DE19853917A1 - Bone-pin cutter has handle, housing with top and bottom covers, holder, hole, rotor and hollow shaft - Google Patents

Abstract

The cutter incorporates shearing elements driven by a rotary piston unit operated by a control valve. A billet-shaped handle (1) coaxial with the lengthwise axis of the housing (12) is positioned on the top housing-cover (9). The top end of the operating valve is integrated in the handle. The bottom housing cover (13) has a holder (14) for the plug-in connection for a cutter-head. The handle has a hole (26) containing the projecting pin as an extension of the rotor's (10) hollow shaft (15) the bottom end of which has an inner hexagonal part forming a drive connection with the shearing-pin.

Description

The invention relates to a bolt separator for surgical orthopedic Operations for separating or cutting round or profiled ones Metal parts, which are fixed at one end in the bone mass.

After implanting Schanz screws and / or Steinmann nails and their corresponding fixation in the bone mass must protruding bolt ends can be shortened to the appropriate length. Bolts have a very high strength, so a very high shear force is required. Bolt cutters of the brand are widely used in the hospital sector SYNTHES, each consisting of a set of cutting heads for different Bolt types and diameters as well as two ring spanners with long lever arms exist to drive the cutting heads. The cutting heads consist of two concentrically mounted pipes that have cutting plates on one end, which have eccentric bores, the diameter of which is approximately that of the corresponding bolts to be cut. At the other end of the pipes are, for example. Hexagonal connections are provided on the ring spanners with long lever arms be attached so that the necessary high shear moment is applied can. In the starting position, the holes in the cutting inserts of both coincide Tube. The shaving head can now be pushed onto the bolt to be separated become. Are the levers spread apart in the starting position moved, the bolt is sheared off. When operating the two levers you can however, uncontrolled forces are transferred to the shear, which u. a. a Loosening of the implants in the bone can result.

To avoid these disadvantages, DE 87 08 571 U1 Bolzeritrenngerät proposed that a pressure-operated Rotary piston drive has. The rotary lobe is in a cylindrical housing housed, on the upper housing part directly a spool for Actuation is provided. In the lower part of the housing are a shear sleeve and one of Rotary piston driven shear dome added. Housing upper part and Lower part of the housing are four outside the cylindrical housing shell Screws evenly distributed around the circumference. However, this device is difficult and unwieldy to use. In addition, there is a change from that SYNTHES lever device for the bolt cutting device according to DE 87 08 571 U1 for the  Expensive for users, since a complete set of shaving tools is also supplied got to.

The invention is therefore based on the object of a bolt cutting device at the outset Specify the type described, with which the disadvantages of the prior art Technology to be eliminated.

This object is achieved by the features of claim 1. The Subclaims contain advantageous developments of the invention.

According to the invention, a pressure medium-operated rotary piston drive is used for a Bolt cutting device with a coaxial to the longitudinal axis of the drive housing aligned stick-like handle. This is an exact The device can be placed centrally on the protruding bolts. An im Upper area of the handle integrated actuator valve for the drive simply by pressing the operator's finger on an operating button switched. The operator does not have to exert large forces, so that Danger of the device axis tipping or tilting with respect to the pin axis is reduced to a minimum, thereby loosening the implants in the bone is avoided. Thanks to the form-fitting plug-in shaving head holder Device for the shaving heads of the SYNTHES lever device available in the clinic or other common shaving heads.

The invention is illustrated below using an exemplary embodiment described. Show it:

Fig. 1 is a cross sectional view of a bolt separation device according to the invention,

Fig. 2 plan view of the open housing (without the top cover),

Fig. 3 operating valve,

Fig. 4 top view of the upper lid.

As can be seen from FIG. 1, the housing 12 of the rotary piston drive consists of a cylinder jacket which is closed with an upper cover 9 and a lower cover 13 so as to be pressure-tight. In the cylinder space, two partition walls 11 are arranged, which bear sealingly against the rotor shaft 15 and divide the cylinder space into two segments. The partition walls 11 are provided with stops 37 for the respective end position of the rotor blades 16 ( FIG. 2). In the two covers 9 , 13 , the rotor shaft 15 of the rotor 10 , which axially penetrates the cylinder space, is mounted in bearing bushings 8 and in a sealing manner. The rotor shaft 15 is hollow and has a hexagon socket 22 at its lower end for establishing the drive connection with the shear pin 23 . The receptacle 14 for the cutting head 19 is flanged to the lower cover 13 coaxially with the rotor shaft 15 . This receptacle 14 has a hexagon socket connection 24 which fixes the shear sleeve 25 in a rotationally fixed manner relative to the drive housing 12 . The cutting head 19 is secured in the receptacle 14 by a resilient pressure piece 20 .

On the upper cover 9 , a stick-like, ergonomically shaped handle 1 is flanged coaxially to the longitudinal axis of the housing, which has a bore 26 aligned with the hollow rotor shaft 15 and penetrating the handle 1 lengthways. The actuating valve for the drive is integrated in the upper end of the handle 1 ( FIG. 3). A rotary slide valve 6 is mounted in a valve bushing 5 . From the rotary valve 6 , two parallel line channels 27 lead in the axial direction through the handle 1 to the upper cover 9 . The two line channels 27 are alternately connected by the rotary valve 6 to the compressed air connection or the environment. They each open into a connection bore 28 in the upper cover 9 . From each of these connection bores 28 lead connection channels 29 in the upper cover 9 to each of the two segments of the cylinder space. As a result, the double torque can be achieved. The connecting channels 29 are formed by intersecting bores which are oriented at an angle to one another and parallel to the plane of the cover 9 and which are closed by sealing plugs 35 on the outer circumference of the upper housing cover 9 ( FIG. 4). This arrangement of the connecting channels 29 results in a particularly weight-saving design of the upper cover 9 . Depending on the switching position of the rotary valve, the rotor blades 16 are pressurized 6 times on one side and sometimes on the other side. The air displaced on the other side of the rotor blade can escape through the conduit duct 27 which is opened from the rotary valve 6 to the surroundings.

The rotary slide 6 has a pinion 4 which meshes with a toothed section of an actuating pin 2 . The actuating pin 2 passes through the handle 1 transversely to its longitudinal axis. The valve can be switched to the on or off position by moving it into the end positions of the pin 2 . Alternatively, the pin could be held in the off position by spring force, for example. To actuate the shear drive, the pin must then be pressed into the on position against the spring force. In this case, the pin can advantageously be aligned in the axial direction of the handle 1 and can be configured at the top of the handle as a switch button that can be conveniently operated with the thumb.

Reference list

1

Handle

2nd

Actuating pin

3rd

Control button

4th

pinion

5

Valve bushing

6

Rotary valve

7

Connector

8th

Bearing bush

9

Housing cover, top

10th

rotor

11

partition wall

12th

casing

13

Housing cover, below

14

Holder for cutting head

15

Rotor shaft

16

Rotor bushing

17th

Sealing ring

18th

Bearing bush

19th

Cutting head

20th

Thrust piece, springy

21

mother

22

Hexagon socket

23

Shearthorn

24th

Hexagon socket connection

25th

Shear sleeve

26

drilling

27

Conduit

28

Connection hole

29

Connecting channel

30th

O-ring

32

O-ring

33

O-ring

34

O-ring

35

Sealing plug

36

Seal, silicone

37

attack

40

disc

41

cylinder head screw

42

Dowel pin

43

Dowel pin

44

Dowel pin

Claims (12)

1. Bolt cutting device for surgical orthopedic operations, for cutting or cutting round or profiled metal parts, which are fixed at one end in the bone dimensions, with the help of known shear elements such as shear bushing and shear mandrel, which are driven by a rotary piston unit that can be actuated via a control valve are characterized in that

• - On the upper housing cover ( 9 ) a coaxial to the longitudinal axis of the housing ( 12 ) aligned stick-like handle ( 1 ) is provided, in the upper end of which the actuating valve for the drive is integrated, and
• - On the lower housing cover ( 13 ) a receptacle ( 14 ) for the positively pluggable connection of a cutting head ( 19 ) is arranged.

2. Bolt separator according to claim 1, characterized in that the handle ( 1 ) in extension of the hollow shaft ( 15 ) of the rotor ( 10 ) has a bore ( 26 ) for receiving the bolt protrusion. 3. Bolt separator according to claim 2, characterized in that the rotor hollow shaft ( 15 ) has an internal hexagon ( 22 ) at its lower end, for establishing the drive connection with the shear pin ( 23 ). 4. Bolt cutting device according to one of claims 1 to 3, characterized in that the cutting head receptacle ( 14 ) on the lower housing cover ( 13 ) has a hexagon socket ( 24 ) which fixes the shear sleeve ( 25 ) rotatably relative to the housing ( 12 ), and that a resilient pressure piece ( 20 ) is arranged in the hexagon socket ( 24 ). 5. Bolt separator according to one of claims 1 to 4, characterized in that the actuating valve is designed as a rotary slide valve ( 6 ). 6. Bolt separator according to one of claims 1 to 5, characterized in that the actuating valve via a handle ( 1 ) transversely penetrating actuating pin ( 2 ) in the on and off position is switchable. 7. Bolt separating device according to one of claims 1 to 5, characterized in that the actuating valve can be switched against the force of a spring by means of a switch button which can be operated with the thumb from above in the axial direction of the handle ( 1 ), the switch button being not actuated by the Spring force is kept in the off position. 8. Bolt separator according to one of claims 1 to 7, characterized in that two parallel line channels ( 27 ) are provided in the handle ( 1 ) in the longitudinal direction thereof, which produce the line connections from the actuating valve to the cylinder space of the rotary piston unit. 9. Bolt separator according to claim 8, characterized in that in the upper housing cover ( 9 ) connecting channels ( 29 ) are guided, the line connections from the two line channels ( 27 ) of the handle ( 1 ) to each of the two segments formed by partitions ( 11 ) of the cylinder space. 10. Bolt separator according to claim 9, characterized in that the connecting channels ( 29 ) are each formed by intersecting, mutually angled and parallel to the cover plane holes which are closed on the outer circumference of the upper housing cover ( 9 ) by sealing plugs ( 35 ). 11. Bolt separator according to one of claims 1 to 10, characterized in that the housing ( 12 ) is clamped with cylinder screws ( 41 ) which are arranged within the housing shell. 12. Bolt separator according to claims 9 and 11, characterized in that two cheese head screws ( 41 ) are arranged in the region of the partition walls ( 11 ).