Medical instrument

The invention relates to a medical instrument comprising at least one movable tool element and at least one actuating element which is mounted such as to be pivotal about a pivotal axis and is coupled to the at least one tool element for the purposes of moving the tool element as a result of a pivotal movement of the actuating element, wherein, for the pivotal mounting of the at least one actuating element, there is provided a pivotal bearing comprising a bearing shaft holder and a bearing shaft which is held in the bearing shaft holder in a working position, wherein the at least one actuating element incorporates the bearing shaft or the bearing shaft holder, wherein the bearing shaft holder has an insertion opening and is insertable through the insertion opening into the bearing shaft holder in a direction that is transverse or substantially transverse to the pivotal axis.

FIELD OF THE INVENTION

The present invention relates to medical instruments generally, and more specifically to a medical instrument comprising at least one movably arranged tool element and at least one actuating element which is mounted such as to be pivotal about a pivotal axis and is directly or indirectly coupled to the at least one tool element for the purposes of moving the tool element as a result of a pivotal movement of the actuating element, wherein, for the pivotal mounting of the at least one actuating element, there is provided a pivotal bearing comprising a bearing shaft holder and a bearing shaft which is held in the bearing shaft holder in a working position, wherein the at least one actuating element incorporates the bearing shaft or the bearing shaft holder.

BACKGROUND OF THE INVENTION

Medical instruments of the type described hereinabove are known in various forms. The pivotal bearing of one or more actuating elements of the instruments is usually realized in that the bearing shaft holder is in the form of a bore into which the bearing shaft is slid coaxially with respect to the longitudinal axis defined thereby and is fixed by riveting, a swelling process or by means of a screw connection for example. The disadvantage of this however are the high assembly costs associated with the construction of the pivotal bearing.

SUMMARY OF THE INVENTION

In a first aspect of the invention, a medical instrument comprises at least one movable tool element and at least one actuating element which is mounted such as to be pivotal about a pivotal axis and is directly or indirectly coupled to the at least one tool element for the purposes of moving the tool element as a result of a pivotal movement of the actuating element. For the pivotal mounting of the at least one actuating element, there is provided a pivotal bearing comprising a bearing shaft holder and a bearing shaft which is held in the bearing shaft holder in a working position. The at least one actuating element incorporates the bearing shaft or the bearing shaft holder. The bearing shaft holder has an insertion opening. In an assembly position, the bearing shaft is insertable through the insertion opening into the bearing shaft holder in a direction that is transverse or substantially transverse to the pivotal axis.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a medical instrument comprising at least one movable tool element and at least one actuating element which is mounted such as to be pivotal about a pivotal axis and is directly or indirectly coupled to the at least one tool element for the purposes of moving the tool element as a result of a pivotal movement of the actuating element, wherein, for the pivotal mounting of the at least one actuating element, there is provided a pivotal bearing comprising a bearing shaft holder and a bearing shaft which is held in the bearing shaft holder in a working position, wherein the at least one actuating element incorporates the bearing shaft or the bearing shaft holder, wherein the bearing shaft holder has an insertion opening and wherein, in an assembly position, the bearing shaft is insertable through the insertion opening into the bearing shaft holder in a direction that is transverse or substantially transverse to the pivotal axis.

In particular, the development proposed in accordance with the invention enables the bearing shaft to be arranged or formed on the at least one actuating element or on the instrument including being formed in one piece manner with the instrument or the at least one actuating element for example, and, for the purposes of assembling the instrument, simply introducing the bearing shaft into the bearing shaft holder by inserting it through the insertion opening. Further elements, tools or working steps, such as are necessary in the known instruments in order to form a fitting of two mutually pivotal parts of the instrument, are not then required for the assembly of the at least one actuating element on the instrument. After the insertion of the bearing shaft into the bearing shaft holder, the at least one actuating element can be pivoted, especially directly, about the pivotal axis in order to directly or indirectly move the at least one tool element in a desired manner as a result of such a pivotal movement.

It is advantageous if the bearing shaft that has been inserted into the bearing shaft holder is movable from the assembly position into the working position in which the bearing shaft is held captive in the bearing shaft holder by pivoting it about the pivotal axis. This permits the specially formed bearing shaft holder together with the bearing shaft in particular to be designed in such a way that the bearing shaft is insertable into the bearing shaft holder firstly by means of a purely translatory movement whereafter it is movable by means of a pivotal movement into the working position in which the bearing shaft is held captive in the bearing shaft holder, i.e. in a position in which it cannot be moved back out of the bearing shaft holder through the insertion opening by a translatory movement.

The medical instrument can be constructed in a particularly simple manner if the insertion opening is in the form of a slot opening the bearing shaft holder on one side thereof. The bearing shaft can then be inserted through the slot into the bearing shaft holder in a direction transverse to the pivotal axis.

The bearing shaft can be inserted into the bearing shaft holder in a particularly simple and direct manner if the slot extends away from the pivotal axis in the radial direction.

It is expedient if the slot comprises mutually facing inner surfaces. These can then establish the width of the slot in a simple manner.

The insertion opening can be produced in a particularly simple manner if the inner surfaces run parallel or substantially parallel to a plane containing the pivotal axis. They can then be prepared by a saw-cut or by milling when forming the slot for example.

It is advantageous if the width of the slot is smaller than a diameter defined by the bearing shaft holder. Such a slot enables a suitably formed bearing shaft to be securely held captive in the bearing shaft holder when the instrument is not in the assembly position. It is only when in the assembly position that the bearing shaft can be inserted into or removed from the bearing shaft holder via the slot.

It is expedient if the bearing shaft holder comprises at least one hollow cylindrical inner wall surface section which is concentric with the pivotal axis. An inner wall surface section that has been formed in this way makes it possible for a pivotal movement of the bearing shaft and thus of the e.g. at least one actuating element about the pivotal axis to be guided in a defined manner.

It is advantageous if the bearing shaft comprises at least one cylindrical wall surface section which is concentric with the pivotal axis. It is expedient if two wall surface sections of this type are provided. In particular, cylindrical wall surface sections in cooperation with one or more corresponding hollow cylindrical inner wall surface sections of the bearing shaft holder can lead to a defined pivotal movement of the bearing shaft in the bearing shaft holder.

In accordance with a further advantageous embodiment of the invention, provision may be made for an outer diameter of the bearing shaft which is defined by the at least one cylindrical wall surface section and an inner diameter of the bearing shaft holder which is defined by the at least one inner wall surface section to be mutually matched for play-free or substantially play-free pivoting of the bearing shaft in the bearing shaft holder. This arrangement makes it possible to provide a defined pivotal movement of the at least one actuating element about the pivotal axis.

The bearing shaft can be produced in a particularly simple manner if it is formed from a cylindrical or substantially cylindrical base body and comprises two flattened portions which are laterally spaced from the pivotal axis. The flattened portions can be produced in a simple manner by milling, filing or some other process for machining the base body. In particular, the bearing shaft can be formed in one piece manner with the instrument or the at least one actuating element.

Expediently, the flattened portions run in parallel with each other. In particular, this makes it possible to introduce the bearing shaft in a defined manner, through a slot which laterally opens the bearing shaft holder, into the slot which advantageously may comprise inner surfaces running parallel to each other.

It is advantageous if the spacing of the flattened portions from each other is smaller than the width of the insertion opening. It is then possible to introduce the bearing shaft through the insertion opening into the bearing shaft holder in a defined manner and without jamming.

It is expedient if the instrument comprises an actuating device which comprises the at least one actuating element and a second actuating element which is arranged immovably on the instrument. In particular, such an actuating device makes it possible to hold the instrument securely on the one hand, and to move the at least one tool element in a defined and delicate manner by appropriate manipulation of the at least one actuating element on the other.

It is advantageous if the bearing shaft holder comprises a stop for limiting a pivotal movement of the actuating element in a working position in which the bearing shaft is held captive in the bearing shaft holder. A pivotal movement of the at least one actuating element on the instrument can be limited by the stop in a simple and secure manner.

The stop can be produced in a particularly simple manner if it is in the form of a projection formed on the bearing shaft holder. In particular, it can be formed in one piece manner with the bearing shaft holder.

It is advantageous if the stop defines that position of the actuating elements whereat they are pivoted away from each other to the maximum extent or are pivoted towards one another to the maximum extent. Thus in particular, extreme positions of the actuating elements relative to each other can be defined in a simple manner and the relative movability thereof with respect to one another can be limited.

It is expedient if the stop comprises a stop surface on which a flattened portion of the bearing shaft abuts flatly, at least to a partial extent, in that position in which the actuating elements are pivoted away from each other or towards one another to the maximum extent. Thus in particular, as small a surface pressure as possible can be achieved when the bearing shaft strikes the stop whereby the service life of the instrument can be maximized.

In accordance with one advantageous embodiment of the invention, provision may be made for the at least one actuating element to be in the form of a pivotal branch which comprises a first coupling element that, in a coupling position, is movable into engagement with a second coupling element which is arranged or formed on the at least one tool element or on a force transmission member that is coupled thereto. The first and second coupling elements thus serve, in particular, to directly or indirectly transfer the force that was introduced into the at least one actuating element to the at least one tool element. To this end in particular, the coupling elements may engage with one another with a force-locking and/or positive engagement, whereby they advantageously enable a movement relative to each other, in particular, a translatory and/or a pivotal movement.

It is expedient if the instrument compromises a restoring device for automatically transferring the at least one actuating element from a position in which it is deflected from a basic position back into the basic position, wherein the basic position defines that working position in which the at least one actuating element is rotated though the largest pivotal angle in relation to the assembly position. Thus in particular, the restoring device can prevent the instrument from being transferred into the assembly position in which the bearing shaft can be removed from the bearing shaft holder without the application of an external force, i.e. when it is in the unactuated state. The restoring device thus virtually forms a protecting device for the instrument in order to prevent unintentional dismantling thereof. In particular, it can be formed in such a manner that in the assembly position, the actuating elements of the actuating device are either pivoted towards one another to the maximum extent or they are pivoted away from each other to the maximum extent.

The restoring device can be produced in a particularly simple manner if it comprises at least one restoring member which is supported directly or indirectly on the at least one actuating element or is held thereon. The restoring member can, in particular, be in the form of a spring element which can be designed as a compression or tension member in order to hold the actuating elements towards one another to the maximum extent or away from each other to the maximum extent, without the user having to exert any force on the at least one actuating element. The at least one restoring member can be fixed or fastened to the at least one actuating element by means of a fastening part in the form of a clip or a screw for example. As an alternative or in addition thereto, the at least one restoring member can also be fastened to the at least one actuating element with a force-locking or positive engagement by clamping, for example a free end of the at least one restoring member or another part thereof can engage in a recess or in an undercut in the at least one actuating element with positive or substantially positive engagement and/or be held therein in force-locking manner by being clamped therein.

It is advantageous if the instrument is in the form of a sliding shaft instrument incorporating a sliding shaft which comprises two mutually displacable shaft parts. A large number of medical instruments such as clamps, shears, punches or the like for example can be formed with the aid of such a sliding shaft.

It is expedient if the at least one tool element is arranged or formed at a distal end of the sliding shaft. In connection therewith, for example, this may be a punching tool having a knife-edge which is displacable in the distal or proximal direction and is movable against a corresponding second tool element in the form of an anvil member in order to work on bones or tissue for example.

It is advantageous, if the sliding shaft instrument is in the form of a bone punch. In particular, such a device enables bones and other types of body tissue to be worked on in a simple and defined manner.

A medical instrument bearing the general reference symbol10is illustrated schematically inFIG. 1. It is in the form of a sliding shaft instrument incorporating a sliding shaft18comprising two mutually displacable shaft parts14and16. The shaft parts14and16are mounted such as to be relatively displacable parallel to the longitudinal axis20with the aid of a guidance means which is not illustrated in detail.

At the distal end thereof, the lower shaft part14of the sliding shaft18carries a projection22which points upwardly and projects transversely with respect to a longitudinal axis20of the sliding shaft18and which forms an anvil24for a knife-edge26that cooperates therewith and is arranged or formed at a distal end of the upper shaft part16. The knife-edge26forms a first tool element28which, together with the anvil24forming a second tool element30, defines a punching device32of the instrument10forming a bone punch34.

Furthermore, the instrument10comprises an actuating device36which incorporates two relatively pivotal branches38and40which form a respective actuating element42and44of the actuating device36. The branch38protrudes in a direction transverse to the longitudinal axis20from a proximal end of the lower shaft part14. In particular, the actuating element42and the shaft part14may be formed in one piece manner. A thumb rest in the form of a projection pointing in the proximal direction protrudes from the branch38. Overall then, the branch38is arranged on the instrument10such as to be immovable.

The branch40is mounted such that it is pivotal relative to the branch38about a pivotal axis50. For this purpose, the instrument10comprises a pivotal bearing52comprising a bearing shaft holder54and a bearing shaft56which is rotatable or pivotal therein about the pivotal axis50. The bearing shaft56is formed on a plate-like coupling section58of the actuating element44and protrudes from a side face thereof. It is formed of a cylindrical base body60and has two flattened portions62and64which define side faces66and68that run in parallel with one another.

At the free end70thereof, the coupling section58comprises a slot-like recess72having a width74which corresponds to an outer diameter76of a coupling stud78that is arranged or formed on the shaft part16. The cylindrical coupling stud78is arranged transversely of the longitudinal axis20in a recess80of the shaft part16which is open towards the shaft part14. The end70is rounded in the form of a semicircle. The width of the recess80corresponds to the thickness82of the coupling section58so that the latter is guided laterally in the recess80.

At the end46, i.e. in the transitional region between the shaft part14and the actuating element42, there is formed a mounting section84which comprises a through hole86. The through hole86is closed by lateral wall regions88and90and opens up the mounting section84in the upward direction to the downwardly open recess80, both proximally as well as downwardly. Mounting cheeks92and94project downwardly from the wall regions88and90, these cheeks being semicircular when viewed from the side. The width of the through hole86corresponds to the thickness82of the coupling section58so that it can be introduced through the through hole86, and the coupling stud78and the recess72which form the coupling elements96and98are movable into engagement with one another.

The bearing shaft holder54is formed on the mounting cheeks92. It comprises a hollow cylindrical inner wall surface section100which extends over a peripheral angle102of approximately 210°. A diameter104of the bearing shaft holder defined by the inner wall surface section100corresponds to an outer diameter110defined by two cylindrical wall surface sections106and108of the bearing shaft56which are located diametrically opposite each other with respect to the pivotal axis50.

The bearing shaft holder54is opened laterally, namely, in a direction transverse to the pivotal axis50, by an insertion opening112. This is in the form of a slot114which opens the bearing shaft holder54on one side. It extends away from the pivotal axis50in the radial direction. The slot114comprises two mutually facing inner surfaces116and118which run in parallel with each other and with a plane120containing the pivotal axis50. The inner surfaces116are spaced from each other by a distance which corresponds to the width170of the slot114. The width170corresponds to the spacing of the side faces66and68from each other. The bearing shaft54can thus be pushed into the bearing shaft holder54through the slot114.

The bearing shaft56is arranged on the coupling section58in such a manner that it defines a longitudinal axis122which coincides with a longitudinal axis124defined by the recess72. The slot114likewise defines a longitudinal axis126which intersects a longitudinal axis128of the coupling stud78. The described alignment of the longitudinal axes122and124as well as126and128makes it possible for the coupling section58to be brought into engagement with the mounting section84when in an assembly position such as is illustrated schematically inFIG. 2. In the assembly position, the longitudinal axes122and126are aligned in parallel with each other so that the bearing shaft56is insertable into the bearing shaft holder54through the slot114by means of a purely translatory movement and the coupling stud78is insertable into the recess72at the same time.

Once the bearing shaft56has been fully inserted into the bearing shaft holder54as is schematically illustrated inFIG. 4, then, as a result of the selected dimensions of the diameter104and the outer diameter110, it is possible for the actuating element44to pivot about the pivotal axis50, namely, through a maximum pivotal angle130which, in the assembly position, is defined between the side face66and a stop surface132of a stop134which is formed on the bearing shaft holder54in the form of a projection. This stop is provided for limiting a pivotal movement of the actuating element44about the pivotal axis50. The stop surface132defines a plane which runs in parallel with a further plane136containing the pivotal axis50. The planes120and136likewise define therebetween a pivotal angle138which corresponds to the pivotal angle130.

Furthermore, the instrument10comprises a restoring device140against the effect of which the actuating element44can be pivoted in the direction of the actuating element42. The restoring device140comprises a leaf spring146which is fixed to a free end144of the branch40by means of a screw142and is provided at the other free end thereof with a slot148thereby leaving two protruding projections150which are each rolled up so as to form a seating152or eye for a mounting pin154that is formed at a free end156of a second leaf spring element158and engages in the seatings152so that the leaf spring element158and the leaf spring146are pivotal relative to each other about a pivotal axis defined by the mounting pin154. As an alternative or in addition thereto, the free end144of the leaf spring146can also be fixed to the branch40with a force-locking or positive engagement by clamping, for example the free end144of the leaf spring146or another part thereof can engage in a recess that is not illustrated in detail in the Figures or in an undercut in the branch40with positive or substantially positive engagement and/or be held therein in force-locking manner by being clamped therein.

The leaf spring element158is slightly bent at its other free end160and projects into a recess162in the actuating element42. The recess162has a stop surface164which faces in the direction of the shaft part16. The end160abuts against the stop surface164in the recess162. The restoring device140comprising the leaf spring146and the leaf spring element158which form the respective restoring members166and168keeps the two actuating elements42and44in a basic position that is illustrated schematically inFIG. 5in which they are pivoted away from each other to the maximum extent. In this basic position, the flattened portion62abuts against the stop surface132and thus limits a movement of the branch40away from the branch38. The branch40can now be pivoted against the effect of the restoring device140towards the branch38. As long as the pivotal angle in the working position in which the bearing shaft56is held captive in the bearing shaft holder54is smaller than the pivotal angle130, the bearing shaft56cannot escape from the bearing shaft holder54through the slot114.

The particular configuration of the pivotal bearing52makes it possible to assemble the instrument10without tools in a simple manner. Thus the bearing shaft46is merely inserted into the bearing shaft holder54. The pivotal bearing is thus virtually screw-less.

It is also conceivable in principle for the pivotal bearing52described above in connection with a bone punch34to be usable in any hand grip of a medical instrument which comprises two relatively pivotal actuating elements. In particular, such a hand grip of the instrument may be connectable to a shaft thereof in releasable manner for example as is often the case with endoscopic tubular shaft instruments.