Shaft connector

A shaft connector configured to connect a shaft that has to be partly inserted through the skull of patient to the skull of the patient, the shaft connector comprising a skull connecting part, a shaft bush with a shaft clamp to fixate a shaft within the shaft bush, a bush clamping device to fixate the shaft bush relative to the skull connecting part so that a settable direction of the bush channel axis relative to the central axis is fixated as desired, an operating provision including a first and a second handle configured and arranged to be engaged by a single hand, the operating provision being configured to bring the bush clamping device from the release position in the clamping position by movement of the first handle relative to the second handle without exerting a force on the skull via the skull connecting part.

FIELD

The invention relates to a shaft connector for connecting a shaft that has to be partly inserted through the skull of patient to the skull of the patient.

BACKGROUND

U.S. Pat. No. 4,681,103 discloses a shaft connector configured to connect a shaft that has to be partly inserted through the skull of patient to the skull of the patient. The shaft connector has an adaptor housing that includes external screw thread with which the adaptor housing can be mounted in a hole that has been drilled in the skull of a patient. The shaft connector also includes a shaft bush or probe socket with a swivel ball. The probe socket defines a bush channel that extends along a bush channel axis. A set screw is provided to fixate a shaft within the probe socket. A clamp plate having a central hole with a diameter that is smaller than that of the swivel ball is arranged in the adaptor housing. A locking ring having external screw thread that engages internal screw thread on the adapter housing co-operates with the clamp plate so that the clamp plate can be pressed downward to force the clamp plate against the swivel ball thereby locking it in place between the adaptor housing and the clamp plate. If the locking ring is loose, the probe socket can swivel within the adaptor housing.

WO-98/17191 discloses a similar device. In this case the connection between the adaptor housing and the skull is effected by means of hooks on distal ends of flexible legs that are connectable to the adaptor housing. The hooks engage a hole drilled in the skull on the inside of the skull. The adapator housing can be connected to the skull by tightening a first locking ring having internal screw thread that engages external screw thread on the adaptor housing. A second locking ring with external screw thread that engages internal screw thread can be used to fixate a shaft bush having a swivel ball into a desired directional position in the adaptor housing.

SUMMARY OF THE INVENTION

A disadvantage of the known devices is that to fixate the swivel ball inside the adaptor housing a locking ring with screw thread that engages the adaptor housing has to be tightened. When one has only one hand available, tightening the locking ring will result in exerting a force on the skull via the adaptor housing. This may change the position of the adaptor housing and with that of the probe socket relative to the skull and the brain tissue. Such an inadvertent position change is highly undesirable because it may lead to brain damage when a shaft is inserted into the brain. Additionally the connection between the adaptor housing and the skull is vulnerable and possible varying forces that may deteriorate the connection should preferably be prevented.

The present invention is directed to a shaft connector in which these disadvantages are alleviated.

To that end the invention provides a shaft connector that is configured to connect a shaft that has to be partly inserted through the skull of patient to the skull of the patient, wherein the shaft connector comprises a skull connecting part having a proximal end and a distal end. The skull connecting part includes a skull connecting provision and an inner wall that bounds a skull connecting part channel that extends along a central axis and that has a distal channel end. The skull connector also comprises a shaft bush that includes a shaft bush wall defining a bush channel that extends along a bush channel axis. Further, the shaft connector includes a bush clamping device that is arranged in the skull connecting part, that has a clamping position and a release position, the bush clamping device in the clamping position being configured to fixate the shaft bush relative to the skull connecting part so that a direction of the bush channel axis relative to the central axis, which direction may be varied within a range of directions in the release position of the bush clamping device, is fixated as desired. An operating provision of the shaft connector is configured to engage the bush clamping device and to move the bush clamping device between the clamping position and the release position. In a first aspect the operating provision includes at least a first handle and a second handle. The first and the second handles are configured and arranged to be engaged by a single hand and the operating provision is configured to bring the bush clamping device from the release position in the clamping position by movement of the first handle relative to the second handle without exerting a force on the skull via the skull connecting provision.

Therefore, the invention provides a shaft connector according to claim1.

By virtue of the fact that the shaft bush may be fixated in a desired direction by engagement of the first and the second handle with a single hand without exerting a force on the skull connecting provision, a very user friendly shaft connector is provided. The stability of the connection between the skull and the shaft connecting part is not brought into danger because of forces that are exerted on that connection during fixating the shaft bush relative to the skull connecting part. Thus the position of the skull connecting part relative to the skull, which position at least partly defines the position of the shaft within the skull which is very precarious, is maintained unaffected and stable. Optionally a third handle may be provided as will be elucidated in the detailed description.

In an embodiment, the rotational position of the first handle and the second handle relative to the skull connecting part may be settable without changing the position of the first handle relative to the second handle.

This embodiment facilitates that the surgeon may position the handles so relative to his own working position and other instruments that operating the handles is easy for him.

In an embodiment, the shaft bush of the shaft connector may include a shaft clamp that is configured to fixate a shaft within the shaft bush50. The shaft clamp of the shaft bush may include a first shaft clamp handle and a second shaft clamp handle. The first and the second shaft clamp handles may be configured and arranged to be engaged by a single hand and the shaft clamp may be configured to bring shaft clamp from the release position in the clamping position by movement of the first shaft clamp handle relative to the second shaft clamp handle without exerting a force on the skull via the skull connecting provision.

By virtue of the fact that the shaft may be fixated in a desired position relative to the shaft bush by engagement of the first clamp handle and the second clamp handle with a single hand without exerting a force on the skull via the skull connecting provision, a very user friendly shaft connector is provided. Consequently, the position of the skull connecting part relative to the skull, which position as stated before at least partly defines the position of the shaft within the skull which is very precarious, is maintained unaffected and stable. It should be noted that the novel shaft clamp may also be applied in a shaft connector that does not have the novel operating provision with the first and the second handle. Optionally a third clamp handle may be provided as will be elucidated in the detailed description.

To facilitate the possibility of positioning the shaft clamp handles in a favorable position relative to the surgeon and other instruments, in an embodiment of the shaft connector the rotational position of the first shaft clamp handle and the second shaft clamp handle relative to the shaft bush may be settable without changing the position of the first shaft clamp handle relative to the second shaft clamp handle.

In an embodiment, the skull connection provision may include a substantially cylindrical part that extends proximally from the distal end of the skull connecting part. A stop surface may be provided at a proximal end of the substantially cylindrical part and may extend substantially perpendicular to the central axis. The skull connecting part may further include an outer surface wall that is circular symmetric around the central axis and that extends from a proximal end of the cylindrical part substantially parallel to the central axis in the proximal direction and diverges radial outwardly, thus providing a concave transition zone that is configured to accommodate skin on the skull that surrounds the hole in which the skull connecting part may be mounted. The stop surface may engage the outer surface of the skull and thus provide a large, stability providing bearing surface. The transition zone with the special contour provides space for the skin that surrounds the hole in the skull. Thus, a minimal amount of skin has to be removed which is important in view of minimizing the cicatrix mark that remains after the surgery. The aspects of this embodiment may also be applied in a skull connector that does not have the features of the first and the second handle in the operating provision.

In yet another embodiment, the shaft bush of the shaft connector may include a substantially spherical distal shaft bush end that is pivotably accommodated in the skull connecting part so that the shaft bush is pivotable relative to the skull connecting part. In order to obtain a maximum range of pivot angles relative to the central axis of the skull connecting part in combination with a minimal diameter of the hole that has to be drilled in the skull, in the present embodiment the substantially spherical distal shaft bush end may be positioned adjacent the distal channel end of the skull connecting part so that in a mounted position of the skull connecting part in a hole in a skull, the substantially spherical distal shaft bush end is positioned below an outer surface of skull. The aspects of this embodiment may also be applied in a skull connector that does not have the features of the first and the second handle in the operating provision.

Other aspects are described in the dependent claims and will be elucidated in the detailed description.

DETAILED DESCRIPTION

In its most general terms shaft connector10is disclosed that is configured to connect a shaft that has to be partly inserted through the skull of patient to the skull of the patient. The shaft may, for example, be a tool, an endoscope, a catheter, a drain or a trocar. The figures show examples of the various embodiments that will be described hereafter.

The embodiments of the shaft connector10have in common that they all comprise a skull connecting part20having a proximal end and a distal end. The skull connecting part20includes a skull connecting provision22and an inner wall24that bounds a skull connecting part channel26that extends along a central axis L1and that has a distal channel end26a. The shaft connector10also comprises a shaft bush50. The shaft bush50includes a shaft bush wall52defining a bush channel54that extends along a bush channel axis L2. Next, the shaft connector comprises a bush clamping device110that is arranged in the skull connecting part20. The bush clamping device110has a clamping position and a release position. In the clamping position the bush clamping device is configured to fixate the shaft bush50relative to the skull connecting part20so that a direction of the bush channel axis L2relative to the central axis L1, which direction may be varied within a range of directions in the release position of the bush clamping device110, is fixated as desired. The shaft connector10also comprises an operating provision130configured to engage the bush clamping device110and to move the bush clamping device110between the clamping position and the release position.

In an embodiment, of which two different examples are shown inFIGS. 1-3and5, the operating provision130may include at least a first handle136and a second handle140. The first and the second handles136,140may be configured and arranged to be engaged by a single hand and the operating provision130may be configured to bring the bush clamping device110from the release position in the clamping position by movement of the first handle136relative to the second handle140without exerting a force on the skull via the skull connecting provision22. This is advantageous in that the stability of the connection between the shaft connector10and the skull is maintained. Thus the position of a shaft that is inserted through the shaft bush50into the brain of the patient is also stable. This is of crucial importance. Because the surgeon can operate the operating provision130with a single hand, the skull connector is very user friendly. The surgeon has his other hand freely available for manipulating other instruments or, for example, the shaft of which he wants to fixate its position.

In an embodiment, of which two different examples are shown inFIGS. 1-3and5, the rotational position of the first handle136and the second handle140relative to the skull connecting part20may be settable without changing the position of the first handle136relative to the second handle140. This embodiment facilitates that the handles136,140may be freely rotated and thus be brought into a position that is easily accessible for the surgeon.

In an embodiment, of which examples are shown inFIGS. 1-3and5, the operating provision130may include a third handle138. The first and the second handles136,140and the third handle and the second handles138,140may be configured and arranged to be engaged in pairs by a single hand and the operating provision may be configured to bring the bush clamping device110from the release position in the clamping position by movement of the first handle136relative to the second handle140without exerting a force on the skull via the skull connecting provision22, and to bring the bush clamping device110from the clamping position in the release position by movement of the third handle138relative to the second handle140without exerting a force on the skull via the skull connecting provision22. An embodiment with three handles136,138,140has the advantage that both for releasing and for clamping a press movement may be used. Pressing together two handles is an operation that can be easily performed with a single hand, for example, by engaging one handle with a thumb and the other one with the index finger.

Also in the embodiment with the three handles136,138,140, the rotational position of the first handle136, the second handle140and the third handle138relative to the skull connecting part20may be settable without changing the position of the first handle136, the second handle140and the third handle138relative to each other.

In an embodiment, of which two examples are shown inFIGS. 1-3and5, the second handle140may be positioned between the first handle136and the third handle138.

In an embodiment, of which two examples are shown inFIGS. 1-3and5, the operating provision130may include a first operating part132that is connected to the skull connecting part20that carries the first handle136. The operating provision130may also include a second operating part134that is connected to the skull connecting part20and that carries the second handle140. The first operating part132may be moveable relative to the second operating part134from a clamping position, that is associated with the clamping position of the operating provision130, to the release position, that is associated with the release position of the operating provision130, and vice versa.

In an embodiment, of which two examples are shown inFIGS. 1-3and5, the first operating part132also carries the third handle138. The movability of the first operating part132relative to the second operating part134may involve a rotation around the central axis L1.

In that example, both the first operating part132and the second operating part134are also simultaneously rotatable around the central axis L1relative to the skull connecting part20so that the rotational position of the handles relative to the skull connecting part20is settable. Thus the handles136,138,140can be positioned so that the surgeon can readily engage the handles.

In an embodiment, of which the features to be described are clearly visible in the example that is shown inFIG. 3, the first operating part132may include a first ring142that extends in a plane that is perpendicular to the central axis L1. The first ring142has a central ring axis that coincides with the central axis L1and has a first contact surface144with a first sloping section146. The second operating part134includes a second ring148that extends in a plane that is perpendicular to the central axis L1. The second ring148has a central ring axis that coincides with the central axis L1and has a second contact surface150with a second sloping section152. In fact, both rings142and148each include in the example shown three sloping sections146,152. Both the first contact surface144and the second contact surface150each include a stop surface160,162, in fact three stop surfaces that limit the rotation of the two rings142,148relative to each other. The first contact surface144contacts the second contacting surface150. The first ring142and the second ring148are superimposed onto each other to form a ring set having a variable ring set height H. The ring set has a flat bottom surface156that is in contact with the bush clamping device110. The ring set has a flat top surface158that is positioned under a ridge30of the skull connecting part20. The first sloping section146and the second sloping section152are positioned so relative to each other that these two sloping sections co-operate upon rotation of the first ring142relative to the second ring148thereby increasing or decreasing the ring set height H.

In an embodiment, the first and the second sloping sections146,152may each include more than two stages, for example, three stages. A first stage that is associated with a release position, an intermediate second stage that is associated with a position in which movement of the shaft bush50is possible but inhibited by a friction force, and a second stage that is associated with the clamping position. In another embodiment, the sloping section146,152may include a plurality of stages thus providing a sort of a ratchet for exerting variable clamping forces.

In an embodiment, of which an example is shown inFIGS. 1-3, the ridge30of the skull connecting part20is part of a ridge ring32having outer screw thread34that engages inner screw thread36of the skull connecting part20so that the distance between the ridge30and the seat28is settable by rotation of the ridge ring32. By virtue of the ridge ring32, the skull connecting part20may be releasable from a mold in which the skull connecting part20may be manufactured by means of, for example, injection molding. By virtue of the separate ridge ring32, any manufacturing tolerance may be compensated for by turning the ridge ring32in such a position that the height between the ridge ring32and an upper side the bush clamping device110is as desired.

In an alternative embodiment, of which an example is shown inFIG. 4, the shaft connector includes a first operating part182that carries the first handle186and that is connected to the skull connecting part20and pivotable along a pivot axis L3that crosses and extends substantially perpendicular to the central axis L1. The first operating part182includes at least one cam surface184—in the example shown inFIG. 4two cam surfaces184—that has an eccentric contour relative to the pivot axis L3and that engages the bush clamping device110. The pivot position of the first operating part182along the pivot axis L3relative to the skull connecting part20is settable by operating the first handle186. An radial outwardly extending flange could be provided on the skull connecting part20to form a second handle that can, for example, be engaged by the index finger while the first handle186is engaged by the thumb of the same hand of the surgeon to fixate the shaft bush50in the desired angular position relative to the skull connecting part20.

In an embodiment, of which an example is shown inFIGS. 1-3, the skull connecting part20may include a seat28adjacent the distal channel end26a. The shaft bush50may include a substantially spherical distal shaft bush end56having a proximal side and a distal side. The bush clamping device110may include a bush clamp provision112that engages the proximal side of the substantially spherical distal shaft bush end56in the clamping position and presses the spherical distal shaft bush end56with the distal side thereof against the channel seat28. The bush clamping device110may further have an operating provision engagement part114that is fixedly connected to the bush clamp provision112. The bush clamping device110of that embodiment is movable in the direction of the central axis L1between the clamping position and the release position.

In an embodiment, the skull connector10may include a biasing member configured to bias the bush clamping device to the release position. An example of such a biasing member is shown inFIG. 2. The example of the biasing member is a push spring164that is positioned between the bush clamping device110and the inner wall24of the skull connecting part20. The spring164urges the bush clamping device110away from the seat28when the operating provision is brought form the clamping position to the release position. It is clear that the biasing member may be embodied in alternative manners. For example, the biasing member may be embodied as a ring of compressible material between the bush clamping device110and the skull connecting part20.

In an embodiment, of which an example is shownFIGS. 1-3, the bush clamp provision112includes a lower ring116and the operating provision engagement part114includes an upper ring118having a top engagement surface that is engaged by the operation provision130. The upper ring118and the lower ring116are fixedly connected to each other via spokes122. The inner wall24of the shaft connecting part20may include indentations38for accommodating the spokes122. Thus the diameter of the skull connecting part20, especially adjacent the proximal end of the skull connecting provision22may be kept minimal while simultaneously an optimally large pivot range for the shaft bush50may be provided. Radially between the indentations38enough wall material is present to provide sufficient strength to the skull connecting part20. At the position of the indentations the wall of the skull connecting provision may be very thin so that the angles over which the shaft bush50may be tilted relative to the central axis L1are maximal.

In an embodiment, of which an example is shown inFIG. 3, the lower ring116may include interruptions120so that lower ring segments116′ are provided that are each connected with at least one spoke122. The ring segments116′ have some radial movement possibility so that in the clamping position each ring segment116′ may be optimally inserted between the inner wall24and the spherical distal shaft bush end56so that each segment may contribute to exerting a clamping force on the spherical distal shaft bush end56.

In an embodiment, the ring116or the ring segments116′ may have a tapering converging configuration when viewed in the direction of the central axis L1form the proximal end to the distal end. When moved towards the seat28, the ring or the ring segments116are wedged between the inner wall24and the substantially spherical distal shaft bush end56thus fixating the spherical distal shaft bush end56and with that the shaft bush50in its desired position.

In an alternative embodiment, the spokes122may be configured to bias the ring segments116′ outwardly in a radial direction of the ring116. The inner wall24at the level of the lower ring116may have a tapering configuration so that when moving from the release to the clamping position, the ring segments116′ are moved from a position in which the tapering inner wall has a larger diameter to a position in which the tapering inner wall has a smaller diameter whereby the ring segments116′ are forced to move inwardly in a radial direction. When moving from the clamping position to the release position, the ring segments116′ are moved from a position in which the tapering inner wall has a smaller diameter to a position in which the tapering inner wall has a lager diameter whereby the ring segments116′ move outwardly in the radial direction by the bias force of the spokes122.

In an embodiment of the shaft connector10, the shaft bush50may include a shaft clamp58that is configured to fixate a shaft within the shaft bush50. An embodiment of the shaft clamp58of the shaft bush50of which two examples are shown inFIGS. 2,3and5, may include a first shaft clamp handle82and a second shaft clamp handle88. The first and the second shaft clamp handles82,88are configured and arranged to be engaged by a single hand and the shaft clamp58is configured to bring shaft clamp58from the release position in the clamping position by movement of the first shaft clamp handle82relative to the second shaft clamp handle88without exerting a force on the skull via the skull connecting provision22. In an embodiment, of which an example is shown inFIGS. 2 and 3, the movement of the first shaft clamp handle82relative to the second shaft clamp handle88may be a rotational movement around the shaft bush axis L2to bring the shaft clamp58from the clamping position to the release position and vice versa. In an alternative embodiment, of which an example is shown inFIG. 5, the first shaft clamp handle82may be moved in the direction of the shaft bush axis L2relative to the second shaft clamp handle88to bring the shaft clamp58from the clamping position to the release position and vice versa. In the example ofFIG. 5, the external diameter of the slitted bush may have an axial portion with a large outer diameter and an axial portion with a small outer diameter relative to the large outer diameter. When the ring, that carries the first shaft clamp handles82, is positioned over the portion with the small outer diameter, the shaft clamp58is in the release position. When that ring is positioned over the portion with the large outer diameter, the bush segments are pressed in a radial inward direction and the shaft clamp58is in the clamping position.

In an embodiment, the rotational position of the first shaft clamp handle82and the second shaft clamp handle88relative to the shaft bush50may be settable without changing the position of the first shaft clamp handle82relative to the second shaft clamp handle88. That is advantageous because the surgeon can than position the handles82,88optimally relative to him- or herself and relative to the patient.

In yet another embodiment, of which an example is shown inFIGS. 2 and 3, the shaft clamp58may include a third shaft clamp handle90. The first and the second shaft clamp handles82,88and alternatively the first and the third shaft clamp handles82,90are configured and arranged to be engaged in pairs by a single hand. In that embodiment the shaft clamp58is configured to bring the shaft clamp58from the release position in the clamping position by movement of the first handle82relative to the second handle88without exerting a force on the skull via the skull connecting provision22, and to bring the shaft clamp58from the clamping position in the release position by movement of the third shaft clamp handle90relative to the first shaft clamp handle82without exerting a force on the skull via the skull connecting provision22. Also in the embodiment with three shaft clamp handles82,88,90it is for the same reasons as mentioned above in relation to the embodiment with the two shaft clamp handles advantageous when the rotational position of the first shaft clamp handle82, the second shaft clamp handle88and the third shaft clamp handle90relative to the shaft bush50is settable without changing the position of the first handle136, the second handle140and the third handle138relative to each other.

When, as is the case in the example ofFIGS. 2 and 3, the first shaft clamp handle82is positioned between the second shaft clamp handle88and the third shaft clamp handle90, the shaft clamp58may be brought from the clamping position to the release position as well as from the release position to the clamping position via a press movement. Exerting a force by pressing on two handles is easy because it can be easily done with a single hand by engaging a pair of handles82,88or alternatively a pair of handles82,90between the index finger and the thumb. The other hand thus remains available for other tasks, for example holding the shaft that has to be fixated.

As shown in the example ofFIGS. 2 and 3, the shaft clamp58may include an inner tapering wall part60with a diminishing diameter that is defined by the shaft bush wall52adjacent the proximal end of the shaft bush50. The shaft clamp58may include a clamp bush62with a clamp bush wall64defining a clamp bush channel66that extends along bush channel axis L2. The clamp bush wall64may include slits68that extend substantially parallel to the bush channel axis L2. A distal end of the clamp bush wall64defines shaft clamping segments64′ that are bounded by the slits68. The clamping segments64′ have radial inwardly directed clamping surfaces70that are configured to engage a shaft. A radial outwardly directed clamp bush wall part72at the distal end of the clamp bush wall64co-operates with the inner tapering wall part60. The clamp bush62is axially moveable within the shaft bush wall52. A clamp bush operating provision74is provided to control the axial position of the clamp bush62relative to the shaft bush wall52and includes at least the first and the second shaft clamp handle82,88.

When the clamp bush62is pressed by the clamp bush operating provision74into the tapering wall part60, the clamping segments64′ are forced in a radial inward direction. The clamping surfaces70are then pressed against the shaft and fixate the shaft relative to the shaft bush50. When the clamp bush62is withdrawn by the clamp bush operating provision74from the tapering wall part60, the clamping segments64′ may bias in a radial outward direction, thereby releasing the shaft that was previously fixated by the clamping surfaces70of the clamping segments64′.

The clamp bush operating provision74may include a cam notch76that is axially fixed relative to the shaft bush wall52. That embodiment of the clamp bush operating provision74also includes a cam surface78that is part of the clamp bush62and that is configured to co-operate with the cam notch76. A rotation of the clamp bush62relative to the cam notch76results in a axial movement of the clamp bush62. The cam notch76may be part of a notch ring80that is connected to the shaft bush wall52so that it is axially fixed relative to the shaft bush wall52and rotatable around the shaft bush wall52. The first shaft clamp handle82may also be connected to the notch ring80. A clamp bush skirt84that extends parallel to the clamp bush wall64and that is connected to the clamp bush wall via a connecting flange86may be provided to carry the cam surface78and the second shaft clamp handle88and, if present, also the third clamp handle90. By virtue of the notch ring80and the clamp bush62, the first, second and optional third clamp bush handle may be rotated without rotating the shaft bush wall52and without movement of the shaft clamp handles82,88,90relative to each other.

Turning now again to the skull connecting part20. The skull connection provision22may include in an embodiment a substantially cylindrical part40extending proximally from the distal end of the skull connecting part20. A stop surface42may be present at a proximal end of the substantially cylindrical part40and extend substantially perpendicular to the central axis L1. The stop surface42may provide a stable support surface that engages an outer surface of the skull that bounds the hole that has been drilled in the skull. Also, the stop surface42provides a well-defined indication in relation to the extent to which the skull connecting part20has to be inserted into the drilled hole. The cylindrical part40may carry outer screw thread44that is configured to engage the hole in the skull. The screw thread44may be a tapering screw thread44. In an alternative embodiment the cylindrical part40may include flexible legs with radial outwardly extending hooks on the distal ends thereof that engage an inner side of the skull bounding the hole in the skull. An example of such a connecting provision is described in US WO-98/17191.

In an embodiment, of which examples are shown inFIGS. 1-5, the skull connecting part20may include an outer surface wall46that is circular symmetric around the central axis L1and that extends from a proximal end of the cylindrical part40substantially parallel to the central axis L1in the proximal direction and diverges radial outwardly, thus providing a concave transition zone48that is configured to accommodate skin on the skull that surrounds the hole in which the skull connecting part20may be mounted. Such a concave transition zone48provides the advantage that a minimum amount of skin has to be removed from the skull, thus minimizing the scar mark on the skull after the operation. Preferably, the radial diverging is gradually so that a smooth transition zone48is obtained.

In an embodiment, of which examples are shown in all the figures, the shaft bush includes a substantially spherical shaft bush end56that is pivotally accommodated in the skull connecting part20so that the shaft bush50is pivotable relative to the skull connecting part20. In such an embodiment, it is advantageous when the substantially spherical distal shaft bush end56is positioned adjacent the distal channel end26aof the skull connecting part20, so that in a mounted position of the skull connecting part20in a hole in a skull, the substantially spherical distal shaft bush end56is positioned below an outer surface of skull. In such a configuration, it is possible to provide a maximum range of angles over which the direction of the shaft bush channel axis L2may be varied relative to the central axis L1and that in combination with a minimum hole diameter in the skull of the patient. In an embodiment that has a substantially cylindrical part40extending from the distal end of the skull connecting part20, such a configuration may be obtained by positioning the seat28at a distal end of the cylindrical part40and by positioning the substantially spherical distal shaft bush end56in the cylindrical part40.

The various features described in combination for certain embodiments may be applied separate from each or in other combinations so as to form other embodiments.

The priority document included some additional claims that are repeated hereunder as clauses:11. The shaft connector according to clause 10 (now claim10), wherein the ridge (30) of the skull connecting part (20) is part of a ridge ring (32) having outer screw thread (34) that engages inner screw thread (36) of the skull connecting part (20) so that the distance between the ridge (30) and the seat (28) is settable by rotation of the ridge ring (32).15. The shaft connector according to clause 14 (now claim13), the inner wall (24) of the shaft connecting part (20) including:indentations (38) for accommodating the spokes (122).16. The shaft connector according to clause 14 or 15 (now claim13and clause 15), the lower ring (116) including:interruptions (120) so that lower ring segments (116′) are provided that are each connected with at least one spoke (122).17. The shaft connector according to any one of clause 14-16 (now claim13and clauses 15-16), the lower ring (116) having a tapering converging configuration when viewed from in the direction of the central axis (L1) the proximal to the distal end skull connecting part (20) so that in a clamping position of the bush clamping device (110), the lower ring (116) is wedged between the inner wall (24) and the substantially spherical shaft bush end (56) thus fixate the spherical shaft bush end (56) in its position.20. The shaft connector according to clause 19 (now claim15), wherein the rotational position of the first shaft clamp handle (82) and the second shaft clamp handle (88) relative to the shaft bush (50) is settable without changing the position of the first shaft clamp handle (82) relative to the second shaft clamp handle (88).23. The shaft connector according to clauses 21 or 22 (now claim16or17), wherein the first shaft clamp handle (82) is positioned between the second shaft clamp handle (88) and the third shaft clamp handle (90).27. The shaft connector according to clause 26 (now claim20), the third shaft clamp handle (90) being connected to the clamp bush skirt (84).

It will be apparent to those having ordinary skill in the art that various modifications and variations can be made to the shaft connector as disclosed herein. Other embodiments will be apparent to those having ordinary skill in the art from consideration of the specification. It is intended that the specification and examples are considered as exemplary only. Other aspects, features and advantages will be apparent upon an examination of the attached drawings and appended claims.