DE9006694U1 - screwdriver - Google Patents

Description

HOEGER,

PATEN. TANLAELTE UHLANDStRASSE 14 c · D 7OOO STUTTGART 1

&Aacgr; 49279 u Applicant: AESCUTJVP AG

u-219 7200 Tuttlingen

June 12, 1990

SHOE DISC

The invention relates to a screwdriver designed for surgical applications with a head and a shaft that carries the screw blade, is guided axially in the handle and rotates relative to the handle around the screwdriver axis.

A screwdriver of the type mentioned above for surgical purposes is described, for example, in DE Patent 3 539 502. The handle of this screwdriver consists of two handle parts that are located one behind the other in the direction of the screwdriver axis, but are adjacent to one another but can be rotated against one another. The shaft is anchored in a rotationally fixed manner in the front handle part, i.e. the part facing the screw blade. When turning, the rear handle part lies in the palm of the user's hand, while the front handle part is turned with the thumb, middle and index fingers. This allows the screw to be turned very comfortably and, above all, very sensitively. However, this screwdriver is not suitable for tightening or loosening a screw using relatively high forces.

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This is of course possible with a screwdriver such as that described in US Patent 4,480,668, in which the screwdriver is securely anchored in the one-piece handle. However, this screwdriver does not allow a screw to be positioned and tightened particularly delicately.

Even with a surgical hand instrument described in European patent application 0287823, which can be used as a screwdriver, only powerful, but not delicate, screwing is possible. In the surgical hand instrument, a ^r ; shaft is rotatable in the handle and mounted coaxially to it.

Two gears are attached to the shaft and a pawl on the handle, which can be selectively engaged with one of the two gears Ij. Depending on which gear the pawl is currently engaging with, the shaft is rotated in one or the opposite direction when the handle is turned. In the opposite direction, the shaft can be rotated around the screwdriver axis relative to the handle, but this movement requires a lot of force because the resistance of the pawl pressing on the tooth flanks must be overcome, which is why this movement cannot be carried out sensitively.

The aim of the innovation is to provide a screwdriver of this type, which is simple in design and which allows a screw to be turned both sensitively and with a small torque and by applying relatively high forces.

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This task is solved with a screwdriver of the type mentioned above in an innovative manner by providing a releasable locking mechanism that eliminates the ability to rotate.

The new screwdriver is particularly suitable for turning mini-Q-steosynthesis screws. On the one hand, it can be used to carefully screw in the small screws and, on the other hand, to transfer relatively large forces to the screw blade and thus to the screws when tightening and especially when loosening these screws. When performing an operation, it is very advantageous if the various operations mentioned can be carried out with one tool.

The locking mechanism can be advantageously released or established by means of an axial displacement of the shaft relative to the handle. It is advantageous in this case that the switching from the phase in which the screw is turned with sensitivity to the phase in which the screw is turned with force, or the switching in the opposite direction, can be carried out using only the hand in which the screwdriver is lying.

It is advantageous if the shaft outside the area enclosed by the handle has an extension that is connected to it in a rotationally fixed manner and protrudes from it. Such an extension allows small torques to be transferred to the screw to be screwed in more precisely using finger pressure than if the torque were applied directly to the shaft.

A 49 279 u AESCULAP AG

A solution or production of the locking by means of axial displacement of the shaft can advantageously be carried out if the locking is formed by a locking element in the handle and in the shaft, with one element advantageously forming at least one recess and the other element at least one projection, which can be brought into engagement with one another by a rotational movement and an axial movement of the shaft relative to the handle. With these locking elements, the production of the locking is very simple. For example, the two elements are moved into a position facing one another by rotating the shaft about the screwdriver axis relative to the handle and then towards one another until the projection engages in the recess. It is advantageous if there are several recesses which are the same distance from the screwdriver axis and the same orientation with respect to the axis, with adjacent recesses being uniformly spaced, and if there are at most as many projections as there are recesses.

Advantageously, the recess is designed as a hole running parallel to the screwdriver axis in the surface of the extension facing the handle and the projection is designed as a bolt running parallel to the screwdriver axis and protruding from the handle. To create the locking, in this design of the screwdriver, the hole is opened by rotating the shaft around the screwdriver axis relative to the handle.

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aligned with the bolt, then the hole and bolt are moved towards each other by an axial displacement of the shaft relative to the handle until the bolt is inserted into the hole.

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The shaft is designed with a knurled disk that protrudes from the front of the handle. In this design of the screwdriver, the bolts protrude from the front of the handle and the holes are inserted into the surface of the knurled disk that faces the front of the handle. The knurled disk not only serves to accommodate the holes, but also enables a particularly finely tuned transfer of small forces to the screw to be screwed in. The handle rests on the palm of the user's hand and is held with the ring finger and little finger, while the thumb, middle finger and index finger turn the knurled disk.

It is advantageous if the lock is held in the released position by spring force.

In a favorable arrangement for holding the lock in the released position with spring force, the spring runs in a guide that is aligned radially to the shaft, and an annular groove is provided on the shaft into which a holding element that is attached to the end of the spring facing the shaft fits. With such an arrangement, the shaft can be connected to the handle in a mechanically relatively stable manner.

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AESCULAP AG

Such an arrangement is also advantageous because it can easily be improved in such a way that the shaft can also be held mechanically relatively stable in a second position relative to the handle. This second position is preferably a

It is only necessary that a second annular groove is provided on the shaft, adjacent to the first annular groove but closer to the screw blade than the latter. With this arrangement, the new screwdriver can be anchored securely in both of its working positions, whereby the change from one position to the other can be accomplished without great effort. This is particularly true when the spring forms a ball-locking position with the holding element.

Another way of holding the lock in the released position with spring force is to have the spring with its end facing ^{the blade attached} to an extension of the shaft and its other end attached to the handle. When the recesses and the bolt(s) are turned into the correct position relative to one another, all that is required to create the lock is to press the spring against the screw to be screwed in.

The installation of the spring is particularly easy if it is arranged between the handle and the knurled disk or inside the handle in a widening of the hole in which the shaft is guided in the handle.

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The following description of preferred embodiments of the screwdriver according to the innovation serves to provide further explanation in conjunction with the drawing. Show:

Figure 1:

In longitudinal section: a first embodiment of the screwdriver according to the innovation shown in such a way that the shaft is rotatably connected to the handle;

Figure 2:

the same representation as in Figure 1, with the difference that the shaft is connected to the handle in a rotationally fixed manner;

Figures 3 and 4:

in longitudinal section and in a representation in which the shaft is rotatably connected to the handle, a second and a third embodiment of the screwdriver according to the innovation, which differ from the first embodiment in the way in which the screwdriver is held in its two working positions.

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The screwdriver 1 shown in Figures 1 and 2 consists of a handle 2 and a shaft 4. The handle 2 has a cylindrical and axially guided hole 3 extending from its front side 16, in which the rear part of the shaft 4 is inserted and guided. At least the part of the shaft 4 enclosed by the handle 2 is cylindrical and its diameter is approximately the same as the diameter of the hole 3.

A screw clamp is formed on the end of the shaft 4 facing away from the handle 2, and the part of the shaft 4 not enclosed by the handle 2 also has devices such as a collet, a clamping sleeve and a gripping disk for holding the screw to be screwed in. These parts, which are generally designated with the reference number 18 in the figures, are of no importance for the innovation. They will therefore not be discussed further below.

Bolts 6 protrude from the front side 16 of the handle 2, which is in a plane perpendicular to the screwdriver axis, and all have the same distance from the screwdriver axis and the distance between adjacent bolts is uniform. In front of the front side 16 there is a knurled disk 5 which is connected to the shaft 4 in a rotationally fixed manner and which protrudes perpendicularly from the shaft and is arranged coaxially to it. On its surface facing the front side 16, the knurled disk 5 has holes 7 which correspond to the bolts 6 in terms of number, design and orientation and position with respect to the screwdriver axis.

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In the representation shown in Figure 1, the front side 16 and the knurled disk 5 are so far apart that the bolts 6 do not engage in the holes 7. In this position, the knurled disks 5 and thus the shaft 4 are movable relative to the handle 2 (rotatable position). If the knurled disk 5 is rotated relative to the handle 2 so that the bolts 6 are aligned with the holes 7 and the shaft 4 is then moved axially towards the handle 2, the holes 6 fit into the ^holes 7 and thus connect the knurled disk 5 to the handle 2 in a rotationally fixed manner (rotatable position). In the representation shown in Figure 2, the knurled disks 5 are 'er ^-iff 2 and the knurled disk 5 in this position to each other.

In order to facilitate the engagement of the bolts 6 in the holes 7, the bolts are rounded at their ends facing the holes and the holes are conically widened at their ends facing the bolts.

In order to be able to fix the knurled disk 5 in the two positions mentioned, shown in Figures 1 and 2, to the handle 2, two annular grooves 9 and 10 are provided on the area of the shaft 4 guided in the hole 3, and a ball locking position 8 is provided in the handle 2, which is guided in a hole 17 running radially to the screwdriver axis and aligned perpendicularly to it. If the ball locking position 8 engages in the annular groove 10, the bolts 6 engage in the holes 7 and lock it in the annular groove that is further away from the front side 16 than the annular groove 10.

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9, holes 7 and bolts 6 are spaced apart from one another. By using the ball locking mechanism 8, on the one hand, the change from one position to the other can be carried out without great expenditure of force *■■■'-& on the other hand, the shaft is mechanically relatively stable in the two positions.

The handle 2 consists of a front handle part 11 or 12 facing the cutting blade and a rear handle part 11 or 12. The hole 3 ends at the interface between the two handle parts. In the handle part 12, a hole extension 14 arranged coaxially to the hole 3 and closed on one side begins at the interface. A sleeve 13 is pressed into the hole extension 14, which has a larger diameter than the hole 3, the inner diameter of which is equal to the diameter of the hole 3. The sleeve 13, which abuts the interface between the two handle parts, is at least as much shorter than the hole extension 14 as the change in distance between the knurled disk 5 and the front side 16 when changing from the rotating to the non-rotating position. The end of the shaft extending into the hole extension 14 forms a screwed-on circular disk 15 which projects radially beyond the shaft cross-section and whose diameter lies between the inner diameter of the hole extension 14 and that of the sleeve 13.

The two handle parts 11 and 12 are permanently connected to each other. However, the connection is only made after the shaft 4 has been pushed through the hole 3 from the front side 16.

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pushed through, the sleeve 13 is placed on the shaft end, the circular disk 15 is screwed onto the shaft and finally the handle part 12 is put over the shaft end and the sleeve 13, which is then pressed into the hole extension 14.

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XII UVSi. \&Lgr;1~ CSllJkSaX Oil JTWOJ. UXWII XXOU. l# UXC3 aOIlülUQ XsS ail UGIII UItSIII The end of the sleeve 13 facing the handle end is shown in FIG. In the non-rotatable position, the circular disk 15 is located at or near the closed end of the extension 14.

If a screw held by the screw blade is to be screwed into a bone plate using the screwdriver 1, for example, the knurled disk 5 with the handle 2 is initially in the rotating position, i.e. in the position shown in Figure 1. The surgeon holds the screwdriver 1 in his hand so that the palm of his hand is at the end of the handle and the little finger and the ring finger are at the handle 2. He places the screw at the intended 1 ν* α \\ +■

the middle and index finger turns the knurled disk 5. He is able to carry out the rotation very sensitively. To tighten the screw, after the surgeon has first turned the knurled disk relative to the handle 2 so far that the holes 7 are aligned with the bolts 6, the knurled disk 5 is pushed back, whereby the bolts 6 engage in the holes 7 and the ball locking mechanism 8 comes out of the ring groove 9 and snaps into the ring groove 10. The surgeon can now tighten the screw by turning the handle 2 with a greater torque. In order to increase the force

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To improve transmission during tightening, the handle can have surfaces or - essentially - grooves running parallel to the screwdriver axis.

To remove the screw, proceed in the reverse order: First, insert the screwdriver into

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After changing to the rotatable position, the screw can be completely unscrewed again by simply turning the edge disk 5.

The rear end of the handle 2 can be designed as a handle cap that can rotate freely around the screwdriver axis. ^This allows the friction between the handle and the surgical glove in the palm area to be minimized when tightening and loosening the screw.

The embodiments of the screwdriver according to the innovation shown in Figures 3 and 4 differ from the previous example only in the type of fixation in the non-rotatable and ⁱⁿ the ^rotatable position. _{The two} screwdrivers 20 and ²⁵ are held ⁱⁿ the rotatable position ^by means of the pressure of compression springs arranged coaxially with the shaft 4. In order to reach the non-rotatable position, the handle must be pressed against the spring force in the direction of the screw to be screwed in, whereby the bolts 6 are brought into engagement in the holes 7.

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All structural details that have nothing to do with the fixation in the two positions mentioned are identical in the three examples. These details will therefore not be discussed in more detail in the description of screwdrivers 20 and 25.

In the screwdriver 20 shown in Figure 3, the hole 3 has a cylindrical widening 21 coaxial with the hole 3 at its end adjacent to the handle part 12. The widening is at least long enough to accommodate a clamping ring 23 attached to the shaft 4, a compression spring 22 in the relaxed state placed on the shaft 4 and a ring 24 pressed into the widening 21. The clamping ring 23 faces the transition between the hole 3 and the widening 21 and its outer diameter is slightly smaller than the inner diameter of the widening 21. The compression spring 22 is arranged between the two rings 23 and 24. Its inner diameter is larger than the outer diameter.

24 is slightly larger than the outside diameter of the shaft 4. The spring 22, the clamping ring 23 and the ring 24 are installed in the expansion 21 before the front and rear handle parts 11 and 12 are firmly connected to one another. When the spring 21 is relaxed, the handle 2 and the knurled disk 5 are spaced apart such that the bolts 6 do not engage in the holes 7, i.e. the screwdriver is in the rotating position.

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In order to get into the non-rotating position, the operator first rotates the knurled disk relative to the handle 2 in order to align the bolts 6 with the holes 7. He then presses the handle 2 against the spring force in the direction of the screw to be screwed in. In doing so, the shaft 4 and thus the clamping ring 23 are moved in the direction of the front part 12. The compression spring 22 is thereby compressed and pressed against the ring 24. At the same time, the bolts 6 engage in the holes 7. When the pressure on the handle 2 is removed, the spring 22 relaxes again, whereby the clamping ring 23 - and thus the shaft 4 - are moved in the direction of the front side 16 and the bolts 6 are retracted from the holes 7, i.e. the rotating position is returned.

In the screwdriver 25 (Figure 4), the compression spring 26 is not enclosed in the handle 2, but is positioned between the front side 16 and the knurled disk 5. For radial fixing of the compression spring 26 inserted into the shaft 4,

The spring 26 has a cylindrical recess 27 running along the shaft 4, which has an inner diameter that is approximately the same size as the outer diameter of the compression spring 26. The spring 26 is installed by putting it on the shaft 4 before the latter is inserted into the hole 3. The compression spring 26 is long enough in the relaxed state that the bolts 6 do not engage in the holes 7. In other words, this means that in the relaxed state the handle and knurled disk can rotate against each other. To get into the rotationally fixed position, the operator carries out the same steps as for

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Using the screwdriver 20. As long as the pressure is applied, the compression spring 26 is pressed into the recess 27 by means of the front side 16 of the handle 2 and is thereby compressed, with the bolts 6 simultaneously engaging in the holes 7. When the pressure ceases, the compression spring 26 relaxes again and the bolts 6 are withdrawn from the holes 7.

When using screwdrivers 20 and 25 to screw in a screw held by the screw blade, for example in a bone plate, the screw is placed in the hole provided and then screwed in by turning the knurled disk 5 while holding the handle, without exerting pressure on the handle 2 in the direction of the screw to be screwed in (rotatable position). Only when the screw is to be tightened, after the bolts have been aligned with the holes, does the transition to the non-rotatable position take place by pressing the handle against the spring force in the direction of the screw to be screwed in and tightening the screw by turning the handle forcefully. When loosening and unscrewing the screw, the steps are carried out in the reverse order.

Claims (1)

HOEGER, STBLLRBCHt '&PARTNER PATENT ATTORNEYS UHLANDSTRASSE 14 c - D 7OOO STUTTGART 1 A 49278 u Applicant: AESCULAP AG d-214 7200 Tuttlingen 24 April 1990 PROTECTION 2CLAIMS 1. Screwdriver for surgical applications, with a handle and a shaft carrying the screw blade, guided axially in the handle and rotatable relative to the handle about the screwdriver axis, characterized in that a releasable lock is provided which cancels the rotatability of the shaft relative to the handle. 2. Screwdriver according to claim 1, characterized in that the locking can be released and produced by means of an axial displacement of the shaft (4) relative to the handle (2). 3. Screwdriver according to one of the preceding claims, characterized in that the shaft (4) outside the area enclosed by the handle (2) has an extension which is connected to it in a rotationally fixed manner and protrudes from it. A 49 279 u AESCULAP AG - 17 - 4. Screwdriver according to one of the preceding claims, characterized in that the locking mechanism is formed by a locking element on the handle (2) and on the shaft (4). Screwdriver according to claim 4, characterized in that one element forms at least one recess and the axial element forms at least one projection, which can be brought into contact with one another by a rotary movement and an axial movement of the blade (4) relative to the handle (2). 6. Screwdriver according to claim 5, characterized in that there are several recesses which have the same distance from the screwdriver axis and the same orientation with respect to the axis, adjacent recesses being uniformly spaced from one another, and that there are at most ^SO many projections as recesses. 7. Screwdriver according to claim 5 or 6, characterized in that the recess is designed as holes (7) running parallel to the screwdriver axis in the surface of the said extension facing the handle (2) and the projections are designed as holes running parallel to the &Aacgr; 49 279 U AESCULAP AG - 18 - Screwdriver lizard-shaped bolts (6) protruding from the front (16) of the handle (2) are formed. Screwdriver according to one of claims 3 to 7, characterized in that the extension is designed as a knurled disk (5) arranged coaxially to the shaft and the front side (16) of the handle (2) and projecting perpendicularly from the shaft (4). 9. Screwdriver according to one of the preceding claims, characterized in that the locking mechanism is held in the unlocked position by means of spring force. 10. Screwdriver according to claim 9, characterized in that a spring is guided in a hole (17) in the handle (2) that runs radially toward the shaft (4) and that an annular groove (10) is provided on the shaft (4), into which a holding member that is supported on the end of the spring facing the shaft engages. 11. Screwdriver according to claim 10, characterized in that for holding the locking in the A 49 279 u '.·."...· ..*\.* AESCULAP AG - 19 - locked position, a second annular groove (10) is provided on the switch (4) which is adjacent to the first annular groove (9) and closer to the front side (16) than the first annular groove (9). 12. Screwdriver according to claim 10 or 11, characterized in that the spring forms a ball locking position (8) with the holding member. 13. Screwdriver according to claim ?, characterized in that a spring (22, 26) coaxially surrounds the shaft (4) and rests with one end facing the screw blade on an extension of the shaft (4) and with its other end on the handle (2). 14. Screwdriver according to claim 13, characterized in that the spring is arranged between the front side (iö) of the handle (2) and the knurled disk (5). 15. Screwdriver according to claim 13, characterized in that the spring is arranged inside the handle (2) in a widening (21) of the hole (3) between a clamping ring (23) fastened to the shaft (4) and a ring (24) fastened to the handle (2).