Apparatus and method for dictating at least one of a desired location and a desired trajectory for association of a landmark with a patient tissue

An apparatus for transferring location and/or trajectory information from a reference surface to a patient tissue surface for guiding placement of a landmark includes a landmark guiding structure. At least two locating feet are provided, each being laterally spaced from, and indirectly connected to, the landmark guiding structure. A holdaway structure is connected to each locating foot and to the landmark guiding structure. The landmark guiding structure is placed in desired location and/or a desired trajectory with respect to the reference surface. Each locating foot is adjusted into guiding contact with a particular portion of the reference surface. Each locating foot is maintained in the guiding contact position, and the apparatus is placed with each locating foot in guiding contact with a particular portion of the patient tissue surface. A method of transferring location and/or trajectory information from a reference surface to a patient tissue surface is also disclosed.

TECHNICAL FIELD

The present invention relates to an apparatus and method for dictating at least one of a desired location and a desired trajectory for association of a landmark with a patient tissue and, more particularly, to an apparatus and method for transferring at least one of location and trajectory information from a reference surface to a patient tissue surface for guiding placement of a landmark.

BACKGROUND OF THE INVENTION

In the installation of a prosthetic shoulder joint into a patient's body, a glenoid component is implanted into the glenoid vault of the patient's scapula. An obverse surface of the glenoid component is configured for articulating contact with a humeral component carried by the patient's humerus. A reverse surface of the glenoid component is secured to the bone surface of the glenoid vault.

Because the shoulder prosthesis is normally provided to correct a congenital or acquired defect of the native shoulder joint, the glenoid vault often exhibits a pathologic, nonstandard anatomic configuration. A surgeon must compensate for such pathologic glenoid vault anatomy when implanting the glenoid component in striving to achieve a solid anchoring of the glenoid component into the glenoid vault. Detailed preoperative planning, using two- or three-dimensional internal images of the shoulder joint, often assists the surgeon in compensating for the patient's anatomical limitations. 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 transferring at least one of location and trajectory information from a reference surface to a patient tissue surface for guiding placement of a landmark is described. The reference surface substantially replicates three-dimensionally at least a portion of the patient tissue surface. A landmark guiding structure is provided. At least two locating feet are provided. Each locating foot is laterally spaced from, and indirectly connected to, the landmark guiding structure. A holdaway structure is connected to each locating foot. Each holdaway structure is adjustably connected to the landmark guiding structure to indirectly and adjustably attach the locating foot to the landmark guiding structure in a spaced-apart relationship therewith. A manipulation handle is connected to the landmark guiding structure. The landmark guiding structure is placed in at least one of a desired location and a desired trajectory with respect to the reference surface. Each locating foot is adjusted relative to the landmark guiding structure, via adjustment of the holdaway structure, into guiding contact with a particular portion of the reference surface. Each locating foot is maintained in the guiding contact position, the apparatus is removed from the reference surface, and the apparatus is placed with each locating foot in guiding contact with a particular portion of the patient tissue surface corresponding to a particular portion of the reference surface such that at least one of the desired location and desired trajectory of the landmark guiding structure at the reference surface is replicated by the landmark guiding structure at the patient tissue surface.

In an embodiment of the present invention, a method of transferring at least one of location and trajectory information from a reference surface to a patient tissue surface is described. The reference surface substantially replicates at least a portion of the patient tissue surface. A landmark guiding structure is provided. At least two locating feet are provided, each locating foot being laterally spaced from, and indirectly connected to, the landmark guiding structure. A holdaway structure is connected to each locating foot. Each holdaway structure is adjustably connected to the landmark guiding structure to indirectly and adjustably attach the locating foot to the landmark guiding structure in a spaced-apart relationship therewith. A manipulation handle connected to the landmark guiding structure is provided. The landmark guiding structure is placed in at least one of a desired location and a desired trajectory with respect to the reference surface. Each locating foot is adjusted relative to the landmark guiding structure, via adjustment of the holdaway structure, into guiding contact with a particular portion of the reference surface. Each locating foot is maintained in the guiding contact position. The apparatus is removed from the surface. The apparatus is placed with each locating foot in guiding contact with a particular portion of the patient tissue surface corresponding to a particular portion of the reference surface such that at least one of the desired location and desired trajectory of the landmark guiding structure at the reference surface is replicated by the landmark guiding structure at the patient tissue surface.

In an embodiment of the present invention, an adjustable instrument for dictating at least one of a desired location and a desired trajectory for association of a landmark with a patient tissue is described. An elongate landmark guiding structure has longitudinally spaced proximal and distal guiding ends separated by a guiding shaft. At least two holdaway structures are adjustably connected to the landmark guiding structure for longitudinal motion relative to the landmark guiding structure. At least two locating feet are provided, each locating foot being laterally spaced from the landmark guiding structure. Each locating foot is directly connected to a holdaway structure and, via the holdaway structure, is indirectly connected to the landmark guiding structure. Each holdaway structure is adjustable to place the locating foot associated therewith into a predetermined locating foot position such that, when the locating feet have all achieved the predetermined locating foot positions, contact between each of the locating feet and corresponding predetermined portions of the patient tissue results in an orientation of the landmark guiding structure 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.

DESCRIPTION OF EMBODIMENTS

In accordance with the present invention,FIG. 1depicts an adjustable instrument100for dictating at least one of a desired location and a desired trajectory for association of a landmark with a patient tissue. The instrument100includes an elongate landmark guiding structure102having longitudinally spaced proximal and distal guiding ends104and106, respectively, separated by a guiding shaft108. The longitudinal direction is shown inFIG. 1by longitudinal arrow110, and a lateral direction is described herein as being within a plane perpendicular to the longitudinal direction.

As can be seen inFIG. 1, a guiding throughbore112extends longitudinally through the landmark guiding structure102. Here, the throughbore112is a simple core or lumen running through the center of the landmark guiding structure102, but it is also contemplated that the throughbore may be laterally offset from a center of the landmark guiding structure102, may be an open groove or other laterally accessible feature of the guiding structure, or may have any other suitable structure for interacting with a landmark in a specific application of the present invention.

At least two holdaway structures114(three shown inFIG. 1) are adjustably connected to the landmark guiding structure102and configured for longitudinal motion relative to the landmark guiding structure. For a particular application of the present invention, holdaway structure(s)114having any number, configuration, arrangement, symmetry (or asymmetry), or any other qualities may be provided and can be readily configured by one of ordinary skill in the art for a particular application of the present invention. In the embodiment ofFIG. 1, the holdaway structures114are each connected to the landmark guiding structure102via an interlocking (tongue and groove) arrangement with a groove116on the guiding shaft108. In other words, at least a portion of each holdaway structure114is shown inFIG. 1as riding movably within a corresponding groove116to allow the holdaway structures114to be moved longitudinally toward and away from the distal guiding end106of the landmark guiding structure102. There may be fewer or more grooves116than holdaway structures114for a particular application of the present invention, as desired, with some grooves optionally having more than one holdaway structure, and other grooves optionally having no holdaway structures, associated therewith.

At least two locating feet118(three shown inFIG. 1) are laterally spaced from the landmark guiding structure102. Each locating foot118is laterally spaced from the landmark guiding structure102. Each locating foot118is directly connected to a holdaway structure114and is, via the holdaway structure, indirectly connected to the landmark guiding structure102. The connection between a particular holdaway structure114, an associated locating foot118, and the landmark guiding structure102may be adjustable to allow the holdaway structure to provide or facilitate relative longitudinal motion between locating foot and the landmark guiding structure. As with the holdaway structure(s)114, there may be locating feet118having any number, configuration, arrangement, symmetry (or asymmetry), or any other qualities, and one of ordinary skill in the art can readily provide a desired set of locating feet118for a particular application of the present invention. There may be none, one, or more than one locating foot/feet118provided to a single holdaway structure114. The locating feet118may have any configuration as desired (e.g., including rough “gripping” portions, tapered points, or any other structures), and the locating feet118associated with a single instrument100need not be identical or even similar in any physical property. Optionally, and as shown inFIG. 2, at least four locating feet118may be laterally (though not necessarily symmetrically or evenly) spaced from each other about the guiding shaft108. Each locating foot118may be, during certain portions of the operation of the instrument100(as will be described below), substantially longitudinally adjacent to, and laterally spaced from, the distal guiding end106of the landmark guiding structure102for a particular application of the present invention.

A manipulation handle120of any suitable type may be connected to the landmark guiding structure102for grasping by a user. The manipulation handle120shown inFIG. 1is similar to a screwdriver handle, but it is contemplated that any other type of handle (not shown) such as, but not limited to, a t-handle, orthopedic or “pistol grip” handle, or the like, may be provided for a particular application of the present invention.

A locking mechanism122may be provided to the instrument100to selectively maintain at least one locating foot118in a desired position (as will be described below) during use—generally involving manipulation and/or relocation—of the instrument100. As shown inFIGS. 1 and 3, the locking mechanism122takes the form of a locking collar, which can be turned to tighten simultaneously or concurrently about the guiding shaft108and the holdaway structures114, once the holdaway structures have been adjusted as desired, to prevent relative motion between the locating feet118and the landmark guiding structure102.

In contrast,FIGS. 4 and 5depict an instrument100′ which is substantially similar to that ofFIGS. 1-3, other than the configuration of the locking mechanism122. InFIGS. 4 and 5, the locking mechanism122′ takes the form of a plurality of cam-locks, each associated with a different holdaway structure114′. These cam-lock structures are operated in a known manner, in which a lever carried by the holdaway structure114′ is lifted or pushed to either squeeze a cam laterally inward against the guiding shaft108′ or to pull the holdaway structure114′ laterally outward and into a frictional fit with the groove116′. Regardless of the type of operation, the cam-locks shown inFIGS. 4 and 5can be used to individually prevent relative motion between the holdaway structures114′ and the guiding shaft108′, once the holdaway structures have been adjusted as desired, to prevent relative motion between the locating feet118′ and the landmark guiding structure102′. Accordingly, unlike the instrument100shown inFIGS. 1-3, the holdaway structures114′ of the instrument100′ ofFIGS. 4 and 5can be individually adjusted and tightened. Alternately, though not shown, a unitary cam-lock could also or instead be provided to simultaneously or concurrently actuate the locking mechanism122′ of the instrument100′ ofFIGS. 4 and 5. One of ordinary skill in the art could readily provide a suitable reversible or permanent locking mechanism122having any desired format, configuration, or structure for a particular application of the present invention.

Returning to the instrument100as shown inFIGS. 1-3, the interface between the guiding shaft108, the holdaway structures114, and the locating feet118is shown in detail inFIG. 2. At least one originally provided locating foot118(optionally along with an associated holdaway structure114) can be removable from the instrument100and thereby be interchangeable with a separately provided auxiliary locating foot (not shown) having some physical property that differs from the locating foot being replaced. For example, in the instance where a locating foot118has a squared-off profile, the user may wish to instead use an auxiliary locating foot having a pointed or sharpened profile. As another example, and as shown inFIG. 2, the locating foot118and/or the holdaway structure114may include a bridge region224which serves to space the locating foot118laterally from the guiding shaft108, and the user may wish to instead use a locating foot and/or holdaway structure having a longer or shorter bridge structure, to space the auxiliary locating foot a different lateral distance than was the originally provided locating foot being replaced.

It should be noted that the bridge region224of the embodiments shown in the Figures is not definitively associated with either the locating foot118or the holdaway structure114, since these two structures are shown as being integrally formed as one piece. It is contemplated, however, that—particularly when separated locating feet118and holdaway structures114are provided—any provided bridge regions224may, contrary to the depicted arrangement, be clearly associated with one or the other of the locating foot or holdaway structure and separate from the other one. Whether via a bridge region224or another physical construct, however, the holdaway structure114will be characterized in the below discussion as the portion of the instrument100which provides the described lateral spacing between at least one locating foot118and the landmark guiding structure102, for clarity.

As previously alluded to, and as shown inFIGS. 1 and 3, at least one locating foot118may be connected to a holdaway structure114having an elongate attachment portion126configured for mating connection with a corresponding receiver portion on the guiding shaft108of the landmark guiding structure102. For example, the attachment portion126shown in the Figures acts as the “tongue” in the tongue-and-groove sliding connection with the groove116serving as the receiving portion. In this arrangement, the attachment portion126is longitudinally slidable with respect to the groove116to selectively adjust a longitudinal position of an associated locating foot118with respect to the landmark guiding structure102. Through use of an auxiliary locating foot or a laterally-adjustable locating foot (not shown), the locating foot can be selectively laterally adjusted with respect to the landmark guiding structure102.

Accordingly, through the structures shown and described herein and/or equivalents thereto, the effective or “working” position of each locating foot118may be adjusted in several degrees of freedom with respect to the guiding shaft108, as desired for a particular use application of the present invention. The positions of the locating feet118are adjustable in order to place the guiding shaft108into a desired orientation with respect to an underlying surface in order to provide a guiding function to a two- or three-dimensional landmark to be associated with that underlying surface, as will now be discussed with reference toFIGS. 6-7.

As a matter of terminology, a two-dimensional landmark will be described herein as being any pen 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 instrument100of 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. The use environment will be described herein as being a medical use environment, wherein a device is penetrating into a relatively stationary patient tissue, but could be any suitable environment in which a device moves in at least one dimension toward or away from a relatively stationary substrate.

The patient tissue is shown and described herein as a glenoid vault, 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.

The desired location and/or desired trajectory 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 instrument100, such as, but not limited to, the specification of predetermined desired positions for each locating foot118to be placed into to embody the desired location and/or trajectory. These predetermined locating foot118positions could, for example, be based upon preoperative images of the patient tissue acquired in any suitable manner.

One example format for such predetermined locating foot118positions could be a group of numerical specifications representing the lateral and longitudinal distances that the user should place the locating feet118into. The user may optionally replace one or more existing holdaway structures114or locating feet118on the instrument100with separately provided auxiliary holdaway structures and locating feet. The holdaway structure(s)114, whether original or auxiliary/replacement, may be longitudinally adjusted with respect to the guiding shaft108to help place each locating foot118into its predetermined locating foot position. Optionally, one or more scales (not shown) could be used to assist with placement of the locating feet118into the predetermined locating foot position. For example, a graduated numerical scale could be marked out longitudinally along the exterior of the guiding shaft108and each holdaway structure114could slide longitudinally until reaching an indicated location along the numerical scale. It is also contemplated that some sort of setting stand or setting jig (not shown) may be used to interact with and help guide the locating feet118into their predetermined locating foot positions.

Regardless of how the locating feet118achieve the predetermined locating foot positions in the just-described process, once the locating feet are in those positions, contact between the preset locating feet and corresponding predetermined portions of the patient tissue surface will result in an orientation of the landmark guiding structure 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. In other words, once the locating feet have achieve the predetermined locating foot positions (however that occurs) and are placed into contact with predetermined portions of the patient tissue surface, the locating feet will hold the guiding shaft108in an orientation with respect to the patient tissue surface that reflects at least one of the desired location and the desired trajectory. A landmark (e.g., a marking pen, guide pin, drill bit, bovie knife, or any other landmarking tool/structure) can then be guided by the guiding shaft108(e.g., by being passed through the throughbore112) and into contact with the patient tissue surface at the desired location and/or trajectory.

Another means of placing the landmark into contact with the patient tissue surface at the desired location and/or desired trajectory uses a reference surface628, as shown inFIG. 6. The reference surface628is at least a portion of a physical model630substantially replicating three-dimensionally at least a portion of the patient tissue surface, and may be generated, for example, from preoperative imaging of the patient tissue surface. The reference surface628shown inFIG. 6is a glenoid surface of a scapula, with only a relevant portion of the scapula being embodied in the depicted three-dimensional physical model630.

The physical model630or other structure embodying a physical reference surface628may be provided in any suitable manner. The term “model” is used herein to indicate a replica or copy of a physical item, at any relative scale and represented in any medium, physical or virtual. The patient tissue model may be a total or partial model of a subject patient tissue, and may be created in any suitable manner. For example, and as presumed in the below description, the patient tissue model may be based upon computer tomography (“CT”) data imported into a computer aided drafting (“CAD”) system. Additionally or alternatively, the native patient tissue model may be based upon digital or analog radiography, magnetic resonance imaging, or any other suitable imaging means. A virtual patient tissue model will generally be displayed for the user to review and manipulate preoperatively, such as through the use of a computer or other graphical workstation interface. A physical model630may be fabricated, optionally based upon the virtual patient tissue model, as a tangible (e.g., material and palpable) representation of the physical structures at the operative site inside the patient's body by any suitable method such as, but not limited to, selective laser sintering (“SLS”), fused deposition modeling (“FDM”), stereolithography (“SLA”), laminated object manufacturing (“LOM”), electron beam melting (“EBM”), 3-dimensional printing (“3DP”), contour milling from a suitable material, computer numeric control (“CNC”), other rapid prototyping methods, or any other desired manufacturing process.

Once the physical model630has been manufactured and prepared for use (e.g., mechanically or chemically cleaned, cured, sterilized, or the like) using any suitable process(es), it is available for use before and/or during surgical procedures to help set up the instrument100for the guiding function(s) as described herein.

As shown inFIG. 6, the desired location632and/or desired trajectory634for placement of a landmark may be embodied in the physical model630in any suitable manner. The landmark will be described with respect toFIGS. 6-7Gas a three-dimensional landmark, such as a guide pin, having both a desired location and a desired trajectory. For example, the user could “eyeball” or hand-place a landmark into association at a desired location632and desired trajectory634with respect to the reference surface628. As another example, the physical model630could be manufactured with a protrusion extending out from the reference surface628at the desired location632and desired trajectory634. As yet another example, the physical model630could be manufactured with an aperture (not shown) extending into the material of the physical model at the desired location632and desired trajectory634, and the user could optionally temporarily or permanently place a guide pin or other elongate structure into the aperture to show the desired trajectory634extending outward from the reference surface628. Regardless of how the reference surface628is configured, it is contemplated that the desired location632and desired trajectory634will be associated with the reference surface628in a manner to facilitate transfer of the relevant location and trajectory information to the instrument100, and using the instrument, to the patient tissue surface during the surgical procedure.FIGS. 7A-7Gillustrate one example of a sequence of operation for such transfer.

InFIG. 7A, the desired location632and desired trajectory634have been already associated with the reference surface628, using any of the aforementioned techniques or any other suitable means, in such a way as to be transferrable to the instrument100. The landmark guiding structure102is shown as being near the reference surface628, but has not yet been positioned to reflect the desired location632or desired trajectory634.

Turning toFIG. 7B, the landmark guiding structure102has been repositioned with respect to the reference surface628so that the distal guiding end106is located substantially at the desired location632and the throughbore112is substantially collinear with the desired trajectory634. (ThoughFIGS. 7A-7Gare two-dimensional schematic cross-sectional views of the described process, one of ordinary skill in the art should be able to mentally extrapolate the three-dimensional interactions based on the depicted portions of the process.) Accordingly, the instrument100is being held inFIG. 7Bsuch that the throughbore112of the landmark guiding structure102reflects or embodies the desired trajectory634, and the distal guiding end106reflects or embodies the desired location632, for transfer from the reference surface628to the patient tissue surface.

InFIG. 7C, one or more locating feet118have been selected and connected to the landmark guiding structure102via the holdaway structure114(optionally with a bridge region224). The locating feet118are shown as having simple rectilinear shapes, but may have any desired feature(s) (e.g., anchoring spikes, traction pads) or shape(s), and may be configured to be located any desired lateral distance from the landmark guiding structure102, as suitable for a particular application of the present invention. As depicted inFIG. 7C, the locating feet118are longitudinally spaced from the reference surface628.

The locating feet118are adjusted longitudinally relative to the landmark guiding structure102by manipulation of the corresponding holdaway structure(s)114into the position shown inFIG. 7D. Though only two locating feet118are shown inFIGS. 7A-7G, one of ordinary skill in the art will understand that a suitable number of locating feet118should be used to provide reasonable certainty that the desired location632and desired trajectory634are being embodied by the instrument100for transfer from the reference surface628with a desired degree of accuracy. The locating feet118should each be adjusted with respect to the landmark guiding structure102into “guiding contact” with a particular portion of the reference surface628.

Stated differently, and as shown inFIGS. 7E-7F, when all of the locating feet118have achieved their respective guiding contact positions and are being maintained in those positions (e.g., through action of a locking mechanism122), the instrument100will embody the desired location632and desired trajectory634in such a way that the three-dimensional positioning of the locating feet118in their guiding contact positions can then be placed (e.g., by lowering in the longitudinal direction110) into corresponding positions upon the patient tissue surface736to transfer the desired location and desired trajectory from the reference surface628to the patient tissue surface. A reasonably knowledgeable user should be able to approximately replicate placement of the locating feet118upon the patient tissue surface736by visually “eyeballing” the placement. However, when an appropriate number of locating feet118are used, which have previously been set into the guiding contact positions through use of the reference surface628, the landmark guiding structure102will likely “rock” or otherwise shift with respect to the patient tissue surface736upon initial contact. This action is similar to that of a table sitting on an uneven substrate and will remain until the instrument100has been moved slightly to more exactly place each locating foot118into guiding contact with a particular portion of the patient tissue surface736corresponding to the particular portion of the reference surface628which was used to “set” the instrument into the desired location632and the desired trajectory634. Once a close correlation has been achieved with the positioning of the instrument100on the patient tissue surface736reflecting the positioning of the instrument on the reference surface628, the user will likely feel that the instrument100seems secure and steady upon the patient tissue surface and can have reasonable confidence that the desired location632and desired trajectory634are being adequately accurately transferred or replicated from the reference surface to the patient tissue surface. This confidence arises, in part, from the unique topography of a patient tissue surface736, which is reflected in the reference surface628and was used to place a suitable number of locating feet118into guiding contact positions.

For example, and as shown inFIG. 7F, the instrument100has been placed and adjusted to that the locating feet118squarely and firmly contact the patient tissue surface736. Between the user's own “dead reckoning” and the positive indication provided by the close fit between the locating feet118and the patient tissue surface736, the user can be fairly certain that the distal guiding end106is located at the desired location632and that a landmark inserted through the throughbore112will contact the patient tissue surface736at the desired location632, as set with the assistance of the reference surface628.

As shown inFIG. 7G, a landmark738has, indeed, been inserted through the throughbore112and penetrates into the patient tissue surface736at the desired trajectory634. Optionally, the landmark738may have been originally positioned in the reference surface628, as previously mentioned, and carried from the reference surface to the patient tissue surface736by the instrument100.

When the landmark is a two-dimensional landmark (not shown), the trajectory may not be important, as long as the desired location632is transferred from the reference surface628to the patient tissue surface736. However, one of ordinary skill in the art will be able to readily configure an instrument100having an appropriate number of locating feet118with suitable type, configuration, orientation, and other physical properties for a particular application of the present invention.

When the desired location632and/or desired trajectory634have been transferred from the reference surface628to the patient tissue surface736, the instrument can be removed from the patient tissue surface736. The landmark738remains in place and can be used for any desired purpose. The sequence ofFIGS. 7A-7Gmay be repeated as desired to place a plurality of landmarks738in the same patient or in different patients, with intermediate sterilizations and reconfigurations of the instrument100occurring as appropriate.

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 instrument100are 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 instrument100could be used with any type of landmark, temporary or permanent. The instrument100could 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 distance indicator 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.