Patent Description:
It is often necessary to track the position of tissue during surgical procedures. Computer-assisted surgical systems have been developed that are commonly used to perform precise surgical tasks. These systems require accurate information throughout the duration of the procedure regarding the positions of tissue to operate properly.

Fiber optic systems have been developed to track objects in space. The optical fibers used in these systems include a number of sensing sections located along their lengths. One type of sensing section, called a fiber Bragg grating, reflects a certain wavelength of light depending in part upon the strain experienced by the optical fiber at the sensing section. By analyzing the reflected wavelengths, a three-dimensional model of the shape of the optical fiber may be generated. A system and method for determining the trajectory of an optical fiber are described in detail in <CIT>. Document <CIT> discloses a fiber optic sensing device comprising: an optical fiber including at least two fiber cores spaced apart so that mode coupling between the fiber cores is reduced; wherein each fiber core has an associated Rayleigh scatter signature and different segments of each fiber core correspond to a portion of the associated Rayleigh scatter signature; a frequency domain reflectometer coupled to the optical fiber configured to obtain a Rayleigh scatter pattern associated with each of multiple fiber segments from each core and use the Rayleigh scatter patterns to determine a strain parameter for each of the multiple fiber segments from each core; and a computing device configured to determine a position and/or shape of a portion of the fiber based on the determined strain parameters.

Conventional tracking systems used during surgical procedures are associated with a number of disadvantages that can include a failure to provide high accuracy and high sampling rate, and lacks an ability for robust tracking that is not easily affected by a surgical procedure or by surgical workflow. Fiber optic tracking systems are conventionally implemented using bone screws or other similar methods of coupling to hard tissue, which may be invasive.

In some procedures, surgical robots are utilized to perform certain tasks during surgery. Some of these tasks involve the use of surgical instruments inside an incision. Some of these surgical instruments are sharp and could inadvertently damage the soft tissue surrounding an incision if they come into contact with the soft tissue.

In accordance with one aspect of the present disclosure that is not part of the invention, there is provided a fiber optic tracking system for tracking tissue including a light source, a first optical fiber including a plurality of first sensing sections, a second optical fiber including a plurality of second sensing sections, a sensing unit, and a controller operatively coupled to the sensing unit. The first optical fiber has a first fixed sensing point located along a length of the first optical fiber that is fixed relative to tissue. The first optical fiber is configured to receive a first optical signal from the light source. The first sensing sections are configured to modify the first optical signal in response to a deformation of the first optical fiber. The second optical fiber has a second fixed sensing point located along a length of the second optical fiber that is fixed relative to the tissue. The second optical fiber is configured to receive a second optical signal from the light source. The second sensing sections are configured to modify the second optical signal in response to a deformation of the second optical fiber. The sensing unit is configured to receive modified optical signals from the first optical fiber and the second optical fiber. The controller is configured to determine locations in a working coordinate system of the first fixed sensing point and the second fixed sensing point using the modified optical signals and determine a pose of the tissue based on the locations of the first fixed sensing point and the second fixed sensing point.

The invention provides a fiber optic tracking system in accordance with Claim <NUM> of the appended claims. According to one aspect, the present disclosure is directed to a fiber optic tracking system including a surgical port configured to be inserted into an incision, a light source, an optical fiber having a plurality of fixed sensing points located along a length of the optical fiber that are fixed relative to the surgical port, a sensing unit, and controller operatively coupled to the sensing unit. The optical fiber is configured to receive an optical signal from the light source. The optical fiber includes a plurality of sensing sections arranged along the length of the optical fiber and configured to modify the optical signal received by the optical fiber in response to a deformation of the optical fiber. The sensing unit is configured to receive a modified optical signal from the optical fiber. The controller is configured to determine locations in a working coordinate system of the fixed sensing points using the modified optical signal. The surgical port includes a flexible wall configured to contact an incision, wherein a section of the optical fiber is flexible and coupled to the flexible wall such that the section of the optical fiber can conform to the incision, when in use, wherein at least two of the fixed sensing points are located within the section, and wherein the controller is configured to determine a shape of the incision using the locations of the fixed sensing points.

The disclosure further provides a method of tracking a surgical, which is not part of the invention. In accordance with yet another aspect, the present disclosure is directed to a method of tracking an incision including inserting a surgical port into the incision, providing a light source, and coupling an optical fiber to the surgical port such that a plurality of fixed sensing points along a length of the optical fiber are fixed relative to the surgical port. The optical fiber is configured to receive an optical signal from the light source. The optical fiber includes a plurality of sensing sections arranged along the length the optical fiber and configured to modify the optical signal received by the optical fiber in response to a deformation of the optical fiber. The method further includes receiving a modified optical signal from the optical fiber and determining locations in a working coordinate system of the fixed sensing points based on the modified optical signal. The surgical port includes a flexible wall configured to contact an incision, wherein a section of the optical fiber is flexible and coupled to the flexible wall such that the section of the optical fiber is capable of conforming to the incision, and wherein at least two of the fixed sensing points are located within the section. The method further comprises determining a shape of the surgical port using the locations of the fixed sensing points.

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate several embodiments that, together with the description, serve to explain the principles and features of the present disclosure.

Reference will now be made in detail to exemplary embodiments of the present disclosure, examples of which are illustrated in the accompanying drawings.

Referring to the figures, systems for tracking the locations and/or orientations of incisions and/or rigid objects (e.g., hard tissue such as bones, surgical instruments, etc.) during surgery are shown and described. The systems described herein utilize shape sensing fiber optics to determine the locations of points in three-dimensional space corresponding to hard tissue or incisions. In some embodiments, one or more optical fibers are attached to hard tissue. In accordance with the invention, optical fibers are incorporated into a surgical port located inside an incision. The locations of the rigid objects and/or the incision may be provided to an operator or to a computer assisted surgery (CAS) system. The systems outlined herein provide accurate tracking without the need for large incisions or invasive pins traditionally used to mount vision trackers for navigated surgeries. Additionally, the optical fibers may eliminate the need for line of sight vision tracking.

Referring to <FIG>, a fiber optic tracking system <NUM> is shown according to an exemplary embodiment. The fiber optic tracking system includes a light source <NUM> configured to emit an optical signal (e.g., light), a sensing unit <NUM>, and a controller <NUM> operatively coupled to the sensing unit <NUM>. One or more optical fibers <NUM> are configured to receive the optical signal from the light source <NUM> and to each emit a modified optical signal that is received by the sensing unit <NUM>. Each optical fiber <NUM> includes a number of sensing sections <NUM> along its length that modify the optical signal in response to a deformation of the optical fiber <NUM>. The controller <NUM> is configured to use information from the sensing unit <NUM> regarding the modified optical signal to determine a shape of each optical fiber <NUM>. The optical fibers <NUM> are coupled to an object (e.g., hard tissue or, in accordance with the invention, a surgical port), and the controller <NUM> tracks the object using information regarding the shapes each of the optical fibers <NUM>. As used herein, tracking an object refers to determining the location, pose in six dimensions (i.e., the location and the orientation), and/or the shape of the object.

Referring to <FIG>, the light source <NUM> is shown in a block diagram of the fiber optic tracking system <NUM> according to an exemplary embodiment. The light source <NUM> is configured to emit an optical signal (e.g., light) into each of the optical fibers <NUM>. In some embodiments, the light source <NUM> is coupled to an end of the optical fiber <NUM>. In some embodiments, the light source <NUM> emits a specific band (i.e., a range of light wavelengths) or bands of optical signals. By way of example, the light source <NUM> may emit only light in the visible spectrum. The emitted band or bands may be modified by changing the type or operating parameters of the light source <NUM> or by applying an optical filter to an output of the light source <NUM>. The light source <NUM> is preferably a broadband light source or a tunable laser (e.g., an ELED, LED, or SLD). In some embodiments, the light source <NUM> is operatively coupled to the controller <NUM> such that the controller <NUM> may vary the optical signal emitted from the light source <NUM>. In other embodiments, the light source <NUM> is operatively decoupled from the controller <NUM>. In some embodiments, the light source <NUM> emits a different optical signal into each of the optical fibers <NUM>. In other embodiments, the light source <NUM> emits the same optical signal into each optical fiber <NUM>.

Referring still to <FIG>, the sensing unit <NUM> is shown. The sensing unit is configured to receive the modified optical signal from each optical fiber <NUM>. In some embodiments, the sensing unit <NUM> is coupled to the same end of the optical fiber as the light source <NUM> (e.g., with an optical coupler), and the modified optical signal is reflected back to the sensing unit <NUM>. The sensing unit can be configured to identify which modified optical signals come from the sensing sections <NUM>. The sensing unit <NUM> may also compare the modified optical signal to the optical signal emitted by the light source <NUM>. By way of example, the sensing unit <NUM> may be configured to determine which wavelengths of light are present in the modified optical signal and compare those wavelengths to the wavelengths present in the optical signal emitted by the light source <NUM>. In some embodiments, the light source <NUM> and the sensing unit <NUM> are incorporated into the same device. The sensing unit <NUM> may comprise, for example, a conventional reflectometer, such as a frequency domain reflectometer. The sensing unit <NUM> is operatively coupled to the controller <NUM> such that the controller <NUM> receives information regarding the modified optical signal from the sensing unit <NUM>. In some embodiments, some actions described herein as being performed by the sensing unit <NUM> are instead performed by the controller <NUM> and vice versa.

The fiber optic tracking system <NUM> includes a controller or processing circuit, shown as the controller <NUM>. The controller <NUM> can include a processor <NUM> and memory device <NUM>. Processor <NUM> can be implemented as a general purpose processor, an application specific integrated circuit (ASIC), one or more field programmable gate arrays (FPGAs), a group of processing components, or other suitable electronic processing components. Memory device <NUM> (e.g., memory, memory unit, storage device, etc.) is one or more devices (e.g., RAM, ROM, Flash memory, hard disk storage, etc.) for storing data and/or computer code for completing or facilitating the various processes, layers and modules described in the present application. Memory device <NUM> may be or include volatile memory or non-volatile memory. Memory device <NUM> may include database components, object code components, script components, or any other type of information structure for supporting the various activities and information structures described in the present application. According to an exemplary embodiment, memory device <NUM> is communicably connected to processor <NUM> via controller <NUM> and includes computer code for executing (e.g., by processing circuit and/or processor) one or more processes described herein.

The fiber optic tracking system <NUM> may further include a vision tracking system <NUM>, camera <NUM>, a display <NUM>, a computer assisted surgical system <NUM> and a surgical robot <NUM>, all of which are described herein.

The optical fibers <NUM> are configured to receive an optical signal (e.g., visible light, ultraviolet light, etc.) from the light source <NUM> and guide the optical signal along a length of the optical fibers <NUM>. Referring to <FIG>, <FIG>, according to an exemplary embodiment, the optical fibers <NUM> each include one or more cores, shown as cores <NUM>, along which the optical signal propagates. The cores <NUM> are made from a transparent material (e.g., glass) to allow the optical signal to travel along the length of the core <NUM>. In some embodiments, each core <NUM> is surrounded by one or more outer layers. The outer layers may be or include one or more cladding layers having a refractive index selected to reduce or eliminate a leakage of the optical signal, strengthening layers to prevent breakage of the core <NUM>, nonreactive layers to prevent reaction of the optical fiber <NUM> with the surrounding environment, protective layers to prevent damage to the interior of the optical fiber <NUM>, or other types of layers. In the embodiment shown in <FIG>, the optical fiber <NUM> is a tri-core fiber including three cores <NUM>. The three cores <NUM> are all surrounded by a cladding outer layer <NUM>, which is in turn surrounded by a protective outer layer <NUM>. In other embodiments, the optical fiber <NUM> includes more or fewer than three cores <NUM>. In some embodiments, the optical fiber <NUM> includes one or more single core optical fibers bundled together. In some embodiments, some or all of the length of the optical fiber <NUM> is flexible. In other embodiments, the optical fiber <NUM> includes a rigid portion <NUM> (e.g., the rigid portion <NUM> shown in <FIG>).

Referring to <FIG>, according to an exemplary embodiment, arranged along the length of the optical fiber <NUM> are the sensing sections <NUM>. The sensing sections <NUM> are spaced apart from one another. In some embodiments, the sensing sections <NUM> are spaced a uniform distance apart from one another (e.g., <NUM>, <NUM>, <NUM>, etc.). In other embodiments, a distance between each sensing section <NUM> varies. Each sensing section <NUM> has a sensing component <NUM> associated with each core <NUM>. In some embodiments, the sensing components <NUM> are located at the same points along each core <NUM> relative to one end of the optical fiber <NUM>. By way of example, in the embodiment shown in <FIG>, each core <NUM> has a sensing component located in the same cross-sectional plane. In other embodiments, the sensing components <NUM> of one core <NUM> are staggered along the length of the core <NUM> relative to the sensing components <NUM> of another core <NUM>.

The sensing components <NUM> modify the optical signal traveling through the core <NUM> with which each sensing component <NUM> is associated. In one embodiment, the sensing component <NUM> is a fiber Bragg grating. A fiber Bragg grating is a section of the core <NUM> along which the refractive index of the material of the core <NUM> changes repeatedly over a grating period <NUM>, as illustrated in <FIG> depicting an exemplary embodiment. In <FIG>, the shaded and unshaded sections of the core <NUM> have different refractive indices. A fiber Bragg grating reflects a particular narrow band of light wavelengths, the wavelengths of this band being dependent in part upon the length of the grating period <NUM>. A fiber Bragg grating can be created by periodically varying the refractive index of the core <NUM> using various methods, such as exposing the core <NUM> to ultraviolet light. In other embodiments, other types of sensing components <NUM> are used. The sensing components <NUM> produce modified optical signals based on strain or local bend of the core <NUM> or changes thereto (e.g., caused by deformation of the optical fiber <NUM>). By way of example, as a fiber Bragg grating experiences strain, the band of reflected wavelengths shifts (e.g., changes in wavelength).

In some embodiments, the sensing components <NUM> in one fiber each return a distinct modified optical signal. By way of example, in an embodiment that incorporates fiber Bragg gratings, each sensing component <NUM> has a different grating period <NUM> such that the reflected wavelength band for each sensing component <NUM> is unique to that sensing component <NUM>. The controller <NUM> may be configured to identify the portion of the modified optical signal associated with each sensing component <NUM> based on the wavelengths of the modified optical signal. The controller <NUM> may be configured to monitor the reflected wavelength band associated with each sensing component <NUM> for a shift in wavelength. The controller <NUM> may then utilize this shift in wavelength to determine the strain on the corresponding sensing component <NUM>. Some sensing components <NUM> are sensitive to other environmental factors, such as temperature. In some embodiments, the controller <NUM> is configured to compensate for these factors when determining strain. By way of example, the controller <NUM> may be operatively coupled to a temperature sensor (e.g., that measures an ambient room temperature, that measures a temperature of a body into which the optical fiber <NUM> is inserted, etc.) and may be configured to modify the determined strain at each sensing component <NUM> by a temperature-dependent factor.

The determined strain at each sensing component <NUM> may be used to determine a shape of the optical fiber <NUM> using methods previously known in the art. The method selected is dependent on the number and arrangement of cores <NUM> and the type of sensing components <NUM> used, among other factors. In some cases, it may be advantageous to modify (e.g., decrease) the distance between the sensing sections <NUM> in order to increase the accuracy of the determined shape. The locations of each sensing section <NUM> along the length of the optical fiber <NUM> may be predetermined and stored in the memory device <NUM>. In some embodiments, the optical fibers <NUM> may each have as few as one sensing section <NUM>. In some such embodiments, the location and/or orientation of part of the optical fiber <NUM> is determined using another method. By way of example, the optical fiber may be fixed relative to another component that is visually tracked (e.g., the outer ring tracker <NUM>).

The shape sensing capabilities of the optical fibers <NUM> provide a relative location of each point along the length of the optical fiber <NUM>. In order to track the absolute location of each point along the length of the optical fiber <NUM>, the optical fiber <NUM> may be located in a working coordinate system. The working coordinate system may be any type of three-dimensional coordinate system (e.g., a Cartesian coordinate system, a polar coordinate system, etc.). It may be advantageous to locate the origin at a specific point of interest (e.g., at the center of a robotic instrument, such as the surgical robot <NUM>, at the fiber base <NUM>, etc.), however any origin and orientation of the working coordinate system may be selected. The working coordinate system may be defined in relation to the surgical environment (i.e., the room in which a surgical procedure takes place) or in relation to an object within the surgical environment. Accordingly, the working coordinate system may move relative to the surgical environment if the object around which the working coordinate system is defined moves relative to the surgical environment.

To locate the optical fibers <NUM> in the working coordinate system, a pose (i.e., the location and the orientation) of each optical fiber <NUM> may be determined. According to an exemplary embodiment shown in <FIG>, the light source <NUM>, the sensing unit <NUM>, and the controller <NUM> are contained within a fiber base <NUM>. In this embodiment, a portion of each of the optical fibers <NUM> has a fixed location and orientation relative to the fiber base <NUM> near where each optical fiber <NUM> meets the fiber base <NUM>. If a pose of the fiber base <NUM> in the working coordinate system and a shape of the optical fiber <NUM> are known, then the pose of each optical fiber <NUM> can be determined. In some embodiments, the pose of the fiber base <NUM> is determined by fixing it relative to another component, the pose of which in the working coordinate system has been previously determined. In some embodiments, this component is tracked using other means (e.g., the vision tracking system <NUM>). In other embodiments, this component has a fixed location relative to the coordinate system. By way of example, if the fiber optic tracking system <NUM> is employed in an operating room, the fiber base <NUM> may be fixed to a component that is permanently fixed to the operating room floor.

In other embodiments, such as the embodiment illustrated in <FIG>, the fiber optic tracking system <NUM> tracks the fiber base <NUM> or another object to determine its pose. This may be accomplished using a vision tracking system <NUM> shown in <FIG> and <FIG>. The vision tracking system <NUM> includes a camera <NUM> operatively coupled to the controller <NUM>. The camera <NUM> may be located such that the field of view of the camera <NUM> is minimally obscured. By way of example, the camera <NUM> may be located on a ceiling or on an elevated stand. In some embodiments, the vision tracking system <NUM> uses vision recognition (e.g., of shapes, of colors, of reflective surfaces) to determine the pose of the fiber base <NUM> or another object in the working coordinate system. In some embodiments, the vision tracking system <NUM> recognizes the fiber base <NUM> directly. In other embodiments, one or more visual trackers <NUM> are attached to the fiber base <NUM> in predetermined locations. The visual trackers <NUM> include easily identifiable vision targets (e.g., retroreflective targets, targets with specific patterns, etc.). These vision targets may allow the controller <NUM> to determine both the location and the orientation of the visual trackers <NUM>. By way of example, the vision targets may include a set of three retroreflective spheres in a known, fixed orientation relative to the vision tracker. Upon determining the location and/or pose of the one or more visual trackers <NUM>, the controller <NUM> may determine the pose of the fiber base <NUM> using previously known information regarding the relative poses of the trackers <NUM> and the fiber base <NUM>.

Referring to <FIG>, the fiber optic tracking system <NUM> according to an exemplary embodiment may alternatively locate the fiber base <NUM> or another object in the working coordinate system using a tracked probe <NUM>. The tracked probe <NUM> may be used to determine the location and/or contour (e.g., shape) of surfaces in the working coordinate system by contacting the surfaces. The tracked probe <NUM> may include a blunt end <NUM> used to contact the various surfaces. In other embodiments, the end <NUM> is sharp or otherwise shaped. The location of the end <NUM> is tracked as it is moved across a surface in order to determine the locations at which the end <NUM> contacts the surface. By way of example, one or more visual trackers <NUM> may be attached to a portion of the tracked probe <NUM> in order to determine a pose of the tracked probe <NUM>, from which the location of the end <NUM> can be determined using previously known information regarding the relative 6D poses of the end <NUM> and the visual trackers <NUM>. In other embodiments, the pose of the tracked probe <NUM> is otherwise determined. The tracked probe <NUM> may then be moved across one or more surfaces of the fiber base <NUM> to locate it in the working coordinate system. In some embodiments, the fiber base <NUM> includes one or more checkpoints <NUM>. The checkpoints <NUM> may have a predefined shape that can be recognized by the controller <NUM>. The checkpoints <NUM> may be placed in preset locations on the fiber base <NUM> such that, upon contacting the checkpoints <NUM> with the tracked probe <NUM>, the pose of the fiber base <NUM> may be determined. By way of example, an operator may contact a checkpoint with the end <NUM> and indicate to the controller <NUM> that the checkpoint <NUM> is contacted. In other embodiments, another conventional tracking system may be used to determine the pose of the fiber base <NUM>.

In one exemplary embodiment of the fiber optic tracking system <NUM>, the working coordinate system is defined relative to the fiber base <NUM>. A first optical fiber <NUM> runs from the fiber base <NUM> to a first object (e.g., the surgical robot <NUM>). A second optical fiber runs from the fiber base <NUM> to a second object (e.g., hard tissue <NUM>). Once the poses of both objects are known relative to the fiber base <NUM>, the pose of first object relative to the second object can be calculated. Accordingly, the pose of an object relative to the surgical environment does not necessarily need to be determined.

Hereinafter, the fiber optic tracking system <NUM> is used to determine the shape, size, and/or pose of soft tissue (e.g., soft tissue <NUM>), hard tissue (e.g., hard tissue <NUM>), and features (e.g., incisions, holes, protrusions, etc.) thereof. As shown in the exemplary embodiments, not within the scope of the invention, of <FIG>, the optical fibers <NUM> may be coupled (e.g., directly or indirectly) to a surface of the tissue or may extend partially inside of the tissue. An anchoring mechanism <NUM> may be used to prevent relative motion (e.g., a change in location or a change in orientation) between certain portions of the optical fibers <NUM> (e.g., the fixed sensing points <NUM>, a section of the optical fiber <NUM>) and the tissue. In some embodiments, the optical fibers <NUM> are coupled directly to the surface of the tissue using the anchoring mechanism <NUM>. The anchoring mechanism <NUM> may include staples, sutures, screws, tacks, pins, tape, barbs, or other mechanisms, and may be made from metal, plastic, some form of resorbable material, or another material. Each optical fiber <NUM> may be held at multiple points along its length by multiple anchoring mechanisms <NUM>. Alternatively, each optical fiber <NUM> may be held at just a single point along its length by one anchoring mechanism <NUM>.

As shown in <FIG> and <FIG>, the anchoring mechanism <NUM> is a tack configured to be pressed into tissue (e.g., with a tool similar to a stapler). In this embodiment, the optical fiber <NUM> is coupled to the anchoring mechanisms <NUM> such that they are fixed relative to one another at points along the length of the optical fiber <NUM>. By way of example, the optical fiber <NUM> may include a number of loops of material (e.g., plastic) that are fixed (e.g., formed as an integral part of the protective outer layer <NUM>) at regular intervals along the length of the optical fiber <NUM>. These loops may each define an aperture <NUM> configured to receive an anchoring mechanism <NUM>. The optical fiber <NUM> may be of sufficient strength that the anchoring mechanisms <NUM> may be removed from the tissue by applying a tensile force to the optical fiber <NUM>. Referring to <FIG>, an optical fiber <NUM> includes a barb extending therefrom configured as an anchoring mechanism <NUM>.

In some embodiments, such as the embodiment shown in <FIG>, the anchoring mechanism <NUM> is configured to penetrate or attach to the surface of tissue (e.g., bone, soft tissue, etc.) to couple the optical fiber <NUM> to the tissue. When anchoring an optical fiber <NUM> to bone, the anchoring mechanism <NUM> may couple to the outer surface of the bone (e.g., using adhesive), may extend into an outer layer of the bone, or may extend into the inter-medullary canal of the bone. In some embodiments, the anchoring mechanism <NUM> imparts a force on the optical fiber <NUM> to hold the optical fiber <NUM> directly against tissue. Alternatively, the optical fiber <NUM> may be indirectly coupled to the tissue using the anchoring mechanism <NUM>, as shown in a portion of <FIG>. The optical fibers <NUM> may be coupled to a screw, pin, standoff, or other member, which in turn is coupled directly to the tissue. Alternatively, the optical fiber <NUM> may be coupled to material adjacent the tissue such as the muscle or cartilage adjacent a bone. In some embodiments, the optical fibers <NUM> include a rigid portion <NUM> that is configured to extend at least partially inside the tissue. By way of example, the rigid portion <NUM> may extend partially inside of an inter-medullary canal of a bone. The rigid portion <NUM> may be straight to facilitate penetration through the inner-medullary canal. A straight rigid portion <NUM> can be aligned with a bone to provide further information regarding the orientation of the bone. In some embodiments, an aperture is created (e.g., by drilling, using a needle) in the tissue, and the rigid portion <NUM> or a flexible portion of the optical fiber <NUM> is inserted into the tissue. In this case, the optical fiber <NUM> may be held in place by the anchoring mechanism <NUM>, by coupling to material adjacent the tissue, by the portion of the optical fiber <NUM> that enters into the tissue being shaped to engage the hole into which it enters, or by some other means. The rigid portion <NUM> may be straight, curved, or otherwise shaped.

The system <NUM> may include one or more tools <NUM> used in the process of attaching the optical fibers <NUM>. The tool <NUM> may be configured to at least one of pierce hard or soft tissue, grasp an optical fiber <NUM>, insert an optical fiber <NUM> into tissue, couple an anchoring mechanism <NUM> to tissue and/or the optical fiber <NUM>, and remove an optical fiber <NUM> and/or anchoring mechanism <NUM> from tissue. Referring to the embodiment shown in <FIG>, the tool <NUM> is configured to press anchoring mechanisms <NUM>, shown as tacks, into tissue (e.g., hard tissue). The tool <NUM> may hold the tacks in place until they are attached to the tissue. As shown, a handle <NUM> of the tool <NUM> is squeezed, storing energy (e.g., in a spring) until the energy is released, impacting the tack into the tissue.

Referring to <FIG>, the tool <NUM> is shown according to an alternative embodiment. The tool <NUM> includes a handle <NUM>, a shaft <NUM> that may be made from a flexible material, and a tip <NUM> forming a hollow shape. The tool <NUM> may be used with a prior-made incision. As shown, the tip <NUM> is annular and includes a slot that allows it to move over an optical fiber <NUM>. Once over the optical fiber <NUM>, the tip <NUM> may be moved along the length of the optical fiber <NUM> until it contacts, for example, a barbed anchoring mechanism <NUM> as depicted in <FIG>. In some embodiments, two similar tools <NUM>, each with tips <NUM> of different sizes are used. When applying the anchoring mechanism <NUM>, a tip <NUM> smaller than the barbs is used to push the barbs into tissue. When removing the anchoring mechanism <NUM>, a tip <NUM> larger than the barbs can be slid past the barbs and used to remove the barbs. By way of example, the tool <NUM> may be used to pull on the optical fiber <NUM> at a point beyond the barb. By way of another example, the tool <NUM> may be moved beyond the barb and used to pull back on the barb to remove it. In situations where the tool <NUM> is used to insert an anchoring mechanism <NUM> through soft tissue towards hard tissue, shaft <NUM> may be made from a flexible material to allow the shaft <NUM> to bend when contact is made with the hard tissue, allowing the optical fiber <NUM> to slide along the bone to reach a final insertion point.

Referring to <FIG> and <FIG>, the tool <NUM> is shown according to another alternative embodiment, wherein the tool <NUM> is inserted through an incision in soft tissue surrounding hard tissue. The tool <NUM> may include a handle <NUM>, a shaft <NUM>, and a tip <NUM>. In some embodiments, a small incision is made using known techniques (e.g., piercing with a needle, etc.), and the tool <NUM> is inserted into the small incision. In other embodiments, the tip <NUM> of the tool <NUM> is sharpened to facilitate insertion into the soft tissue, forming an incision as the tool <NUM> is inserted. The tool <NUM> may be configured to hold the optical fiber <NUM> in place relative to the tool <NUM> during the process of insertion (e.g., by placing the optical fiber in a groove <NUM>). The groove <NUM> may be tapered and/or textured to effectively hold the optical fiber <NUM> without any actuating parts. The tool <NUM> may be configured to release the optical fiber <NUM> upon removal of the tool <NUM> from the soft tissue. The tool <NUM> may be configured to attach the optical fiber <NUM> to the hard tissue requiring only a small incision in the soft tissue to access the hard tissue, facilitating the tool <NUM> being minimally invasive.

In some embodiments, the tool <NUM> is configured to apply the anchoring mechanism <NUM> to the tissue. By way of example, the tool <NUM> may include a mechanism for driving a staple into hard tissue. The tool <NUM> may additionally be configured to drive a visual tracker <NUM> or a checkpoint <NUM> into tissue to facilitate location tracking. In some embodiments, the pose of the tool <NUM> is tracked in the working coordinate system (e.g., using a visual tracker <NUM> or by attachment to an optical fiber <NUM>). The controller <NUM> may use the pose of the tool <NUM> to identify a location in the working coordinate system where the optical fiber <NUM>, visual tracker <NUM>, or checkpoint <NUM> is coupled to the tissue. The tool <NUM> may be powered (e.g., pneumatically, hydraulically, electrically, etc.), may operate using energy provided by an operator (e.g., by striking the tool <NUM>, by loading a spring, etc.), or may be unpowered.

In some embodiments, the system <NUM> includes multiple tools <NUM>, each performing a different function. By way of example, a first tool <NUM> may guide the optical fiber <NUM> into an incision, and a second tool <NUM> may apply the anchoring mechanism <NUM>. In some embodiments, there is no soft tissue surrounding the hard tissue or the soft tissue is cut away prior to attachment of the optical fibers <NUM>. By way of example, the soft tissue surrounding the hard tissue may be separated by an incision such that the hard tissue is not obstructed by the soft tissue. In some such embodiments, the tool <NUM> is still used to apply the anchoring mechanism <NUM> to the tissue and/or the optical fiber <NUM>. In some embodiments where an operator has a direct line of sight to the tissue where the optical fiber <NUM> will be anchored, the tool <NUM> may be a standard medical driver able to insert a screw, tack, staple, or other anchoring mechanism <NUM>. In other embodiments, the optical fiber <NUM> is otherwise coupled to the tissue (e.g., applying tape by hand).

Referring to <FIG>, the fiber optic tracking system <NUM> according to an exemplary embodiment, not within the scope of the invention, is shown configured to determine a pose of a rigid object, shown as hard tissue <NUM>, in the working coordinate system. As shown in <FIG>, the rigid object is hard tissue <NUM>, specifically bone, however the fiber optic tracking system <NUM> may be used to detect the pose of any rigid object (e.g., a surgical instrument, a tooth, etc.) or soft tissue. In some embodiments, one or more optical fibers <NUM> are used to track hard tissue <NUM>, and a visual tracker <NUM>, the tracked probe <NUM>, a checkpoint <NUM>, and/or any other methods described herein may be used to initially determine the pose of the hard tissue <NUM> relative to the optical fiber <NUM>. In some embodiments, the fiber optic tracking system <NUM> uses at least one optical fiber <NUM> attached (e.g., directly or indirectly) to the hard tissue <NUM> at at least two non-colinear points to determine the pose of the hard tissue <NUM>. In another embodiment, the fiber optic tracking system <NUM> utilizes multiple optical fibers <NUM>, each attached (e.g., directly or indirectly) to the hard tissue <NUM> at at least one point, when determining the pose of the hard tissue <NUM>.

By way of a first example, the system <NUM> may include three optical fibers <NUM>, each coupled to the hard tissue <NUM> or another rigid object such that a fixed sensing point <NUM> (e.g., as shown in <FIG>) along the length of each fiber <NUM> is fixed (i.e., has a fixed location) relative to the hard tissue <NUM>. If the locations of three or more fixed sensing points <NUM> in the working coordinate system are determined, and the locations of the three or more fixed sensing points <NUM> relative to the hard tissue <NUM> are determined, then the pose of the hard tissue <NUM> in the working coordinate system can be determined. Alternatively, the system <NUM> may include one or more optical fibers <NUM> that are fixed relative to the hard tissue <NUM> at more than one fixed sensing point <NUM>. By way of example, the system <NUM> may include one optical fiber <NUM> that is fixed relative to the hard tissue <NUM> at two fixed sensing points <NUM> and another optical fiber <NUM> that is fixed relative to the hard tissue <NUM> at one fixed sensing point <NUM>. Alternatively, fewer than three fixed sensing points <NUM> may be used to determine the pose of the hard tissue <NUM> if the fixed sensing points <NUM> are fixed relative to the hard tissue <NUM> and the one or more optical fibers <NUM> associated with the fixed sensing points <NUM> each have a fixed orientation relative to the hard tissue <NUM> at the fixed sensing points <NUM>. In such an embodiment, the locations of the fixed sensing points <NUM> and the orientations of the optical fibers <NUM> at the fixed sensing points <NUM> in the working coordinate system may be determined, and the locations of the fixed sensing points <NUM> and the orientations of the optical fibers <NUM> at the fixed sensing points <NUM> relative to the hard tissue <NUM> may be determined, thereby facilitating the determination of the pose of the hard tissue <NUM> in the working coordinate system. In a first example, the optical fibers <NUM> may be assumed to be tangent to the hard tissue <NUM> at the fixed sensing points <NUM>. In another example, a section of an optical fiber <NUM> may be held against a surface of the hard tissue <NUM> such that the optical fiber <NUM> conforms to a contour of a surface of the hard tissue <NUM>. More optical fibers <NUM> and/or fixed sensing points <NUM> may be utilized to increase the accuracy of the determined pose.

In <FIG>, a surrogate knee model <NUM> is shown. The model <NUM> includes a number of pieces of hard tissue <NUM>, shown as surrogate bones, surrounded by material, shown as soft tissue <NUM>. It should be understood that the fiber optic tacking approach described herein may be employed on the hard tissue of a human or animal or on another rigid object. Referring to <FIG>, an optical fiber <NUM> is shown partway through the process of insertion into the soft tissue <NUM> of the model <NUM>.

Referring to <FIG>, the optical fibers <NUM> are shown attached to the hard tissue <NUM>. In some embodiments, the fiber optic tracking system <NUM> is configured to track more than one piece of hard tissue <NUM> simultaneously. This may be accomplished using additional optical fibers <NUM> or by attaching a single optical fiber <NUM> to multiple pieces of hard tissue <NUM>. As shown in <FIG>, at least three optical fibers <NUM> are attached to the hard tissue <NUM> such that at least one fixed sensing point <NUM> (shown in <FIG>) along the length of each optical fiber <NUM> is in a fixed location relative to the hard tissue <NUM> (i.e., has a fixed relationship to the hard tissue <NUM>, is fixed relative to the hard tissue <NUM>). Once the optical fibers <NUM> are attached, locations of the points <NUM> in the working coordinate system can be determined.

The shape and pose of each optical fiber <NUM> in the working coordinate system may be determined using the modified optical signals as described above. The controller <NUM> may be configured to determine the locations of the fixed sensing points <NUM> in the working coordinate system by determining the locations of the fixed sensing points <NUM> along the length of each optical fiber <NUM>. In one such instance, the optical fibers <NUM> are attached such that the fixed sensing points <NUM> are each located at an endpoint of their respective optical fibers <NUM>. By way of example, the anchoring mechanism <NUM> may hold the endpoint of the optical fiber <NUM> in contact with an exterior surface of the hard tissue <NUM>. In another instance, the locations of the fixed sensing points <NUM> along the length of the optical fiber <NUM> may be predetermined and set at a specified distance along the length of the optical fiber <NUM>. By way of example, the optical fiber <NUM> may be sutured to the hard tissue <NUM> such that the fixed sensing point <NUM> is located at a specified distance along the length of the optical fiber <NUM>. The predetermined location of the point <NUM> along the length of the optical fiber <NUM> may be visibly marked (e.g., by a change in color of the outer layers of the optical fiber <NUM>) to facilitate accurate attachment by an operator. By way of another example, the optical fiber <NUM> may be manufactured and/or assembled such that the anchoring mechanism <NUM> has a fixed relationship to a point along the length of the optical fiber <NUM>, such as shown in <FIG>.

In some embodiments, the controller <NUM> may be configured to determine the locations of the fixed sensing points <NUM> using information from the tracked probe <NUM>. By way of example, the operator may contact the end <NUM> of the tracked probe <NUM> to the various fixed sensing points <NUM> to register their locations in the working coordinate system. In some embodiments, the pose of the tool <NUM> is tracked while attaching the optical fiber <NUM> to the hard tissue as described above (e.g., by tracking an optical fiber attached to the tool <NUM>, using a visual tracking system, etc.). The pose of the tool <NUM> may be used to determine the locations of the fixed sensing points <NUM>. By way of example, if the fixed sensing point <NUM> is located between a staple and the hard tissue <NUM>, the pose of the tool <NUM> while attaching the staple may be used to determine the location of the fixed sensing point <NUM>. As shown in <FIG>, the tool <NUM> inserts the optical fibers <NUM> through an incision in soft tissue <NUM> surrounding the hard tissue <NUM>. In some embodiments, the anchoring mechanism <NUM> is configured to couple the optical fiber <NUM> to the hard tissue <NUM> beneath the outer surface of the soft tissue <NUM> such that a fixed sensing point <NUM> is located beneath the outer surface of the soft tissue <NUM> (e.g., between an outer surface of the soft tissue <NUM> and the hard tissue <NUM>). By way of example, the anchoring mechanism <NUM> may be a suture that couples the optical fiber <NUM> directly to an outer surface of the hard tissue <NUM> such that a fixed sensing point <NUM> is provided directly on an outer surface of the hard tissue <NUM>. Accordingly, tracking the location of the fixed sensing point <NUM> using the pose of the tool <NUM> may be beneficial, as the fixed sensing point <NUM> may be obscured by the soft tissue <NUM>.

In some embodiments, the controller <NUM> is configured to determine the locations of the fixed sensing points <NUM> along the length of each optical fiber <NUM> by moving the one or more optical fibers <NUM>. The controller <NUM> may be configured to analyze the relative movements of each of the optical fibers <NUM> to determine which points along the length of each optical fiber <NUM> are stationary relative to points along the lengths of the other optical fibers <NUM> or relative to other points on the same optical fiber <NUM>. The points that do not move relative to points on the other optical fibers <NUM> or relative to points on the same optical fiber <NUM> may be considered fixed sensing points <NUM>. Alternatively, the optical fiber <NUM> may be configured to sense the force imparted on the optical fiber <NUM> at different points along the length of the optical fiber <NUM> (e.g., using measured strains at points along the length of the optical fiber <NUM>). The force sensing may be done using an additional core <NUM> or an additional optical fiber <NUM> that runs along the same path as optical fiber <NUM> used to determine the pose of an object. In embodiments where the anchoring mechanism <NUM> imparts a force on the optical fiber <NUM> (e.g., where the anchoring mechanism <NUM> is a staple that holds the optical fiber <NUM> against a bone), the optical fiber <NUM> may experience a sharp increase in bending deflection and/or force on the optical fiber <NUM> near the anchoring mechanism <NUM>. The bending deflection and/or force at different points along the length of the optical fiber <NUM> may be used to determine the location of the fixed sensing points <NUM>. By way of example, the rate of change of bending deflection and/or force applied to the optical fiber <NUM> along the length of the may be analyzed to locate the fixed sensing points <NUM>. Areas of the optical fiber <NUM> where this rate of change has a high magnitude may be fixed sensing points <NUM>.

To determine the pose of the hard tissue <NUM> in the working coordinate system, the controller <NUM> may be configured to determine a shape of a surface <NUM> (e.g., the surface <NUM> shown in <FIG>) of the hard tissue <NUM> and the locations of the fixed sensing points <NUM> relative to the surface <NUM>. The controller <NUM> then registers the shape of the surface <NUM> to a three-dimensional model of the hard tissue <NUM>. Knowing the locations of the fixed sensing points <NUM> relative to the hard tissue <NUM>, the controller <NUM> is configured to determine the pose of the hard tissue <NUM>. By way of example, a three-dimensional model of a bone may be generated prior to an operation using conventional scanning techniques (e.g., computerized tomography (CT) scanning, magnetic resonance imaging (MRI), etc.). The controller <NUM> is configured to register the pose of the surface <NUM> to the three-dimensional model (e.g., by matching contours of the surface <NUM> to a section of the three-dimensional model) such that the pose of the entire hard tissue <NUM> can be determined using the pose of the surface <NUM> in the working coordinate system.

To determine the shape and pose of the surface <NUM> relative to the fixed sensing points <NUM>, the controller <NUM> determines a shape and a pose of the surface <NUM> in the working coordinate system, and compares this to the locations of the fixed sensing points <NUM> in the working coordinate system. The shape and the pose of the surface <NUM> may be determined using a variety of methods. By way of example, the shape and the pose of the surface <NUM> may be determined by running the tracked probe <NUM> over the surface <NUM> of the hard tissue <NUM>. The controller <NUM> may configured to record the locations in the working coordinate system of points on the surface <NUM> that are contacted by tracked probe <NUM>. The controller may then calculate the shape and pose of the portion of the surface <NUM> contacted by the tracked probe <NUM>.

In some embodiments, the tracked probe <NUM> incorporates a force sensor (e.g., a strain gauge, an optical fiber <NUM> configured to measure force or strain, etc.) near the end <NUM> to determine when the end <NUM> contacts the surface <NUM>. When the end <NUM> is contacting the surface <NUM>, the tracked probe <NUM> experiences an axial compressive force, causing a deflection (i.e., a strain) of the tracked probe <NUM>. An optical fiber <NUM> may be configured such that it is axially fixed to the tracked probe <NUM> at two fixed points, where at least one sensing section <NUM> is disposed between the two fixed points. These sensing sections <NUM> experience the same strain as the tracked probe <NUM> between the two fixed points. Using the material properties of the tracked probe <NUM> and the strain measured by these sensing sections, the compressive force on the tracked probe <NUM> is determined. In some embodiments, the temperature near the tracked probe <NUM> is measured (e.g., with a thermocouple, with a thermistor, etc.), and the measured strain is compensated for temperature. In some such embodiments, a second optical fiber <NUM> is included near where this strain is measured. The second optical fiber <NUM> is axially fixed at two points such that it remains a constant length. However, only one of the points is fixed relative to the tracked probe <NUM>. Accordingly, this second optical fiber <NUM> experiences no change in strain when a force is applied to the tracked probe <NUM>. Because the strain measurements measured by sensing sections <NUM> on the second optical fiber <NUM> vary with temperature but not axial force, they can be used to determine the temperature surrounding the tracked probe <NUM>.

By way of another example, the pose of the surface <NUM> may be determined using conventional imaging techniques to capture a three-dimensional model of the hard tissue <NUM> and/or the surroundings of the hard tissue <NUM>. In this example, registration of the surface <NUM> to the three-dimensional model may not be necessary, as the pose of the three-dimensional model may be provided by the imaging. Intraoperative imaging (i.e., imaging performed during surgery) may be used as it can provide pose information after the optical fibers <NUM> have been attached. The imaging may additionally locate the optical fibers <NUM> relative to the hard tissue <NUM>. By way of yet another example, if an incision surrounding the hard tissue <NUM> is large enough, video recognition may be used to identify the surface <NUM>. A camera, such as the camera <NUM> or another camera, may be configured to capture an image of the surface <NUM>. The controller <NUM> may then match this image to a portion of the three-dimensional model.

Alternatively, in embodiments where a section of each optical fiber <NUM> is held against the surface <NUM>, the shape and pose of each optical fiber <NUM> may be used to determine the contours and the pose of the surface <NUM>. By way of example, this may be employed when two or more points within a section of each optical fiber <NUM> held against the surface <NUM> are attached directly to the surface <NUM> of the hard tissue <NUM> (e.g., such that the points are fixed sensing points <NUM>). If the optical fiber <NUM> is attached such that the length of optical fiber <NUM> contacting the surface <NUM> is not mobile relative to the hard tissue <NUM> (e.g., the optical fiber is taut along this length), then the optical fiber <NUM> follows a contour of the surface <NUM>, and one or more of these contours may be matched to the three-dimensional model of the hard tissue <NUM>. Depending upon the length of the contour followed by the optical fiber <NUM>, multiple of these contours may be used to more accurately match to the three-dimensional model.

Referring to <FIG> and <FIG>, a surgical instrument <NUM>, shown as a cutting tool, is used to perform a surgical operation according to an exemplary embodiment. The pose of the surgical instrument <NUM> in the working coordinate system may be determined using any conventional methods or any of the methods described herein (e.g., using the vision tracking system <NUM>, by tracking one or more optical fibers <NUM> attached to the surgical instrument <NUM>, etc.). The pose of the surgical instrument <NUM> and the poses of the one or more pieces of hard tissue <NUM> may be sent to a computer-assisted surgical system <NUM>. The computer-assisted surgical system <NUM> may include one or more pieces of tracked or navigated surgical equipment (e.g., cutting tools, surgical robots, etc.), shown as surgical robots <NUM>, controlled using information supplied by the fiber optic tracking system <NUM>. The surgical robot <NUM> may guide or control the surgical instrument <NUM> or any other surgical instruments during surgery. In some embodiments, parts of the fiber optic tracking system <NUM>, such as the tracked probe <NUM> or the tool <NUM>, are controlled by the surgical robot <NUM>.

As shown in <FIG> and <FIG> the fiber optic tracking system may include a graphical user interface or display <NUM> operatively coupled to the controller <NUM>. In some embodiments, the display <NUM> is part of the computer-assisted surgical system <NUM>. As shown in <FIG> and <FIG>, the display <NUM> displays or indicates a relative pose of one or more of the pieces of hard tissue <NUM>, the optical fibers <NUM>, the tracked probe <NUM>, and the surgical instrument <NUM>. In other embodiments, the display <NUM> additionally or alternatively displays the soft tissue <NUM>, other tissue, and/or another item. <FIG> shows an exemplary screenshot of the display <NUM>. This screenshot shows three-dimensional hard tissue models <NUM> of the pieces of hard tissue <NUM>, three-dimensional optical fiber models <NUM> of the optical fibers, and a three-dimensional surgical instrument model <NUM> of the surgical instrument <NUM>. Having the display <NUM> show the relative poses of the various objects assists an operator in accurately navigating during a surgery, as many of these objects would normally be obscured during an operation (e.g., by soft tissue <NUM>).

Referring to <FIG>, a surgical port <NUM> used to sense a shape and/or a pose of an incision in soft tissue <NUM> of a body (e.g., a human body, a body of an animal, etc.) is shown according to an exemplary embodiment of the invention. The surgical port <NUM> is configured to be inserted within (e.g., completely within, partially within, etc.) the incision. The surgical port <NUM> includes an outer protrusion, shown as outer ring <NUM>, an inner protrusion, shown as inner ring <NUM>, and a flexible wall <NUM> coupling the outer ring <NUM> to the inner ring <NUM> and forming a central aperture. The flexible wall <NUM> is coupled to the inner ring <NUM> and the outer ring <NUM> as shown in <FIG> such that it forms a continuous (e.g., elliptical, circular, rectangular, etc.) shape. The inner ring <NUM> and the outer ring <NUM> may be flexible or rigid. <FIG> and <FIG> show the surgical port <NUM> in place during a surgery. The surgical port <NUM> may be used to retract the incision to facilitate access to the interior of a body through the incision. The flexible wall <NUM> covers and contacts the incision and protects the surrounding soft tissue <NUM>. The inner ring <NUM> may be inserted into the incision by, for example, bending it over upon itself. Once the inner ring <NUM> is located inside of the incision, the outer ring <NUM> may be rolled such that the flexible wall <NUM> is retracted onto the outer ring <NUM>. This applies tension to the flexible wall <NUM>, conforming the flexible wall <NUM> to the shape of the incision and causing the incision to retract (i.e., increase in size). Once fully retracted, at least a portion of the outer ring <NUM> contacts the soft tissue <NUM> surrounding the incision, resting upon an outer surface of the body as shown in <FIG> and <FIG>. In other embodiments, the outer ring <NUM> and inner ring <NUM> may be otherwise shaped.

As shown in <FIG>, one or more optical fibers <NUM> of the fiber optic tracking system <NUM> are integrated into the surgical port <NUM> according to an exemplary embodiment of the invention. In some embodiments, the fiber optic tracking system <NUM> includes the surgical port <NUM> and does not track the hard tissue <NUM>. As shown in <FIG>, the optical fibers <NUM> are radially distributed around the flexible wall <NUM>, conform to the contours of the flexible wall <NUM>, and extend away from the surgical port <NUM> to connect to the fiber base <NUM>. Sections of the optical fibers <NUM> contacting the flexible wall <NUM> are flexible, allowing them to deform to conform to the contours of the flexible wall <NUM> if the flexible wall <NUM> deforms. The portions of the optical fibers <NUM> extending towards the fiber base <NUM> are omitted from <FIG> for clarity, although it should be understood that the optical fibers <NUM> extend away from the incision and past the outer ring <NUM>. The optical fibers <NUM> are coupled to the surgical port <NUM> such that one or more fixed sensing points <NUM> along the lengths of each of the optical fibers <NUM> have a fixed relationship to the surgical port <NUM>. Specifically, one or more of the fixed sensing points <NUM> may have a fixed relationship to the outer ring <NUM>, the inner ring <NUM>, and/or the flexible wall <NUM>. <FIG> shows exemplary locations of fixed sensing points <NUM>, although it should be understood that the fixed sensing points <NUM> may be included on each optical fiber <NUM>, and that there may be a different number (e.g., <NUM>, <NUM>, <NUM>, <NUM>, etc.) of fixed sensing points <NUM> on each optical fiber <NUM>. The optical fiber <NUM> may be coupled to the flexible wall <NUM> such that the optical fiber has a number of fixed sensing points <NUM> fixed relative to the flexible wall <NUM>. The optical fibers <NUM> may be coupled to an interior surface or an exterior surface of the flexible wall <NUM> or located inside of the flexible wall <NUM> itself. In some embodiments, the optical fibers <NUM> are permanently coupled to the flexible wall <NUM> (e.g., the flexible wall <NUM> is molded around the optical fibers <NUM>). In other embodiments, the optical fibers <NUM> may be removable from the flexible wall <NUM> (e.g., adhered to an exterior surface of the flexible wall <NUM>).

The fiber optic tracking system <NUM> may be configured to use the optical fibers <NUM> to determine a shape, size, and pose of the flexible wall <NUM>. Because the flexible wall <NUM> contacts and conforms to the soft tissue <NUM> surrounding the incision, this information can be used to determine the shape, size, and pose of the incision. As the flexible wall <NUM> is retracted onto the outer ring <NUM>, it conforms to the shape of the incision. The radially placed optical fibers <NUM> conform to the shape of the incision as well, each following a contour of the incision. As shown in <FIG>, the optical fibers <NUM> extend longitudinally along the surgical port <NUM>. In other embodiments, the optical fibers <NUM> are angled relative to the longitudinal direction. By way of example, the optical fibers <NUM> may form a spiral shape along a surface of the flexible wall <NUM>. Such an arrangement facilitates providing detailed information regarding the shape of the incision using a relatively small number of optical fibers <NUM>.

The controller <NUM> may determine a shape and a pose of each of the optical fibers <NUM> in the working coordinate system. The controller <NUM> may then be configured to locate the fixed sensing points <NUM> along the length of each optical fiber <NUM>. Once the fixed sensing points <NUM> are located along an optical fiber, their locations in the working coordinate system are known. In some embodiments, a section of an optical fiber <NUM> may be fixed to the flexible wall <NUM> such that any point along the portion is a fixed sensing point <NUM>. In other embodiments, each optical fiber <NUM> is fixed relative to the flexible wall <NUM> at a number of fixed sensing points <NUM> separate from one another. In some embodiments, the locations of the fixed sensing points <NUM> along the length of each optical fiber <NUM> are predetermined and stored in the memory device <NUM>. By way of example, the optical fibers <NUM> may be bonded to the flexible wall <NUM> in a precise location when manufacturing the surgical port <NUM>. In some embodiments, the locations of the fixed sensing points <NUM> along the length of each optical fiber <NUM> are determined by contacting the portion of the optical fiber <NUM> that is fixed to the flexible wall <NUM> with the tracked probe <NUM>. In other embodiments, other methods of locating the fixed sensing points <NUM> are utilized.

The controller <NUM> may be configured to determine a curve that best fits the fixed sensing points <NUM> corresponding to each optical fiber <NUM>. This curve may be substantially similar to the shape of the portion of the optical fiber <NUM> coupled to the flexible wall <NUM>. The controller <NUM> may then calculate a shape that forms a best fit to all of the curves. This shape may be substantially similar to the shape of the flexible wall <NUM> and the incision. The controller <NUM> may then match the locations of the fixed sensing points <NUM> on the determined shape to the locations of the fixed sensing points <NUM> in the working coordinate system to locate the shape in the working coordinate system. Additionally, the locations of the fixed sensing points <NUM> may be used to determine the size of this shape. Because the flexible wall <NUM> conforms to the shape of the incision, the pose and size of this shape may be used to determine a pose, a size, and a shape of the incision. The addition of more fixed sensing points <NUM> may increase accuracy when determining the shape of the incision, especially if the soft tissue <NUM> surrounding the incision experiences a non-uniform load (e.g., a singular hook-shaped retractor pulling on the incision).

As shown in <FIG>, the flexible wall <NUM> wraps around the soft tissue <NUM> at the incision, such that if a surgical instrument, such as the surgical instrument <NUM>, stays within the central aperture, the surgical instrument will not contact the soft tissue <NUM> surrounding the incision. This prevents accidental damage to the soft tissue <NUM> that might otherwise occur without the shape and pose information provided by the optical fibers <NUM>. Additionally, the flexible wall <NUM> allows the surgical port <NUM> to conform to outside forces, such as the wound retractors shown in <FIG>, while still providing shape and pose information.

Referring to <FIG>, in some embodiments, a tracker, shown as outer ring tracker <NUM>, is removably or selectively coupled to the outer ring <NUM>. The outer ring tracker <NUM> may be attached to the outer ring <NUM> after the outer ring <NUM> is rolled to retract the flexible wall <NUM>. As shown in <FIG>, the outer ring tracker <NUM> is annular and couples to the outer ring <NUM> by applying a circumferential clamping force. To produce the clamping force, a compressive force is exerted on a slot <NUM> in the outer ring tracker <NUM> (e.g., by tightening a screw extending perpendicular to the slot <NUM>), decreasing an inner diameter of the outer ring tracker <NUM>. In other embodiments, the outer ring tracker <NUM> is otherwise held onto the outer ring <NUM>. By way of example, the outer ring tracker <NUM> may include a clamp that extends on either side of the flexible wall <NUM> and applies a clamping force on the outer ring <NUM>. The outer ring tracker <NUM> is coupled to the outer ring <NUM> such that relative motion between the outer ring tracker <NUM> and the outer ring <NUM> is prevented.

The outer ring tracker <NUM> includes a tracking mechanism for determining a pose of the outer ring tracker <NUM> in the working coordinate system. Because the outer ring tracker <NUM> has a fixed relationship to the outer ring <NUM>, the pose of the outer ring tracker <NUM> may be used to determine a pose of the outer ring <NUM>. Because the outer ring <NUM> contacts an outer surface of the body and the flexible wall <NUM> forms a continuous shape coupled to the outer ring <NUM>, the pose of the outer ring tracker <NUM> may be used to determine a pose of an entry into the incision in the working coordinate system. By way of example, the entry may be considered the inner diameter of the outer ring <NUM>.

The controller <NUM> may be configured to register the pose of the outer ring tracker <NUM> relative to the optical fibers <NUM> to determine where along the length of the optical fibers <NUM> the entry is located. The information regarding the pose of the entry may be used to determine which points along the length of each optical fiber <NUM> are fixed sensing points <NUM> coupled to the flexible wall <NUM>. By way of example, the controller <NUM> may consider all of the points along each optical fiber <NUM> that are located beyond the entry to be fixed sensing points <NUM>, and use these fixed sensing points <NUM> when determining the shape of the incision. By way of another example, the controller <NUM> may consider all of the points along each optical fiber <NUM> that are located a certain distance beyond the entry to be fixed sensing points <NUM>. By way of yet another example, the controller <NUM> may determine a pose of the inner ring <NUM> in the working coordinate system and consider the points along the lengths of the optical fibers <NUM> that are located between the outer ring <NUM> and the inner ring <NUM> to be fixed sensing points <NUM>. One or more optical fibers <NUM> may be used to determine a pose of the inner ring <NUM> in the working coordinate system (e.g., by attaching an optical fiber <NUM> to a circumference of the inner ring <NUM>).

In the embodiment shown in <FIG>, a portion of the surface of the outer ring tracker <NUM> facing away from the soft tissue <NUM> is retroreflective, and the vision tracking system <NUM> is used to determine its pose in the working coordinate system. In other embodiments, one or more visual trackers <NUM> or checkpoints <NUM> are coupled to the outer ring tracker <NUM> and used to determine the pose of the outer ring tracker <NUM>. In yet other embodiments, one or more optical fibers <NUM> are coupled to the outer ring tracker <NUM> and used to determine the pose of the outer ring tracker <NUM>. In yet other embodiments, the controller <NUM> determines the pose of the outer ring tracker <NUM> using another method. Given a fixed relationship between the outer ring tracker <NUM> and the entry (e.g., because the outer ring tracker <NUM> is coupled to the outer ring <NUM>), the controller <NUM> may use the pose of the outer ring tracker <NUM> to determine a pose of the entry.

In some embodiments, the outer ring tracker <NUM> is omitted. The tracked probe <NUM> may be run along the surface of the outer ring <NUM> to determine the shape and pose of the entry. Alternatively, one or more optical fibers <NUM> may be fixed to the surgical port <NUM> at one or more fixed sensing points <NUM> whose locations relative to the surgical port <NUM> are known. After determining the locations of these fixed sensing points <NUM> in the working coordinate system, the shape and pose of the surgical port <NUM> are known. If the pose of the entry relative to the rest of the surgical port <NUM> is known, then the pose of the entry in the working coordinate system is known. The addition of more fixed sensing points <NUM> further increases the accuracy of this method. Once the shape of the incision and the pose of the entry have been determined, the shape and pose of the incision are known.

In some embodiments, the controller <NUM> provides the shape and the pose of the incision determined using the surgical port <NUM> to the computer-assisted surgical system <NUM>. The computer-assisted surgical system <NUM> may use this information when determining a pathway for the surgical robot <NUM> to follow when performing an operation. Without the fiber optic tracking system <NUM>, the computer-assisted surgical system <NUM> would lack information regarding the shape and pose of the incision, and could cause the surgical instrument <NUM> to come into contact with and damage the soft tissue <NUM> surrounding the incision. The information provided by the fiber optic tracking system <NUM> allows the computer-assisted surgical system <NUM> to ensure that the surgical instrument <NUM> used during the operation (e.g., a cutting tool) stays within the central aperture of the surgical port <NUM>, preventing contact between the surgical instrument <NUM> and the soft tissue <NUM>.

In some embodiments, the fiber optic tracking system <NUM> tracks the hard tissue <NUM> and does not track the incision. In other embodiments, the fiber optic tracking system <NUM> tracks the incision and does not track the hard tissue <NUM>. In yet other embodiments, the fiber optic tracking system <NUM> tracks the hard tissue <NUM> and the incision. In some such embodiments, the fiber optic tracking system <NUM> includes separate optical fibers <NUM> for tracking the hard tissue <NUM> and the incision. In other such embodiments, one or more optical fibers <NUM> are used to track both the incision and the hard tissue <NUM>. By way of example, an optical fiber <NUM> may be coupled to the flexible wall <NUM> and extend inside the body through the incision to be coupled to a surface of the hard tissue <NUM>. Accordingly, each optical fiber <NUM> in such an arrangement would have one or more fixed sensing points <NUM> and one or more fixed sensing points <NUM>.

In some embodiments, the display <NUM> displays to a user a shape and a pose of the incision (e.g., including the pose of the entry) or the surgical port <NUM>. In some such embodiments, the display <NUM> additionally displays the relative poses of one or more of the pieces of hard tissue <NUM>, the optical fibers <NUM>, the tracked probe <NUM>, and the surgical instrument <NUM>. Having the display <NUM> show the relative poses of the various objects relative to the incision assists an operator in accurately navigating during an operation. By way of example, the display may show the operator how close the surgical instrument <NUM> is to contact with the soft tissue <NUM>.

In an alternative embodiment, optical fibers <NUM> are attached to or inserted into soft tissue <NUM> and used to track an incision or some other area of interest. One or more optical fibers <NUM> may be inserted into or attached to the soft tissue <NUM> using the tool <NUM> and an anchoring mechanism <NUM> or some other method or attached to the exterior of the soft tissue <NUM>. The locations of the incisions and the points of attachment of the optical fibers <NUM> to the soft tissue <NUM> may be determined. By way of example, the tracked probe <NUM> may be moved across one or more of the areas of interest (e.g., an inner surface of the incision), any exposed points of contact between the optical fibers <NUM> and the soft tissue <NUM> (e.g., where the optical fiber <NUM> meets the exposed surface of the soft tissue <NUM>), and the exposed soft tissue <NUM>. Alternatively, the tool <NUM> may be tracked when inserting or attaching the optical fibers <NUM> to locate the optical fibers <NUM>. The relative poses of the optical fibers <NUM>, the soft tissue <NUM>, and the area of interest may be determined, and this may be used to track the area of interest based on the poses of the optical fibers <NUM>. This information may be provided to a computer assisted surgical system <NUM> and/or a display <NUM>.

As shown in <FIG>, the fiber optic tracking system <NUM> according to an exemplary embodiment can be used to determine the dimensions, shape, and/or pose of an object <NUM>. As shown, the object <NUM> is soft tissue <NUM> (e.g., a human leg tracked at the exterior of the body), however a similar method may be used with hard tissue <NUM> or any other type of object <NUM>. One or more optical fibers <NUM> may be wrapped around or otherwise held against an outer surface of the object <NUM>, and the shapes and poses of the optical fibers <NUM> may be determined as discussed above. The optical fibers <NUM> may be held in place relative to the object <NUM> (e.g., using an anchoring mechanism <NUM> such as tape, by wrapping the optical fibers <NUM> tightly around the object <NUM>, etc.) at a number of fixed sensing points <NUM>. Sections of the optical fibers <NUM> may be held in place relative to the object <NUM> such that the shapes of those sections conform to contours of the outer surface of the object <NUM>. The locations of the fixed sensing points <NUM> in these sections may be used to determine the overall shape, dimensions, and/or pose of the object <NUM>. The optical fibers <NUM> may be placed in certain key locations (e.g., between toes), providing the location and/or pose of certain parts of the object <NUM> (e.g., toes, fingers, a heel, etc.). This may facilitate registration of the shape information from the optical fibers <NUM> to a model of the object <NUM>. The overall shape and/or dimensions of the object <NUM> may be used in further operations for alignment with other devices or other purposes.

The foregoing descriptions have been presented for purposes of illustration and description. They are not exhaustive and do not limit the disclosed embodiments to the precise form disclosed. Modifications and variations are possible in light of the above teachings or may be acquired from practicing the disclosed embodiments. For example, the described implementation includes software, but the disclosed embodiments may be implemented as a combination of hardware and software or in firmware. Examples of hardware include computing or processing systems, including personal computers, servers, laptops, mainframes, microprocessors, and the like. Additionally, although disclosed aspects are described as being stored in a memory, one skilled in the art will appreciate that these aspects can also be stored on other types of computer-readable storage devices, such as secondary storage devices, like hard disks, floppy disks, a CD-ROM, USB media, DVD, or other forms of RAM or ROM.

Claim 1:
A fiber optic tracking system (<NUM>), comprising:
a surgical port (<NUM>) configured to be inserted into an incision;
a light source (<NUM>);
an optical fiber (<NUM>) having a plurality of fixed sensing points (<NUM>) located along a length of the optical fiber that are fixed relative to the surgical port, wherein the optical fiber:
is configured to receive an optical signal from the light source (<NUM>); and
includes a plurality of sensing sections (<NUM>) arranged along the length of the optical fiber and configured to modify the optical signal received by the optical fiber in response to a deformation of the optical fiber;
a sensing unit (<NUM>) configured to receive a modified optical signal from the optical fiber; and
a controller (<NUM>) operatively coupled to the sensing unit and configured to determine locations in a working coordinate system of the fixed sensing points using the modified optical signal,
wherein the surgical port (<NUM>) includes a flexible wall (<NUM>) configured to contact an incision, wherein a section of the optical fiber (<NUM>) is flexible and coupled to the flexible wall (<NUM>) such that the section of the optical fiber can conform to the incision, when in use, wherein at least two of the fixed sensing points (<NUM>) are located within the section, and wherein the controller (<NUM>) is configured to determine a shape of the incision using the locations of the fixed sensing points; and
wherein the surgical port includes an outer protrusion (<NUM>) coupled to the flexible wall, wherein the controller (<NUM>) is configured to determine a pose (i.e. the location and orientation) of the outer protrusion (<NUM>) in the working coordinate system, and wherein the controller (<NUM>) is configured to determine a pose of an entry to the incision in the working coordinate system based on the pose of the outer protrusion (<NUM>).