to use hard material for the inner wall of the guide tube.

Specifically, the stainless steel guide tubes commonly used are just as subject to wear as projectiles and applicators. Surprisingly, the service life of the guide tubes could be extended far beyond the typical service life of a conventional stainless steel guide tube.

The guide tube is preferably dimensionally stable. This means that it does not deform under its own weight in a practically relevant way. For example, with a typical length of 10 cm and clamped on one side, it will not deform by more than 0.5 mm, preferably no more than 0.3 mm, 0.2 mm, or even no more than 0.1 mm, i.e., by a maximum of 0.5%, 0.3%, 0.2%, or 0.1% of the length. The same applies to other lengths. In simpler terms: the guide tube is a piece of pipe and not a piece of hose. These requirements can be easily met, for example, using the polymer materials mentioned.

The dimensional stability avoids the need for a special adjustable mounting to ensure the desired straightness of the guide tube. With non-dimensionally stable tube sections, there is a risk that unwanted deformation could lead to deviations from the desired trajectory for the internal volume, which would be fundamentally detrimental to projectile motion and hinder higher projectile velocities and frequencies.

Furthermore, it is preferred that the projectile material be significantly harder than the material of the inner wall of the guide tube. Accordingly, the hardness of the projectile, at least on its outer surface in contact with the guide tube, is preferably greater than 170HV0.1, with the following lower limits being increasingly preferred: 180HV0.1, 190HV0.1, and finally 200HV0.1. Besides metals, particularly steel, ceramics and composite materials are also suitable. Particularly hard metals are not necessarily required; The guide tube according to the invention also opens up application possibilities for somewhat softer metals. The inventors' experiments have shown significantly reduced wear on the projectiles, namely, much less abrasion of the outer wall areas of the projectile that come into contact with the inner wall of the guide tube. In this context, it is particularly advantageous, for economic reasons alone, to dispense with the hard coatings of projectiles commonly used in the prior art.

Furthermore, the materials suitable for the guide tube according to the invention are typically significantly lighter than metals, particularly stainless steel. In this sense, densities of at most 3 kg/l are preferred for the guide tube (at least on the inside, preferably in general), with the following upper limits becoming increasingly preferred: 2.5 kg/l, 2.0 kg/l, and finally 1.5 kg/l. It is generally advantageous to save weight, which is particularly true for the designs commonly used and also preferred in the present case, with a handpiece separate from a base unit.

The pressure wave device according to the invention is preferably designed to be applied externally to a patient's skin area using the applicator. In other words, it is a device for extracorporeal use, unlike devices known from the prior art for lithotripters, which break up body calculi using long, thin applicators that are usually inserted through catheters or similar devices. When applied externally, the therapeutically desired pressure waves are coupled into the body, whereby a contact medium (e.g., ultrasound gel) can be used for impedance matching.

Furthermore, the applicator can be made up of several parts for impedance reasons, i.e. in order to better adapt the impedance of the applicator relevant for the pressure waves in the area of collision with the projectile to the impedance of the contact medium or the body tissue. The example shows a typical geometry of an applicator's outer surface that is suitable for contact. The contact surfaces are flat and, to avoid injuries, not too small, typically at least 1 ^cm² or more.

The guide tube length can be advantageously limited to a range of approximately 5-20 cm, for example. This length is sufficient for efficient acceleration and, at the same time, allows for a compact design. This is especially true for the preferred arrangement of the guide tube completely housed within a device housing. Such a device housing can be a handpiece supplied with pneumatic pressure from a base station. The base station is less mobile (e.g., it is mounted on a cart), and the handpiece is guided by the operator's hand.

In this context, it is preferred that the handpiece also contains a pneumatic switching valve, i.e. the pneumatic pulses responsible for the acceleration are generated by a valve action in the housing or at its edge, but not in the base unit or at the other end of the supply line.

The aforementioned applicator is preferably elastically held in at least one elastomer ring, thus decoupled from the housing or other suspension. This is useful to prevent excessive coupling of pressure waves into the housing. On the other hand, the elastomer ring only allows limited movement (in terms of the center of gravity movement, i.e., overall movement) of the applicator. This is clearly visible in the exemplary embodiment with a plurality of elastomer rings.

Typical achievable projectile velocities can range between 5 m/s and 60 m/s. Repetition frequencies of at least 10 Hz, preferably at least 20 Hz, or even at least 25 Hz, are preferably achievable. The return movement of the projectile before the new acceleration can be achieved, for example, by the collision with the applicator and/or by a counterpressure chamber already known in the prior art (as in the embodiment) or in another way.

A further advantage of the invention can arise from the use of sensors to detect the position and/or velocity of the projectile. Hall sensors are particularly well suited for this purpose and are significantly less affected by a non-metallic guide tube material, especially a polymer material.

In addition, optical detection devices can be considered, and the use of polymer materials also allows for transparent materials, such as transparent polyamide.

As in the cited prior art, a pneumatic device for accelerating the projectile is preferred in the present context. Such an acceleration device typically applies pressure to an end of the guide tube opposite the applicator for acceleration. However, it is not necessary; the projectile could also be accelerated electromagnetically, for example, by a coil wound around the guide tube in conjunction with a ferromagnetic projectile. Traveling magnetic fields in conjunction with ferromagnetic projectiles are also possible.

The invention also relates to the use of a tube as a guide tube for a relevant device and to the use of a projectile therefor, in particular an uncoated metal projectile and preferably an uncoated VA projectile.

In the following, the invention is explained in more detail using an embodiment which relates to all claim categories and whose individual features may also be essential in other combinations. Figure 1 shows a device according to the invention in longitudinal section with a schematically illustrated pneumatic drive.

Figure 1 shows a medical device, designated overall by 10, for treating the human body with mechanical pressure waves, in this case for soft tissue treatment as part of pain therapy. The device consists of a handpiece 12 and a pneumatic compressed gas supply device 32, explained in more detail below. A treating physician, for example, can grasp the handpiece 12 and place it on a suitable area of skin with the right end shown in Figure 1, with the handpiece 12 positioned approximately perpendicular to the skin.

A housing 14 is provided with a proximal end cap 16 and a distal end cap 18, each of which is designed to be removable. A guide tube 24 is held in the housing and arranged axially and concentrically. A projectile 20 is guided in the guide tube, the path of movement of which along the interior of the guide tube 24 is limited on the right side by an applicator 22, specifically by its proximal side 30. This applicator forms a distal stop for the projectile 20, with the proximal stop of the projectile 20 being designated 28 and forming a simple end of the guide tube 24. This end is magnetic, so that the projectile 20 can be fixed there with a certain holding force. The length of the guide tube 24 is typically approximately 5 cm - 20 cm, with the exemplary embodiment shown here having a guide tube length of 16 cm.

The pneumatic drive 32 embodies the compressed gas supply device and comprises a conventional pneumatic compressor 34 (or a compressed gas cylinder), with the compressor 34 covering a typical operating range of up to approximately 10 bar. A compressed gas connection 40 of the handpiece 12 is supplied via a pressure line 36 and a switching valve 38, which communicates with the guide tube 24 via an opening 42 therein. The switching valve 38 can be a solenoid valve. A controller 44 is connected to it via a control line 46, which is shown in dashed lines. The controller 44 can be designed as a structural unit with the compressor 34 and thus form a base unit for supplying the handpiece 12, with the switching valve 38 advantageously being attached to the latter. This has the advantage that the volume to be filled by the pressure pulse is small. This allows for stronger and faster pulses. Accordingly, the controller 44 and the compressor 34 are connected by a line in Figure 1. The base unit and handpiece 12 are then connected via a supply line combining the pneumatic line 36 and the control line 46.

Starting from a resting state of the device 10, i.e., at the start of operation, the closed switching valve 38 is opened by the controller 44. The state shown in Figure 1, in which the guide tube 24 is connected to the outside atmosphere, is thus changed to a state represented by the right-hand box of the valve symbol, with the supply pressure being applied to the guide tube 24 via the connection 40. The projectile 20 is initially in its initial position, indicated by 48 in Figure 1. The built-up pressure accelerates the projectile 20 toward the impact body, but is released before impact by switching the switching valve 38 back on, thus venting the volume in the guide tube 24 located "behind" the projectile 20. The projectile 20 impacts the impact body 22 without braking, whose distal (slightly convex) end surface 58 rests on the patient's skin and transmits a mechanical pressure wave into the body. The applicator 22 performs an axial movement due to its elastic suspension in the two elastomer O-rings 56.

Immediately after impact, the projectile 20 moves back. This is aided by a counterpressure chamber 52, which is connected to the guide tube 24, specifically its distal end shortly before the proximal side 30 of the impact body 22, in a manner not shown in detail here. In this counterpressure chamber, the displacement due to the movement of the projectile 20 creates a Counterpressure leading back to the proximal stop, i.e. the magnetic end piece 28.

After a certain time, the switching valve 38 is switched again, so that a new triggering process begins. This specific time, together with the switch-on time of the switching valve 38, results in the reciprocal of the set frequency. Typical impact velocities of the projectile are in the range of 5 m/s - 60 m/s. In contrast to the prior art document referred to here, the guide tube 24 consists of a polyamide tube that is extruded and/or drilled and remachined (with a sharp punch) to the correct internal dimensions. Specifically, polyamide PA6 was used, which, according to measurements, has a hardness of approximately 16HV0.1. In this range, such measurements are subject to a certain degree of scatter. Specifically, this is an average value with a scatter between 14 and 18HV0.1. In any case, this value is well below the stated upper limits.

The length, as already stated, is 160 mm with a wall thickness of 1 mm, an inner diameter of 6 mm, and consequently an outer diameter of 8 mm. The projectile used is slightly smaller, with a maximum outer diameter of 5.96 mm.

Projectile 20 is made of uncoated stainless steel. This results in Vickers hardness values starting at approximately 200HV0.1. Hardened stainless steel is above 400HV0.1, although experience has shown that the conventionally used surface coating increases this value even further. Due to its layer characteristics, it is difficult to characterize, but even on uncoated end surfaces, the coating increases the Vickers hardness to over 500HV0.1, to give one example. The density of guide tube 24, in contrast to conventional steel (at just under 8 kg/l), is only around 1.1-1.2 kg/l, typically 1.14 kg/l, i.e., a good 1/7. In initial tests, service lives of the guide tube of well over 15 million pulses were easily achieved.

Claims

Claims 1 . Device (10) for treating a human or animal body with mechanical pressure waves, which device comprises: a dimensionally stable guide tube (24), a projectile (20) movable in the guide tube (24), a device (34-46, 58) for accelerating the projectile (20) in the guide tube (24) for the movement and an applicator (22) at one end of the guide tube (24) for the impact of the accelerated projectile (20) thereon to generate the pressure waves and for coupling the pressure waves into the body, characterized in that the guide tube (24) consists at least on the inside of a material with a hardness of at most 150HV0.1 according to the Vickers scale. 2. Device (10) according to claim 1, wherein the applicator (22) is designed to be placed on a skin area of a patient. 3. Device (10) according to claim 1 or 2, wherein the guide tube (24) has a length between 5 cm and 20 cm. 4. Device (10) according to one of the preceding claims, comprising a housing (14) in which housing (14) the entire guide tube (24) and the projectile (20) are arranged. 5. Device (10) according to one of the preceding claims, in which the applicator (22) is elastically suspended by means of at least one elastomer ring. 6. Device (10) according to one of the preceding claims, in which the at least inner material of the guide tube (24) is a polymer material, in particular polyamide. 7. Device (10) according to one of the preceding claims, in which the at least inner material has a density of at most 3 kg/l. 8. Device (10) according to one of the preceding claims, wherein the guide tube (24) consists of the material as a solid material. 9. Device (10) according to one of the preceding claims, in which the projectile (20) consists of a material with a hardness of at least 170HV0.1 according to the Vickers scale, in particular of metal, in particular of VA steel. 10. Device (10) according to one of the preceding claims, wherein the projectile (20) is uncoated. 11. Device (10) according to one of the preceding claims with a position detection device, in particular with at least one Hall sensor for detecting the position of the projectile and/or at least one optical detection device for detecting the position of the projectile (20), wherein the guide tube (24) is transparent. 12. Device (10) according to one of the preceding claims, in which the acceleration device (34-46, 58) is a pneumatic device which can accelerate the projectile (20) by applying pressure to the guide tube (24). 13. Device (10) according to one of the preceding claims, which has a handpiece (12) with the guide tube (24), the projectile (20) and the applicator (22), which can be held and guided by hand by an operator during treatment, and a base device for supplying the handpiece (12). 14. Use of a tube with at least an inner material having a hardness of at most 150HV0.1 according to the Vickers scale as a guide tube (24) for a device (10) according to one of the preceding claims. 15. Use of a projectile (20) for a device (10) according to one of the Claims 1-13, in particular a metal projectile and preferably an uncoated stainless steel projectile.