Abstract:
In a device for introducing shock waves into a living body by way of at least one element ( 4; 12; 14 ) which transmits the shock waves and upon which shock pulses act, wherein at least one spring member ( 2 ) is used for generating the shock waves, a tensioning device is associated with the spring member and allows for an abrupt release of the spring member while delivering a shock pulse.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The invention relates to an apparatus for introducing shock waves into a living body via at least one element which transmits the shock waves and on which shock pulses act, at least one spring member serving to generate the shock pulses. The apparatus is preferably designed as a medical handheld appliance which can be used both in intracorporeal shock wave lithotripsy and in extracorporeal shock wave orthopedics as part of the disintegration of calculi or superficially in the case of diseased parts of the body. 
         [0002]    A device of this kind is generally known for example from U.S. Pat. No. 4,549,535 for the treatment of humans. Since it has a soft tip, it cannot be used for lithotripsy. 
         [0003]    The disintegration of concretions in vivo by the use of shock waves (lithotripsy) is already used successfully in modern medicine. The concretions, such as kidney stones, are disintegrated in the body of a human into small fragments, which are then intended to be excreted from the body via the urinary tract. 
         [0004]    In the present case, a shock wave is understood to mean in particular any compression wave generated by an impact. 
         [0005]    The prior art describes various apparatuses and methods for generating shock waves for disintegrating concretions in a living body. Thus, the U.S. Pat. No. 5,868,756 describes a handheld appliance for use in intracorporeal shock wave lithotripsy, said appliance having a probe which serves as a waveguide for transmitting shock waves and is dimensioned in an appropriate manner for introduction into an endoscope. 
         [0006]    The shock energy for generating the shock waves is obtained in this handheld appliance by a projectile or percussion part that can move back and forth pneumatically in a guide tube, specifically in that it periodically strikes an appropriately large mass part which then transfers the impact force acting on its target area to the probe adjoining the mass part. 
         [0007]    This US document also states that instead of a pneumatic drive for the percussion part, a hydraulic or electromagnetic drive can alternatively be realized. 
         [0008]    Furthermore, DE 197 25 477 C2 describes a medical instrument in the form of a handheld appliance for treating biological tissue (orthopedics), said medical instrument being intended to generate extracorporeal pressure waves. These pressure waves are intended to be introduced into the body of living beings with the aid of a transmitting element. To this end, the transmitting element has a blunt probe tip having a flat output interface, by way of which unfocussed, mechanically generated pressure waves can then be coupled into the biological tissue. 
         [0009]    In this instrument, the pressure wave itself is generated by a percussion part that is accelerated pneumatically to a speed of more than 5 m/s and impinges on the transmitting element, it being intended that the probe tip execute a stroke of less than 1 mm. With this handheld appliance, it is further intended that the energy of the pressure waves be distributed evenly over a large region of action, such as an entire region of inflammation, for example. 
         [0010]    For example, U.S. Pat. No. 1,796,444 discloses an apparatus for treating the human body with shock waves. In order to generate the shock waves, a spring element is tensioned and then abruptly released. The tensioning device for the spring element is a drive. Disadvantageously, a sudden, abrupt triggering is not possible therewith, since the spring element remains connected to the tensioning device the whole time. 
         [0011]    However, the known handheld appliances all have pressure or shock wave generators, and have relatively complicated designs since a compressor, control unit and handpiece are required. 
         [0012]    It is an object of the invention to provide an apparatus for introducing or applying shock waves into or onto a living body, the shock wave generator of which has a simple structure and also delivers an exact “hard” impact force. Furthermore, the apparatus should be low-maintenance and be highly suitable for intra- and for extracorporeal treatment, preferably of the human body. 
       SUMMARY OF THE INVENTION 
       [0013]    The foregoing object is achieved according to the invention in a simple manner in the case of an apparatus for introducing shock waves into a living body by the features described hereinbelow. 
         [0014]    A tensioning device is assigned to the spring member and enables the spring member to be triggered abruptly, emitting a shock pulse. 
         [0015]    By means of a shock wave generator which is designed in this way, it is advantageously possible that the probe transmitting shock waves can be acted on periodically with relatively high (“hard”) impact energy, specifically in a similar manner to the firing rate of a machine gun, for which reason the subject matter of the invention can also be called a lithogun or orthogun. The “hard” impact force is achieved primarily by a low-mass element having a high impact velocity. 
         [0016]    According to the present invention, it is expedient that preferably a pneumatic or cylindrical mechanical compression spring serves as the spring member and is connected to a percussion part such that it emits the spring force of the compression spring, when its compressive stress is released suddenly, to the transmitting element in the form of a shock pulse. 
         [0017]    In this case, the percussion part can be formed as a piston which is guided in a housing part and has a head part that emits the shock pulses and an adjoining cylindrical hollow part. The cylindrical compression spring, which generates the spring forces, is guided at least partially in the hollow part, it being expedient in this case that the compression spring is supported at one end on the rear side of the head part of the piston and at the other end on a housing part of the apparatus. 
         [0018]    In a further preferred exemplary embodiment, the apparatus for emitting a shock pulse to the transmitting element should take place pneumatically. To this end, the apparatus preferably comprises a projectile. 
         [0019]    Preferably, the apparatus for emitting a shock pulse also comprises a device for subjecting the projectile to the action of compressed air. In a particularly preferred embodiment, said device comprises a piston which is guided in a cylinder. As a result, when the piston has a larger cross section than the projectile, an even greater pressure, depending on the cross-sectional area ratio selected, can advantageously be applied to the projectile. 
         [0020]    The cylinder is advantageously connected via a flexible tube to a channel in which the projectile is located. In this channel, the projectile can accelerate until is strikes the transmitting element. 
         [0021]    The channel for guiding the projectile can be provided in a barrel having a housing. Set-down surfaces, feet or a suspension apparatus can be integrally formed on the housing. 
         [0022]    The piston is accelerated preferably by means of spring force. To this end, the piston is likewise assigned a spring member. The piston advantageously has a rib as a guide for the spring member. 
         [0023]    In order to tension and release the spring guided in the percussion part or in the rib of the piston in order to subject the projectile to the action of compressed air, it is advantageous when the piston of the percussion part has along its outer casing at least one rack, into which a pinion engages, said pinion having a toothed ring only on part of its circumference, e.g. over 180° of its circumference, a worm also being possible instead of the pinion. Instead of a separate rack, a toothing formation can also be formed directly in the outer casing of the percussion part. 
         [0024]    If the pinion is now rotated, the percussion part moves away from the probe as soon as the partial toothed ring is in engagement with the rack, and the spring guided in the piston of said percussion part is compressed. As soon as the toothed ring of the pinion leaves the rack, that is to say comes out of engagement, the compressed spring can abruptly release its tension and the spring force released thereby accelerates a projectile to the desired speed. This projectile strikes a probe, and generates a shock wave in the applicator, which for its part transfers a corresponding shock wave to the object to be treated. 
         [0025]    The respective rotations of the pinion expediently take place by motor, and here by means of a battery-powered electric motor, upstream of which is preferably connected a reduction gear in order to reach suitable rotational speeds of the pinion, which influence the respective impact frequencies. 
         [0026]    However, the context of the invention should not include only the arrangement just described, but rather any conceivable retaining apparatus which retains the tensioned compression spring and then releases it in a triggered manner. 
         [0027]    When use is made of the apparatus according to the invention for intracorporeal shock wave lithotripsy, it is expedient that here the element that transmits the shock waves is designed in the manner of a probe, in order that it can be introduced into an endoscope, specifically for disintegrating concretions such as kidney stones or gall stones in a living body. 
         [0028]    By contrast, when use is made of the apparatus according to the invention for extracorporeal shock wave orthopedics, dermatology and esthetics (cellulite), it is expedient that the element thereof that transmits the shock waves is formed as a rounded spherical segment for applying to the living body. Although this apparatus is suitable also for disintegrating concretions from outside, it is possible to use it to treat above all diseased parts of the body of a human or in animals, in particular in the regions of the tendons, ligaments, bones and the skin (cellulitis, wounds), with shock waves. 
         [0029]    In order to handle the apparatus according to the invention properly, it is expedient that it is formed as a medical handheld appliance, i.e. this handheld appliance should only have a size, as seen from its external dimensions, which allows the appliance to be held properly in an adult hand. 
         [0030]    This apparatus which is formed as a medical handheld appliance can, in addition to a housing for accommodating the shock wave generator, also advantageously be provided such that optionally an attachment having a probe for lithotripsy or one for orthopedics can be releasably attached to the housing thereof. With such a modular system, the number of types is advantageously reduced, thereby increasing the cost-effectiveness of such a handheld appliance. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0031]    Further features and advantages of the present invention are given in the following description of preferred exemplary embodiments in conjunction with the drawing, in which: 
           [0032]      FIG. 1  shows the principle of a shock wave generator according to the invention, 
           [0033]      FIG. 2  shows a perspective view of a medical handheld appliance, which is equipped with a shock wave generator according to  FIG. 1  and is suitable for intracorporeal shock wave lithotripsy, 
           [0034]      FIG. 3  shows a perspective view on an enlarged scale of a possible interchangeable attachment for the appliance according to  FIG. 2 , for use in extracorporeal shock wave orthopedics, 
           [0035]      FIGS. 4 to 6  show the principle of a further exemplary embodiment of the shock wave generator according to the invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0036]    The principle of a shock wave generator  1  illustrated schematically in  FIG. 1  has, in order to generate shock pulses, a spring member  2  in the form of a cylindrical compression spring, which is operatively connected to a percussion part  3  which in turn transfers the shock pulses generated to an element  4  that transmits shock waves. The compression spring  2  consists of spring steel, but other materials, such as plastic for example, can also be used. 
         [0037]    The percussion part  3 , which is suitably guided in a housing  5  of the apparatus illustrated in  FIG. 2 , consists of a type of piston having a head part  3 . 1  that emits the shock pulses and a cylindrical hollow part  3 . 2  adjoining said head part  3 . 1 . 
         [0038]    The compression spring  2  is partially guided in the hollow part  3 . 2  and is supported at its right-hand end on the rear side of the head part  3 . 1  and at its left-hand end on a portion (not illustrated in more detail) of the housing  5 . The percussion part  3  itself is arranged coaxially with respect to the element  4  that transmits the shock waves. 
         [0039]    Furthermore, the hollow part  3 . 2  of the percussion part  3  has along its outer casing an integral toothing formation or an attached rack  6 , into which a pinion  7  or a worm (not illustrated) can be engaged periodically. The pinion  7  has to this end a toothed ring  8  on only a part of its circumference, the profile of said toothed ring  8  corresponding to the profile of the rack  6 . In the present exemplary embodiment, the partial toothed ring  8  is limited to a circumferential range of 180°; this is preferred, but it can also be larger or smaller. 
         [0040]    The pinion  7  itself is driven via a battery-powered electric motor—indicated by the arrow  9  in FIG.  1 —located in the housing  5 , a suitable reduction gear being connected upstream of said motor. 
         [0041]    The medical handheld appliance—designated  10 —illustrated in simplified form in  FIG. 2  is in the present case set up for use in intracorporeal shock wave lithotripsy. To this end, there is provided a releasable attachment  11 , the element of which—designated  12 —that transmits shock waves is designed in the form of a probe. Therefore, this element  12  can be introduced into an endoscope and the distal end of the probe is thus available for disintegrating calculi by means of shock waves transmitted via the probe. 
         [0042]    In the event that the handheld appliance  10  according to  FIG. 2  is intended to be used for extracorporeal shock wave orthopedics, the attachment  11  can also be exchanged for an attachment  13  ( FIG. 3 ), the element of which—designated  14 —that transmits shock waves has at its contact region a kind of rounded spherical segment  14 . 1  that is suitable for external application to a part of the body of a human or animal. Both attachments  11  and  13  are suitable for disintegrating concretions such as kidney stones, urinary stones or gall stones, the attachment  13  in particular being more suitable for subjecting diseased areas of the body, such as tendon or ligament regions, bone parts, areas of skin or simply wounds, to shock waves. 
         [0043]    The medical handheld appliance  10  has a size which allows it to be held comfortably by an adult user in their hand. 
         [0044]    The present invention functions as follows: 
         [0045]    The shock wave generator  1 , which is accommodated in the housing  5 , is driven counterclockwise at approximately 5 Hz (300 rpm) by an electric motor via a reduction gear (symbolically arrow  9 ), as a result of which the toothed ring  8  engages periodically in the rack  6  and the percussion part  3  moves to the left by the length of the rack  6 , thereby compressing the compression spring  2  by this amount. The impact energy being stored in the compression spring  2  in the process is then released suddenly, i.e. abruptly, specifically as soon as the last tooth of the toothed ring  8  leaves the rack  6 . By way of this spring force, which is available on account of the brief release of tension in the compression spring  2 , the element  4  or  12  or  14  is acted on abruptly, it being possible also to provide a mass part as it were as a buffer between the end portions of these elements and the head part  3 . 1 . 
         [0046]    On account of the abrupt impact of the head part  3 . 1  against the respective element  4  or  12  or  14 , shock waves are produced in the latter and are then used either to disintegrate calculi or else, for example, to break down calcifications in particular areas of the body, such as in areas of the shoulder. How often this impact should take place per second depends in turn on the rotational speed of the pinion  7  and this in turn depends on the desired intensity of the respective treatment. 
         [0047]      FIGS. 4 to 6  show a further exemplary embodiment of a shock wave generator  1 . 1  according to the invention. This has, similarly to the preceding exemplary embodiment, a spring member  2 . This is introduced between an impact plate  15  and a piston  16 . In order to guide the spring member  2 , a rib  17  is integrally formed on the piston  16 . The piston  16  is guided in a cylinder  18 . Adjoining the latter is a flexible tube  19  in which a valve may be integrated if appropriate for better control or blocking. The flexible tube  19  is connected to a barrel  20 . The barrel  20  comprises a housing  21  and a guide tube  22  for a projectile  23 . At one end of the barrel  20  there is arranged a transmitting element  4 . 
         [0048]    The piston  16  and the rib  17  have, similarly to the preceding exemplary embodiment, a toothing formation  6 . This is operatively connected to a pinion  7  which only partially has a toothed ring  8 . 
         [0049]    The present invention functions as follows: 
         [0050]    Similarly to the above-described exemplary embodiment, the shock wave generator  1 . 1 , too, is driven in the clockwise direction by an electric motor (not illustrated) via a reduction gear, the drive being symbolized by the arrow  9 . In the process, the toothed ring  8  of the pinion  7  engages in the toothing formation  6 , moves the piston  16  in the direction of the arrow  24  and presses the spring element  2  against the impact plate  15 . In the process, the spring element  2  stores kinetic energy or impact energy. This is then suddenly, i.e. abruptly, released when the last tooth of the toothed ring  8  of the pinion  7  leaves the toothing formation  6 . By way of this spring force, which is available on account of the brief release of tension in the compression spring  2 , the piston  16  is then moved abruptly, as illustrated in  FIG. 6 , counter to the direction of the arrow  24  and presses the air located in the cylinder  18  and flexible tube  19  into the channel  22  in the barrel  20 . As a result, the projectile  23  is shot onto the transmitting element  4 . On account of the abrupt impact of the projectile  23  on the transmitting element  4 , shock waves are produced in the latter, similarly to the above exemplary embodiment, and then may serve for the uses that have already been described. 
         [0051]    Overall, the present invention provides a modular, cost-effective medical handheld appliance, which on account of its mechanical mode of operation is very robust and thus low-maintenance and can supply relatively high, precise impact energy and thus shock waves, which is of great advantage both for the user and for the respective patient.