Device for use in computer-assisted surgery

Abstract

An apparatus for computer-assisted surgery includes a body, an optical element coupled to the body, a fiducial coupled to the body, and a calibration element, which may be a pointer tip or a divot, used individually or in combination.

Description

[Technical Field]

[0001] (CROSS-REFERENCE TO RELATED APPLICATIONS) This application claims the benefit of U.S. Non-Provisional Patent Application No. 18 / 047,553, filed October 18, 2022, the contents of which are incorporated herein by reference in their entirety.

[0002] FIELD OF THE INVENTION The various exemplary embodiments disclosed herein relate generally to devices for use in computer-assisted surgery (CAS). [Background technology]

[0003] The registration and calibration process in computer-assisted surgery typically uses several separate and discrete components. Summary of the Invention [Means for solving the problem]

[0004] A summary of various exemplary embodiments is presented below. In the following summary, some simplifications and omissions may be made in order to highlight and introduce some aspects of various exemplary embodiments and are not intended to limit the scope of the present invention. Detailed descriptions of exemplary embodiments adequate to enable those skilled in the art to make and use the concepts of the present invention follow in the following sections.

[0005] Various embodiments relate to an apparatus for computer-assisted surgery, the apparatus including a body, an optical element coupled to the body, a fiducial coupled to the body, and a calibration element.

[0006] Various embodiments are described in which the device comprises at least three optical elements.

[0007] Various embodiments are described in which the device comprises at least three criteria.

[0008] Various embodiments are described in which the calibration element is a calibration divot that forms a depression on the body configured to receive a surgical instrument.

[0009] Various embodiments are described in which the calibration divot further comprises a flat cylindrical positioning divot.

[0010] Various embodiments are described in which the calibration divot further comprises a conical positioning divot.

[0011] Various embodiments are described in which the calibration element is a pointer tip extending from the body.

[0012] Various embodiments are described in which the pointer tip is adapted to receive a first pointer extension.

[0013] Various embodiments are described in which the pointer tip is detachable from the body.

[0014] Various embodiments are described in which the pointer tip is attached to a pointer extension on the body.

[0015] Various embodiments are described that further include a second pointer extension having a different length than the first pointer extension.

[0016] Various embodiments are described, further including data representing the as-manufactured dimensions of the device.

[0017] Further various embodiments relate to an apparatus for computer-assisted surgery comprising a body, an optical element, the optical element configured to be visible to a position camera, the optical element, a reference, the reference being radiopaque, and a calibration element, wherein the optical element, the reference, the body, and the calibration element are held in fixed positions relative to each other.

[0018] Various embodiments are described in which the calibration element is a calibration divot that forms a depression on the body configured to receive a surgical instrument.

[0019] Various embodiments are described in which the calibration divot further comprises a flat cylindrical positioning divot.

[0020] Various embodiments are described in which the calibration divot further comprises a conical positioning divot.

[0021] Various embodiments are described in which the calibration element is a pointer tip attached to the body.

[0022] Various embodiments are described in which the pointer tip is configured to receive a first pointer extension.

[0023] Various embodiments are described in which the pointer tip is detachable from the body.

[0024] Various embodiments are described in which the pointer tip is attached to a pointer extension on the body.

[0025] Various embodiments are described that further include a second pointer extension having a different length than the pointer extension.

[0026] Various embodiments are described, further including data representing the as-manufactured dimensions of the device. [Brief explanation of the drawings]

[0027] For a better understanding of various exemplary embodiments, reference is made to the accompanying drawings, in which an embodiment of an apparatus for use in computer-assisted surgery is shown. [Figure 1] FIG. 1 is a front perspective view of an apparatus for use in computer-assisted surgery. [Figure 2] FIG. 2 is a rear perspective view of the device of FIG. 1. [Figure 3] FIG. 2 is an exploded view of the device of FIG. 1. [Figure 4] FIG. 2 is a plan view of the device of FIG. 1. [Figure 5] FIG. 2 is a right side view of the device of FIG. 1. [Figure 6] FIG. 2 is a bottom view of the device of FIG. 1. [Figure 7] FIG. 2 is a front view of the device of FIG. 1. [Figure 8] FIG. 2 is a rear view of the device of FIG. 1. [Figure 9] FIG. 2 is a bottom perspective view of the device of FIG. 1. [Figure 10] FIG. 1 is a top view of another apparatus for use in computer-assisted surgery. [Figure 11] FIG. 11 is a right side view of the device of FIG. 10. [Figure 12] FIG. 11 is a rear view of the device of FIG. 10. [Figure 13] FIG. 11 is a top perspective view of the device of FIG. 10. [Figure 14] FIG. 11 is a top perspective view of the device of FIG. 10.

[0028] For ease of understanding, the same reference numbers are used to indicate components having substantially the same or similar structure and / or substantially the same or similar function. DETAILED DESCRIPTION OF THE INVENTION

[0029] The present description and drawings exemplify the principles of the present invention. Thus, it should be understood that those skilled in the art can devise various configurations that, although not explicitly described or shown herein, embody the principles of the present invention and are encompassed within the scope of the present invention. Furthermore, all examples shown herein are expressly intended primarily for educational purposes to aid the reader in understanding the principles of the present invention and the concepts contributed by the inventor(s) to advance the present technology, and should not be construed as being limited to such specifically shown examples and conditions. Additionally, the term "or," as used herein, refers to a non-exclusive logical or (i.e., and / or) unless otherwise indicated (e.g., "or otherwise" or "or alternatively"). Furthermore, the various embodiments described herein are not necessarily mutually exclusive, as some embodiments can be combined with one or more other embodiments to form new embodiments.

[0030] Before a computer-assisted surgery (CAS) procedure is performed, the CAS system learns the positions and relationships of various elements, such as the patient (based on images of the patient, which may be obtained by fluoroscopy, X-ray, CT, MRI, etc.) and medical instruments (e.g., scalpels, saws, drills, bone screws, implants, robots, etc.). To enable the CAS to locate the patient, the patient typically has a navigation array attached somewhere on their body, often attached to a bone for stability. These navigation arrays can be monitored by a localization device or system, such as a spatial camera, one of which is commercially available from Northern Digital Inc. Spatial cameras typically use an internal coordinate system defined by the camera rather than the patient's position (the spatial camera can be positioned at various positions relative to the patient). The navigation array can be an array of reflective spheres that reflect light back to the spatial camera (the spatial camera or other light source can emit infrared (IR) light and then use a stereo camera to sense the IR light reflected back from the spheres, thereby making it possible to spatially locate the spheres). Alternatively, the navigation array may be an LED (or other point light source) that emits light that is sensed by the spatial camera (no reflection is necessary). Furthermore, instead of a navigation array and a spatial camera, the spatial system may use electromagnetic devices that emit signals that can be used by a receiver to determine their spatial position, or other known systems for navigation of devices.

[0031] Many surgeries use imaging devices (e.g., fluoroscopy, x-ray, CT, MRI) to take images of the patient that can be useful to the surgeon during surgery. Fiducials, such as radiopaque markers, can be attached to the patient before imaging occurs. These fiducials create relatively well-defined landmarks in the images that can later be used to transform between the patient coordinate system and the camera coordinate system. Imaging devices typically have their own internal coordinate system that is defined by the imaging device itself and has no fixed relationship to the spatial camera's coordinate system (the camera can typically be placed at various positions relative to the imaging device).

[0032] A navigation array may also be attached to the surgical instrument so that the CAS system can track the spatial position of the instrument. The spatial camera tracks the position of the navigation array, and therefore the surgical instrument, in the camera's coordinate system. However, the spatial camera's knowledge of the surgical instrument's position in the camera's coordinate system is only part of the picture. It is useful for the CAS system to know where the instrument is relative to the patient.

[0033] To achieve this, various processes are used when setting up the CAS system before surgery. One process is used to enable the CAS system to harmonize the spatial camera coordinate system, the patient coordinate system, and the imaging device coordinate system; this process is typically called registration. During registration, the CAS system determines the relationship between the various coordinate systems. That is, if the CAS system knows the spatial relationship between the navigation array connected to the patient (monitored by the spatial camera) and the fiducials connected to the patient (appearing in the images created by the imaging device), the CAS system can mathematically / spatially relate that information so that the patient's images can be properly registered with or superimposed on the patient in 3D space.

[0034] The CAS system also needs to know the spatial relationship between the navigation array and the tip of the surgical instrument, since the tip is the part that may be altering the patient's tissue. A separate process is typically used to enable the CAS to achieve this relationship, called calibration. The term calibration can be used to describe a scenario in which the CAS system learns the distance or geometric relationship between the array and the tip of the tool, for example, when the CAS system does not know the exact shape of the surgical instrument. If the CAS system allows the use of saw blades of any length, the user may need to calibrate the tip of the blade. To accomplish this, the CAS system can use a "pointer," which is another surgical instrument with a sharp tip, shaft, and navigation array connected to the shaft so that the tip is located at a fixed position relative to the array. The CAS system is programmed to know this fixed geometric relationship, and therefore can use the pointer to obtain a geometric point in 3D space, such as the tip of the saw blade (other points on the saw blade, such as a divot on the saw blade that has a known relationship to the tip of the saw blade, can also be used), and then estimate the relationship between the tip of the saw blade and the navigation array.

[0035] In some scenarios, the CAS system may require that only a specific length of saw blade be used (and know its expected blade length and shape, sometimes referred to as a pre-calibrated instrument). In such cases, the CAS system can perform what is typically called a calibration verification. In a calibration verification, the user touches the tip of a pointer to the tip of the saw blade (or a divot, as described above), and the CAS system determines whether the tip of the pointer is where the tip of the saw blade (or divot) is expected to be located spatially.

[0036] These processes harmonize the spatial relationships between the various elements of the CAS system. In this way, the CAS system knows where the tip of the saw blade is relative to the patient, not just the camera system, and the images can be correlated to the patient's actual position, providing the surgeon with information unavailable to the eye, such as the location of bones or nerves obscured by the patient's skin. Prior systems often used separate devices for navigation arrays, fiducials, and pointers. Such systems introduced additional imprecision and complexity into surgical procedures, such as grasping multiple elements during various stages of the surgical flow.

[0037] Exemplary embodiments of devices for use in computer-assisted surgery are described that combine some or all of a reflective sphere, a radiopaque fiducial, a pointer, and a divot into one device. This can reduce the number of devices required for alignment and / or calibration, thus streamlining these processes and simplifying surgical workflow. The pointer and divot, individually or in combination, may be referred to as calibration elements.

[0038] 1-9 illustrate an exemplary embodiment of an apparatus for use in computer-assisted surgery.

[0039] 1-9 show an apparatus 10 that includes a body 12. The body 12 has four posts 14, each supporting a reflective sphere 16. The reflective spheres 16 are optically visible to the camera, and thus provide an optical element.

[0040] The posts 14 are shown as elongated conical cylinders, but may be any shape and may have different lengths. The posts 14 may simply be mounting locations on the body 12.

[0041] The posts 14 are injection molded with the body 12. While shown as being integrally injection molded with the body 12, the posts 14 may be separate components attached by any method, including by snap-fit, threaded fit, separate fasteners, or collet features. While the posts 14 are shown as elongated conical cylinders, they may be any shape. Also, different posts 14 may be of different lengths or the same length. In this embodiment, the posts 14 are the same length, so the reflective spheres 16 lie in a horizontal plane. The reflective spheres 16 form an optically visible array. The reflective spheres 16 may be attached to the posts 14 by snap-on features 17, although other attachment mechanisms and methods may be used. The reflective spheres 16 provide optical elements. While the reflective spheres 16 are used as an example of optical elements, optical elements may take other shapes. The reflective spheres 16 are an example of passive optical elements. In other embodiments, the optical elements may instead be active optical elements, which may include precision light sources, e.g., light emitting diodes (LEDs), that emit light that is captured by the camera and then used to determine the position of the optical elements. With knowledge of the spatial location of the optical elements, the CAS system can use a priori knowledge of the spatial relationships of various features of the device 10 to one another to determine the spatial locations of those features, such as fiducials 18, which are described in more detail below.

[0042] Each post 14 supports a respective optically reflective sphere 16. The reflective spheres 16 form an optically visible array. They are shown connected to the ends of the posts 14 with snap-on features. The purpose of each sphere 16 is to be visible to a localization device, such as a spatial camera. The fiducials 18 provide marks that appear on images captured by an imaging device (such as a fluoroscope or x-ray). The marks can be used to determine positional information relative to the patient. The device may also include divots that can be used to calibrate the instrument, as described above. The device 10 holds the reflective spheres 16, fiducials 18, the pointer extension post 22 with the pointer tip 23, and the divots 28, 29 in a fixed spatial relationship. The CAS system is programmed to know this fixed geometric relationship and can therefore beneficially use that information during alignment and / or calibration.

[0043] The body 12 is shown as having four reflective spheres (or optical elements). However, it should be noted that more than four spheres can be used, with three spheres typically being sufficient. The reflective spheres 16 may also be optical elements having other shapes, such as cubes, elongated tips, or paddle shapes. The reflectivity of the optical elements may be partially reflective or fully reflective. Reflectivity may be achieved during manufacturing using paint, coating, impregnation, or other techniques. The optical elements may also be molded as an integral part of the post 14.

[0044] The fiducials 18 are typically molded into the body 12, but can also be attached to the body 12 using a snap fit or fasteners. The fiducials 18 are radiopaque and are visible, for example, during a C-arm X-ray (CBCT) scan of the patient while the device 10 is positioned or attached to the patient. The fiducials 18 may be separate components mounted by any method, including being attached by a snap fit, a threaded fit, a separate fastener, a collet feature, or an overmolding. By radiopaque, it is intended that the fiducials 18 are detectable from the surrounding material by X-ray (for other imaging devices, the fiducials may be any other material that clearly shows up in the captured image). Thus, the fiducials 18 may be partially transparent and partially translucent to X-rays, so that the location of the fiducials 18 can be obtained by processing the X-ray image after an X-ray scan of the patient is taken with the device 10 positioned on or attached to the patient.

[0045] Because the CAS system knows the spatial relationships between the reflective sphere 16, the fiducial 18, the pointer tip 23, and the divots 28, 29, the CAS system can calculate the positions and orientations of the fiducial 18, the pointer tip 23, and the divots 28, 29. The fixed relationship between the reflective sphere 16 and the fiducial 18 can be used in the alignment process described above.

[0046] The device 10 also includes a pointer extension post 22. The pointer extension post 22 may be integrally formed with the body 12 or may be attachable to the body 12. The CAS system needs to know the spatial relationship of the device's features relative to the tip 27. Therefore, the CAS system must know whether a pointer extension is attached to the device 10. This knowledge can be achieved via a configuration GUI screen, or by a machine vision system that evaluates an image of the device 10 and determines from image analysis whether a pointer extension is attached. Alternatively, the device 10 can include electronics, such as an RFID sensor, proximity sensor, or the like, to determine whether a pointer extension is attached and, possibly, what length the pointer extension is. The device 10 can include wireless communication to communicate this information to the CAS system.

[0047] As shown in FIG. 1 , a pointer extension 26 terminating in a pointer tip 27 can be attached to the device 10 via a pointer extension post 22. The pointer extension 26 can be of any length necessary to perform the necessary calibration. The pointer extension post 22 can be integral with the body 12 or can be one or more separate components attached by any method, including by a snap fit, a threaded fit, a separate fastener, or a collet feature. The pointer extension post 22 can be of any length and cross-section and can be located in various positions on the body 12, including, for example, any of arrow positions A, B, and C (shown in FIG. 10 ). The pointer extension post 22 terminates in a tip 23. When the device 10 is used without the pointer extension 26, this allows for a relatively short pointer that is unobtrusive for imaging. When the device 10 is used with the pointer extension 26, this allows for a longer pointer that can be more convenient for the surgeon during alignment, for example, when the tip 27 is in contact with a surgical instrument. The pointer extension 26 can be attached to the pointer extension post 22 by any method, including by a snap fit, a threaded fit, a separate fastener, or a collet feature. The pointer extension 26 can be any shape or size and any length. Multiple pointer extensions 26 can be provided in different lengths. In such cases, the CAS system is configured with the extension dimensions, and provisions are made to inform the CAS system which extension is being used. A variety of pointer tip shapes and types can be used.

[0048] The body 12 forms a conical divot 28 terminating in a point and a cylindrical divot 29 terminating in a flat surface. The conical divot 28 provides a point for a complementary surgical instrument feature to engage during calibration (or calibration verification). The cylindrical divot 29 provides a flat surface for a complementary instrument feature to engage during calibration (or calibration verification). For example, the end of a medical instrument having its own navigation array can be brought into contact with the conical divot 28 or the flat divot 29. The positions and orientations of the conical divot 28 and the flat divot 29 relative to the reflective sphere 16, the fiducial 18, and the pointer tip 27 are known, and therefore the CAS system can use this known relationship in calibrating (or verifying) the surgical instrument.

[0049] A number of mounting holes 34 may be provided for attachment to an arm or other component of a medical device. The device 10 may be attached to the patient using double-sided tape or other fastening methods.

[0050] To aid in handling of device 10, ears 35 are shown on the sides of body 12. Although ears 35 are shown as flat structures extending away from the sides of body 12, ears 35 can take other shapes and sizes.

[0051] The reflective ball 16, the datum 18, the pointer tip 27 (which may be extended by a pointer extension), and / or the divots 28, 29 are held in fixed positions relative to one another by the body 12. Thus, the system 10 provides a device 10 with multiple features, any combination of which may be used.

[0052] The body 12 may be made of injection-molded plastic, and preferably at least partially made of a radiolucent material, such as, for example, injection-molded plastic or a machined polymer. The posts 14 may be integral with or separate from the body 12 and may be made of injection-molded plastic, such as a machined polymer. If the posts 14 are made separate from the body 12, they may be made of a metal, such as, for example, stainless steel, titanium, aluminum, etc. The reflective ball 16 may be molded or machined plastic with a reflective coating, paint, or tape. The pointer extension post 22 may be integral with or separate from the body 12 and may be made of, for example, injection-molded plastic, machined plastic, stainless steel, titanium, etc. The pointer extension 26 may be made of injection-molded plastic, machined plastic, stainless steel, titanium, etc. The datum 18 may be made of stainless steel, titanium, ceramic, and / or tantalum, or any other radiopaque material.

[0053] The CAS system may use manufacturing specifications for the locations of the reflective ball 16, datum 18, pointer tip 27, and conical divot 28 and flat divot 29. However, due to manufacturing tolerances, there will be variations in the actual manufactured locations of the reflective ball 16, datum 18, pointer tip 27, conical divot 28, and flat divot 29. Therefore, after manufacturing, the device 10 can be precisely measured to determine the actual locations of the reflective ball 16, datum 18, pointer extension post 22, tip 27, flat divot 29, and conical divot 28. This manufacturing measurement data may be used by the CAS system in place of the manufacturing specifications to achieve improved accuracy.

[0054] 10-14 show another embodiment of an apparatus for use in computer-assisted surgery.

[0055] 10-14 show an apparatus 110 that includes a body 112. The body 112 has four posts 114, each supporting a reflective sphere 116. The reflective spheres 116 are optically visible to the spatial camera. The reflective spheres 116 thus provide an optical element. As noted above, the number of optical elements can vary, as can the types of optical elements.

[0056] The posts 114 are shown as elongated conical cylinders, but may be any shape and may have different lengths. The posts 114 may simply be mounting locations on the body 112.

[0057] The posts are injection molded with the body 112. While shown as being injection molded integrally with the posts 114, the posts 114 may be separate components attached by any method, including by a snap fit, a threaded fit, a separate fastener, or a collet feature. If the posts 114 are made separately from the body 112, they may be made of a metal such as, for example, stainless steel, titanium, or aluminum. While the posts 114 are shown as elongated conical cylinders, they may be any shape and may have different lengths. The posts 114 may simply be attachment locations on the body 112.

[0058] The posts 114 each support a respective optically reflective sphere 116. The reflective spheres 116 are optically visible to the spatial camera.

[0059] The reflective spheres 116 form an optically visible array. While the reflective spheres 116 are shown threadably connected to the end of each post 114, other attachment mechanisms and methods may be used. As noted above, the purpose of each reflective sphere 116 is to be visible to a camera using visible or infrared light. As noted above, the reflective spheres 116 may alternatively be replaced by LEDs. The purpose of the reflective spheres 116 is to be visible to a location-determining device, such as a spatial camera, to determine the position of the optical array, which in turn allows the CAS system to determine the positions of various features of the device. (Alternatively, the CAS system and the camera system may be a single computing device, or they may be separate devices that communicate with each other.) Any or all of the different posts 114 may be of different lengths from one another, or may be the same length. The embodiment of FIG. 1 shows posts 14 that lie in a common plane, i.e., the posts 14 are the same length so that they lie substantially in a plane. The embodiment of FIG. 11 shows posts with varying heights that position the spheres such that they are not in a common plane.

[0060] Also attached to the body 112 are a number of fiducials 118. These may be attached to the body using a snap fit, fasteners, or molded into the body 112. The fiducials 118 are radiopaque and are visible during a C-arm x-ray scan of the body 112 and the patient. The fiducials 118 may be separate components mounted by any method, including being attached by a snap fit, a threaded fit, separate fasteners, or a collet feature. The fiducials 118 may be made of stainless steel, titanium, ceramic, and / or tantalum, or any other radiopaque material.

[0061] The body 112 also supports a pointer extension post 122 having a pointer tip 123. The pointer extension post 122 may be integral with the body 112 or may be one or more separate components attached by any method, including by a snap fit, a threaded fit, a separate fastener, or a collet feature. The pointer extension post 122 may be of any length and cross-section and may be located at various locations on the body 112, including, for example, any of arrow positions A, B, and C. Different pointer extensions 126 may have different lengths and each terminate at a tip 127. This allows a relatively short pointer extension post 122 to be out of the way for imaging while supporting a longer pointer for accuracy checks. The pointer extension 126 may be attached by any method, including by a snap fit, a threaded fit, a separate fastener, or a collet feature. The pointer extension post 122 may support a measurement extension 126 that snaps, threads, attaches with a fastener, or the like, to the pointer extension post 122. If a pointer extension 126 is used in the procedure, the user may specify to the CAS system which pointer extension is being used (if only one length extension is provided), or the user may specify which pointer extension is being used (if multiple length extensions are available) (i.e., indicate the length and position of the measurement tip) using various methods. One approach is for the user to input information about the measurement tip 126 to be used via a graphical user interface (GUI). Another approach is to place the tip 127 of the measurement tip 126 at a divot on another instrument or navigation array with a known position. Additionally, machine vision recognition or other techniques, as described above, can be utilized.

[0062] Body 112 forms a conical divot 128 and / or a cylindrical or flat divot 129. The conical divot 128 terminates in a point. The cylindrical divot terminates in a flat surface. The point and / or flat surface provide a surface for a complementary instrument feature to mate with for use during calibration. Divots 128 and 129 have the same functionality as described above with respect to body 112.

[0063] The back or other side of the body 112 may be partially hollow and supported by a web 130 .

[0064] A number of mounting holes 134 may be provided on the body 112 for attachment to an arm or other component of a medical device. The system 110 may be attached to the patient using double-sided tape or other fastening methods.

[0065] Ears 135 are shown on the sides of body 112 to aid in handling device 110. Body 132 is shown for attachment to the patient using double-sided tape or other adhesive methods.

[0066] The reflective sphere 116, the datum 118, and the extension post 122 are held in fixed positions relative to one another by the body 112. Thus, the system 110 provides a multi-function device. Any of these features may be used in any combination.

[0067] Although each of the embodiments is described above in terms of their structural arrangement, it should be understood that the present invention also encompasses associated methods of using the above-described embodiments.

[0068] While various exemplary embodiments have been described in detail with particular reference to certain illustrative aspects thereof, it should be understood that the invention is capable of other embodiments and its details are capable of modifications in various obvious respects. As will be readily apparent to those skilled in the art, variations and modifications of the various embodiments and combinations thereof may be effected while remaining within the spirit and scope of the invention. Accordingly, the foregoing disclosure, description, and drawings are for illustrative purposes only and do not in any way limit the invention, which is defined solely by the claims.

[0069] [Embodiment] (1) An apparatus for computer-assisted surgery, comprising: The main body and an optical element coupled to the body; a reference coupled to the body; a calibration element; An apparatus comprising: (2) The device of embodiment 1, wherein the device comprises at least three optical elements. (3) The device of embodiment 1, wherein the device comprises at least three criteria. (4) The device of embodiment 1, wherein the calibration element is a calibration divot forming a recess on the body configured to receive a surgical instrument. (5) The apparatus of claim 4, wherein the calibration divot further comprises a flat, cylindrical positioning divot.

[0070] (6) The apparatus of claim 4, wherein the calibration divot further comprises a conical positioning divot. (7) The device of embodiment 1, wherein the calibration element is a pointer tip extending from the body. (8) The device of embodiment 7, wherein the pointer tip is adapted to receive a first pointer extension. (9) The device of embodiment 7, wherein the pointer tip is removable from the main body. (10) The device of embodiment 7, wherein the pointer tip is attached to a pointer extension on the body.

[0071] (11) A system comprising the device described in embodiment 8, further comprising a second pointer extension having a different length than the first pointer extension. (12) A system comprising the device described in embodiment 1 and further comprising data representing the dimensions of the device at the time of manufacture. (13) An apparatus for computer-assisted surgery, comprising: The main body and an optical element, the optical element configured to be visible to a position camera; a reference, the reference being radiopaque; and a calibration element; The apparatus, wherein the optical element, the reference, the body, and the calibration element are held in fixed positions relative to one another. (14) The device of claim 13, wherein the calibration element is a calibration divot forming a recess on the body configured to receive a surgical instrument. (15) The apparatus of claim 14, wherein the calibration divot further comprises a flat, cylindrical positioning divot.

[0072] (16) The apparatus of claim 14, wherein the calibration divot further comprises a conical positioning divot. (17) The device of claim 13, wherein the calibration element is a pointer tip attached to the body. (18) The device of embodiment 17, wherein the pointer tip is configured to receive a first pointer extension. (19) The device of embodiment 17, wherein the pointer tip is removable from the body. (20) The device of embodiment 17, wherein the pointer tip is attached to a pointer extension on the body.

[0073] (21) A system comprising the device described in embodiment 17, further comprising a second pointer extension having a different length from the pointer extension. (22) A system comprising the device described in embodiment 13 and further comprising data representing the dimensions of the device at the time of manufacture.

Claims

1. 1. An apparatus for computer-assisted surgery, comprising: The main body and an optical element coupled to the body; a reference coupled to the body; a calibration element; An apparatus comprising:

2. The apparatus of claim 1 , wherein the apparatus comprises at least three optical elements.

3. The device of claim 1 , wherein the device comprises at least three criteria.

4. The apparatus of claim 1 , wherein the calibration element is a calibration divot forming a recess on the body configured to receive a surgical instrument.

5. The apparatus of claim 4 , wherein the calibration divot further comprises a flat, cylindrical positioning divot.

6. The apparatus of claim 4 , wherein the calibration divot further comprises a conical positioning divot.

7. The device of claim 1 , wherein the calibration element is a pointer tip extending from the body.

8. The device of claim 7 , wherein the pointer tip is adapted to receive a first pointer extension.

9. The device of claim 7 , wherein the pointer tip is removable from the body.

10. The device of claim 7 , wherein the pointer tip is attached to a pointer extension on the body.

11. 10. A system comprising the apparatus of claim 8, further comprising a second pointer extension having a different length than the first pointer extension.

12. 10. A system comprising the device of claim 1, further comprising data representing as-manufactured dimensions of the device.

13. 1. An apparatus for computer-assisted surgery, comprising: The main body and an optical element, the optical element configured to be visible to a position camera; a reference, the reference being radiopaque; and a calibration element; The apparatus, wherein the optical element, the reference, the body, and the calibration element are held in fixed positions relative to one another.

14. The apparatus of claim 13 , wherein the calibration element is a calibration divot forming a recess on the body configured to receive a surgical instrument.

15. The apparatus of claim 14 , wherein the calibration divot further comprises a flat, cylindrical positioning divot.

16. The apparatus of claim 14 , wherein the calibration divot further comprises a conical positioning divot.

17. The device of claim 13 , wherein the calibration element is a pointer tip attached to the body.

18. 18. The device of claim 17, wherein the pointer tip is configured to receive a first pointer extension.

19. 18. The device of claim 17, wherein the pointer tip is removable from the body.

20. 18. The device of claim 17, wherein the pointer tip is attached to a pointer extension on the body.

21. 20. A system comprising the apparatus of claim 17, further comprising a second pointer extension having a different length than the pointer extension.

22. 14. A system comprising the device of claim 13, further comprising data representing as-manufactured dimensions of the device.

Images