DE102009048835A1 - Drive for bone saw has connection rod for driving saw blade of bone saw, where multiple drive units are provided for driving connection rod and drive units are interconnected in parallel with each other - Google Patents

Abstract

The drive has a connection rod (7) for driving a saw blade of a bone saw (1). Multiple drive units are provided for driving the connection rod. The drive units are interconnected in parallel with each other. The drive units have a common coupling unit. Independent claims are also included for the following: (1) a saw blade with a saw blade area; (2) a bone saw with an output; and (3) a method for operating a bone saw.

Description

The invention relates to a transmission for a bone saw with a connecting rod for driving a saw blade of the bone saw. Moreover, the invention relates to a saw blade for a bone saw. Likewise, the invention relates to a bone saw with a drive and an output, wherein the output comprises a holding device for a saw blade with a plurality of saw teeth. The invention also relates to a method for operating a bone saw, in which a saw blade is driven by means of a connecting rod.

Generic bone saws, in particular related gear, are well known in the prior art and have been used successfully for many years in orthopedic surgery, with an essential feature of such bone saws is that they provide the best possible functioning soft tissue protection. This means that, for example, a softer tissue surrounded by a bone can not be injured or only insignificantly damaged by a moving saw blade, but that only the harder bone is sawn by means of the saw blade of the bone saw. This ensures that neither a patient nor a user of the bone saw can be injured, in particular by saw teeth of the moving saw blade.

A relevant motor-driven saw or bone saw is for example from the published patent application DT 2 400 696 known. This motor-driven saw has a gear for driving a saw blade, in which a rotating drive member is mounted on a saw blade holder, that is, the saw blade holder is mounted on the rotating drive member. A saw spindle closer to the guide spindle also supports the blade holder in such a way that it can be moved by means of the rotating drive member on the one hand translationally relative to the guide spindle and on the other hand rotatably pivoted about the guide spindle. By means of such a guide arrangement, it is achieved that a toothed region of the saw blade, at least in regions, passes through a substantially elliptical trajectory, as a result of which the soft tissue protector mentioned at the outset can be achieved. Although a soft tissue protection can be achieved due to these overlapping trajectories, a uniform cutting performance over the entire length of the saw blade can not be consistently ensured, since the trajectories differ from each other, in particular with respect to juxtaposed saw teeth along the saw blade. In this respect, the saw cut performance differs regionally.

It is an object of the present invention to further develop generic bone saws or related gear, so that an improved saw cut quality can be achieved.

The object of the invention is achieved on the one hand by a gearbox for a bone saw with a connecting rod for driving a saw blade of the bone saw, wherein the transmission is characterized in that it has more than one drive means for driving the connecting rod.

The fact that the connecting rod is drivable with more than one drive device, it is possible to operate this and in particular so that the saw blade of the bone saw with previously unattainable movement sequences.

In particular, the saw blade can ideally be moved over its entire useful length on particularly smooth trajectories, whereby, for example, the sawing quality of an equipped with the present transmission bone saw can be significantly improved.

The term "drive means" in the context of the invention describes any means by which the connecting rod can be driven directly. In this respect, the present connecting rod is also directly connected to each drive device. Thus, the present transmission has both a first drive member and a further drive member, which are directly in operative contact with the connecting rod.

The term "connecting rod" describes a component or component group of the transmission which can form or comprise a saw blade carrier.

In this respect, it is advantageous if the connecting rod comprises a saw blade carrier, with which the saw blade and the connecting rod can be reliably coupled together.

In this context, it is also conceivable that the saw blade can configure the connecting rod itself, so that the drive means for driving the saw blade are mounted directly on the saw blade.

On the other hand, the object of the invention is also achieved by a bone saw with a drive and an output, wherein the output comprises a holding device for a saw blade with a plurality of saw teeth, and in which the output is driven in such a way that by means of the output more than 30 % of the saw teeth are movable on a true circular path.

For the purposes of the invention, the term "true circular path" generally describes a movement path with essentially a single radius with respect to a relevant center, whereby the present true circular path differs approximately from elliptical circular paths.

Although it is possible with the motor-driven saw described at the beginning as prior art, that the path of movement of a sawtooth is substantially circular. However, this is possible only for individual saw teeth in a specific area of the saw blade. In the deviating areas essentially only elliptical trajectories can be realized.

Advantageously, in the present case the output is driven by means of two mutually parallel drive means, so that more than 30% of the saw teeth can be moved on a true circular path.

Due to this exact vornehmbare Sägeschnitte a surgical success and subsequent healing success can be significantly improved.

In the present case, essentially the connecting rod of the transmission according to the invention and / or the saw blade can be regarded as "output".

If the output is driven in such a way that more than 50% of the saw teeth, preferably more than 80% of the saw teeth, are movable on a true circular path, the saw quality can be further improved compared with the prior art.

Moreover, with the bone saw, if each of the saw teeth of the saw blade is movable in a true circular path, it is no longer necessary for a user of the bone saw to additionally concentrate on a specific area of the saw blade during an operation in order to select precisely that area of the saw blade. on which the saw teeth can be moved in a true circular path.

In this respect, a comprehensive and 100% soft tissue protection can be achieved, thereby substantially reducing injury to the patient or the user. Especially with regard to the latter, this also significantly improves the occupational safety.

A further solution to the object of the present invention proposes a saw blade for a bone saw, wherein the saw blade has an overall length of more than 30 mm, preferably of more than 50 mm.

With such a long blade, a variety of particularly advantageous saw cuts can be made.

A preferred embodiment provides that the saw blade has a toothed saw blade area with a length of more than 30 mm, preferably of more than 50 mm. As a result, surgical interventions can be made even better.

Advantageously, it is possible for the first time that all the teeth of such a saw blade configured in such a long way can pass through a true circular movement when the saw blade is driven by means of the transmission underlying the invention.

It is particularly advantageous if the saw blade has a spherical shape. This makes it easy to realize unusual saw cut variants.

In addition, if the saw blade includes a temperature sensor, damage to a bone or surrounding tissue due to excessive temperature input of a superheated saw blade can be effectively prevented.

Preferably, the performance of a bone saw, which is equipped with such a saw blade, automatically reduced, so that an overheating hazard is almost impossible.

A power reduction can be achieved in a simple manner, for example, if a speed reduction is made to the bone saw.

It is also conceivable that a critical temperature in the area of the saw blade is displayed acoustically or visually on the bone saw, whereupon the user can interrupt the use of the bone saw in a timely manner until the temperature has been correspondingly reduced.

With regard to overheating protection, it is advantageous if the bone saw has a device for regulating a drive power as a function of a determined saw blade temperature. The present control device can then control, for example, the number of revolutions of the bone saw down, when the control device receives information from the temperature sensor of the overheating protection that the temperature at the saw blade has reached or has already reached a critical value.

Since such a control device conventional bone saws already advantageous for themselves further developed, the features with respect to this control device, in particular with regard to the overheating protection of the saw blade, even without the other features of the invention are advantageous.

In order to ensure a true circular path on the saw blade, it is advantageous if the bone saw has a transmission according to one of the features described here. Even if the saw blade has a spherical shape, a particularly good soft tissue protection can be ensured on each tooth.

In addition, the bone saw can be further developed exceptionally advantageous if the bone saw has an endoscopic device.

By means of such an endoscopic device, it is advantageously always possible to ensure stable access to a sawing area. This is extremely advantageous, for example, with regard to minimally invasive interventions on a spinal column, in which the surgical or sawing area can not be accessed from the back of a patient, or only with difficulty.

Ideally, the endoscopic device is rigid, so that a particularly stable access, in particular for a saw blade with a length of more than 30 mm or more than 50 mm can be provided.

It is understood that the present endoscopic device can be advantageously supplemented by suitable optics and / or lighting means.

In addition, the endoscopic device can be firmly integrated on or in a housing of the bone saw, if the bone saw to be designed and used only for specific applications.

However, it is particularly advantageous if the bone saw has a device for receiving an endoscopic device. This makes it possible to fix the endoscopic device fixed, but releasably attached to the housing of the bone saw, if appropriate.

Furthermore, it is advantageous if the bone saw has a saw blade according to at least one of the features described here.

The object of the invention is further achieved by a method for operating a bone saw, in which a saw blade is driven by means of a connecting rod, and in which the connecting rod is driven according to the invention by means of two drive means.

If the connecting rod in the context of the invention is driven simultaneously with two drive means, the connecting rod can advantageously be moved in such a way that ideally at each position of the saw blade a true circular path movement is achieved. This, in turn, not only a comprehensive and thus particularly good, known per se soft tissue protection in relation to the saw teeth of the saw blade is ensured, but it can also be achieved advantageously also an exceptionally uniform cutting performance over the entire blade length.

A preferred embodiment therefore also provides that the present drive devices are connected in parallel with one another. In this respect, each of the drive devices can control the connecting rod individually and set in motion, so that the connecting rod and the saw blade can follow almost any trajectories.

A particularly preferred embodiment provides that the transmission has two drive means for driving the connecting rod. Already two such drive means are sufficient in particular to be able to control and move the connecting rod in a particularly advantageous manner.

It is understood that the two drive means can be driven independently and each by itself. A structurally particularly simple embodiment, however, provides that the drive means are arranged in a common drive train.

A preferred variant of the method provides that the drive devices are operated simultaneously and synchronously with one another. As a result, the transmission and thus also the bone saw can be structurally simply converted into reality, since a more complicated control of the drive devices is not required.

This simultaneous and synchronous operation of the two drive means can be achieved structurally particularly simple by a common coupling member. Therefore, it is also advantageous if the drive means have a common coupling member. By means of the coupling member, the two drive means can be structurally particularly easily operatively connected to each other.

A further advantageous variant of the method provides that one of the two drive devices is driven by the further of the two drive devices.

This can be achieved structurally, for example, by designing such a common coupling element as a toothed wheel, which can mesh with corresponding toothed wheels of the drive devices.

For example, if the drive devices are configured identically, the present transmission can be made exceptionally simple, since it comprises fewer different transmission elements.

The transmission structure can be further advantageously simplified when at least one of the drive means has a drive shaft to which the connecting rod is mounted drivable. Preferably, two drive devices are each configured as such a drive shaft.

In this respect, the object of the invention is also achieved by a transmission for a bone saw with a connecting rod and with a drive shaft for direct driving of the connecting rod, in which the connecting rod is drivably mounted on the drive shaft, wherein the transmission is characterized in that the connecting rod a has further drive shaft for direct driving.

Not only drive shafts of the drive means can be mounted on or inside the connecting rod, but another shaft, in particular a shaft of the common coupling member, the connecting rod easily penetrate and be stored on both sides of the connecting rod in a housing of the bone saw, if the connecting rod more than one Material recess, preferably two or three material recesses, has.

If, in addition, at least one of the drive devices is configured as an eccentric shaft, the connecting rod can be driven along a circular path with structurally simple means. Preferably, two drive devices are designed as such eccentric shafts.

In this context, it is advantageous if the drive means are mounted eccentrically with respect to the Pleuellängsmittelachse at the connecting rod.

If the drive devices penetrate the connecting rod, the transmission can be made particularly compact. This is particularly true when the drive means are designed as drive shafts, both of which penetrate the connecting rod and are mounted on both sides of the connecting rod in a housing of the transmission.

Thus, two rotating drive means, such as the drive shafts described above, can easily cooperate with the present connecting rod, it is advantageous if the connecting rod has two drive shaft bearings.

In order to be able to individually set the gearbox and in particular the bone saw with respect to differently shaped saw blade geometries, it is advantageous if at least one of the drive devices is mounted displaceably.

By such a variable storage differs in particular the transmission of generic bone saws from the prior art, in which a drive device is always stationary, such as in a housing of the bone saw, stored.

In the present case, a drive shaft of the drive device may be mounted in the housing of the bone saw, for example by means of concentrically configured bearing shells of a bearing, wherein these bearing shells are rotatably mounted in the housing relative to a corresponding bearing seat.

Since such a displaceably mounted drive device already advances in itself considered generic bone saw gear advantageous, relevant features are also without the other features of the invention advantageous.

Another extremely advantageous embodiment provides that the transmission has ceramic bearings.

Be used for storing drive shafts of the transmission ceramic bearings, can be dispensed with any lubrication of the existing bearings of the transmission advantageously. In this respect, can be dispensed with lubricants such as fats and / or oils on the present gear or on the existing bone saw.

This is especially advantageous in a sterile surgical environment because the risk of contamination of the surgical environment by such fats or oils is completely eliminated, although these are mostly biocompatible. In addition, such ceramic bearings can be designed maintenance-free.

In particular, for the aforementioned reasons, it is particularly advantageous if the present drive devices have ceramic bearings.

Since such ceramic bearings develop generic gearbox for bone saws exceptionally advantageous, the features described in this respect are also without the other features of the invention advantageous.

Furthermore, it is advantageous if the center of gravity or the center of gravity of the connecting rod is arranged essentially in the center of a connecting rod bearing or in a region between two drive devices, as a result of which the transmission as a whole can be operated with lower vibration.

Preferably, the connecting rod is constructed such that its center of gravity is disposed substantially at the center of a conrod bearing, such as on a rotation axis of one of the two drive means. Ideally, the focus is on the axis of rotation of the saw blade nearest the drive means. As a result, the bone saw can be operated particularly low vibration, whereby the saw quality can be increased.

It is advantageous if the center of gravity of the connecting rod between two drive shafts of the proposed drive means is located. This also allows a much higher quality sawing be achieved on the present bone saw.

If the connecting rod itself can not be designed such that its center of gravity is arranged between the two drive devices, it is advantageous if the transmission or its transmission elements are provided with a corresponding balancing mass.

By means of such a balancing mass of the total center of gravity, which is formed from the center of gravity of the connecting rod and the center of gravity of the balancing mass, advantageously in a center or center of rotation of a connecting rod bearing or in the area between the two drive means or their storage areas are moved to the connecting rod.

If, in addition, at least one compensating mass is provided, which is arranged on the connecting rod, vibrations in the gear can advantageously be reduced during the operation of the bone saw. As a result, the achievable sawing quality can be further advantageously increased.

It is understood that the transmission can be actuated by different drive motor concepts. For example, the bone saw, in particular the gear of the bone saw, can be driven hydraulically or pneumatically. It is particularly advantageous if the gearbox or the bone saw has a device for coupling at least one of the drive devices to a mechanical motor shaft. A mechanical motor shaft offers a structurally simple motor drive concept.

It is understood that the present invention can be advantageously used on both human and animal bodies.

In particular, the present transmission can also be used advantageously in other motor-driven saws. Thus, ideally, the use of the present invention is not limited to a bone saw.

It is understood that the features of the solutions described above or in the claims can optionally also be combined in order to implement the advantages in a cumulative manner.

Further advantages, objects and features of the present invention will be explained with reference to the appended drawings and their description, in which an example of a bone saw and a transmission with two drive means for a connecting rod are shown and described.

Show it:

1 schematically a perspective view of a bone saw with a transmission comprising a directly driven with two drive shafts connecting rod;

2 schematically a front view of the bone saw from the 1 ;

3 schematically a partially sectioned view of the bone saw from the 1 . 2 along the section line AA according to the 2 ;

4 schematically a partially sectioned view of the bone saw from the 1 to 3 along the section line BB according to the 2 ;

5 schematically a partially sectioned view of the bone saw from the 1 to 4 along the section line CC according to the 4 ;

6 schematically a schematic view of a means of the bone saw from the 1 to 5 driven saw blade, wherein at each point of the saw blade real circular motion is realized; and

7 schematically a schematic diagram of an alternative transmission with two drive cranks for a connecting rod of this transmission and with a balancing mass for the connecting rod.

The in the 1 shown bone saw invention 1 has a two-part housing 2 on which a first half of the housing 3 comprises, on which a second housing half 4 by four Allen screws 5 (here only exemplarily numbered) can be screwed on.

On the front side 6 the bone saw 1 protrudes a connecting rod 7 a gearbox 8th (please refer 3 to 5 ) of the bone saw 1 through the housing 2 through to the outside.

At one of the housing 2 opposite end 9 of the connecting rod 7 is a saw blade carrier 10 present on which saw blades 11 , as an example in the illustration according to the 6 is shown, can be attached.

At the back 12 the bone saw 1 a Flanscheinrichtung not shown here for a mechanical motor shaft (also not shown here) can be flanged and fixed, so that the bone saw 1 in her case 2 does not accommodate a drive motor. In this respect, the bone saw 1 very compact build. A mechanical motor shaft, for example, has the great advantage over pneumatic drive concepts that an exhaust air from the pneumatic system does not get into the surgical area or has to be taken out of it consumingly.

In the illustration according to the 2 is the bone saw 1 shown in a front view. Schematically, in this illustration, the section lines AA and BB through the bone saw 1 drawn through, their sections in the following 3 and 4 are shown.

In the partially sectioned view according to the 3 along the section line AA is easy to see that the connecting rod 7 in the middle of the housing 2 the bone saw 1 is arranged, wherein the connecting rod 7 on the one hand by means of a first drive means 13 for direct driving of the connecting rod 7 and secondly according to the invention by means of a second drive device 14 for direct driving of the connecting rod 7 Is provided.

Because of the connecting rod 7 directly from two drive devices 13 and 14 is driven, the connecting rod can 7 at least in the area of the saw blade carrier on a true circular path 15 , as shown for example in the illustration according to the 6 is shown to be moved.

Both the first drive device 13 as well as the second drive means 14 is in this embodiment, each as a rotating drive shaft 16 respectively 17 (see in particular 4 and 5 ), wherein the first drive shaft 16 around a first axis of rotation 18 and the second drive shaft 17 around a second axis of rotation 19 can rotate.

Here is both the first drive shaft 16 as well as the second drive shaft 17 each as an eccentric shaft 20 respectively 21 designed as well in the presentation according to the 4 is recognizable.

Due to the double drive shafts 16 respectively 17 can the connecting rod 7 along the central axis 22 the bone saw 1 with a circular movement on the one hand according to the first double arrow 23 (see in particular 3 ) move back and forth and on the other hand according to the further double arrow 24 (please refer 4 ) move upwards and downwards, so that from this total the true circular path described above 15 results.

The two drive shafts 16 and 17 are each transverse to the central axis 22 arranged, taking the connecting rod 7 pierced and wherein the connecting rod 7 on the two drive shafts 16 and 17 each with a ceramic bearing 25 respectively 26 (please refer 4 ) is stored.

The two drive shafts 16 respectively 17 are also on the one hand in a bearing plate 27 and on the other hand directly in the second housing half 4 stored. The storage of the two drive shafts 16 respectively 17 in the bearing plate 27 or in the second housing half 4 takes place here also on more ceramic bearings 28 and 29 respectively 30 and 31 ,

The bearing plate 27 is with other hexagon socket screws 32 (here only in the example 4 numbered) on the first housing half 3 firmly but detachably screwed on.

Both the first drive shaft 16 as well as the second drive shaft 17 each wear a gear 33 respectively 34 (please refer 3 ), each with a further helical gear 35 a common coupling member 36 comb.

The common coupling link 36 is in this embodiment as a about a rotation axis 37 rotating shaft 38 configured, which also both in the second housing half 4 as well as in the bearing plate 27 by means of further ceramic bearings 39 and 40 is stored.

Advantageously, the rotation of the two drive shafts 16 and 17 by means of the rotating shaft 38 of the common coupling member 36 synchronized so that both drive shafts 16 and 17 always run in sync as soon as the first drive shaft 16 over her drive bevel gear 42 is driven.

In this respect, the two drive devices 13 and 14 in a common powertrain 43 of the transmission 8th arranged.

The connecting rod 7 is advantageously designed in this embodiment such that its focus 44 (please refer 5 ) directly on the second axis of rotation 19 is located, as in the supervision of the 5 is indicated. Alternatively, it would already be beneficial if the center of gravity 44 in one area 45 between the two drive devices 13 and 14 which would already result in an excellent vibration reduction on the bone saw 1 can be achieved.

That in the 6 saw blade shown 11 can be in a toothed saw blade area 50 and in an unperforated saw blade area 51 be divided, with the saw blade 11 with its unperforated saw blade area 51 on the saw blade carrier 10 can be attached.

The toothed saw blade area 50 is with a variety of saw teeth 52 (numbered here only as an example).

In this embodiment, the saw blade 11 Overall, a length of about 80 mm, with the toothed saw blade area 50 Total length 53 of 60 mm.

Thanks to the described transmission 8th can the saw blade 11 be moved so that every point of the saw blade 11 , in particular every sawtooth 52 of the toothed saw blade area 50 a real circular path 15 . 54 or for example 55 (only quantified by way of example).

When in the 7 shown schematic representation 100 is an alternative gearbox 108 shown, which is essentially a connecting rod 107 with a saw blade 111 , a first drive crank 113 , a second drive crank 114 and a common coupling element 136 includes.

The first drive crank 113 turns around a first axis of rotation 118 while the second drive crank 114 around a second axis of rotation 119 rotates.

Both a first ceramic bearing 125 as well as a second ceramic warehouse 126 are in this embodiment on a frame 161 stored a bone saw, not shown here in detail, wherein at least the drive crank 114 movable on the frame 161 is stored since the second ceramic bearing 126 as an adjustable storage facility 162 is designed. Thus, the transmission can 108 individually on differently designed saw blades 111 be adjusted, thereby advantageously the sawing quality of this transmission 108 equipped bone saw can be further improved significantly.

An additional development shows the present transmission 108 on, as there is a balancing mass 163 comprising, which a mass balance with respect to the Pleuelmasse 164 of the connecting rod 107 causes by the balancing mass 163 in particular vibration-reducing to the second ceramic bearing 126 acts. By means of the balancing mass 163 becomes the focus 144 of the connecting rod 107 as the overall focus 165 with regard to the connecting rod mass 164 and the balancing mass 163 in the center of rotation of the second ceramic bearing 126 shifted, wherein the center of rotation present with the second axis of rotation 119 falls together. Advantageously, this reduces the vibration excitation with respect to the entire bone saw, so that a much more precise saw cut can be achieved.

It goes without saying that the exemplary embodiments explained above are only a first embodiment of the transmission according to the invention for a bone saw or a bone saw and a saw blade. In this respect, these embodiments are not intended to be limiting with respect to the present invention.

All disclosed in the application documents features can be claimed as essential to the invention, provided that they are new individually or in combination over the prior art.

LIST OF REFERENCE NUMBERS

1

Bone

2

casing

3

first half of the housing

4

second housing half

5

Allen screws

6

front

7

pleuel

8th

transmission

9

The End

10

blade carrier

11

sawblade

12

back

13

first drive device

14

second drive device

15

real circular path

16

first drive shaft

17

second drive shaft

18

first axis of rotation

19

second axis of rotation

20

first eccentric shaft

21

second eccentric shaft

22

central axis

23

first double arrow

24

another double arrow

25

first ceramic bearing

26

second ceramic bearing

27

bearing plate

28

another ceramic bearing

29

another ceramic bearing

30

another ceramic bearing

31

another ceramic bearing

32

additional hexagon socket screws

33

first gear

34

another gear

35

helical gear

36

common coupling element

37

axis of rotation

38

rotating shaft

39

another ceramic bearing

40

another ceramic bearing

41

wave eye

42

pinion gear

43

powertrain

44

Center of gravity of the connecting rod

45

Area

50

serrated saw blade area

51

imperforate saw blade area

52

saw teeth

53

length

54

another real circular path

55

another real circular path

100

Schematic diagram

108

alternative transmission

107

pleuel

111

sawblade

113

first drive crank

114

second drive crank

118

first axis of rotation

119

second axis of rotation

125

first ceramic bearing

126

second ceramic bearing

136

common coupling element

144

Center of gravity of the connecting rod

160

direction of rotation

161

frame

162

movable storage facility

163

Leveling compound

164

Pleuelmasse

165

Center of gravity

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 2400696 [0003]

Claims (11)

Transmission ( 8th ; 108 ) for a bone saw ( 1 ) with a connecting rod ( 7 ; 107 ) for driving a saw blade ( 11 ) of the bone saw ( 1 ), characterized in that the transmission ( 8th ; 108 ) more than one drive device ( 13 . 14 ; 113 . 114 ) for driving the connecting rod ( 7 ; 107 ) having. Transmission ( 8th ; 108 ) according to claim 1, characterized in that the drive means ( 13 . 14 ; 113 . 114 ) are connected in parallel to each other and / or the drive means ( 13 . 14 ; 113 . 114 ) a common coupling element ( 36 ; 136 ) exhibit. Transmission ( 8th ; 108 ) according to claim 1 or 2, characterized in that at least one of the drive means ( 13 . 14 ; 113 . 114 ) a drive shaft ( 16 . 17 ), preferably an eccentric shaft ( 20 . 21 ), on which the connecting rod ( 7 ; 107 ) is drivably mounted. Transmission ( 8th ; 108 ) according to one of claims 1 to 3, characterized in that at least one ( 114 ) of the drive devices ( 13 . 14 ; 113 . 114 ) is mounted displaceable. Transmission ( 8th ; 108 ) according to one of claims 1 to 4, characterized in that the center of gravity ( 44 ) or an overall focus ( 165 ) of the connecting rod ( 7 ; 107 ) essentially in focus ( 19 ; 119 ) of a connecting rod bearing ( 26 ; 126 ) or in one area ( 45 ) between two drive devices ( 13 . 14 ; 113 . 114 ), wherein in particular at least one mass balance ( 163 ) for the connecting rod ( 7 ; 107 ) is provided. Saw blade ( 11 ) for a motorized bone saw ( 1 ), in particular according to one of claims 8 to 10, characterized in that the saw blade ( 11 ) has a length of more than 30 mm, preferably more than 50 mm, the saw blade ( 11 ), in particular a toothed saw blade area ( 50 ) with a length ( 53 ) of more than 30 mm, preferably more than 50 mm. Saw blade ( 11 ) according to claim 6, characterized in that the saw blade ( 11 ) has a spherical shape. Bone saw ( 1 ) with a drive and an output ( 7 ; 107 ), in which the output ( 7 ; 107 ) a holding device ( 10 ) for a saw blade ( 11 ) with a large number of saw teeth ( 52 ), characterized in that the output ( 7 ; 107 ) is driven in such a way that by means of the output ( 7 ; 107 ) more than 30% of the saw teeth ( 52 ) on a real circular path ( 15 . 54 . 55 ) or each of the saw teeth ( 52 ) on a real circular path ( 15 . 54 . 55 ) are movable. Bone saw ( 1 ) according to claim 8, characterized by a device for regulating a drive power as a function of a determined saw blade temperature. Bone saw ( 1 ) according to claim 8 or 9, characterized by an endoscopic device or means for receiving such endoscopic device. Method for operating a bone saw ( 1 ), in which a saw blade ( 11 ) by means of a connecting rod ( 7 ; 107 ), characterized in that the connecting rod ( 7 ; 107 ) by means of two drive devices ( 13 . 14 ; 113 . 114 ), which are operated in particular simultaneously and synchronously with each other.

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