Patent Description:
Computer assisted surgery has made considerable progress in recent years, for example to plan and visualize a surgical approach for a surgeon to reach a surgical target inside a patient's body. To assist the surgeon in properly operating a surgical tool, such as a drill or a biopsy needle, in accordance with the planned surgical approach, a surgical arm may be used. The surgical arm is adjustable relative to multiple adjustment axes and, once properly adjusted in accordance with the planned surgical approach, permits an exact guidance of the surgical tool to the surgical target.

It will be appreciated that a proper adjustment of the surgical arm is of utmost importance for an optimal surgical result. At the same time, the adjustment has to be performed as quickly as possible to shorten the duration of the surgical procedure and the resulting stress on the patient.

<CIT> discloses a bone incision block including an incision guide, a localization reference adjustably attached to the incision guide, a fastener for fastening to a bone, and an adjustment device. The incision guide defines an incision plane, and the localization reference enables the incision plane to be spatially determined. The adjustment device is operatively coupled between the fastener and the incision guide, wherein the incision plane can be set relative to the bone via the adjustment device, and a spatial position of the adjustment device can be determined via a registration element.

<CIT> discloses an MRI guided interventional system with a frame comprising colour coded actuators.

There is a need for a surgical arm that can be adjusted quickly and in an exact manner. Also, there is a need for providing visual guidance for efficiently operating such a surgical arm.

The invention is defined in independent claims <NUM> and <NUM>, further embodiments are described in the dependent claims.

According to one aspect, a surgical arm is presented, the surgical arm comprising a first interface configured to receive a device for performing or assisting a surgical procedure and also comprising multiple adjustment members configured to adjust the surgical arm relative to a respective adjustment axis. The surgical arm further comprises at least two operating members configured to operate different ones of the adjustment members, wherein the operating members are marked with different visual codings. The surgical arm further comprises at least two locking members associated with different ones of the operating members. Each of the locking members is configured to lock the arm in position with respect to a specific movement relative to the respective adjustment axis of the associated operating member. The locking members are respectively coded with the same visual coding as the operating member associated with the respective adjustment axis.

The surgical arm may be a mechanical element configured to be used during a surgical procedure (e.g., in a sterile operating room). The surgical arm may be used by a surgeon for placing and/or aligning a surgical tool or any other device (e.g., a guidance member for the surgical tool). In one example, the surgical arm may be used for properly orienting a biopsy needle or other surgical tool. As such, the first interface may be configured to receive a guidance device such as a needle sleeve shaped to receive the biopsy needle, or such as a drill sleeve.

The adjustment members may be mechanical components, for example gearwheels, toothed racks or (ball) joints. The adjustment members may be configured to move at least one moveable part of the surgical arm along and/or around a specific axis.

Each particular adjustment axis may be a rotational or a translational axis. In case of a rotational adjustment axis, the surgical arm may be configured to be moved around this axis. In case of a translational axis, the surgical arm may be configured to be moved along this axis. For example, the surgical arm may comprise two rotational adjustment axes and two translational adjustment axes. In another example, the surgical arm may only comprise one rotational adjustment axis and one translational adjustment axis. The respective rotational and translational adjustment axes may be perpendicular to one another.

The operating members may be manually or electrically (e.g., by an electric motor) operable. Each of the operating members may be configured such that by operating the operating member, the surgical arm will be moved around a specific rotational adjustment axis or along a specific translational adjustment axis associated with the operating member. In one example, one or more of the operating members may be rotatable elements, such that rotating the operating members in a first rotation direction causes the surgical arm to be moved in a first adjustment direction relative to a specific adjustment axis associated with the operating member. When rotating the operating member in a second rotation direction different from (e.g., opposite to) the first rotation direction, the surgical arm may be moved in a second adjustment direction different from (e.g., opposite to) the first adjustment direction relative to the specific adjustment axis. In other examples, the operating members may be slidable elements (e.g., levers) or pushable elements (e.g., buttons).

The visual codings may be cognitively detectable by a human observer (e.g., a user such as a surgeon) and/or electrically detectable by an electronic component (e.g., a camera of a surgical navigation system). Different visual codings may be clearly distinguishable from one another by the human observer as well as the electronic component. In one example, the visual codings may be different colors. In another example, the visual codings may be different visual patterns, e.g., different geometric forms. In yet another example, the visual codings may be different shadings, e.g., dashed and/or dotted lines.

The locking members may be manually or electrically (e.g., by an electric motor) operable. Like the operating members, the locking members may also be rotational, slidable and/or pushable elements. When one of the locking members is operated to be active (i.e., locking), the surgical arm may no longer be adjustable relative to the specific adjustment axis of the associated operating member. In other words, in a locked state, the locking member may fix the surgical arm with respect to a specific movement (e.g., rotatory or translatory) relative to a specific alignment axis.

The respective visual codings of a locking member and an associated operating member may be identical. For example, if a specific operating member associated with a respective adjustment axis is encoded with a blue color, the locking member associated with the specific operating member may also be encoded with a blue color. In another example, if a specific operating member is encoded with a dotted pattern, the locking member associated with said operating member may also be encoded with the dotted pattern.

In some implementations, the operating members as well as the locking members may be configured rotatably. As described above, rotating the operating member in a first rotation direction may cause the surgical arm to be adjusted in a first adjustment direction. Likewise, rotating the locking member in a first direction may fix an alignment of the surgical arm relative to a specific alignment axis. Additionally, rotating the locking member in a second direction different from the first direction may enable further alignment of the surgical arm relative to the specific alignment axis. The operating members and the locking members may for example be represented by rotatable turning knobs or pivotably mounted levers.

At least a first one of the adjustment members may be configured to adjust the surgical arm along a translational adjustment axis. At least a second one of the adjustment members may be configured to adjust the surgical arm around a rotational adjustment axis. In one variant, a specific adjustment member may be associated with a specific adjustment axis. Alternatively, two or more adjustment members may be associated with the same adjustment axis. In the latter variant, a first adjustment member may be configured to adjust the surgical arm in one direction (e.g., a positive x-direction) and a second adjustment member may be configured to adjust the surgical arm in a second direction (e.g., a negative x-direction).

In some variants, the surgical arm may comprise a second interface for receiving a tracking device configured to be tracked by a surgical navigation system. The tracking device may for example be an optical tracking device such as a reflective marker. Additionally, or in the alternative, the surgical arm may comprise the tracking device configured to be tracked by a surgical navigation system.

As said, the different visual codings may be different colors. One operating member and the locking members associated with that operating member may be encoded in yellow, and a different operating member associated with a different locking member may be encoded in blue.

In some embodiments, the surgical arm may further comprise a guidance device coupled to the first interface. The guidance device may define an operative axis and may be configured to guide a surgical tool along the operative axis. The guidance device may be configured to be received by (e.g., to be coupled to) the first interface.

According to a second aspect, a method of providing visual guidance for operating a surgical arm according to a pre-determined surgical approach is provided. The surgical arm comprises a first interface configured to receive a device for performing or assisting a surgical procedure and multiple adjustment members configured to adjust the surgical arm relative to a respective adjustment axis. The surgical arm further comprises at least two operating members configured to operate different ones of the adjustment members, wherein the operating members are marked with different visual codings. The surgical arm further comprises at least two locking members associated with different ones of the operating members. Each of the locking members is configured to lock the arm in position with respect to a specific movement relative to the respective adjustment axis of the associated operating member. The locking members are respectively coded with the same visual coding as the operating member associated with the respective adjustment axis. The method comprises the steps of determining at least one of a current position and a current orientation of the first interface or a device received by the first interface, and determining, based on the pre-determined surgical approach, at least one of a target position and a target orientation of the interface or the device. The method further comprises the step of, based on a difference between at least one of the current and target positions and the current and target orientations, determining that an adjustment of the surgical arm is required relative to at least one adjustment axis; and triggering a display of the visual coding associated with the at least one operating member associated with the at least one adjustment axis so as to provide visual guidance.

The steps may be performed by a processing unit of a computer system (e.g., as part of a surgical navigation system). The processing unit may trigger a display unit (e.g., a monitor) of the computer system to provide the visual guidance.

The pre-determined surgical approach may be a planned trajectory of a surgical tool for reaching an area within a patient's body where a surgical procedure is to be performed. For example, the pre-determined surgical approach may correspond to the planned trajectory of a biopsy needle that is to be entered into the skull of a patient. The pre-determined surgical approach may be pre-operatively planned using a computer system, such as a surgical navigation system.

The planned trajectory may comprise a starting point (e.g., an entry point into the body) according to the pre-determined surgical approach. Alternatively or additionally, the planned trajectory may comprise an endpoint (e.g., an anatomical target) according to the pre-determined surgical approach.

In some variants, the visual guidance may comprise a display of the visual coding in combination with an indication of a direction in which the associated operating member is to be operated. For example, if the visual codings are different colors and the operating members are configured rotatably, visual guidance may be provided by displaying a color coding of a specific operating member together with the image of an arrow depicting a direction in which the rotatable operating member is to be rotated.

The visual guidance may further comprise a display of the visual coding in combination with an indication of an amount by which the associated operating member is to be operated. The indication of an amount by which the associated operating member is to be operated may be in the form of a first number of geometric elements (and/or a first geometric form such as a circle having a first size) in association with the visual coding of the operating member. For example, the operating members may be rotatably mounted and the indication could be represented by a number of segments of a circle representative of a number of degrees by which a specific operating member has to be turned.

The method may further comprise displaying a second number of geometric elements (and/or a second geometric form such as a circle having a second size different form the first size) in association with a visual coding different than the visual coding of the first number of geometric elements (and/or the first geometric form), the second number of geometric elements (or the second geometric form) being indicative of an amount by which the associated operating member has been operated. In the above described example, a first number of segments of a circle may be filled with a visual coding associated with the respective operating member and a second number of segments of the circle may be filled with a visual coding different from the visual coding associated with the respective operating member.

In some variants, the method may further comprise determining a specific adjustment axis relative to which the surgical arm deviates the most among all adjustment axes from the pre-determined surgical approach. In this case the method may further comprise prioritising the provision of visual guidance for said specific adjustment axis over any other adjustment axis.

The method may further comprise the step of trigger a display of a numerical value indicative of an amount by which a specific adjustment axis deviates from the pre-determined surgical approach. The method may further comprise triggering a display of a superposition of at least one of the current position and the current orientation of the first interface or a device received in the first interface relative to the pre-determined surgical approach.

In some implementations, the at least one of a current position and a current orientation of the first interface or the device received by the first interface may be determined by tracking, using a surgical navigation system, a tracking device that is in a fixed spatial relationship with at least one of the first interface and the device received by the first interface.

According to a further aspect, a computer program product is presented, the computer program product comprising computer program instructions to perform the method steps of the above described method when executed by a processor.

According to a further aspect, a system comprising the surgical arm as described above and the above described computer program product is presented.

In the following description, exemplary embodiments of a surgical arm and a technique of providing visual guidance for operating the surgical arm will be explained with reference to the drawings. The same reference numerals will be used to denote the same structural features.

<FIG>, <FIG> and <FIG> show an embodiment of a surgical arm <NUM> that is configured to be used during a surgical procedure. The surgical arm <NUM> is intended to be attached to a support frame (not shown) that is fixedly positioned in an operating room relative to a patient. As an example, the surgical arm <NUM> may be attached via the support frame to an operating table or an operating chair. In some variants, the surgical arm <NUM> is used for computer-assisted neuro-surgery, for example to guide a surgical tool towards a surgical target (e.g., a tumor) within the patient's skull.

The surgical arm <NUM> comprises an interface <NUM> configured to receive a device for performing or assisting the surgical procedure. In the present embodiment, the device interface <NUM> is configured as a sleeve with a cylindrical through-hole. It will be apparent to one skilled in the art that the device interface <NUM> could also be configured in a different manner, for example as a rail.

The device to be received by the device interface <NUM> can be a surgical tool or can be configured to cooperate with (e.g., to guide) a surgical tool. In the exemplary embodiment of <FIG>, <FIG> and <FIG>, the device interface <NUM> is configured to receive a guidance device <NUM> for a biopsy needle, a surgical drill or other any surgical tool. The guidance device <NUM> is concentrically received within the sleeve-like device interface <NUM> and defines an operative axis <NUM>. In the present embodiment, the guidance device <NUM> has a cylindrical through-hole configured to guide the surgical tool along the operative axis <NUM> towards the surgical target within the patient. It will be appreciated that in other embodiments, the guidance device <NUM> could be realized as a guide rail or otherwise.

The arm <NUM> comprises a further interface <NUM> configured to receive a tracking device <NUM> that is to be tracked by a surgical navigation system. In the present embodiment, the tracking device <NUM> is an optical tracking device and comprises four reflective spheres that are located spaced apart from each other at the end of four respective arms. Of course, the tracking device <NUM> could also be configured to comprise active light sources or other trackable elements. Moreover, the tracking device <NUM> could also be integrally formed with a component of the surgical arm <NUM>, such as the guidance device <NUM> or the device interface <NUM>.

In the present embodiment, the tracker interface <NUM> is part of the guidance device <NUM>, which in turn is detachably mounted in the device interface <NUM> (see <FIG> and <FIG>). In other embodiments, the tracker interface <NUM> is mounted to the device interface <NUM> or another component of the surgical arm <NUM> with a fixed relationship to the device interface <NUM>.

As shown in the exploded view of <FIG>, the surgical arm <NUM> comprises four adjustment members <NUM>, <NUM>, <NUM> and <NUM> configured to adjust the surgical arm <NUM> relative to different adjustment axes <NUM>, <NUM> and <NUM>. The adjustment members <NUM>, <NUM>, <NUM> and <NUM> are operated by operating members <NUM>, <NUM>, <NUM> and <NUM>. In the present embodiment, the operating members <NUM>, <NUM>, <NUM> and <NUM> are configured rotatably, i.e., as turning knobs. However, the present disclosure is not limited thereto. For example, one or more of the operating members <NUM>, <NUM>, <NUM> and <NUM> could also be configured for translatory movement (e.g., as slidable and/or pushable elements). Moreover, one or more of the operating members <NUM>, <NUM>, <NUM> and <NUM> could be configured to be electrically operable by an electric motor (not shown).

In the present embodiment, each of the operating members <NUM>, <NUM>, <NUM> and <NUM> is configured to operate exactly one of the adjustment members <NUM>, <NUM>, <NUM> and <NUM>. Operating one or more of the operating members <NUM>, <NUM>, <NUM> and <NUM> serves to adjust the surgical arm <NUM> relative to at least one adjustment axis <NUM>, <NUM> and <NUM>. More specifically, as illustrated in <FIG>, operating the operating member <NUM> translatorily moves the surgical arm <NUM> along adjustment axis <NUM> in two opposite directions according to double-headed arrow <NUM>. Likewise, operating the operating member <NUM> translatorily moves the surgical arm <NUM> along adjustment axis <NUM> in two opposite directions according to double headed arrow <NUM>. The two adjustment axes <NUM>, <NUM> extend perpendicular to each other.

On the other hand, operating member <NUM> is configured to rotationally move the surgical arm <NUM> around adjustment axis <NUM> in two opposite directions according to double headed arrow <NUM>. Further, operating member <NUM> is configured to rotationally move the surgical arm <NUM> around adjustment axis <NUM> in two opposite directions according to double headed arrow <NUM>.

As is clear from the above description, operating member <NUM> and operating member <NUM> are configured to adjust the surgical arm <NUM> relative to adjustment axis <NUM> in a translatory and in a rotatory manner, respectively. Adjustment member <NUM> is configured to adjust the surgical arm <NUM> along adjustment axis <NUM> and adjustment member <NUM> is configured to adjust the surgical arm <NUM> around adjustment axis <NUM>. In an alternative embodiment, adjustment axis <NUM> and adjustment member <NUM> may coincide. In this or another embodiment, operating member <NUM> and operating member <NUM> may be configured to adjust the surgical arm <NUM> relative to different adjustment axes.

Each of the operating members <NUM>, <NUM>, <NUM> and <NUM> is marked with a different visual coding. The different visual codings can easily be distinguished by a human operator of the surgical arm <NUM> without significant cognitive effort.

In the drawings, each of the operating members <NUM>, <NUM>, <NUM> and <NUM> is exemplarily marked with a different geometric pattern. In particular, operating member <NUM> is marked with a pattern in the form of a grid. Further, operating member <NUM> is marked with a pattern in the form of dots. Operating member <NUM> is marked with a pattern in the form of straight lines. Operating member <NUM> is marked with a pattern in the form of black and white diamonds. It is to be understood that the visual codings in the form of geometric patterns of the operating members <NUM>, <NUM>, <NUM> and <NUM> only serve as an illustrative example and are not limited thereto. In another example, the operating members <NUM>, <NUM>, <NUM> and <NUM> may be marked with visual codings in the form of different colors (e.g., red, green, yellow and blue, respectively).

The surgical arm <NUM> depicted in <FIG>, <FIG> and <FIG> further comprises locking members <NUM>, <NUM>, <NUM> and <NUM>. Locking member <NUM> is not visible in <FIG>, but is shown in <FIG>. Each of the locking members <NUM>, <NUM>, <NUM> and <NUM> is associated with exactly one of the operating members <NUM>, <NUM>, <NUM> and <NUM>. That is, locking member <NUM> is associated with operating member <NUM>, locking member <NUM> is associated with operating member <NUM>, locking member <NUM> is associated with operating member <NUM> and locking member <NUM> is associated with operating member <NUM>. The association between the locking members <NUM>, <NUM>, <NUM> and <NUM> and the respective operating members <NUM>, <NUM>, <NUM> and <NUM> is depicted in the drawings by the fact that each of the locking members <NUM>, <NUM> and <NUM> is marked with the same visual coding (i.e., the same geometric pattern) as its associated operating member <NUM>, <NUM>, <NUM> and <NUM>. In more detail, locking member <NUM> is marked with the grid pattern of operating member <NUM>, locking member <NUM> is marked with the dot pattern of operating member <NUM>, locking member <NUM> is marked with the line pattern of operating member <NUM> and locking member <NUM> is marked with the black and white diamond pattern of operating member <NUM>. Reference is made to the respectively marked rings encircling the locking symbols of the locking members <NUM>, <NUM> and <NUM> in <FIG>. The visual codings of the operating members <NUM>, <NUM>, <NUM> and <NUM> and the respective locking members <NUM>, <NUM>, <NUM> and <NUM> will be described in more detail with reference to <FIG> below.

The locking members <NUM>, <NUM>, <NUM> and <NUM> are configured to lock the surgical arm <NUM> in position relative to a dedicated movement relative to the respective adjustment axis <NUM>, <NUM>, <NUM> of an associated operating member <NUM>, <NUM>, <NUM> and <NUM>. That is, after the surgical arm <NUM> has properly been aligned relative to the patient with respect to each one of the adjustment axes <NUM>, <NUM> and <NUM> using the operating members <NUM>, <NUM>, <NUM> and <NUM>, the associated locking member <NUM>, <NUM>, <NUM> and <NUM> is operated such that the corresponding alignment of the surgical arm <NUM> can no longer be changed.

In the embodiment of <FIG>, the locking members <NUM>, <NUM>, <NUM> and <NUM> are configured rotatably, i.e., in the form of rotatable levers. The locking members <NUM>, <NUM>, <NUM> and <NUM> may have a definite locking position. For example, rotating the locking members <NUM>, <NUM>, <NUM> and <NUM> clockwise by <NUM>° may lock the surgical arm <NUM> in position relative to a dedicated movement with respect to the associated adjustment axis <NUM>, <NUM> or <NUM> associated with the respective locking member <NUM>, <NUM>, <NUM> and <NUM>. Further, rotating any of the locking members <NUM>, <NUM>, <NUM> and <NUM> counterclockwise by <NUM>° may unlock the position of the surgical arm <NUM>, i.e., the surgical arm may again be moveable relative to the associated adjustment axis <NUM>, <NUM> and <NUM>.

<FIG> shows the surgical arm <NUM> according to <FIG> in a partly disassembled configuration. In more detail, the guidance device <NUM> is removed from the device interface <NUM>. As shown in <FIG>, the tracker interface <NUM> for detachably receiving the tracking device <NUM> is attached to the guidance device <NUM>. As stated above, the surgical arm <NUM> can be operated with a variety of different surgical tools (e.g., a biopsy needle or a surgical drill). Depending on the specific surgical tool, a different guidance device <NUM>, configured to receive the surgical tool, may have to be inserted into the first interface <NUM>. As the tracker interface <NUM> is attached to the guidance device <NUM>, a positional relationship between the tracking device <NUM> and the guidance device <NUM> can remain fixed and can be defined in advance, which simplifies the tracking process of for example a spatial orientation of the guidance device <NUM> (and, thus, of any surgical tool guided therein).

<FIG> shows an exploded view of the surgical arm <NUM> of <FIG>. The four adjustment members <NUM>, <NUM>, <NUM> and <NUM> are clearly visible.

As can be seen in <FIG>, the adjustment members <NUM> and <NUM> comprise screw threads <NUM>, <NUM> configured to adjust the surgical arm <NUM> upon rotation of the adjustment members <NUM> and <NUM> (via the associated operating member <NUM>, <NUM>) in a translational manner along the associated adjustment axis <NUM>, <NUM>. Further, the adjustment member <NUM> comprises a groove <NUM> accommodating a spherical front end of a shaft <NUM> of the operating member <NUM>. The shaft <NUM> comprises a thread cooperating with a complementary thread in a bore of a stationary member <NUM>. By turning the operating member <NUM>, the shaft <NUM> moves towards or away from adjustment member <NUM> that is tiltable relative to the adjustment axis <NUM>. As the spherical head of the shaft <NUM> is movably captured within the groove <NUM> of the adjustment member <NUM>, a movement of the shaft <NUM> towards or away from the adjustment member <NUM> tilts, or rotates, the latter relative to adjustment axis <NUM>.

In a similar manner as operating member <NUM>, also operating member <NUM> comprises a threaded shaft <NUM> with a spherical head. The thread of shaft <NUM> cooperates with a complementary thread in a bore of adjustment member <NUM>. By turning operating member <NUM>, shaft <NUM> moves towards or away from adjustment member <NUM> that is tiltable relative to the adjustment axis <NUM>. As the spherical head of the shaft <NUM> is captured within a groove <NUM> of the adjustment member <NUM>, a movement of the shaft <NUM> relative to the adjustment member <NUM> tilts, or rotates, the latter relative to the adjustment axis <NUM>.

As can also be gathered from <FIG>, the surgical arm <NUM> further comprises an attachment interface <NUM> configured to attach the surgical arm <NUM> to a support frame (not shown). The support frame, in turn, may be attached to an operating table or an operating chair.

<FIG> shows a top view of a portion of the surgical arm <NUM>, comprising the operating member <NUM> and the locking member <NUM> associated therewith. <FIG>, on the other hand, shows a front portion of the surgical arm <NUM>, comprising the operating member <NUM> and the locking member <NUM> associated therewith. As can be seen in <FIG>, each of the locking members <NUM>, <NUM> is marked with the same visual codings as its associated operating member <NUM>, <NUM>. In particular, locking member <NUM> is marked with the same grid pattern <NUM> as its associated operating member <NUM>. Further, locking member <NUM> is marked with the same line pattern <NUM> as its associated operating member <NUM>. Therefore, it is immediately apparent to the user (e.g., a surgeon) that operating member <NUM> and locking member <NUM> pertain to the same adjustment axis <NUM>. The same holds true for operating member <NUM> and locking member <NUM>.

Furthermore, the different visual codings of the operating members and the associated locking members are also detectable by a camera, such as a camera of a surgical navigation system (e.g., the same camera that is also used to track the tracking device <NUM>). Thus, also a processing unit of the surgical navigation system can determine each association between one of the visually coded operating members and one of the visually coded locking members. Moreover, an association between each visually coded operating member and the respective adjustment axis associated therewith can be known to the processing unit a priori (e.g., can be pre-stored in a storage medium). Consequently, the surgical navigation system can easily determine which operating member to operate in order to adjust the surgical arm <NUM> relative to a specific adjustment axis. Further, the surgical navigation system can determine which locking member to operate in order to lock the surgical arm <NUM> in position relative to a respective adjustment axis. The surgical navigation system may also be able to display said associations to a user in order to provide visual guidance for aligning the surgical arm <NUM>, or to perform the alignment automatically (e.g., via electric motors).

The interaction between the user, such as the surgeon, and the surgical navigation system in order to provide visual guidance for operating the surgical arm <NUM> is now described in further detail with reference to <FIG>, <FIG> and <FIG>.

<FIG> shows a flow diagram <NUM> of an exemplary method of providing visual guidance for operating a surgical arm (e.g., the surgical arm <NUM>) according to a pre-determined surgical approach.

The pre-determined surgical approach may be defined by at least one of a surgical target (e.g., in the form of a point or an extended object such as a tumor) located within a patient's body and an entry point where a surgical tool will enter the patient's body. In some variants, the surgical approach is defined by a trajectory that connects a planned (or actual) entry point at a body surface of the patient with a planned target. The pre-determined surgical approach may be defined by the surgeon pre-operatively using a computer system and previously generated patient images.

The method starts in step S01 with determining at least one of a current position and a current orientation of at least one of the device interface <NUM> and a device (e.g., guidance device <NUM> or a surgical tool accommodated therein) received by the device interface <NUM>. Determining the current position and/or orientation may be performed using a surgical navigation system tracking the tracking device <NUM> within a given coordinate system. As described with reference to <FIG>, a positional relationship between the tracking device <NUM> and the guidance device <NUM> of the surgical arm <NUM> may be known a priori (e.g., because it is fixed). In an operating state of the surgical arm <NUM>, the guidance device <NUM> will be coupled to the device interface <NUM>. As such, the tracking device <NUM> will be in a fixed spatial relationship to the device interface <NUM> and the guidance device <NUM> received therein (and, of course, in a fixed spatial orientation to a surgical tool guided by the guidance device <NUM>). Thus, in the embodiment of <FIG>, the current position and orientation of the first interface <NUM> and the guidance device <NUM> can easily be tracked by the surgical navigation system.

The method continues in step S02 with determining at least one of a target position and a target orientation of the device interface <NUM> or the guidance device <NUM>. The target position and/or orientation will be determined based on the pre-determined surgical approach. As an example, the target position and target orientation of the device interface <NUM> or the guidance device <NUM> may be defined to be concentrically aligned with a linear trajectory connecting the planned or actual entry point (e.g., in the patient's skull) with the surgical target (e.g., a brain tumor).

If a difference between the current and target positions and/or current and target orientations is detected (e.g., by the surgical navigation system), it is determined in step S03 that an adjustment of the surgical arm <NUM> is required relative to at least one adjustment axis (e.g., adjustment axis <NUM>, <NUM> or <NUM>). The difference may for example be given by a distance (e.g., in millimeters) by which a position of the surgical arm <NUM> deviates in a certain direction from the pre-determined surgical approach. Alternatively or additionally, the difference may also be given by an angle (e.g., in degrees) by which an orientation of the surgical arm <NUM> deviates from the pre-determined surgical approach.

If an adjustment according to step S03 is required, the navigation system (e.g., a processing unit thereof) triggers the display of visual guidance for a user in order to properly adjust a position and/or orientation of the surgical arm <NUM> in accordance with the pre-determined surgical approach. Visual guidance may be provided by displaying on a display device a visual coding associated with the at least one operating member <NUM>, <NUM>, <NUM>, <NUM> that is associated with the at least one adjustment axis <NUM>, <NUM>, <NUM> relative to which the surgical arm <NUM> deviates from the pre-determined surgical approach.

The provision of visual guidance will be explained in the following in more detail with reference to <FIG> and <FIG>.

<FIG> shows an exemplary display of a display device, such as a monitor of the surgical navigation system. The display provides visual guidance for operating the surgical arm <NUM> according to the pre-determined surgical approach and based on the visually coded operating members <NUM>, <NUM>, <NUM> and <NUM>.

In <FIG>, a pre-determined surgical approach for reaching a brain tumor is depicted. A planned entry point on a patient's skull is indicated by a circle <NUM> and a planned target location defined by the tumor is indicated by a cross <NUM>. The corresponding surgical approach defines a planned trajectory of a surgical tool (e.g. a biopsy needle). This trajectory is represented by a straight line <NUM> connecting the entry point <NUM> and the target location <NUM>.

In <FIG>, three different views of the pre-determined surgical approach are shown relative to a pre-operative or intra-operative image of the patient's skull. In the top left view of the exemplary display of <FIG>, a cross-sectional front view of the patient's skull is displayed together with a view of the patient's brain <NUM> and the pre-determined surgical approach <NUM>, <NUM>, <NUM>. In the top right view of the exemplary display of <FIG>, a cross-sectional side view of the patient's skull is shown together with a view of the brain <NUM> and the pre-determined surgical approach <NUM>, <NUM>, <NUM>. In other words, the view according to the top right illustration is rotated by <NUM>° with respect to the view according to the top left illustration. In the bottom left illustration of the exemplary display of <FIG>, a view perpendicular to the pre-determined surgical approach <NUM>, <NUM>, <NUM> is shown, i.e., the actual view a surgeon would see before entering a surgical instrument inside the patient's skull. The images of the patient's skull and brain <NUM> in the top row of the exemplary display of <FIG> may be obtained by 3D Computer Tomography (CT) imaging or using Magnetic Resonance Imaging (MRI).

In the bottom right view of <FIG>, visual guidance for operating the surgical arm <NUM> according to the pre-determined surgical approach is provided. In more detail, a schematic representation <NUM> of the surgical arm <NUM> is shown. The schematic representation <NUM> of the surgical arm <NUM> is further accompanied by checkmarks <NUM>, <NUM>. Each of the checkmark <NUM>, <NUM> is associated with a dedicated movement relative to one of the adjustment axes <NUM>, <NUM>, <NUM> by operating one of the four operating members <NUM>, <NUM>, <NUM>, <NUM> and indicates that the surgical arm <NUM> is already aligned with respect to these two adjustment axes <NUM>, <NUM> and the planned surgical trajectory <NUM> (for adjustment axis <NUM>, only the translational movement is completed, whereas a rotational movement is still needed for proper alignment).

Further, the computer system provides the user with information regarding a specific operating member <NUM>, <NUM>, <NUM> and <NUM> associated with a specific adjustment axis <NUM>, <NUM>, <NUM> to be operated for proper alignment of the surgical arm <NUM> (i.e., of the device interface <NUM> and/or the guidance device <NUM>) according to the pre-determined surgical approach. In the embodiment of <FIG>, the user is provided with visual information relating to the operating member <NUM> that is associated with the adjustment axis <NUM>. The information comprises a numerical value <NUM> indicative of an amount by which the alignment of the surgical arm <NUM> deviates from the pre-determined surgical approach <NUM>, <NUM>, <NUM> relative to the adjustment axis <NUM>.

The deviation of the alignment of the surgical arm <NUM> from the pre-determined surgical approach relative to each of the adjustment axes <NUM>, <NUM>, <NUM> may exemplarily be calculated as follows. The pre-determined surgical approach <NUM>, <NUM>, <NUM> may be planned and registered in the coordinate system of a surgical navigation system, e.g., based on image data of a surgical imaging method such as CT or MRI. Further, the position of the tracking device <NUM> received in the second interface <NUM> may be tracked by a tracking component of the surgical navigation system, such as a camera. As the tracking device <NUM> is arranged in a known spatial relationship to a surgical tool received in the first interface <NUM>, the position and/or orientation of the surgical tool (i.e., the actual trajectory of the tool) may be derived based on the known spatial relationship. Said position and/or orientation of the surgical tool may then also be registered into the coordinate system of the surgical navigation system. The angles between the pre-determined surgical approach <NUM>, <NUM>, <NUM> and the position and/or orientation of the surgical tool received in the first interface <NUM> may then be calculated in at least two dimensions, based on the above determinations. As such, the angular distances between the pre-determined surgical approach <NUM>, <NUM>, <NUM> and the actual trajectory of the surgical tool may be known with respect to every alignment axis <NUM>, <NUM>, <NUM>.

Further, the visual information comprises an indication of which of the operating members <NUM>, <NUM>, <NUM> and <NUM> a user has to turn in order to compensate the misalignment associated with the numerical value <NUM>. In the embodiment of <FIG>, the operating members <NUM>, <NUM>, <NUM> and <NUM> are not visually coded with geometric patterns as in <FIG> to 3C, but are visually coded with different colors. It will be appreciated that both types of visual codings are interchangeable and can also be combined. In the present case, operating member <NUM> is marked with a blue color and configured as a turning knob (see <FIG>). Therefore, a user is informed by a text message that the blue knob is to be turned (see reference numeral <NUM>). Visual guidance in regard to an amount <NUM> by which the operating member <NUM> is to be turned and a direction <NUM> in which the operating member <NUM> is to be turned is further provided to the user. In the embodiment of <FIG>, the amount <NUM> by which the operating member <NUM> is to be turned is represented by a number of color-coded rectangles <NUM>. The rectangles <NUM> are coded with the same color as the respective turning knob <NUM> (i.e., blue). A direction <NUM> in which the turning knob <NUM> is to be turned is represented by an arrow, indicating a counterclockwise rotation in the embodiment of <FIG>. It is to be understood that the above-described visual guidance only serves illustrative purposes and is in no way intended to limit the scope of the present disclosure.

The visual guidance regarding a specific operating member associated with a specific adjustment axis as provided to a user will now be described in more detail with respect to <FIG>. In particular, an exemplary alignment process of the surgical arm <NUM> relative to the adjustment axis <NUM> (rotatory alignment) associated with the operating member <NUM> is shown in several steps indicative of a temporal sequence. It will be apparent that similar guidance will be provided for a translator alignment in regard to the axis <NUM> and for alignment relative to the remaining axes <NUM>, <NUM>, but using other colors (e.g., red, yellow and green).

<FIG> shows the beginning of the alignment process of the surgical arm <NUM> around adjustment axis <NUM>. As already shown in the bottom right view of <FIG>, the user is provided with the schematic representation <NUM> of the surgical arm <NUM>, as well as the checkmarks <NUM>, <NUM> indicating that the surgical arm <NUM> is already aligned with respect to translational movements along adjustment axes <NUM> and <NUM>. Additionally, the user is also provided with visual guidance <NUM> as to the operating member that is to be turned, visual guidance <NUM> as to the amount by which the operating member is to be turned, and visual guidance <NUM> as to the direction the operating member is to be turned. Specifically, the visual guidance <NUM> as to the amount the operating member is to be turned is represented by a number of color-coded rectangles <NUM>. In <FIG>, three color-coded rectangles <NUM> are displayed. This display indicates that the operating member marked in blue is to be turned in the direction indicated by arrow <NUM> (i.e., in counterclockwise direction) by four entire turns (three color-coded rectangles <NUM> and the color-coded head of arrow <NUM>). Alternatively, the number of color-coded rectangles <NUM> may indicate a specific amount of degrees (e.g., in steps of <NUM>° or more) by which a particular operating member is to be turned. For example, one color-coded rectangle <NUM> may be indicative of turning the blue operating member by <NUM>° in the direction indicated by arrow <NUM>. Alternatively, one color-coded rectangle <NUM> may be indicative of turning the blue operating member by <NUM>° in the direction indicated by arrow <NUM>. In the case where the color-coded rectangles <NUM> are indicative of an amount of degrees by which the operating members are to be turned, a user may be informed (e.g., haptically) if the operating member has been turned by the specified amount of degrees. For example, the user may be informed that the blue operating member has been rotated <NUM>° in a counterclockwise direction by providing a small mechanical resistance every <NUM>°. Thus, the user may need to apply a slightly greater force to overcome the mechanical resistance in order to rotate the turning knob further.

The required number of turns by which a specific operating member is to be turned may exemplarily be calculated as follows. Each of the operating members <NUM>, <NUM>, <NUM> and <NUM> may be provided with a thread member for operating the respective adjustment member <NUM>, <NUM>, <NUM> and <NUM>. The thread members may have known thread pitches. For example, the operating members <NUM> and <NUM> configured to operate the adjustment members <NUM> and <NUM>, respectively, may be turning knobs and may have a pitch of <NUM>. Turning the turning knobs <NUM> or <NUM> for an entire turn (i.e., <NUM>°) may thus for example cause the biopsy arm <NUM> - and hence also a surgical tool received inside the first interface <NUM> - to move along the respective adjustment axes <NUM> or <NUM> by <NUM>. Depending on the dimensions of the mechanical components of the surgical arm <NUM>, moving the surgical arm <NUM> by <NUM> along an adjustment axis may correspond to a rotation of the surgical tool by <NUM>°. In a further example, the operating members <NUM> and <NUM> configured to operate the adjustment members <NUM> and <NUM>, respectively, may also be turning knobs and may have a pitch of <NUM>. Turning the turning knobs <NUM> or <NUM> for an entire turn (i.e., <NUM>°) may thus for example cause the biopsy arm <NUM> - and hence also a surgical tool received inside the first interface <NUM> - to rotate around the respective adjustment axes <NUM> or <NUM> by <NUM>°, depending on the dimensions of the mechanical components of the surgical arm <NUM>. These known relations between an amount of turns of the operating members <NUM>, <NUM>, <NUM> and <NUM> configured as turning knobs and a rotation of the surgical tool relative to a specific adjustment axis <NUM>, <NUM> and <NUM> may be transformed by the computer system into the visual guidance <NUM> as to the amount an respective operating member is to be turned.

<FIG> shows a first intermediate state of the alignment process of the surgical arm <NUM> around adjustment axis <NUM> according to a pre-determined surgical approach. As illustrated in <FIG>, the blue operating member has already been rotated by an amount corresponding to two color-coded rectangles <NUM>. For example, the blue operating member has been rotated by two entire turns or alternatively has been rotated by <NUM>°, or alternatively has been rotated by <NUM>°.

<FIG> shows a later intermediate state of the alignment process of the surgical arm <NUM> around adjustment axis <NUM>. Here, the blue operating member has already been rotated by an amount corresponding to three color-coded rectangles <NUM>. For example, the blue operating member has been rotated by three entire turns or alternatively has been rotated by <NUM>°, or alternatively has been rotated by <NUM>°.

<FIG> shows the final state of the alignment process of the surgical arm <NUM> around the adjustment axis <NUM>. Here, the surgical arm <NUM> is properly aligned in accordance with the pre-determined surgical approach with respect to all possible movements relative to all adjustment axes <NUM>, <NUM>, <NUM>. Therefore, each of the corresponding operating members <NUM>, <NUM>, <NUM> and <NUM> associated with the respective adjustment axes <NUM>, <NUM> and <NUM> is provided with a checkmark <NUM>, <NUM>, <NUM>, <NUM>. Hence, when all operating members <NUM>, <NUM>, <NUM> and <NUM> are provided with checkmarks as depicted in <FIG>, the user may conclude that the alignment process of the surgical arm <NUM> according to the pre-determined surgical approach has ended. In the next step, a surgical procedure may now be performed.

When the adjustment process is completed for a dedicated movement relative to a particular adjustment axis, i.e., when one of the checkmarks <NUM>, <NUM>, <NUM>, <NUM> is displayed, the user will secure this adjustment by operating the associated locking member <NUM>, <NUM>, <NUM>, <NUM>. In some variants, a text message is displayed in this case to explicitly request the user to do so.

In the above embodiments, a surgical arm <NUM> comprising visually coded operating members <NUM>, <NUM>, <NUM> and <NUM> as well as a method of providing visual guidance for operating the surgical arm <NUM> have been presented. As has become apparent from the embodiments, the visual coding of the operating members <NUM>, <NUM>, <NUM>, <NUM> facilitates the identification of a specific operating member <NUM>, <NUM>, <NUM>, <NUM> by a user. Therefore, the alignment process of the surgical arm <NUM> can be made faster upon providing proper visual guidance.

In some variants, locking members <NUM>, <NUM>, <NUM>, <NUM> are associated with the operating members <NUM>, <NUM>, <NUM> and <NUM> and are coded with the same visual coding as the associated operating member <NUM>, <NUM>, <NUM> and <NUM>. Hence, the user easily identifies a specific locking member <NUM>, <NUM>, <NUM>, <NUM> associated with the operating member <NUM>, <NUM>, <NUM>, <NUM> the user is currently operating or wishes to operate next. This further speeds up the alignment process and at the same time increases user convenience. Moreover, as the association between an individual operating member <NUM>, <NUM>, <NUM>, <NUM> and the respective locking member <NUM>, <NUM>, <NUM>, <NUM> is immediately apparent to the user due to the same visual coding, the risk that the user operates a wrong operating member <NUM>, <NUM>, <NUM>, <NUM> and/or locking member <NUM>, <NUM>, <NUM>, <NUM> such that the surgical arm <NUM> is not correctly aligned (e.g., brought out of previously established alignment) is reduced.

Claim 1:
A surgical arm (<NUM>) comprising:
a first interface (<NUM>) configured to receive a device (<NUM>) for performing or assisting a surgical procedure;
multiple adjustment members (<NUM>, <NUM>, <NUM>, <NUM>) configured to adjust the surgical arm (<NUM>) relative to a respective adjustment axis (<NUM>, <NUM>, <NUM>);
at least two operating members (<NUM>, <NUM>, <NUM>, <NUM>) configured to operate different ones of the adjustment members (<NUM>, <NUM>, <NUM>, <NUM>), wherein the operating members (<NUM>, <NUM>, <NUM>, <NUM>) are marked with different visual codings;
characterized in further comprising:
at least two locking members (<NUM>, <NUM>, <NUM>, <NUM>) associated with different ones of the operating members (<NUM>, <NUM>, <NUM>, <NUM>), wherein each of the locking members (<NUM>, <NUM>, <NUM>, <NUM>) is configured to lock the surgical arm (<NUM>) in position with respect to a specific movement relative to the respective adjustment axis (<NUM>, <NUM>, <NUM>) of the associated operating member (<NUM>, <NUM>, <NUM>, <NUM>), wherein
the locking members (<NUM>, <NUM>, <NUM>, <NUM>) are respectively coded with the same visual coding as the operating member (<NUM>, <NUM>, <NUM>, <NUM>) associated with the respective adjustment axis (<NUM>, <NUM>, <NUM>).