Apparatus and method for aiding visualization and/or placing a landmark during a surgical procedure

An apparatus for aiding visualization of a prosthetic implant and concurrently landmarking a patient tissue includes a center post having proximal and distal post ends longitudinally separated by a post body. The post body defines a post axis coaxially therewith. An implant emulator embodies a reference feature of a prosthetic implant. The implant emulator is carried on an outer surface of the center post at a predetermined longitudinal spacing from the distal post end. A guiding device is removably attached to the implant emulator. The guiding device includes an attachment structure attached to the implant emulator. A spacing arm is connected to the attachment structure and extends laterally outward from the post axis. A landmark guiding structure is connected to the spacing arm, spaced apart from the center post, and embodies at least one of a location and a trajectory for placement of a landmark.

TECHNICAL FIELD

The present invention relates to an apparatus and method for aiding visualization and/or placing a landmark during a surgical procedure and, more particularly, to a method and apparatus for aiding visualization of a prosthetic implant and concurrently landmarking a patient tissue during a patient procedure.

BACKGROUND OF THE INVENTION

In the installation of a prosthetic hip joint into a patient's body, an acetabular component (usually a cup) is implanted into the acetabulum of the patient's pelvis. An obverse surface of the acetabular component is configured for articulating contact with a femoral component carried by the patient's femur. A reverse surface of the acetabular component is secured to the bone surface of the acetabulum.

Because the hip prosthesis is normally provided to correct a congenital or acquired defect of the native hip joint, the acetabulum often exhibits a pathologic, nonstandard anatomic configuration. A surgeon must compensate for such pathologic acetabular anatomy when implanting the acetabular component in striving to achieve a solid anchoring of the acetabular component into the acetabulum. Detailed preoperative planning, using two- or three-dimensional internal images of the hip joint, often assists the surgeon in compensating for the patient's anatomical limitations. Additionally, during a surgical procedure, it may be useful for the surgeon to be able to easily visualize a “final” placement of a prosthetic component with respect to the patient tissue.

During the surgery, an elongated pin may be inserted into the surface of the patient's bone, at a predetermined trajectory and location, to act as a passive landmark or active guiding structure in carrying out the preoperatively planned implantation. This “guide pin” may remain as a portion of the implanted prosthetic joint or may be removed before the surgery is concluded. This type of pin-guided installation is common in any joint replacement procedure—indeed, in any type of surgical procedure in which a surgeon-placed fixed landmark is desirable.

In addition, and again in any type of surgical procedure, modern minimally invasive surgical techniques may dictate that only a small portion of the bone or other tissue surface being operated upon is visible to the surgeon. Depending upon the patient's particular anatomy, the surgeon may not be able to precisely determine the location of the exposed area relative to the remaining, obscured portions of the bone through mere visual observation. Again, a guide pin may be temporarily or permanently placed into the exposed bone surface to help orient the surgeon and thereby enhance the accuracy and efficiency of the surgical procedure.

A carefully placed guide pin or other landmark, regardless of the reason provided, will reduce the need for intraoperative imaging in most surgical procedures and should result in decreased operative time and increased positional accuracy, all of which are desirable in striving toward a positive patient outcome.

SUMMARY OF THE INVENTION

In an embodiment of the present invention, an apparatus for aiding visualization of a prosthetic implant and concurrently landmarking a patient tissue is described. A center post has proximal and distal post ends longitudinally separated by a post body. The post body defines a post axis coaxially therewith. An implant emulator embodies a reference feature of a prosthetic implant. The implant emulator is carried on an outer surface of the center post at a predetermined longitudinal spacing from the distal post end. A guiding device is removably attached to the implant emulator. The guiding device includes an attachment structure attached to the implant emulator. A spacing arm is connected to the attachment structure and extends laterally outward from the post axis. A landmark guiding structure is connected to the spacing arm, spaced apart from the center post, and embodies at least one of a location and a trajectory for placement of a landmark.

In an embodiment of the present invention, an apparatus for trialing a portion of an acetabular cup and concurrently placing at least one landmark at an acetabular surgical site is described. A center post has proximal and distal post ends longitudinally separated by a post body. The post body defines a post axis coaxially therewith. A cup emulator represents only a rim portion of an acetabular cup. The cup emulator is carried on an outer surface of the center post at a predetermined longitudinal spacing from the distal post end. The cup emulator is coaxial with the post axis. A pin guide is removably attached to the cup emulator. The pin guide includes an attachment structure attached to the cup emulator. A spacing arm is connected to the attachment structure and extends laterally outward from the post axis. A pin guiding bore is connected to the spacing arm, spaced apart from the center post, and embodies at least one of a location and a trajectory for placement of a landmark with respect to the center post and the cup emulator.

In an embodiment of the present invention, a method of aiding visualization of a prosthetic implant and concurrently landmarking the surgical site is provided. A device is provided, the device comprising a center post having proximal and distal post ends longitudinally separated by a post body. The post body defines a post axis coaxially therewith. An implant emulator embodies a reference feature of a prosthetic implant. The implant emulator is carried on an outer surface of the center post at a predetermined longitudinal spacing from the distal post end. A guiding device is removably attached to the implant emulator. The guiding device includes an attachment structure attached to the implant emulator. A spacing arm is connected to the attachment structure and extends laterally outward from the post axis. A landmark guiding structure is connected to the spacing arm, spaced apart from the center post, and embodies at least one of a location and a trajectory for placement of a landmark. The distal post end is placed in contact with a patient tissue at the surgical site. A position of the implant emulator with respect to the patient tissue is adjusted. The implant emulator is placed in a desired visualization position with respect to the patient tissue. With the implant emulator maintained in the desired visualization position, a landmark is placed into at least one of a desired landmark location and a desired landmark trajectory with respect to the patient tissue with the aid of at least one of the post lumen and the landmark guiding structure.

DESCRIPTION OF EMBODIMENTS

In accordance with the present invention,FIG. 1depicts an apparatus100for aiding visualization of a prosthetic implant and concurrently landmarking a patient tissue. The apparatus100includes a center post102having proximal and distal post ends104and106, respectively, longitudinally separated by a post body108. The post body108defines a post axis110coaxially therewith. Optionally, the distal post end106may include at least one tissue-engaging feature112, such as the teeth or spikes shown in the Figures, to help prevent the distal post end from sliding along a patient tissue. The post body108may include a post lumen114extending longitudinally therethrough between the proximal and distal post ends104and106, coaxially with the post axis110.

As shown inFIG. 1, a tubular housing116may at least partially laterally surround the post body108. The housing116may be provided for any reason, including protection and/or manipulability of the of the center post102. For example, when the housing116is used to help a user manipulate the center post102, a grip118and/or trigger post120may be provided to assist the user with holding the center post102in a pistol-type gripping posture.

Optionally, a key122may be provided on the center post102, such as at the proximal post end104as shown inFIG. 1. When present, the key122may be used to rotationally manipulate the center post102, indicate a rotational orientation of the center post, provide a “stop” function to limit another structure's longitudinal motion with respect to the apparatus100, or for any other reason.

An implant emulator124, depicted inFIG. 1, may be provided to the apparatus100to embody a reference feature of a prosthetic implant. The term “emulator” is used herein to indicate a structure used with the apparatus100which imitates at least a portion of another “model” structure which is not directly used with the apparatus concurrently with the emulator. The term “reference feature” is used herein to indicate a dimension, physical configuration, or other feature of interest of the model structure. For example, the physical structure of the depicted implant emulator124imitates or represents (but does not necessarily exactly duplicate) a reference feature that is a rim of an acetabular cup implant. The substantially circular implant emulator124shown emulates a footprint, silhouette, and/or significant dimension of the acetabular cup implant to help the user envision how that reference feature (here, the implant rim) will interact and/or relate to the patient tissue. The term “significant dimension” is used herein to indicate some physical property or measurement of a structure that is of particular interest to a user of the apparatus100. For example, a maximum diameter and/or maximum depth of an acetabular cup implant could each be a significant dimension to the user during the same or different phases of the implantation surgery. As another example, a center of rotation and/or implant length may be a significant dimension for a femoral or humeral implant.

The patient tissue is shown and described herein as an acetabulum, but the patient tissue could be any desired types such as, but not limited to, hip joints, shoulder joints, knee joints, ankle joints, phalangeal joints, metatarsal joints, spinal structures, long bones, soft tissue, or any other suitable use environment for the present invention. Likewise, the prosthetic implant is described herein as an acetabular cup, but could be any permanently, semi-permanently, and/or temporarily installed non-native structure used to supplement and/or supplant the function of any desired type of native or previously altered patient tissue.

The emulation function of the implant emulator124may be assisted for some visualization use environments of the present invention by a direct correlation between the shape of the implant emulator and the reference feature of the model structure. However, it is contemplated that, even in those particular visualization use environments, the size of the implant emulator124may be scaled differently from the size of the reference feature of the model structure. For example, a specific implant emulator124might represent a rim of an acetabular cup by having a substantial correlation in shape with that cup rim, but the implant emulator could be scaled down from the actual size of the cup rim (e.g., 90% scale) so that the implant emulator124could be used by a surgeon to visualize a final installed position of the cup rim even if the acetabulum is still in a “native state” before any planned or anticipated intraoperative reaming procedure has taken place. In some embodiments, however, at least a portion of the implant emulator124could be substantially similar in size and/or shape to at least a corresponding portion of the implant being emulated, as desired for a particular use environment of the present invention.

The implant emulator124is carried on an outer surface of the center post102and is at a predetermined longitudinal spacing from the distal post end106. For example, and as shown inFIG. 1, the implant emulator124could be a relatively planar construct extending substantially laterally from the post axis110at a distance “A” from the distal post end106. Optionally, and especially in situations when the implant emulator124has some rotational symmetry in the lateral plane, the implant emulator could be coaxial with the post axis110so that the implant emulator is “centered around” the post axis. However, when the implant emulator124is not substantially planar, any desired feature of the implant emulator can be used as a reference point for the longitudinal spacing.

It is contemplated that the combination of a significant dimension of the implant emulator124and the predetermined longitudinal spacing (“A”, inFIG. 1) could correspond directly to a significant dimension and a longitudinal measurement of an available prosthetic implant. The term “significant dimension” is used herein to indicate a one-, two-, or three-dimensional size, shape, or other physical property of the prosthetic implant that is of interest to the user of the apparatus100, especially when that “significant dimension” contributes to the user's being able to visualize, with the aid of the apparatus, what the prosthetic implant would look like when placed in a predetermined relationship with the patient tissue. For example, if the prosthetic implant is an acetabular cup, the significant dimension of the implant emulator124could be an outer diameter corresponding to the cup rim, and the predetermined longitudinal spacing could correspond to a depth of the cup (i.e., a longitudinal distance, or radius, between the rim and a point on the substantially-hemispherical cup body which is at a maximum longitudinal spacing from the rim). In this manner, the approximate outer dimensions of the prosthetic implant can be represented by the shape of the implant emulator124and the position of the implant emulator along the center post102.

In some use environments, it may be desirable for the implant emulator124to be selectively longitudinally movable with respect to the center post102. For example, if the combination of the shape of the implant emulator124and the position of the implant emulator along the center post102are used to represent or refer to the diameter and depth, respectively, of a specific acetabular cup, the user may wish to adjust the apparatus100to represent a different acetabular cup having a different depth and/or diameter. In the depicted apparatus100, the implant emulator124is removably connected to the center post102via a coupling mechanism226, shown inFIG. 2.

More specifically, and as is especially apparent inFIGS. 2 and 3, the implant emulator124shown includes a rim ring228representing a reference feature that is a rim of an acetabular cup. An emulator crossbar230may span the rim ring228, optionally across a full diameter thereof, though it is contemplated that the emulator crossbar could instead span a chord of the rim ring for visualization offset from the center post102. As shown inFIG. 2, the housing116includes a coupling mechanism226which allows entry thereinto of the emulator crossbar230via a coupler channel232, then the implant emulator124can be rotated a short distance clockwise (in the orientation ofFIG. 2) about the post axis110until the emulator crossbar230passes under a coupler overhang234that prevents longitudinal motion of the implant emulator124. InFIG. 2, only one lateral side of the coupling mechanism226is visible, with the other lateral side of the coupling mechanism being blocked from view in this Figure by the center post102.

Optionally, one or more coupler posts236, which could be automatically (e.g., spring-biased) or manually (e.g., via a manipulable collar) retractable into a lower surface of the coupler channel232, could become located in the coupler channel to substantially block rotation of the “connected” emulator crossbar230back into the coupler channel until the user wishes to remove the implant emulator124from the remaining structure(s) of the apparatus100. While one example coupling mechanism226is shown and described herein, one of ordinary skill in the art will be able to provide a permanent or removable coupling scheme to connect a chosen implant emulator124to a center post102in a desired manner.

In the embodiment shown in the Figures, the coupling mechanism226is carried on the housing116. Since the center post102is longitudinally movable with respect to the housing116, this commutation property means that the coupling mechanism226is also longitudinally movable with respect to the center post102. Accordingly, the predetermined longitudinal distance “A” between the distal post end106and the implant emulator124can be changed through manipulation of the housing116to move the coupling mechanism226(holding the implant emulator124) along the center post102.

Optionally, a feature of the apparatus100may be configured to place the implant emulator124at a desired longitudinal spacing along the center post102and/or maintain the implant simulator in that desired spacing. As is visible inFIG. 1, a spring biased pivot member138can be operated in a “wedge” type manner to prevent or allow movement of the housing116with respect to the center post102, but one of ordinary skill in the art can readily provide the apparatus100with a suitable feature for creation and/or maintenance of the longitudinal spacing of the implant emulator124with respect to the distal post end106.

With reference toFIG. 3, a plurality of implant emulators124a,124b,124c, each differing in at least one significant dimension from one another, may be provided. For example, the plurality of implant emulators124a,124b,124cmay have substantially the same physical configuration but differ in scale from each other, such as those shown inFIG. 3which each represent a different “cup size” (rim diameter as the significant dimension) acetabular cup implant. It is also contemplated that an adjustable implant emulator (not shown) could be used to represent a plurality of different implants when suitably adjusted.

More specifically, when a plurality of implant emulators124are provided, a first implant emulator (124a, for example) can be initially connected to the center post102via the coupling mechanism226, then the coupling mechanism is manipulated to release the first implant emulator124aand removably connect a second implant emulator (124b, for example) to the center post102in place of the first implant emulator124a. Accordingly, a user can, through sequential use of multiple implant emulators124a,124b,124cwith the apparatus100, perform a “trialing” procedure to sequentially visualize the reference features (here, the rims) of different sizes of acetabular cups in a particular patient tissue environment with the aid of the apparatus100.

Similarly, the coupling mechanism226can be moved longitudinally along the center post102to simulate or reflect a depth (longitudinal measurement) of a particular implant (here, an acetabular cup). For example, the leftmost implant emulator124aofFIG. 3has a diameter corresponding to a reference feature of a smaller acetabular cup than the larger-diameter rightmost implant emulator124cin that Figure. Generally, a smaller-diameter acetabular cup will be shallower than a larger-diameter acetabular cup, so when the leftmost implant emulator124ais being used with the apparatus100, the longitudinal distance between that implant emulator and the distal post end106will normally be smaller than a corresponding longitudinal distance for the rightmost implant emulator124c, to assist the user with accurately visualizing the longitudinal component of the implant being emulated. Optionally, the position of the implant emulator124with respect to the center post102may be at least partially established and/or indicated through the use of a graduated scale140to aid the user in accurately and/or reproducibly longitudinally locating the implant emulator124with respect to the distal post end106.

Again with reference toFIG. 1, a guiding device142may be removably attached to any suitable structure of the apparatus100, such as the implant emulator124. The guiding device142includes an attachment structure144attached to the implant emulator124or another structure of the apparatus100. A spacing arm146is connected to the attachment structure144and extends laterally outward from the post axis110. A landmark guiding structure148is connected to the spacing arm146, is spaced apart from the center post102, and embodies at least one of a location and a trajectory for placement of a landmark in association with a patient tissue. The guiding device142is shown in magnified solo view inFIG. 4, where details of the attachment structure144can be seen. In the depicted attachment structure144, at least one attachment pin450can be configured for placement in a predetermined arrangement with respect to a corresponding pin cavity (352inFIG. 3) of any implant emulator124. Optionally, there is an interference/“friction” fit between the attachment pin450and the pin cavity352which resists removal of the guiding device142from the implant emulator124, though one of ordinary skill in the art can readily provide attachment between the guiding device142and any other structure of the apparatus100as desired for a particular use environment of the present invention.

While a guiding device142could be integrally formed as a unitary, one-piece construct with a particular implant emulator124for some use environments of the present invention, it is contemplated that, for most use environments of the present invention, the user will desire to have interchangeable guiding devices142. That is, a plurality of guiding devices142, each differing from the others in at least one significant dimension (e.g., length or angle of spacing arm146; configuration, length, or angle of landmark guiding structure148; or any other desired difference) could be provided for sequential (or simultaneous, in some instances) use with the apparatus100. One of ordinary skill in the art could then select the guiding device(s)142having the desired significant dimensions or other physical properties for the use environment at hand. Optionally, a first guiding device142could be selectively replaceable on the implant emulator124(or other structure of the apparatus100) by a second guiding device142having a different significant dimension or other physical property.

As a matter of terminology, a two-dimensional landmark will be described herein as being any pen/pencil mark, bovie burn, pinprick, or other mark which indicates a location, but substantially not a trajectory, of a selected portion of the surface in a user-perceptible form—either via the user's own senses or with the assistance of a perception aid such as, but not limited to, a non-visible light spectrum illuminator. A three-dimensional landmark will be described herein as being any guide pin, Kirschner wire, guidewire, drill bit, or other item which substantially indicates both a location of a selected portion of the surface and a trajectory at which that location is penetrated by the three-dimensional landmark, again in any suitable user-perceptible form. Both two- and three-dimensional landmarks will be referenced collectively herein as “landmarks” and used without discrimination, except where the dimensionality is implicitly or explicitly indicated.

The apparatus100of the Figures may be used to dictate at least one of a desired location and a desired trajectory for association of a landmark with an underlying surface, which will be described herein as a patient tissue surface, optionally while concurrently facilitating visualization by the user of at least one physical feature of an implant to be installed at/near the patient tissue surface, without requiring the use of the implant directly at/near the patient tissue surface for the visualization process.

The desired location and/or desired trajectory for the landmark(s) may be preselected in any desired manner. For example, hand calculations and/or a software program may be used to output a desired location and/or trajectory in any suitable format for physical embodiment in the apparatus100, such as, but not limited to, the specification of predetermined desired positions for each guiding device142to be placed into to embody the desired location and/or trajectory. These predetermined guiding device142positions could, for example, be based upon preoperative images of the patient tissue acquired in any suitable manner.

One example format for such predetermined guiding device142positions could be a group of numerical specifications representing the guiding device to be chosen for use with the apparatus100(e.g., through indicating a desired lateral offset related to a particular spacing arm146length). Optionally, one or more graduated scales (such as that shown at140′ inFIG. 3) could be used to assist with placement of the guiding device142with respect to the patient tissue—in the depicted embodiment, for example, the scaled implant emulator124ccould be placed into a “set” position rotationally about the center post102with the aid of the graduated scale140′. It is also contemplated that some sort of setting stand or setting jig (not shown) may be used to interact with and help set the guiding device142or other apparatus100structures into predetermined positions/orientations to assist with a landmarking process in a desired manner.

To provide another aspect of the landmarking process, the guiding device142can embody a trajectory through use of a passageway extending therethrough, such as the pin guiding bore554shown inFIG. 5. An appropriately sized guide pin or other elongate landmark structure (e.g., a drill bit, marking pen/pencil, bovie knife, or the like) can be inserted through the pin guiding bore554with the guiding device142held in a desired orientation with respect to the patient tissue so that the landmark encounters the patient tissue at a predetermined trajectory. For example, in the embodiment shown in the Figures, the attachment structure144, spacing arm146, landmark guiding structure148, or any other suitable structure of the apparatus100can be configured to hold the pin guiding bore554at a known orientation with respect to the center post102or some other structure of the apparatus. In the depicted embodiment, the guiding device142holds the pin guiding bore554substantially parallel to, and laterally offset from, the post axis110. It is contemplated, though, that a suitable static or adjustable guiding device could be provided by one of ordinary skill in the art to assist with guiding a landmark into any desired trajectory for a particular use environment.

Regardless of how the apparatus100achieves a desired configuration (e.g., through choice and longitudinal positioning of the implant emulator124and/or guiding device142), the relative positioning of the apparatus with predetermined portions of the patient tissue surface will result in an orientation of the guiding device and/or implant emulator with respect to the patient tissue which dictates at least one of the desired location and the desired trajectory for association of the landmark with the patient tissue and/or aids visualization of the prosthetic implant with respect to the patient tissue. These functions will now be further described with reference toFIGS. 6-9.

It is presumed that, inFIGS. 6-9, the apparatus100has been already adjusted into a desired physical configuration for the surgical task being performed. For example, a suitably configured implant emulator124has been chosen and attached to the center post102via the coupling mechanism226, and the longitudinal position of the implant emulator (e.g., the distance “A” inFIG. 1) has already been set. This physical configuration may have been assisted through the use of one or more graduated scales140,140′, which in turn may have been used to transfer intra- or pre-operatively selected settings to the apparatus100. One suitable preoperative planning method is described in copending U.S. patent application Ser. No. 13/282,550, filed 27 Oct. 2011 and titled “System of Preoperative Planning and Provision of Patient-Specific Surgical Aids”, the entire contents of which are incorporated herein by reference. An implant emulator124having a particular size and shape can also be selected for use with the apparatus100via intra- or pre-operative planning methods. The guiding device142has been omitted fromFIGS. 6-7for clarity, but could also be selected for, and/or positioned with respect to, the apparatus through the use of one or more graduated scales140,140′ and/or intra- or pre-operative planning methods.

InFIG. 6, the apparatus100has been placed in close proximity with a patient tissue656(represented here as a pelvis model, for clarity). The distal post end106has been placed adjacent to, and optionally in contact with, an acetabulum658of the patient tissue656. For example, the user can rest the distal post end106in an approximate center of the concave acetabulum658“cup”. The tissue-engaging feature112can assist with maintaining the distal post end106in the established contacting relationship as desired by the user by engaging the patient tissue656.

The position of the apparatus100is then manipulated by the user in order to adjust a position of the implant emulator124with respect to the acetabulum658until the implant emulator achieves a desired visualization position with respect to the patient tissue656. For example, in the sequence ofFIGS. 6-7, the patient tissue656is in substantially the same position in both Figures, but the apparatus100has been precessed or rotated about the distal post end106—which remains in substantially the same intersection point with respect to the acetabulum658inFIGS. 6 and 7. During adjustment of the position of the apparatus100, the implant emulator124may be adjusted within a concave feature (e.g., the acetabulum658) in a ball-and-socket type manner. It is also contemplated that the apparatus100could stay substantially in the same angular relationship to the acetabulum658, while the apparatus is being rotated (in place) about the post axis110to reflect a substantially rotational (but not precessive or translational) change to the orientation of the implant emulator124with respect to the patient tissue656.

The precession or other movement of the apparatus100with respect to the patient tissue656moves the implant emulator124into a position, as shown inFIG. 7, which aids the user in visualizing how a prosthetic acetabular cup implant corresponding to that particular depicted implant emulator will fit into the acetabulum658during a later stage of the surgical procedure. Optionally, the user can replace the in-use implant emulator124with one having a different size and/or shape (e.g., chosen from a “library” of implant emulators) in response to the visualization—for example, the user could decide that the initial implant emulator would be too small for that particular patient tissue656configuration. The apparatus100can then be repositioned as desired to aid the user in visualizing the replacement implant emulator124with respect to the patient tissue656. Visualization of any suitable implant emulator124with respect to the patient tissue656may aid the user in selecting one of a plurality of available implants (here, acetabular cups) based substantially upon that visual comparison of a position of the implant emulator and/or the distal post end106with respect to the patient's acetabulum658. In other words, once the user is satisfied with the position of the implant emulator124with respect to the patient tissue656, the implant emulator can be correlated with a chosen one of the plurality of available implants. As an example, the user could consult a size marking noted on the particular visualized implant emulator124to choose an implant having a corresponding (though not necessarily identical) significant dimension, such as an acetabular cup rim diameter. The user could also or instead refer to the longitudinal distance “A” between the distal post end106and the implant emulator124to choose an implant having a corresponding (though not necessarily identical) significant dimension, such as an acetabular cup depth.

The apparatus100can be useful to a surgeon for its visualization properties alone. However, as shown inFIGS. 8-9, the apparatus100can also or instead be used to help landmark the patient tissue656using a two- or three-dimensional landmark. More specifically, the guiding device142could be connected to the implant emulator124or another structure of the apparatus100before and/or during the surgical procedure, to achieve the configuration shown inFIG. 8. The particular guiding device142used for a specific patient tissue656could have been chosen from a library of available guiding devices. The apparatus100is then manipulated if desired (including a pure rotation about the post axis110) until the guiding device142embodies or “projects” a predetermined location and/or trajectory for placement of a landmark with respect to the patient tissue656. For example, a desired landmark location could be on a certain area of an acetabular rim, and a desired landmark trajectory could be substantially parallel to, and laterally offset from, the post axis110with the apparatus100maintained in a desired implant visualization orientation with respect to the acetabulum658.

Once the guiding device142has achieved the desired landmark location and landmark trajectory, in any suitable manner, the guiding device can be used to guide the landmark into that landmark location and landmark trajectory. As shown inFIG. 9, a guide pin960has been inserted into a desired landmark location (represented by the “X” at962) of the patient tissue656, with the desired landmark trajectory964being imparted to the guide pin960during guiding of the guide pin through the pin guiding bore554. Instead of, or in addition to, insertion of the guide pin960as a three-dimensional landmark, a marking device or other landmarking aid could be deployed through similar use of the apparatus100to provide a two-dimensional landmark (not shown), having no landmark trajectory, at the landmark location962. As another alternative, a drill bit (not shown) could be directed through the pin guiding bore554to penetrate into the patient tissue656at a desired landmark location and landmark trajectory, and then removed, leaving behind an aperture in the patient tissue embodying that landmark location and landmark trajectory.

Any suitable numbers and configurations of guiding devices142could be used with the apparatus100for sequential and/or concurrent landmarking tasks as desired by a user. The apparatus100, or portions thereof, could be moved after an earlier landmarking task is completed, in order to permit another, later landmarking task using the same guiding device142as was used in the earlier landmarking task.

It is also contemplated that structures of the apparatus100other than the guiding device142could be used for a primary and/or secondary landmarking task of the apparatus. For example, when the center post102includes a post lumen114, the post lumen could be configured to allow passage of at least a portion of a landmark therethrough and thus the post lumen can function as a guiding device. Stated differently, the post lumen114could act as a guiding bore for a guide pin, drill bit, marking device, or other landmarking aid therethrough in addition to, or instead of, guiding of a landmark by the laterally located guiding device142.

As an example, a drill bit could be inserted into the post lumen114at the proximal post end104and could be guided by the center post102to create a guide hole or other aperture in the patient tissue656longitudinally adjoining the distal post end106. This guide hole could be helpful, for instance, when the implant or another surgical instrument “seats” into a hole in the acetabulum658during a later surgical task. The length of the center post102, a key122, or any other structure could be used as a mechanical stop to limit a depth of insertion of the drill bit into the patient tissue656. A graduated scale140could also or instead be used to inform the user of the depth of insertion of the drill bit into the patient tissue656without necessarily interfering with that insertion.

FIG. 10depicts an optional configuration of the apparatus100ofFIG. 1, in which at least one aperture1066(three shown) is provided in the implant emulator124or another structure of the apparatus100. Each aperture1066may be configured to receive an indicator rod1068which communicates spatial information to the user and/or embodies a “setting” of the apparatus100to assist the user with placing the apparatus100into a desired position for at least one of a visualization task and a landmarking task. Each indicator rod1068may be movably held within a corresponding aperture1066with a predetermined length of the rod extending from the implant emulator124toward the patient tissue656. For example, there could be a friction/interference fit between the indicator rods1068and the apertures1066, a set screw could be used to hold the rods in place, or any other retaining scheme could be provided by one of ordinary skill in the art. It is contemplated that a plurality of apertures1066could be provided to the apparatus100, with only a subset of those apertures receiving indicator rods1068for a particular surgical use of the apparatus.

The predetermined length(s) of the indicator rod(s)1068may be provided, for example, by a preoperative planning system/software which directs the user to select certain lengths of rods from a library and/or to insert rods to a certain “depth” (e.g., guided by a graduated scale marked along the rod) in the apertures1066. When the apparatus100is oriented respective to the patient tissue656such that each indicator rod1068comes into a predetermined relationship with the patient tissue656(e.g., lightly contacting a surface of the acetabulum658), the user then becomes aware that a desired orientation of the apparatus with respect to the patient tissue has been achieved. This awareness could arise via, for example, a simple visual and/or tactile observation, but it is also contemplated that some mechanical, electrical, and/or other non-human means could be used to indicate the positional achievement. For example, a light could come on when contact between all indicator rods1068and the patient tissue656causes an electrical circuit to be completed. This may be particularly helpful if surgical exposure obstructs a user's ability to directly visualize some portion of the patient tissue656.

Instead of, or in addition to, the depicted indicator rods1068and apertures1066, it is contemplated that any desired arrangement of orienting structures could be provided to the apparatus100by one of ordinary skill in the art to assist the user with bringing the apparatus into a desired position with respect to the patient tissue656by contacting portions of the patient tissue other than those to be landmarked. However, it is also contemplated that the orienting structures (e.g., the indicator rods1068and/or apertures1066) may be used to assist with at least one of a landmarking and/or visualizing task directly, as well.

Once the implant emulator124has been used for a visualization task and/or one or more structures of the apparatus100(e.g., the guiding device124and/or a post lumen114) have been used to assist with a landmarking task, the apparatus100can be removed from the patient tissue656and the surgical tasks can proceed apace, optionally using the apparatus-placed guide pin960as an ongoing physical landmark or reference point. The removed apparatus100, or portions thereof, may be disposed of when configured for one-time use or may be sterilized for reuse.

The above description presumes that the apparatus100, or components thereof, are provided, adjusted, and/or otherwise configured responsive to outputs from preoperative software (e.g., when a graduated scale140value is provided) and/or the knowledge/skill of the user (e.g., when an orientation and/or position is “eyeballed” or chosen by the user in real-time with reference to the patient tissue656). However, it is contemplated that one or more of the manipulable structures of the apparatus100may be configured by the user with the assistance of a physical model (not shown) of the native tissue, such as those disclosed in copending U.S. patent application Ser. No. 13/463,075, filed 3 May 2012 and titled “System of Preoperative Planning and Provision of Patient-Specific Surgical Aids”, the entire contents of which are incorporated herein by reference. For example, a user could manipulate the apparatus100into a desired position with respect to a physical model before or during the surgical procedure and then configure one or more indicator rods1068, with the assistance of that physical model, to help transfer the desired position of the apparatus to the patient tissue656corresponding to that physical model.

While aspects of the present invention have been particularly shown and described with reference to the preferred embodiment above, it will be understood by those of ordinary skill in the art that various additional embodiments may be contemplated without departing from the spirit and scope of the present invention. For example, the specific methods described above for using the described apparatus100are merely illustrative; one of ordinary skill in the art could readily determine any number or type of components, sequences of steps, or other means/options for guiding a landmark in a manner substantially similar to those shown and described herein. Any of the described structures and components could be integrally formed as a single piece or made up of separate sub-components, with either of these formations involving any suitable stock or bespoke components and/or any suitable material or combinations of materials. Though certain components described herein are shown as having specific geometric shapes, all structures of the present invention may have any suitable shapes, sizes, configurations, relative relationships, cross-sectional areas, or any other physical characteristics as desirable for a particular application of the present invention. Any structures or features described with reference to one embodiment or configuration of the present invention could be provided, singly or in combination with other structures or features, to any other embodiment or configuration, as it would be impractical to describe each of the embodiments and configurations discussed herein as having all of the options discussed with respect to all of the other embodiments and configurations. The implant emulator124could be provided to, and located longitudinally upon, the center post102in any suitable manner, including as a one-piece unitary construct which does not allow for a change of the longitudinal spacing between the implant emulator and the distal post end106. While a one-dimensional (along a line) “landmark” is nonsensical for most use environments of the present invention, such a one-dimensional landmark could be provided for an appropriate use environment similarly to the two- (location only) and three- (location and trajectory) dimensional landmarks discussed herein. At least a portion of the apparatus100could be patient specific (e.g., a patient-specific guiding device124) for use with remaining stock/generic structures of the apparatus. The guiding device142could be provided to the center post102and/or the implant emulator124in any suitable manner, including as a one-piece unitary construct which does not allow for a change of position of the guiding device with respect to one or more other structures of the apparatus100. The apparatus100could be used with any type of landmark, e.g., two- or three-dimensional, and temporary, semi-permanent, or permanent. The apparatus100could be at least partially disposable or intended for one-time use, possibly by including a sacrifice feature (not shown) rendering the instrument unusable after an initial use—this may be particularly helpful in a medical use environment if the apparatus is not intended for repeat sterilization and reuse. A device or method incorporating any of these features should be understood to fall under the scope of the present invention as determined based upon the claims below and any equivalents thereof.