Patent Description:
Various surgical tracking and navigation techniques are used for assisting a surgeon or for controlling operation of a surgical robot. In some navigation variants, medical image data of a patient are visualized on a display and overlaid with a model, position or trajectory of a handheld surgical instrument tracked by a tracking system. In other variants, a tracked robot arm with a surgical instrument is navigated relative to the patient.

In such tracking and navigating techniques, trackers are commonly attached to a patient anatomy and to the surgical instrument. The relative position between the patient anatomy and a surgical instrument are determined and, for example, visualized or used for robot control.

In the fields of surgical tracking and navigation, it is mandatory that tracking and navigation operations are performed at a high degree of accuracy, since any inaccuracy may result in harming the patient. It is mandatory to not only accurately determine a position of the tracked surgical instrument but to know the exact geometry of the surgical instrument. In particular, the geometric relation between the tracker attached to the surgical instrument and a tip of the surgical instrument has to be known at all times.

Common surgical instruments are designed to be usable for multiple different tasks, e.g., by utilizing a replaceable tip analogous to a common drilling machine or multifunctional tool. Such surgical instruments often comprise multiple instrument parts that can detachably be fixed to each other. For example, a first instrument part may be configured to transfer mechanical or electric energy to a detachable second instrument part that carries a surgical instrument tip. Evidently, each mechanical connection is subject to mechanical play. Due to such mechanical play between instrument parts, the geometric relation between a tracker attached to a first part of the surgical instrument and the instrument tip carried by, or constituting, the other part of the surgical instrument can only be determined in the order of accuracy of the mechanical play. As such, the accuracy of surgical tracking and navigation is negatively impacted if such mechanical play is present.

Of course, there exist further reasons to reduce mechanical play between two parts of a surgical instrument. In some cases, the first instrument part serves as a grip or handle for the surgeon while the second, replaceable instrument part comprises a tip for performing or assisting a surgical procedure. Any mechanical play between the two instrument parts will negatively impact the precision at which the surgical procedure can be carried out.

Document <CIT> discloses a tunneler device. The tunneler device includes a handle formed on a proximal end thereof configured for operable engagement by a user, a shaft extending distally from the handle, a collet supported on the distal end of the shaft, the collet including a plurality of distally extending fingers defining a longitudinal opening, the opening being configured to receive an end of a catheter tube and a connector configured for operable engagement with the collet, wherein the connector is configured to bias the fingers of the collet radially inward upon engagement of the connector with the collet.

Document <CIT> discloses a surgical instrument. The surgical instrument can include a housing, a sheath, and a collar. A surgeon can slide the sheath within the housing to position a distal end of sheath with respect to a distal end of an end-effector. Thereafter, the surgeon may thread the collar onto a threaded end of the housing to compress the housing against the outside surface of the sheath positioned therein.

Document <CIT> discloses a fixed connector with a marker arrangement. The fixed connector is a collet chuck adaptor. A spring collet is fixed to, or integral with, the marker assembly. After inserting a shaft of a medical instrument, a nose piece fastens the spring collet, and thus the marker assembly, to the shaft.

Document <CIT> discloses a coupling for a dimensionally stable connection of a prosthetic part to a retaining element using at least one pair of interconnecting projecting and recessed elements. The projecting and recessed elements of the retaining element that interconnect with the corresponding projecting and recessed elements of the prosthetic part consist of an elastically deformable material. The elastic parts of the projecting and recessed elements of the retaining element can be clamped against the projecting and recessed elements of the prosthetic part by at least one rigid clamping part that is located on the retaining element. The elastically deformable material is a plastic material and a marking element for a navigation system is fixed to the retaining element.

Document <CIT> discloses a tool adapted to be coupled to a power drill. The tool includes a multi-component bit mounted to reverse positions so that in one position its drill element drills a hole and in another position its driver element drives in a fastener.

There is a need to reduce a mechanical play between two parts of a surgical instrument.

The present invention is defined by the features of the independent claims.

Further embodiments are provided by the dependent claims.

According to a first aspect, a fixation device for fixing a first part of a surgical instrument to a second part of the surgical instrument is provided. The fixation device has a longitudinal axis and comprises a fixation body configured to accommodate a portion of the first instrument part and a portion of the second instrument part therein. The fixation body comprises a first fastening member and at least one movable first clamping member configured to clampingly engage at least the first instrument part so as to fix at least the first instrument part to the fixation device. The fixation device further comprises a first actuation member configured to receive at least a portion of the fixation body. The first actuation member comprises a second fastening member configured to engage with the first fastening member. The first actuation member is configured to exert a clamping force on the first clamping member when the second fastening member is in engagement with the first fastening member.

According to one variant, at least one of the fixation body and the first actuation member may have a structural configuration such that the clamping force is adjustable by a relative movement between the fixation body and the first actuation member along the longitudinal axis. The structural configuration may define a shape of at least one of the first fastening member, the first clamping member, the first actuation member and the second fastening member. For example, the structural configuration may comprise a region that is inclined relative to the longitudinal axis. In some variants, multiple such inclined regions may be provided, possibly at different but cooperating components. The inclined regions may thus be configured to cooperate with each other. For example, a first inclined region at the fixation device (e.g., at a location where the first fastening member or the first clamping member is present) cooperates with a second inclined region at the first actuation member (e.g., at a location where the second fastening member is present).

In some variants, the inclined region may comprise at least one planar or non-planar surface. At least a part of the inclined region may be inclined at an angle between <NUM> degrees and <NUM> degrees relative to the longitudinal axis, e.g., between <NUM> degrees and <NUM> degrees, such as at an angle of approximately <NUM> degrees.

The inclined region may extend circumferentially about at least a portion of the longitudinal axis. In case the inclined region fully extends circumferentially about the longitudinal axis, the inclined region may, for example, define a cone or a pyramidal frustum extending along the longitudinal axis. The cone or pyramidal frustum may be coaxial to the longitudinal axis.

The structural configuration may comprise a protrusion extending substantially perpendicular (e.g., towards or away from) the longitudinal axis. The protrusion may extend circumferentially about at least a portion of the longitudinal axis. In some variants, there may be multiple protrusions. For example, at least one of the first actuation member and the first clamping member may each comprise at least one protrusion.

Due to the structural configuration, the clamping force exerted on the first clamping member may depend on the relative position between the fixation body and the first actuation member along the longitudinal axis. For example, moving the fixation body and the first actuation member towards each other may increase the clamping force, and vice versa.

The fixation body has a separating slot extending along an entire length thereof. The separating slot may enable an adaptable cross-section of the fixation body perpendicular to the longitudinal axis of the fixation body.

The cross-section may be adaptable to the size of at least one of the first and second instrument parts to be accommodated by the fixation body.

The fixation body may be a single piece. The fixation body may have a tubular shape, i.e., may comprise an outer surface facing away from the longitudinal axis and an inner surface facing the longitudinal axis. The cross-sectional shape of the fixation body may be defined by the shape of the outer surface and the inner surface. For example, the cross-section of at least one of the outer surface and the inner surface may be circular, elliptic, rectangular or polygonal.

The first actuation member may be configured as a sleeve. The first actuation member may be formed as a single piece. The first actuation member may be rigid. An inner surface of the first actuation member may be shaped to conform to the outer surface of the fixation body, i.e., circular, elliptic, rectangular or polygonal.

One, two or more (e.g., three to ten) first clamping members may be provided. The at least one first clamping member may be a clamping finger configured to be deformed towards the longitudinal axis when the clamping force is exerted thereon. In case of multiple movable first clamping members (e.g., multiple clamping fingers), the first clamping members may be located spaced apart from each other circumferentially around the longitudinal axis. The first clamping members may be located symmetrically around the longitudinal axis. Each of the first clamping members may have a surface facing the longitudinal axis and being shaped based on the shape of at least the first instrument part to be fixed to the fixation device.

The first fastening member and the second fastening member may be configured to releasably engage each other. The first fastening member and the second fastening member may be configured as complementary threads. The complementary threads may be located on the inclined region or spaced apart therefrom. At least one thread parameter (e.g., at least one of a type, size, pitch and tap tolerance) of the complementary threads may be selected based on at least one of the angle at which the inclined region is inclined relative to the longitudinal axis and a play between the fixation body and at least one of the first and second instrument parts when the fixation body is not engaged by the actuation member, i.e., between the unclamped fixation body and at least one of the first and second instrument parts. For example, the pitch of the complementary threads may be at least <NUM>, e.g., at least <NUM>. The pitch may in some implementations be less than <NUM> or less than <NUM>. The complementary threads may be configured in a self-locking manner.

Additionally or alternatively, the first fastening member and the second fastening member may comprise complementary snap fit components. Of course, other components capable of engagement, in particular a form-fitting engagement, can be used as well.

According to one variant, the fixation body may comprise an alignment member configured to align the fixation body with at least one of the first instrument part and the second instrument part in a circumferential direction relative to the longitudinal axis. The alignment member of the fixation body may be configured to cooperate with a complementary alignment member of at least one of the two instrument parts. The alignment member may be a groove or a protrusion. The alignment member may be located on a fixation body surface facing the longitudinal axis.

In some implementations, the fixation body may have a third fastening member and at least one movable second clamping member configured to clampingly engage at least the second instrument part so as to fix at least the second instrument part to the fixation device. The fixation device may further comprise a second actuation member. The second actuation member may be configured to receive at least a portion of the fixation body and may comprise a fourth fastening member. The second actuation member may be configured to exert a clamping force on the second clamping member when the fourth fastening member is in engagement with the third fastening member.

The second actuation member may structurally be similar, or identical, to the first actuation member. The fixation body may have two opposing ends along its longitudinal extension. The first fastening member may be located adjacent one end of the fixation body, and the third fastening member may be located adjacent another end of the fixation body. The second clamping member may structurally be similar, or identical, to the first clamping member.

According to a second aspect, a method for fixing two parts of a surgical instrument to each other using a fixation device having a longitudinal axis is provided. The fixation device comprises a fixation body configured to accommodate a portion of the first instrument part and a portion of the second instrument part therein. The fixation body comprises a first fastening member and at least one movable first clamping member configured to clampingly engage at least the first instrument part so as to fix at least the first instrument part to the fixation device. The fixation device further comprises a first actuation member configured to receive at least a portion of the fixation body. The first actuation member comprises a second fastening member configured to engage with the first fastening member. The first actuation member is configured to exert a clamping force on the first clamping member when the second fastening member is in engagement with the first fastening member. The method comprises accommodating a portion of the first instrument part and a portion of the second instrument part in the fixation body and fastening the second fastening member of the first actuation member to the first fastening member of the fixation body for fixing at least the first instrument part to the fixation device.

According to one variant, the fixation body may have a third fastening member and at least one movable second clamping member configured to clampingly engage at least the second instrument part so as to fix at least the second instrument part to the fixation device. The fixation device may further comprise a second actuation member configured to receive at least a portion of the fixation body. The second actuation member may comprise a fourth fastening member. The second actuation member may be configured to exert a clamping force on the second clamping member when the fourth fastening member is in engagement with the third fastening member. The method may further comprise fastening the fourth fastening member of the second actuation member to the third fastening member of the fixation body for fixing at least the second instrument part to the fixation device.

According to a third aspect, a fixation system is provided. The fixation system comprises a surgical instrument having a first instrument part and a second instrument part. The fixation system further comprises the fixation device as presented herein.

According to one variant, the first instrument part may be configured to transfer mechanical or electrical energy to the second instrument part. The first instrument part may be configured as a grip or handle. The first instrument part may accommodate a battery. The first instrument part may belong to an arm of a surgical robot.

The second instrument part may accommodate a motor powered by a battery in the first instrument part or by a power cord. The second instrument part may comprise a mechanically or electrically operable instrument tip. The instrument tip may be operable by the motor or may be energized by the battery or a power cord. The instrument tip may be (e.g., detachably) attached to the second instrument part or may constitute the second instrument part. The instrument tip may be a tip configured for a surgical procedure, e.g., for drilling, cutting or burring. In other implementations, the instrument tip may be configured to apply an electrical voltage or ultrasound to tissue.

The fixation system may further comprise a tracker attachable or attached to the first instrument part. The tracker may be a tracker for surgical navigation, e.g., an optical or electromagnetic tracker. The fixation device for fixing the first instrument part with the second instrument part may be configured to reduce mechanical play between the first instrument part and the second instrument part (e.g., so as to enable reliably determining the position of the second instrument part, or a portion thereof, based on a tracked position of the first instrument part).

Further features and advantages of the fixation device, the system and the method presented herein are described below with reference to the accompanying drawings, in which:.

The same reference numerals are used to denote the same or similar components.

<FIG> illustrates a schematic representation of a first embodiment of a fixation system <NUM>. The fixation system <NUM> comprises a surgical instrument <NUM> with a first part <NUM> and a second part <NUM>. In the present embodiment, the first and second instrument parts <NUM>, <NUM> have substantially cylindrical shapes of arbitrary cross section. The first and second instrument parts <NUM>, <NUM> are detachably connected to each other (e.g., via a plug-type connection, quick-release connection, tool-holder connection or otherwise). The connection may generally be realized as a form-fitting connection or a frictional connection. Additionally, or in the alternative, the connection may be configured so that a torque can be transmitted between the two instrument parts <NUM>, <NUM>. In some variants, the connection may not, or not fully, reduce a mechanical play between the two instrument parts <NUM>, <NUM>.

The surgical instrument <NUM> may be a powered surgical instrument. In such a case, the first instrument part <NUM> may accommodate a battery and the second instrument part <NUM> may accommodate a motor electrically powered by the battery. In some variants, the motor can alternatively be accommodated in the first instrument part <NUM>. The second instrument part <NUM> further comprises an instrument tip <NUM>. The instrument tip <NUM> may be mechanically powered by the motor. The instrument tip <NUM> may be a drill, a burr or a saw blade.

In other variants, the surgical instrument <NUM> may be a non-powered surgical instrument, like a screw driver having a first instrument part <NUM> configured as a grip or handle and a second instrument part <NUM> with an instrument tip <NUM> configured as a screw driver blade. The first and second instrument parts <NUM>, <NUM> may be connected (e.g., in a form-fitting manner but with a certain mechanical play) such that torque can be transmitted from the grip or handle to the screw driver blade.

The fixation system <NUM> further comprises a tracker <NUM> detachably attached to the first instrument part <NUM>. The tracker <NUM> is a common optical tracker <NUM> comprising three (or more) markers <NUM> trackable, e.g., by a camera of a surgical navigation system (not shown). The markers <NUM> may be active components (e.g., light emitting diodes, LEDs) or passive components (e.g., reflective spheres).

The fixation system <NUM> further comprises a fixation device <NUM> with a longitudinal axis AL. The fixation device <NUM> is configured to fix the first instrument part <NUM> to the second instrument part <NUM>. The fixation device <NUM> is a separate component that can be handled independently (and, e.g., removed) from the first and second instrument parts <NUM>, <NUM>.

The fixation device <NUM> is in some variants configured to reduce or prevent a mechanical play between the first and second instrument parts <NUM>, <NUM>. In such or other variants, the fixation device <NUM> may prevent the first and second instrument parts <NUM>, <NUM> from being separable from each other. As such, the fixation device <NUM> can be used to maintain a geometric relationship between the instrument tip <NUM> of the second instrument part <NUM> and the tracker <NUM> attached to the first instrument part <NUM>.

With continued reference to <FIG>, the fixation device <NUM> comprises a tubular fixation body <NUM> accommodating a portion of the first instrument part <NUM> and a portion of the second instrument part <NUM>. The fixation body <NUM> has a fastening member <NUM> located on an outer surface of the fixation body <NUM> facing away from the longitudinal axis AL. In the present embodiment, the fastening member <NUM> is configured as a thread having a certain pitch of, for example, <NUM>. Moreover, the fixation body comprises movable clamping members <NUM> in clamping contact with both the first and second instrument parts <NUM>, <NUM>.

The fixation device <NUM> further comprises a tubular actuation member <NUM> that is similar to, e.g., a union nut. The actuation member <NUM> is a rigid, sleeve-like component and configured to receive a portion of the fixation body <NUM>. In particular, the actuation member <NUM> is configured to receive the portion of the fixation body <NUM> comprising the movable clamping members <NUM> and the first fastening member <NUM>. The actuation member <NUM> comprises a fastening member <NUM> (i.e., a thread complementary to the thread of the fastening member <NUM>) located on an inner surface of the actuation member <NUM> facing the longitudinal axis AL. The fastening member <NUM> is configured to engage with first fastening member <NUM> when the actuation member <NUM> receives the portion of the fixation body <NUM>, as shown in <FIG>. Evidently, other fastening members capable of (e.g., form-fittingly) engaging each other could be implemented as well.

A more detailed description of the fixation device <NUM> is given below with reference to <FIG>.

<FIG> illustrates a cross-section of the fixation device <NUM> shown in <FIG> in more detail. The fixation device <NUM> is shown with the fixation body <NUM> and the actuation member <NUM> in an engaging configuration.

As shown in <FIG>, the individual clamping members <NUM> of the fixation body <NUM> are separated via longitudinal slots extending parallel to the longitudinal axis AL. The longitudinal slots separate the clamping members <NUM> to form individual clamping fingers <NUM> and enable the clamping members <NUM> to be movable towards the longitudinal axis AL. The radially outer surface of the clamping members <NUM> has an inclined structural configuration (i.e., extends obliquely relative to the longitudinal axis AL) and thus defines a radially outer conical portion. The radially outer surface of the clamping members <NUM> may be inclined at an angle between <NUM> degrees and <NUM> degrees relative to the longitudinal axis, e.g., at <NUM> degrees. The radially inner surface of the fixation body <NUM> has a cylindrical structural configuration (i.e., extends parallel to the longitudinal axis AL).

Further, the radially inner surface of the actuation member <NUM> is inclined relative to the longitudinal axis AL. The radially inner surface of the actuation member <NUM> may be inclined at an angle between <NUM> degrees and <NUM> degrees relative to the longitudinal axis, e.g., at <NUM> degrees. The radially inner surface thus defines a radially inner conical portion which is complementary to the radially outer conical portion of the fixation body <NUM>. The inner diameter of the actuation member <NUM> therefore changes along a length thereof. In particular, the inner diameter of the actuation member <NUM> tapers in a receiving direction, i.e., in the direction in which at least a portion of the fixation body <NUM> is received by the actuation member <NUM>. As a result of the tapering inner diameter of the actuation member <NUM>, the movable members <NUM> are forced, or deflected, towards the longitudinal axis AL when the fixation body <NUM> is partially received within the actuation member <NUM>.

In other words, the actuation member <NUM> is, due to its structural configuration, configured to exert a clamping force on the clamping members <NUM> when, as illustrated in <FIG>, the fastening member <NUM> of the actuation member <NUM> is in engagement with the fastening member <NUM> of the fixation body <NUM>. The engagement of the fastening members <NUM>, <NUM> will therefore maintain the clamping force.

The clamping force exerted on the claiming members <NUM> is directed towards the longitudinal axis AL, i.e., towards the portions of the first and second instrument parts <NUM>, <NUM> accommodated within the fixation body <NUM>. The magnitude of the exerted clamping force is dependent on the relative position between the fixation body <NUM> and the actuation member <NUM> along the longitudinal axis AL and, thus, on the length of engagement between fastening members <NUM>, <NUM>. Due to the exerted clamping force, the first and second instrument parts <NUM>, <NUM> are fixed to the fixation device <NUM> and also to each other. As a result, mechanical play between the first and second instrument parts <NUM>, <NUM> is reduced and the two instruments parts <NUM>, <NUM> are prevented from separating from each other.

<FIG> illustrate schematic representations of the actuation member <NUM> of the fixation device <NUM> shown in <FIG> illustrates the fastening member <NUM>, i.e., the thread, without the fixation body <NUM> being received in the actuation member <NUM>. As shown in <FIG>, the thread tapers in accordance with the inclination of the radially inner surface of the actuation member <NUM>. <FIG> illustrates a cut-out part of the actuation member <NUM> in a perspective view.

<FIG> illustrate schematic representations of the fixation body <NUM> of the fixation device <NUM> shown in <FIG>. <FIG> illustrates the fastening member <NUM>, i.e., the thread, which is provided in a central portion of the fixation body <NUM> along the longitudinal axis AL. <FIG> illustrates the fixation body <NUM> in a perspective view. As can be gathered from <FIG>, the fixation body <NUM> comprises four finger-like clamping members <NUM> separated by slots. The four clamping members <NUM> are located circumferentially about the longitudinal axis AL with each clamping member <NUM> having the same size (i.e., length and width). As a result, the clamping force is exerted homogenously.

Of course, the number of clamping members <NUM> can be selected as needed. In some variants, a single clamping member <NUM> may suffice, whereas in other variants two, three or more than four clamping members <NUM> may be beneficial. In the scenario of <FIG> The circumferential extension of a particular clamping member <NUM> about the longitudinal axis AL is approximately <NUM>° in the scenario of <FIG>. The circumferential extension may generally range between <NUM>° and <NUM>°.

<FIG> illustrates a schematic representation of another fixation body <NUM> comprising four clamping members <NUM> with one separating slot <NUM> extending along the entire length thereof. The full-length slot <NUM> enables an adaptation of the fixation body <NUM>, i.e., its cross-sectional size, perpendicular to the length of the fixation body. The cross-section of the fixation body <NUM> thus adapts itself to the cross-sectional size of at least one of the first and second instrument parts <NUM>, <NUM> accommodated by the fixation body <NUM>. In this embodiment, the fixation body <NUM> is made of a material that is elastically deformable.

<FIG> illustrates a schematic representation of a fixation device <NUM> similar to the fixation device <NUM> shown in <FIG>. The fixation device <NUM> shown in <FIG> differs from the fixation device <NUM> shown in <FIG> in having a fixation body <NUM> that further comprises an alignment member <NUM>. A cross-section of a part of the fixation body <NUM> of <FIG> at the position of the alignment member <NUM> is shown in <FIG>. The alignment member <NUM> shown in <FIG> is a protrusion extending from the radially inner surface of the fixation body <NUM> towards the longitudinal axis AL. The protrusion is configured to engage, for example, a corresponding groove or indentation (not shown) extending along at least a portion of at least one of the first and second instrument parts <NUM>, <NUM>. As a result, the alignment member <NUM> is configured to circumferentially align the fixation body <NUM> with at least one of the first and second instrument parts <NUM>, <NUM>. Aligning the fixation body <NUM> circumferentially with at least one of the first and second instrument parts <NUM>, <NUM> facilitates fastening the second fastening member <NUM> of the actuation member <NUM> to the first fastening member <NUM> of the fixation body <NUM>. Of course, the alignment member <NUM> could alternatively be a groove or indentation, with a mating protrusion being provided at one or both to the first and second instrument parts <NUM>, <NUM>.

<FIG> illustrate schematic representations of cross-sections of differently shaped fixation bodies <NUM>. Each of the fixation bodies <NUM> comprises multiple clamping members <NUM> extending circumferentially about the longitudinal axis AL. The clamping members <NUM> are adapted for clamping instrument parts with different cross-sectional shapes. The clamping members <NUM> shown in <FIG> are adapted for clamping an instrument part <NUM>, <NUM> with an elliptic cross-section. The clamping members <NUM> shown in <FIG> are adapted for clamping an instrument part <NUM>, <NUM> with a quadratic cross-section. The clamping members <NUM> shown in <FIG> are adapted for clamping an instrument part <NUM>, <NUM> with a triangular cross-section. The number of the clamping members <NUM> may be adapted to any suitable number, e.g., <NUM>, <NUM>, <NUM>, <NUM> or more. Further, the shape of the clamping fingers may be adapted to clamp shapes different from the ones shown in <FIG>, e.g., arbitrary polygonal shapes.

<FIG> illustrate schematic representations of alternative fixation devices <NUM>. It is to be noted that the inclinations relative to the longitudinal axis AL are exaggerated for ease of explanation.

The fixation device <NUM> shown in <FIG> comprises an actuation member <NUM> with an inclined radially inner surface shaped so that only a portion of the inner surface forms a cone. Further, the engagement member <NUM> (i.e., thread) is located on the cone shaped part. In other embodiments, the engagement member <NUM> may be located only in the actuation member portion not forming a cone, or it may span all of the inner surface. The fixation body <NUM> has radially inner and outer surfaces in the region of the clamping members <NUM> that have a cylindrical configuration.

The actuation member shown in <FIG> comprises a cone-shaped actuation member <NUM>. In this variant, the actuation member <NUM> has inclined radially inner and outer surfaces that are again cone-shaped. The fixation body <NUM> again has radially inner and outer surfaces in the region of the clamping members <NUM> that have a cylindrical configuration.

The fixation device <NUM> shown in <FIG> comprises an actuation member <NUM> with cylindrical radially inner and outer surfaces. In this variant, the clamping members <NUM> are inclined and have a cone-shape radially outer surface. The clamping members <NUM> are dimensioned so that a cross-section of the fixation body <NUM> at the end of the clamping members <NUM> directed towards the actuation member <NUM> is smaller than an inner cross section of the cylindrical actuation member <NUM>. The cross-section of the fixation body <NUM> at the end of the clamping members <NUM> directed away from the actuation member <NUM> is larger than the inner cross section of the cylindrical actuation member <NUM>. This variant facilitates fastening of the fastening member <NUM> to the fastening member <NUM>, i.e., thread engagement.

The fixation device <NUM> shown in <FIG> differs from the previously shown variants in that no cone-type or similar inclined surface is formed by any part of the fixation device <NUM>. Instead, the actuation member <NUM> comprises a protrusion <NUM> extending from its radially inner surface as a lip circumferentially about and towards the longitudinal axis AL. When the fixation body <NUM> is received by the actuation device, a force is exerted on the movable clamping members <NUM> by the protrusion <NUM>, which causes the clamping members <NUM> to pivot at their end adjacent to the remainder of the fixation body towards the longitudinal axis AL. Depending on the number of clamping members, the protrusion may have a circumferential extension of less than <NUM>°.

The fixation device <NUM> shown in <FIG> comprises a fixation body <NUM> with movable protrusions <NUM> located at the respective radially outer surface of the movable clamping members <NUM> and at the free ends thereof. A force directed towards the longitudinal axis AL is exerted on the clamping members <NUM> when the fixation body <NUM> is received within the actuation member <NUM> and the protrusions <NUM> come into engagement with the radially inner surface of the actuation member <NUM>. In some variants, this radially inner surface may be inclined such that the actuation member <NUM> has a larger inner cross-section at its end facing the fixation body <NUM>.

The fixation devices <NUM> shown in <FIG> are similar to the fixation devices shown in <FIG> and <FIG>. The fixation devices <NUM> shown in <FIG> differ from the fixation devices shown in <FIG> and <FIG> in that the fixation devices <NUM> comprise complementary snap fit elements as fastening members <NUM>, <NUM> instead of complementary threads. For example, the complementary snap fit elements comprise grooves in a radially outer surface of the fixation body <NUM> that extend in a circumferential direction and are spaced apart from each other along the longitudinal axis AL. On the actuation member <NUM>, the complementary snap fit elements comprise T-shaped or L-shaped members configured to engage the grooves under a biasing force directed towards the longitudinal axis AL as the actuation member <NUM> is pushed onto the fixation body <NUM>.

<FIG> schematically shows the the complementary snap fit elements <NUM>, <NUM> in an engaging configuration. The snap fit elements <NUM>, <NUM> are shaped so that a relative movement between the fixation body <NUM> and the actuation member <NUM> along the longitudinal axis AL is enabled in a first direction, and prevented in a second direction opposite to the first direction. In particular, a relative movement with the fixation body <NUM> and the actuation member <NUM> moving further towards each other is enabled. A relative movement with the fixation body <NUM> and the actuation member <NUM> moving away from each other is prevented. To enable a relative movement between the fixation body <NUM> and the actuation member <NUM> along the longitudinal axis AL in the second direction, the complementary snap fit elements <NUM>, <NUM> must be actively disengaged from each other.

While different combinations of the structural elements of the fixation body <NUM> and the actuation member <NUM> have been presented above, it is evident that alternative configurations may be provided.

<FIG> illustrates a schematic representation of another embodiment of a fixation system <NUM> comprising a surgical instrument <NUM>, a fixation device <NUM> and a tracker <NUM>. The surgical instrument <NUM> and tracker <NUM> correspond to the ones shown in <FIG>.

The fixation device <NUM> illustrated in <FIG> comprises, analogous to the fixation device of <FIG>, a fixation body <NUM> with a first fastening member <NUM> and first movable clamping members <NUM> at one end thereof. In addition, the fixation body <NUM> comprises a further fastening member <NUM> and further movable clamping members <NUM> at an opposite end.

Moreover, the fixation device <NUM> comprises a first actuation member <NUM> with a dedicated fastening member <NUM> and a second actuation member <NUM> with another fastening member <NUM>. The fastening member <NUM> of the first actuation member <NUM> is configured to engage with the fastening member <NUM> at one end of the fixation body <NUM> for fixing the first instrument part <NUM> to the fixation device <NUM>. The fastening member <NUM> of the second actuation member <NUM> is configured to engage with the fastening member <NUM> at the other end of the fixation body <NUM> for fixing the second instrument part <NUM> to the fixation device <NUM>. Therefore, each of the instrument parts <NUM> and <NUM> are separately fixed to the fixation device <NUM>.

<FIG> illustrates a schematic representation of the fixation device <NUM> shown in <FIG>. The fixation device <NUM> comprises two symmetric halves along its longitudinal axis AL. Each halve is constructed analogous to the fixation device <NUM> shown in <FIG>. In particular, connecting the fixation bodies <NUM> of two fixation devices <NUM> as shown in <FIG> such that the movable clamping members <NUM> are located in opposite directions results in the fixation device <NUM> shown in <FIG>.

<FIG> illustrates a schematic representation of the fixation body <NUM> of the fixation device <NUM>. The fastening members <NUM>, <NUM> are threads located on the opposite clamping members <NUM>, <NUM>.

<FIG> illustrates a schematic representation of another fixation body <NUM> comprising a slot <NUM> extending along the entire length thereof. Analogous to the slot <NUM> of the fixation body <NUM> shown in <FIG>, the slot <NUM> enables adapting the cross-sectional size of the fixation body <NUM> to the cross-sectional size of the first and second instrument parts <NUM>, <NUM> to be accommodated by the fixation body <NUM>.

Deviating from what is shown in <FIG>, the fixation body <NUM> and the actuation members <NUM>, <NUM> can have any of the configurations discussed above, for example with reference to <FIG>.

<FIG> illustrates a flow diagram <NUM> of a method for fixing the two parts <NUM>, <NUM> of the surgical instrument <NUM> to each other using, for example, the fixation device <NUM> as described with reference to <FIG>. Of course, the method could similarly be performed using the fixation device <NUM> of <FIG>. The method may be performed by surgical personnel in preparation of a surgical procedure.

A first step <NUM> comprises accommodating a portion of the first instrument part <NUM> and a portion of the second instrument part <NUM> in the fixation body <NUM> of the fixation device <NUM>.

A second step <NUM> comprises fastening the fastening member <NUM> of the actuation member <NUM> to the complementary fastening member <NUM> of the fixation body <NUM> for simultaneously fixing the first instrument part <NUM> and the second instrument part <NUM> to the fixation device <NUM>.

In case of using the fixation device <NUM> as described with reference to <FIG>, the first step <NUM> may be analogous as described with reference to the fixation device <NUM>. In method step <NUM>, the two actuation members <NUM>, <NUM> may separately be fastened, via their respective engagement member <NUM>, <NUM>, to the corresponding engagement member <NUM>, <NUM> of the fixation body <NUM>.

In a further step not illustrated in <FIG>, the geometric relationship between the instrument tip <NUM> and the tracker <NUM> may be registered using any known registration technique, such as by bringing the instrument tip <NUM> in abutment with a divot or other structure of a tracked registration device. Once registration has been performed, a surgical procedure involving the surgical instrument <NUM> may be started, and navigation instructions may be calculated by a navigation system based on the position (and/or orientation) of the tracked surgical instrument <NUM> and the registered geometric relationship.

It will be appreciated that the surgical instrument <NUM> could also be part of a surgical robot. In this case, the instrument tip <NUM> of the instrument part <NUM> could be, or could be comprised by, an end effector of the surgical robot, and the other instrument part <NUM> could be comprised by a tracked robotic arm movable in one or more degrees of freedom.

Claim 1:
A fixation device (<NUM>, <NUM>) for fixing a first part (<NUM>) of a surgical instrument (<NUM>) to a second part (<NUM>) of the surgical instrument (<NUM>), the fixation device (<NUM>, <NUM>) having a longitudinal axis (AL) and comprising:
a fixation body (<NUM>, <NUM>) configured to accommodate a portion of the first instrument part (<NUM>) and a portion of the second instrument part (<NUM>) therein, the fixation body (<NUM>, <NUM>) comprising a first fastening member (<NUM>, <NUM>) and at least one movable first clamping member (<NUM>, <NUM>) configured to clampingly engage at least the first instrument part (<NUM>) so as to fix at least the first instrument part (<NUM>) to the fixation device (<NUM>, <NUM>); and
a first actuation member (<NUM>, <NUM>) configured to receive at least a portion of the fixation body (<NUM>. <NUM>) and comprising a second fastening member (<NUM>, <NUM>) configured to engage with the first fastening member (<NUM>, <NUM>), wherein the first actuation member (<NUM>, <NUM>) is configured to exert a clamping force on the first clamping member (<NUM>, <NUM>) when the second fastening member (<NUM>, <NUM>) is in engagement with the first fastening member (<NUM>, <NUM>);
characterised in that
the fixation body (<NUM>, <NUM>) has a separating slot (<NUM>, <NUM>) extending along an entire length thereof, the separating slot (<NUM>, <NUM>) enabling adapting a cross section of the fixation body (<NUM>, <NUM>) perpendicular to the length of the fixation body (<NUM>, <NUM>).