Patent Publication Number: US-11644053-B2

Title: Instrument coupling interfaces and related methods

Description:
FIELD 
     Instrument coupling interfaces and related methods are disclosed herein, e.g., for coupling a surgical instrument to a navigation array or other component. 
     BACKGROUND 
     Navigation or tracking of instruments during surgical procedures has become increasingly popular. Surgical navigation can help surgeons avoid delicate neural or vascular structures when moving instruments within a patient. In spinal surgery, for example, a surgical navigation system can be used during disc removal, bone drilling, implant insertion, e.g., screw and/or cage insertion, and other steps of the surgery. Use of surgical navigation systems can also reduce the amount of X-ray exposure to which the patient and operating room staff are exposed since procedures that do not utilize surgical navigation systems typically perform more steps using fluoroscopy or other X-ray based imaging. 
     A typical navigation system includes an array of markers attached to a surgical instrument, an imaging system that captures images of the surgical field, and a controller that detects the markers in the captured images and tracks movement of the markers within the surgical field. The controller associates a reference frame of the imaging system with a reference frame of the patient and, informed by a known geometry of the array and the instrument, determines how the instrument is being moved relative to the patient. Based on that determination, the controller provides navigation feedback to the surgeon. The arrays can have different types or geometries, which can vary based on the navigation system, type of surgery, and/or location within the patient that is being tracked. 
     The precision of the navigation system strongly depends on the design of the tracked instrument and, in particular, the rigidity of the interface between the navigation array and remainder of the instrument. Welding or integrally-forming the navigation array to the instrument can result in relatively high precision being achieved. Such solutions, however, can be inconvenient, as the capability to decouple the array from the instrument or to couple the array to other instruments is absent. Further, arrangements having the navigation array integrally-formed with the instrument can require separate instruments for standard and navigation use, thereby raising costs for equipment. 
     A number of solutions have been developed to allow the navigation array to be interchangeably attached with one or more instruments. Such interchangeable connections can have a significant influence on precision of the instrument navigation. Interchangeable connections can include interfaces that have dovetail or v-groove geometries to connect the navigation array to the instrument. These solutions can be geometrically overdetermined, i.e., utilizing a larger number of contacting surfaces than is necessary to constrain movement of the two components. Due to manufacturing tolerances and other variations that prevent perfect mating between the many contacting surfaces in such overdetermined configurations, it can be difficult to consistently and repeatably attach the array and the instrument in a desired relative position and orientation. Other variations can be introduced into the interchangeable connection as well, for example, mechanical deformation of one or more connection interfaces that can result from interactions between components during use, etc. In the case of an overdetermined geometry, the larger number of contacting surfaces than necessary can compound the risk and effect of mechanical deformation. As a result, these solutions can allow for situations in which the navigation array can move in one or more degrees of freedom, which can undesirably reduce the precision of the navigation. 
     Accordingly, there is a need for improved devices, systems, and methods to securely couple a first object and a second object in a secure, precise, and repeatable relative position and orientation. 
     SUMMARY 
     Coupling assemblies are disclosed herein that can provide for a known and repeatable orientation of a first object and a second object with minimal relative movement therebetween. A coupling can include a first coupling component having a cylindrical surface with a screw and a pin extending therefrom and a second coupling component having a prismatic surface, a first opening configured to receive the screw, and a second opening configured to receive the pin. In a secured or mated configuration of the first coupling component and the second coupling component, the screw can threadably engage with the first opening and secure the cylindrical surface against the prismatic surface such that two lines of contact are formed therebetween. The pin can be received within the second opening of the second coupling component and can be configured to limit any relative movement between the first coupling component and the second coupling component that is not blocked by engagement of the screw. 
     In one aspect, a coupling for attaching a first object and a second object can include a first coupling component associated with the first object and a second coupling component associated with the second object. The first coupling component can have a cylindrical surface with a screw and a pin extending therefrom. The second coupling component can have a prismatic surface, a first opening configured to receive the screw, and a second opening configured to receive the pin. The first component and the second component can be adapted to mate with one another such that relative motion between the first coupling component and the second coupling component is restricted in all six degrees of freedom. 
     The devices and methods described herein can have a number of additional features and/or variations, all of which are within the scope of the present disclosure. In some embodiments, for example, the pin can include a proximal end, a distal end, and a reduced diameter portion located proximal to the distal end of the pin. The distal end of the pin can be a torus shape. The first coupling component and the second coupling component can be configured such that, when the first coupling component and the second coupling component are mated, at least a portion of the reduced diameter portion of the pin is disposed within the second opening of the second coupling component. In some such embodiments, the pin can be configured to limit relative movement between the first coupling component and the second coupling component along a longitudinal axis of the cylindrical surface. 
     The first coupling component and the second coupling component can be configured such that a clearance exists between the pin and an inner surface of the second opening when the pin of the first component is received within the second opening of the second component. In such embodiments, the distal end of the pin can contact the inner surface of the second opening to restrict movement of the second coupling component relative to the first coupling component. 
     In some embodiments, the first coupling component and the second coupling component can be adapted to mate with one another such that a first line of contact and a second line of contact can extend between the first coupling component and the second coupling component. The first line of contact and the second line of contact can extend between the cylindrical surface of the first coupling component and the prismatic surface of the second coupling component. Particularly, in some embodiments, the first line of contact and the second line of contact can be located on opposite sides of a midline of the cylindrical surface. The first line of contact and the second line of contact can extend along substantially an entire length of the cylindrical surface. 
     The prismatic surface of the second coupling component can include a first end and a second end with a first sidewall and a second sidewall extending therebetween. The first sidewall and the second sidewall can extend at an angle relative to a backstop of the prismatic surface. The first line of contact can extend along the first sidewall of the prismatic surface and the second line of contact can extend along the second sidewall of the prismatic surface. 
     The screw of the first coupling component can include a post having a proximal end, a distal end, and a threaded portion located proximal to the distal end of the screw. The first coupling component can further include a back surface opposite the cylindrical surface, where the back surface is a flat planar surface. In some embodiments, the first coupling component can include a through-hole configured to receive the screw such that the screw extends through the first coupling component perpendicular to the back side of the first coupling component. In some embodiments, the first object can be a surgical instrument and the second object can be a navigation array. 
     In another aspect, a method of coupling a first object and a second object is provided that can include aligning a first coupling component associated with the first object and a second coupling component associated with the second object. The first coupling component can have a cylindrical surface with a screw and a pin extending therefrom, and the second coupling component can have a prismatic surface, a first opening, and a second opening. The method can include advancing the first coupling component with respect to the second coupling component such that the cylindrical surface is seated against the prismatic surface, the screw is received within the first opening, and the pin is received within the second opening. The method can further include securing the first coupling component and the second coupling component in a mated configuration such that relative movement between the first coupling component and the second coupling component is restricted in six degrees of freedom. 
     Further, the method can include limiting relative movement between the first component and the second component by contact between the pin and an inner surface of the second opening. Securing the first component and the second component can further include driving the screw within the first opening. In some embodiments, driving the screw can prevent relative movement between the first component and the second component in at least five degrees of freedom. The method can further the pin restricting relative movement between the first component and the second component after driving the screw to secure the first component and the second component. In some such embodiments, the pin can contact an inner surface of the second opening to restrict relative movement between the first component and the second component. The restricted relative movement between the first component and the second component can be along a longitudinal axis of the cylindrical surface. 
     Driving the screw to mate the first component and the second component can include rotating the screw in a first direction such that a threaded portion of the screw fully engages with a threaded inner surface of the first opening. In some such embodiments, an unthreaded distal end of the screw can extend beyond a back surface of the second component when the screw fully engages with the threaded inner surface of the first opening. 
     In some embodiments driving the screw to mate the first component and the second component can include rotating a handle of a screw assembly in a first direction until a planar surface of the handle abuts a back surface of the first component. 
     The first component and the second can contact one another along a first line of contact and a second line of contact that extend between the cylindrical surface of the first component and the prismatic surface of the second component. In some such embodiments, the first line of contact and the second line of contact can be located on opposite sides of a midline of the cylindrical surface. 
     Any of the features or variations described above can be applied to any particular aspect or embodiment of the present disclosure in a number of different combinations. The absence of explicit recitation of any particular combination is due solely to the avoidance of repetition in this summary. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is an exploded perspective view of a prior art coupling; 
         FIG.  2    is another view of the prior art coupling of  FIG.  1   ; 
         FIG.  3    shows one embodiment of a navigated instrument system including one embodiment of a coupling according to the present disclosure; 
         FIG.  4    is a perspective view of a first coupling component of the system shown in  FIG.  3   ; 
         FIG.  5    is a perspective view of a screw assembly of the first coupling component shown in  FIG.  4   ; 
         FIG.  6    is a perspective view of a second coupling component of the system shown in  FIG.  3   ; 
         FIG.  7    is a perspective view of a cross-section of the second coupling component of  FIG.  6    taken along the line A-A in  FIG.  6   ; 
         FIG.  7 A  is another view of the cross-section of the second coupling component of  FIG.  6    taken along the line A-A in  FIG.  6   ; 
         FIG.  8    is a perspective view of the first coupling component and the second coupling component of the system shown in  FIG.  3    in a mated configuration; 
         FIG.  9    is a schematic illustration of mechanical principles of a coupling according to the present disclosure; 
         FIG.  10    is a cross-sectional view of the coupling of  FIG.  8    taken along the line B-B in  FIG.  8   ; 
         FIG.  11    is another cross-sectional view of the coupling of  FIG.  8    taken along the line C-C in  FIG.  8   ; 
         FIG.  12    is a cross-sectional view of the coupling of the system shown in  FIG.  3    showing the first coupling component and the second coupling component in an ideal-alignment in a mated configuration; 
         FIG.  13    is a cross-sectional view of the first coupling component and the second coupling component of the system shown in  FIG.  3    in a non-parallel alignment in a mated configuration; 
         FIG.  13 A  is an enlarged view of the coupling shown in  FIG.  13   ; 
         FIG.  14    is a perspective view of the coupling of the system of  FIG.  3    with the first coupling component seated within the second coupling component; 
         FIG.  15    is a perspective view of the coupling of the system of  FIG.  3    with the first coupling component mated to the second coupling component; 
         FIG.  16    is a perspective front view of the navigation array associated with the second coupling component of the system of  FIG.  3   ; 
         FIG.  17    is a perspective back view of the navigation array of  FIG.  16   ; 
         FIG.  18    is a perspective view of the instrument adapter associated with the first coupling component of the system of  FIG.  3   ; 
         FIG.  19    is a side view of the instrument adapter of  FIG.  18   ; 
         FIG.  20    is an alternative perspective view of the instrument adapter of  FIG.  18   ; 
         FIG.  21    is a front view of the instrument adapter of  FIG.  18   ; 
         FIG.  22    is a perspective view of the system of  FIG.  3    with the first object associated with the first coupling component aligned with the second object associated with the second coupling component; 
         FIG.  23    is an alternative perspective view of the system of  FIG.  3    with the first object associated with the first coupling component aligned with the second object associated with the second coupling component; 
         FIG.  24    is a perspective view of the system of  FIG.  3    with the first coupling component associated with the first object seated within the second coupling component associated with the second object; 
         FIG.  25    is a side view of the system of  FIG.  3    with the first coupling component associated with the first object seated within the second coupling component associated with the second object; 
         FIG.  26    is a perspective view of the system of  FIG.  3    with the first coupling component associated with the first object secured to the second coupling component associated with the second object; 
         FIG.  27    is an alternative perspective view of the system of  FIG.  3    with the first coupling component associated with the first object secured to the second coupling component associated with the second object; 
         FIG.  28    is a side view of the system of  FIG.  3    with the first coupling component associated with the first object secured to the second coupling component associated with the second object; 
         FIG.  29    is a front view of the system of  FIG.  3    with the first coupling component associated with the first object secured to the second coupling component associated with the second object; 
         FIG.  30    is a top view of the system of  FIG.  3    with the first coupling component associated with the first object secured to the second coupling component associated with the second object; 
         FIG.  31    shows an alternative embodiment of a coupling according to the present disclosure; 
         FIG.  32    shows the coupling of  FIG.  31    in a mated configuration; and 
         FIG.  33    shows the coupling of  FIG.  31    in a mated configuration with a first object associated with a first coupling component and a second object associated with a second coupling component. 
     
    
    
     DETAILED DESCRIPTION 
     Instrument coupling interfaces and related methods are disclosed herein, e.g., for coupling a surgical instrument to a navigation array or other component. An embodiment of a coupling of the present disclosure can include a first coupling component associated with a first object, such as a surgical instrument or a surgical instrument adapter, and a second coupling component associated with a second object, such as a navigation array. The first coupling component can be configured to mate with the second coupling component such that the first object and the second object are disposed in a known position and orientation relative to one another with minimal play or ability for relative movement. The coupling can be fully defined, i.e., can restrict movement in all six degrees of freedom, without having an overdetermined geometry that utilizes a greater number of contacting surfaces than is necessary to achieve desired movement restriction. Accordingly, the coupling can minimize or eliminate navigational inaccuracy associated with system tolerances of the objects and/or components in a navigated instrument system. 
     Prior Art Coupling 
       FIGS.  1  and  2    illustrate a prior art coupling  100  for attaching two objects. The coupling  100  includes a first component  102 A associated with a first object A and a second component  102 B associated with a second object B. The first component  102 A includes four V-shaped protrusions  104  that are received within four corresponding V-shaped recesses  106  of the second component  102 B. The illustrated coupling  100  has an overdetermined geometry in that there are more contact points or contact surfaces than necessary to constrain the objects A, B in the desired degrees of freedom (i.e., the illustrated coupling  100  includes at least eight possible contact surfaces between the first and second components  102 A,  102 B). The number of protrusions and corresponding recesses may be equal to or greater than three. In such a configuration, it can be the case that not all of the eight contact surfaces may actually be in contact with each other, which can allow some degree of “play” or backlash or relative movement between the first object A and the second object B (e.g., due to a gap  110  therebetween, as shown in  FIG.  2   ). In addition, cone or V-shaped surfaces can be very sensitive to tolerances which can lead to varying gap size when mating components are brought together. By way of further example, variation in geometry between objects or parts that are intended to have identical coupling interfaces may prevent achievement of a repeatable known position and orientation between the two mated objects. This risk is exacerbated by an over-constrained or over-determined coupling that has more points of contact than necessary. Given the constraints of such a coupling, tolerances must be tightly controlled, which can increase manufacturing cost and decrease manufacturing yield, or a certain level of inaccuracy must be accepted. Additionally, interaction between components with many small interfacing features, and/or sharp edges or surfaces, e.g., a plurality of V-shaped protrusions as shown in  FIGS.  1  and  2   , etc., can experience mechanical deformation or wear of one or more of the components in the coupling. Such mechanical deformation or wear can result in imperfect coupling and undesired relative movement between the components. While  FIGS.  1  and  2    illustrate a coupling with V-groove geometry, dovetail and other type connections can also be overdetermined and suffer from the inaccuracies described above. 
     Instrument Coupling Interfaces and Related Methods 
     Certain exemplary embodiments will now be described to provide an overall understanding of the principles of the structure, function, manufacture, and use of the devices, systems, and methods disclosed herein. One or more examples of these embodiments are illustrated in the accompanying drawings. Those skilled in the art will understand that the devices, systems, and methods specifically described herein and illustrated in the accompanying drawings are non-limiting exemplary embodiments. The features illustrated or described in connection with one embodiment may be combined with the features of other embodiments. Such modifications and variations are intended to be included within the scope of the present disclosure. 
     Additionally, to the extent that linear or circular dimensions are used in the description of the disclosed devices and methods, such dimensions are not intended to limit the types of shapes that can be used in conjunction with such devices and methods. A person skilled in the art will recognize that an equivalent to such linear and circular dimensions can be determined for different geometric shapes. Further, in the present disclosure, like-numbered components of the embodiments generally have similar features. Still further, sizes and shapes of the devices, and the components thereof, can depend at least on the anatomy of the subject in which the devices will be used, the size and shape of objects with which the devices will be used, and the methods and procedures in which the devices will be used. 
       FIG.  3    illustrates one embodiment of a navigated instrument system  300  including a coupling  308  that can mate a first object (e.g., an instrument adapter  302 ) to a second object (e.g., a navigation array  304 ). The instrument adapter  302  can be configured to receive an instrument  306  therein. The navigation array  304  and the instrument  306  can be positioned within a field of view of a navigation system  307 . The navigation array  304  can be detected by the navigation system  307 , can communicate with the navigation system  307 , or can be otherwise operably coupled to the navigation system  307  to allow the position and/or orientation of an instrument attached thereto by the coupling  308  (e.g., instrument  306  and/or instrument adapter  302 ) to be registered with and tracked by the navigation system. The coupling  308  can achieve consistent relative positioning of the first object and the second object with more stability than traditional couplings, and can be less prone to error introduced by system tolerances (e.g., manufacturing tolerances when creating the various components of the system). The coupling  308  can couple the navigation array  304  to the instrument adapter  302  and/or the instrument  306  in a known and repeatable position with minimal play or ability for relative movement therebetween. Accordingly, the coupling  308  can improve accuracy and reliability of navigation of the instrument  306  by more effectively coupling the two components into a single rigid construct. 
     The coupling  308  can be configured to provide a toggle-free, well oriented coupling with relative movement between the coupled components restricted in all six degrees of freedom. As shown in greater detail in insert box  3 A, the coupling  308  can include a first coupling component  310  associated with the first object (e.g., the instrument adapter  302 ), and a second coupling component  312  associated with the second object (e.g., the navigation array  304 ). The first coupling component  310  and the second coupling component  312  can be formed integrally with the first object  302  and the second object  304 , respectively. For example, a coupling component associated with a first or second object can be manufactured directly on a surface of the object itself. Alternatively, a first and/or second coupling component can be a separate component that is welded, threaded, glued, or otherwise securely associated with or attached to the first and second object, respectively. 
     The first coupling component  310  can be configured to mate with the second coupling component  312  to couple the first object and the second object with minimal play or ability for relative movement therebetween. The first coupling component  310  and the second coupling component  312  can be secured or mated to one another with relative movement therebetween restricted in all six degrees of freedom. As will be discussed in detail below, the coupling  308  can provide a fully defined connection between the first component  310  and the second component  312  based on a cylindrical surface of the first coupling component  310  that can be seated against a prismatic surface of the second component  312  and further secured by a screw. A pin extending from the first coupling component  310  can add stability to the coupling  308  and can further limit movement between the two components. The coupling  308  can have good durability and can mitigate the risk of mechanical deformation to the coupling components  310 ,  312 , for example, by eliminating contact of sharp surfaces or edges and minimizing interaction between the components during coupling and decoupling. 
     A coordinate system will now be described with reference to the coupling  308 , which will be used throughout this disclosure to aid in the description of the coupling and related methods disclosed herein. A Z-axis  314  can extend along a longitudinal axis of a cylindrical surface of the first component  310 . An X-axis  316  can extend perpendicular to a back surface of the first coupling component  310 . In the illustrated assembly, the X-axis can extend along a longitudinal axis of the instrument adapter  302 . A Y-axis  318  can extend perpendicular to both the X-axis and the Z-axis, and transverse to the first coupling component  310  (i.e., the Y-axis can extend along a width of the first component  310 , as will be described below). The coordinate system is shown in box  350 , which is reproduced throughout the Figures for reference. 
       FIGS.  4 - 7    illustrate in greater detail components of the coupling  308 .  FIG.  4    shows the first coupling component  310  (also referred to herein as the first component). The first coupling component  310  can include a cylindrical surface  404 , a screw  410 , and a pin  412 . The screw  410  and the pin  412  can extend from the cylindrical surface  404 . The cylindrical surface  404  can have a convex profile and can extend along a substantial portion of the first coupling component  310 . 
     In some embodiments, the first coupling component  310  can include a first end portion  406  that is proximal to a proximal end  404   p  of the cylindrical surface  404 , and a second end portion  408  that is distal to a distal end  404   d  of the cylindrical surface  404 . The cylindrical surface  404  can extend a length L 1  between the first end portion  406  and the second end portion  408 . In some embodiments, the length L 1  of the cylindrical surface  404  can extend a substantial portion of a length of the first coupling component  310 . The first end portion  406  and the second end portion  408  can have planar surfaces. In some embodiments, the end portions  406 ,  408  can ease manufacturing of the first component  310 . For example, the first coupling component  310  can have chamfered edges, which can be manufactured more easily from a planar surface (i.e., the planar surface of the first and second end portions  406 ,  408 ) than a curved surface. The end portions  406 ,  408  can correspond to geometry of the second coupling component  312  to help align the first coupling component  310  with the second coupling component  312 . 
     As will be described in detail below, the cylindrical surface  404  can be configured such that two lines of contact can extend between the cylindrical surface  404  and the second coupling component  312  when the first coupling component  310  is secured to the second coupling component  312 . The two lines of contact can each be continuous lines. In some embodiments, each line of contact can extend along the entire length L 1  or substantially the entire length L 1  of the cylindrical surface  404 . For example, when the first component  310  is secured to the second component  312 , a first line of contact  303 A can extend along a left-side of the cylindrical surface  404  (relative to a mid-line ML of the cylindrical surface extending along the Z-axis), when viewed from the perspective of  FIG.  4   . A second line of contact  305 A can extend along a right-side of the cylindrical surface  404  (relative to the mid-line ML of the cylindrical surface), when viewed from the perspective of  FIG.  4   . 
     A screw  410  and a pin  412  can extend from the cylindrical surface  404  of the first coupling component  310 . More particularly, the screw  410  and the pin  412  can extend from the cylindrical surface  404  along the X-axis of the first component  310 . In some embodiments, the screw  410  and the pin  412  can be centered with respect to the mid-line ML of the cylindrical surface  404 . The screw  410  and the pin  412  can be configured to be received within corresponding openings in the second component  312 . In some embodiments, the screw  410  and the pin  412  can extend from a planar surface  416  that can be formed or inlayed in the cylindrical surface  404 . In other embodiments, one or both of the screw  410  and the pin  412  can extend from a convex portion of the cylindrical surface  404 . While the illustrated embodiment shows the screw  410  placed proximally of the pin  412  (i.e., closer to the proximal end  404   p  of the cylindrical surface), alternative configurations are within the scope of this disclosure. For example, in some embodiments, the pin  412  can be placed proximally of the screw  410 . 
     The screw  410  can be part of a screw assembly  414 , with the screw  410  disposed in a through-hole of the first component  310 . As shown in  FIG.  4   , only a distal end of the pin  410  extends through the through-hole opening of the first component  310 . This can indicate that the screw assembly  414  is not yet fully tightened with respect to the first component  310 . By way of comparison, the first component  310  shown in  FIG.  3    illustrates the screw assembly  414  in a tightened configuration with respect to the first component. The pin  412  can be formed integrally with the first component  310 . In other embodiments, the pin  412  can be a separate component that can be welded, threaded, glued, or otherwise associated with or attached to the first component  310  such that the pin  412  extends along the X-axis of the first component. 
       FIG.  5    shows the screw assembly  414  of the first component  310 . The screw assembly  414  can include the screw  410  and a handle  418 . The screw  410  can include a post  420  with a threaded portion  422 . The threaded portion  422  can have threads that correspond to a threaded inner surface of an opening of the second component  312 . In some embodiments, the threaded portion  422  can extend from a proximal end  422   p  to a distal end  422   d . The distal end  422   d  of the threaded portion  422  can be located proximal to a distal end  420   d  of the post  420 . In other words, the distal end  420   d  of the post  420  can be unthreaded and, in some embodiments, can take the form of an unthreaded cylinder. A distal surface  421  of the screw  410  can be a planar surface. The unthreaded distal end  420   d  of the screw  410  can help with alignment and can facilitate assembly of the screw  410  with a corresponding opening in the second component  312  (e.g., the unthreaded distal portion  420   d  can help align the screw prior to the threads interfacing to prevent cross-threading due to misalignment). The screw post  420  can extend from a planar outer surface  424  of the handle  418 . As will be described in detail below, the planar surface  424  can be configured to abut a planar back surface of the first component  310 . In some embodiments, the screw  410  can be formed integrally with the handle  418 . In other embodiments, the screw  410  and the handle  418  can be separate pieces that can be securely attached to one another. For example, an assembly pin  426  can be used to attach the screw  410  to the handle  418 . 
     One or more winged portions  428  can be formed on the handle  418 . The winged portion(s)  428  can facilitate easy and secure gripping of the handle  418 , e.g., for rotation of the screw  410  by a user. One or more openings  430  can be formed in the handle  418 . In some embodiments, an instrument can be inserted through the one or more of the opening(s)  430  and can provide increased torque to aid in the rotation of the handle, i.e., for tightening or releasing of the screw  410 . For example, a rod (not shown) can be inserted through opposing openings  430  to provide a greater lever arm, and thereby increase the torque a user can apply to the handle  418 . 
       FIGS.  6  and  7    illustrate the second coupling component  312  in greater detail.  FIG.  6    shows a perspective view of the second coupling component  312  (also referred to herein as the second component). The second coupling component  312  can have a prismatic surface  502  with a first end  504 , a second end  506 , and opposing first and second sides  508 ,  510  extending therebetween. In some embodiments, a planar surface  512  can form a backstop to the prismatic surface  502 . The planar surface  512  can ease manufacturing of the second component  312  and prismatic surface  502 . 
     The prismatic surface  502  can be configured such that the cylindrical surface  404  of the first component  310  can be received within a recess defined by the prismatic surface  502 . As discussed above, in a secured or mated configuration of the first and second components  310 ,  312 , two lines of contact can extend between the cylindrical surface  404  and the second coupling component  312 . More particularly, two lines of contact can extend between the prismatic surface  502  of the second coupling component  312  and the cylindrical surface  404  of the first coupling component  310 . For example, when the first component  310  is mated with the second component  312 , a first line of contact  303 B can extend along the second side  510  of the prismatic surface  502 , which can correspond to the first line of contact  303 A that can extend along the cylindrical surface  404 . A second line of contact  305 B can extend along the first side  508  of the prismatic surface  502 , which can correspond to the second line of contact  305 A that can extend along the cylindrical surface  404 . In some embodiments, the first line of contact  303 B and the second line of contact  305 B can extend along an entire length or substantially an entire length of the second side  510  and the first side  508 , respectively. The first end  504  and the second end  506  of the second component  312  can be configured to receive the first end portion  406  and the second end portion  408  of the first coupling component  310 , respectively. In some embodiments, the first end  504  and the second end  506  can include chamfered corners that can complement a geometry of the first end portion  406  and the second end portion  408  of the first coupling component  310 . 
     The second component  312  can include a first opening  514  and a second opening  516 . In some embodiments, the first opening  514  and the second opening  516  can be through-holes extending through the second coupling component  312 . The first opening  514  can be configured to receive the screw  410  of the first coupling component  310 . Accordingly, the first opening  514  can have a threaded inner surface  518 . The threads of the threaded inner surface  518  can correspond to threads of the threaded portion  422  of the screw  410 . The second opening  516  can be configured to receive the pin  412  of the first coupling component  310 . In some embodiments, the second opening  516  can have a smooth or unthreaded inner surface  517 . A diameter of the first opening  514  can be greater than a diameter of the second opening  516 , as shown in the illustrated embodiment. In other embodiments, the diameter of the first opening  514  can be equal to or smaller than the diameter of the second opening  516 . The first opening  514  and the second opening  516  can be formed in the second component  312  such that they correspond to the screw  410  and the pin  412  of the first component  310 , respectively. As such, in some embodiments, the first opening  514  and the second opening  516  can have different configurations, positioning, or dimensions than that of the illustrated embodiment to properly correspond to and complement the screw  410  and the pin  412 . 
       FIG.  7    shows a perspective view of a cross-section of the second component  312 , taken along the line A-A of  FIG.  6   . A back surface  520  of the second coupling component  312  can be a planar back surface. In some embodiments, the planar back surface  520  can extend parallel to the back stop  512 .  FIG.  7 A  shows another view of the cross-section of the second component  312 , taken along the line A-A of  FIG.  6   . As can be seen in  FIG.  7 A , the first side  508  and the second side  510  of the prismatic surface  502  can extend at an angle α 2  and α 1 , respectively, relative to the Y-axis of the second component  312  (i.e., relative to an axis that extends perpendicular to a longitudinal axis of the first opening and transverse to a longitudinal axis of the prismatic surface). The angle α 2  of the first side  508  can be the same as the angle α 1  of the second  510 . In some embodiments, however, the angle α 2  of the first side  508  and the angle α 1  of the second side  510  can be different. The angles α 1 , α 2  can be selected such that the prismatic surface  502  can be configured to maintain two lines of contact with the cylindrical surface  404  of the first component  310  when the first component  310  and the second component  312  are mated. In some embodiments, the angles α 1 , α 2  can be selected such that the first line of contact and the second line of contact between the cylindrical surface  404  and the prismatic surface  502  can be as far apart as possible for a stable coupling. By way of non-limiting example, the angles α 1 , α 2  can each be about 30°, about 45°, or about 60°. Other angles α 1 , α 2  of less than about 90° are also possible. In some embodiments, the angles α 1 , α 2  can each be about 30°, which can be easier to manufacture. The angles α 1 , α 2  can each be selected such that an angle of intersection α 3  can be between about 30° and about 120°. 
       FIG.  8    illustrates the coupling  308  in a secured or mated configuration, with the first component  310  coupled to the second component  312 . In the mated configuration, the cylindrical surface  404  of the first coupling component  310  can be secured within the recess formed by the prismatic surface  502  of the second coupling component  312 . The screw  410  of the first component  310  can be threadably engaged with the first opening  514  of the second component  312 , and can bring the first component  310  and the second component  312  into a perfect or parallel alignment. To that end, a planar back surface  432  of the first coupling component  310  and the planar back surface  520  of the second coupling component  312  can be in parallel alignment with one another. Further, in the mated configuration, the pin  412  can be received within the second opening  516  of the second coupling component  312 . As will be described in detail below, the pin  412  can limit relative movement between the first coupling component  310  and the second coupling component  312  that may exist due to, for example, frictional forces and/or tolerance variations when the first component  310  and the second component  312  are brought into alignment by the screw  410 . The pin  412  can also serve to provide additional stability to the coupling  308 . 
       FIG.  9    schematically illustrates the mechanical principles of the coupling  308 . More particularly,  FIG.  9    illustrates the ways in which various degrees of freedom can be locked or restricted by aspects of the coupling  308 . A component having a cylindrical surface  12 , a component having a prismatic surface  14 , a screw  16 , and a pin  18  of  FIG.  9    can represent the first component  310  with the cylindrical surface  404 , the second component  312  with the prismatic surface  502 , the screw  410 , and the pin  412  of the coupling  308 , respectively.  FIG.  9    shows a coordinate system with axes X′, Y′, and Z′, which can be similarly defined with respect to the component having the cylindrical surface  12  as the coordinate system with axes X, Y, and, Z, as described herein with respect to coupling  308 . 
     As illustrated in the box  10 , the cylindrical surface  12  seated within a recess formed by the prismatic surface  14  can limit relative movement along, and rotation about, the X′-axis and the Y′-axis. Translation along and rotation about the Z′-axis, i.e., a longitudinal axis of the cylindrical surface  12 , can remain free. The box  20  schematically illustrates the effect of the screw  16  disposed in a through-hole of the component with the cylindrical surface  12  and threadably engaged with an opening in the component having the prismatic surface  14 . The screw can block relative translation along the X′-axis and the Y′-axis, and relative rotation about all three axes (X′, Y′, and Z′). Furthermore, the screw  16  can serve to at least limit, if not block, relative translation along the Z′-axis. In some instances, however, while relative movement along the Z′-axis can be limited by the screw  16 , there may still be the potential for relative translation along the Z′-axis due to, for example, frictional forces. The pin  18  can extend from the cylindrical surface  12  and be received within an opening the component with the prismatic surface  14 . As shown in the box  30 , the pin  18  received within the opening can limit translation along and rotation about the Y′ and Z′ axes, while translation along and rotation about the X′ axis are free. Accordingly, the coupling  308 , as schematically illustrated in  FIG.  9   , can restrict relative movement in all six degrees of freedom. 
     Turning back to  FIG.  8   , the cylindrical surface  404  can be seated within the recess formed by the counterpart prismatic surface  502  and can limit relative movement along, and rotation about, the X-axis and the Y-axis. As will be described further herein, the screw  410  can threadably mate with the first opening  514  in the second component  312  to block relative movement between the first component  310  and the second component  312  in at least five degrees of freedom. The pin  412  can be received in the second opening  516  of the second component  312  and can further limit relative movement between the first component  310  and the second component  312  such that relative movement between the first component  310  and the second component  312  is blocked in all six degrees of freedom. 
     A line of contact  305  can extend along the Z-axis between the first component  310  and the second component  312 . More particularly, the line of contact  305  can extend between the cylindrical surface  404  of the first coupling component  310  and the prismatic surface  502  of the second coupling component  312 . For example, the line of contact  305  can correspond to the second line of contact  305 A,  305 B illustrated on the first coupling component  310  in  FIG.  4    and the second component  312  in  FIG.  6   , respectively. While not visible in  FIG.  8   , an additional line of contact can extend between the first component  310  and the second component  312  on a side of the coupling  308  opposite that of the line of contact  305  (corresponding, for example, to the first line of contact  303 A,  303 B as indicated in  FIGS.  4  and  6   , respectively). It will be appreciated that the illustrated contact lines (e.g.,  305 ,  305 A,  305 B,  303 ,  303 A,  303 B) are representative of contact between the first coupling component  310  and the second coupling component  312  when mated. As such, an exact placement of a line of contact can be a function of a geometry of the first coupling component  310  and the second coupling component  312 , and, more particularly, can be a function of a geometry of the cylindrical surface  404  of the first coupling component  310  and the prismatic surface  502  of the second coupling component  312 . Accordingly, alternative locations of one or more lines of contact than the locations as illustrated in the figures can be possible and within the scope of the present disclosure. 
     The coupling  308  can include an identification pin  802  that can be used as an indicator to prevent mis-assembly of the coupling  308 . The identification pin  802  can be received within a corresponding opening on the back surface  520  of the second coupling component  312 . The identification pin  802  can serve as a visual identifier of a lower end of the second component  312  to prevent an improper assembly of the second coupling component  312  with the first coupling component  310 . Improper assembly of the coupling  308  could cause the screw  410  to be improperly aligned with the second opening  516  and the pin  412  to be improperly aligned with the first opening  514 . Accordingly, the identification pin  802  can help “mistake-proof” assembly, i.e., prevent inadvertent error or mistake in the assembly of the coupling  308 . 
     Additionally, the identification pin  802  can also serve to identify a particular characteristic of the second object  304  associated with the second coupling component  312 . By way of non-limiting example, the identification pin  802  can be a color-coded pin, with a particular color identifying a particular size of the navigation array  304  (or other second object that can be associated with the second coupling component  312 ). In some embodiments, the entire navigation array  304  can be color-coded (e.g., coated, colored, anodized, etc.) to identify the array or a particular characteristic of the array. In this manner, a user can quickly confirm that an intended and properly sized navigation array  304  is being coupled to the first object (e.g., the instrument adapter  302 ) for a particular application. As can be seen in greater detail in  FIG.  10   , a pin receiving opening  804  can extend from the back surface  520  of the second component  312 . The opening  804  can be a blind hole such that the pin  802  can be received within the second component  312  without interfering with the prismatic surface  502  of the second coupling component  312 . In some embodiments, the identification pin  802  and the opening  804  can have corresponding threads that can engage to secure the identification pin  802  within the opening  804 . 
       FIG.  10    shows a cross-sectional view of the coupling  308  in the perfect or parallel alignment, taken along the line B-B of  FIG.  8   . In the illustrated cross-section, the first component  310  and the second component  312  are shown mated such that the coupling  308  can constrain relative movement between the first component  310  and the second component  312  in all six degrees of freedom with minimal play. The first component  310  and the second component  312  can be brought into parallel alignment by the screw  410  engaged with the first opening  514  of the second component  312 . More particularly, the threaded portion  422  of the screw  410  can be fully threadably engaged with the threaded inner surface  518  of the first opening  514  of the second component  312 . In some embodiments, the first coupling component  310  and the second coupling component  312  can be fully coupled when there is full thread engagement of the threaded portion  422  of the screw  410  with the threaded inner surface  518  of the first opening  514 . In such a configuration, the distal end  420   d  of the screw  410  can extend beyond the back surface  520  of the second component  312 . 
     The screw  410  can extend perpendicular to the planar surface  424  of the handle  418 . The assembly pin  426  can secure the screw  410  within the handle  418  to ensure a perpendicular relationship between the screw  410  and the planar surface  424 . Alternatively, the screw  410  and the handle  418  can be formed in a single-piece, such that the screw assembly  414  is a unitary component. Regardless of manufacture, the screw  410  can extend perpendicularly relative to the planar surface  424  of the handle  418  such that, in the mated configuration, the screw assembly  414  can secure the first component  310  and the second component  312  in parallel alignment to one another. In some embodiments, the handle  418  can be sized for optimal engagement depth with the screw  410 , and, more particularly, with the screw post  420 . In other words, the handle  418  can be sized to maximize contact with the screw post  420  throughout a length of the handle  418 . Optimizing the engagement between the screw post  420  and the handle  418  can reduce error in the orientation of the screw  410  relative to the handle  418 . 
     With the screw  410  engaged with the first opening  514  to bring the first component  310  and the second component  312  into the mated configuration, the planar surface  424  of the handle  418  can align with and abut the planar back surface  432  of the first component  310 . The screw  410  can be disposed in a through-hole  409  of the first component  310 . A central-longitudinal axis of the through-hole  409  can be perpendicular to a planar back surface  432  of the first component  310 . Accordingly, the screw assembly  414  can fix the cylindrical surface  404  of the first component  310  against the prismatic surface  502  of the second component  312 . As shown in  FIG.  10   , engagement of the screw  410  with the first opening  514  can secure the first component  310  and the second component  312  into a parallel alignment with one another. 
     Threaded engagement of the screw  410  with the first opening  514  of the second component  312  can block relative movement between the first component  310  and the second component  312  in at least five degrees of freedom. The screw  410  can block relative translation along and rotation about the X-axis and Y-axis. The threadably engaged screw  410  can also block rotation between the first component  310  and the second component  312  about the Z-axis. Furthermore, the screw  410  can serve to at least limit, if not block, relative translation of the first component  310  and the second component  312  along the Z-axis. In some instances, however, while relative movement along the Z-axis can be limited by the screw  410 , there may still be the potential for relative translation along the Z-axis due to, for example, frictional forces between the first component  310  and the second component  312 . 
     The pin  412  can be received within the second opening  516  of the second coupling component  312 . The pin  412  can be configured to further limit relative movement along the Z-axis, which can leave minimal play between the first coupling component  310  and the second coupling component  312 . More particularly, the pin  412  and the second opening  516  can be configured such that there is only a small clearance between the pin and the inner surface  517  of the second opening  516 . As such, relative movement along the Z-axis between the second component  312  and the first component  310  can be restricted to the amount that the second component  312  can move before the inner surface  517  of the second opening  516  contacts the pin  412 . Similarly, the pin  412  can also serve to restrict relative movement along the Y-axis and rotation about the Y-axis and the Z-axis. 
       FIG.  11    shows a cross-sectional view of the coupling  308  taken along a line C-C of  FIG.  8   . In the illustrated view, the pin  412  can be seen extending perpendicularly from the first component  310 . The pin  412  can be received within the second opening  516  of the second component  312  such that a distal surface  1002  of the pin  412  can be flush with the back surface  520  of the second component  312 . In some embodiments, a distal end  412   d  of the pin  412  can have a torus shape with a planar distal surface  1002 . The torus shape of the distal end  412   d  can allow for easier manufacturing than a distal end of another geometry, such as, for example, a sphere, though in other embodiments different distal end geometries, such as a sphere shape, etc., are possible. A proximal end  412   p  of the pin  412  can be seated within the first component  310  such that the pin  412  extends perpendicular to the back side  432  of the first component  310  (i.e., the pin  412  can extend from the first component  310  along the X-axis thereof). In the illustrated embodiment, the pin  412  can be a separate component that can be welded to the first component  310 . As discussed above, in other embodiments the pin  412  can be threaded, glued, or otherwise securely attached to the first component  310 . Alternatively, the pin  412  can be formed integrally with the first component  310 . 
     The pin  412  can have a reduced diameter portion  1004  that can be proximal to the distal end  412   d  of the pin. The pin  412  can include an undercut from the distal end  412   d  to the reduced diameter portion  1004  such that a diameter of the reduced diameter portion  1004  is less than a diameter of the distal end  412   d  of the pin. Similarly, there can be an undercut from the proximal portion  412   p  of the pin to the reduced diameter portion  1004 . As will be described in detail below, the reduced diameter portion  1004  can provide compensation for tolerance and positioning variations between the first component  310  and the second component  312 , when necessary, and can guarantee that two lines of contact remain between the cylindrical surface  404  and the prismatic surface  502  despite any such variations. The reduced diameter portion  1004  can be formed such that, when the pin  412  is received within the second opening  516 , the reduced diameter  1004  portion longitudinally aligns with a substantial portion of the second opening  516 . More particularly, the reduced diameter portion  1004  can align with a proximal end  516   p  of the second opening  516  and extend longitudinally towards a distal end  516   d  of the second opening. 
       FIG.  11    shows two lines of contact between the first coupling component  310  and the second coupling component  312  in the mated configuration. The coupling  308  can be configured such that, with the first component  310  secured to the second component  312 , contact between the cylindrical surface  404  of the first component  310  and the prismatic surface  502  of the second component  312  occurs only along the first and second lines of contact  303 ,  305 . The first line of contact  303  can extend between the cylindrical surface  404  of the first component  310  and the side wall  510  of the prismatic surface  502  of the second coupling component  312 . The first line of contact  303  can extend along the left side of the cylindrical surface  404 , relative to the midline of the cylinder, when viewed from the perspective of  FIG.  11   . The second line of contact  305  can extend between the cylindrical surface  404  and the side wall  508  of the prismatic surface  502  of the second coupling component  312 . The second line of contact  305  can extend along the right side of the cylindrical surface  404 , relative to the midline of the cylinder, when viewed from the perspective of  FIG.  11   . The lines of contact  303 ,  305  can be spaced from one another, e.g., on opposite sides of the cylindrical surface  404  and the prismatic surface  502 , and can thereby provide increased stability in the coupling  308 . By way of non-limiting example, in the illustrated embodiment the cylindrical surface  404  and the prismatic surface  502  can be configured such that a distance between the first and second lines of contact  303 ,  305  can be about 5 mm to about 12 mm. In some embodiments, the distance between the lines of contact  303 ,  305  can be about 9 mm. In other embodiments, however, different distances can be possible based on the sizes of the components being joined, etc. 
     As discussed above, a location of the lines of contact  303 ,  305  can be a function of the geometry of the first coupling component  310  and the second coupling component  312 . Accordingly, the lines of contact  303 ,  305  can fall in a different location on the cylindrical surface  404  and the prismatic surface  502  than that illustrated in the figures. For example, a cylindrical surface  404  with a smaller radius can result in the first line of contact  303  and the second line of contact  305  being located closer to a midline of the cylindrical surface  404  than those illustrated in  FIG.  11   . Stability of the coupling can suffer if the radius of the cylindrical surface  404  becomes too small, as any toggling or tilting of the second component  312  relative to the first component  310  could result in a drastic or disproportionate movement of the second component  312  along the cylindrical surface  404 . Conversely, a cylindrical surface  404  with a larger radius can result in the first line of contact  303  and the second line of contact  305  being located farther from the midline of the cylindrical surface  404  than those illustrated in  FIG.  11   . If the radius of the cylindrical surface  404  becomes too large, a portion of the cylindrical surface  404  intended to be received within a recess of the prismatic surface  502  can approximate a flat surface, thereby preventing the intended coupling. An angle of the prismatic surface  502  (e.g., the angle α 1 , α 2 , and/or α 3 ) can also affect the location of the first line of contact  303  and the second line of contact  305 . 
     A geometry of a cylindrical surface  404  and/or a prismatic surface  502  can be adjusted based on factors such as, for example, application requirements and/or manufacturing constraints, so long as, in a mated configuration, a first line of contact and a second line of contact extend between the cylindrical surface  404  of the first coupling component  310  and the prismatic surface  502  of the second coupling component  312 . In some embodiments, the cylindrical surface  404  and the prismatic surface  502  can be designed such that the lines of contact  303 ,  305  can be located as far apart as possible while maintaining a stable coupling. There can be a direct relationship between a diameter of the cylindrical surface  404  and a rotational error of the coupling  308  (i.e., rotational error can increase with an increase in the diameter of the cylindrical surface  404 ). As such, a diameter of the cylindrical surface  404  can be optimized in accordance with a design of the prismatic surface  502  to have an acceptable amount of rotational error for a particular usage. Additional factors that can be taken into consideration in determining a geometry of the coupling  308  can include the relationship between the angles of the prismatic surface  502  and a height of the resulting coupling  308 , as well as a length of the lines of contact  303 ,  305  and the stability and manufacturing of the coupling  308 . More particularly, increasing the angle α 1 , α 2  of the prismatic surface  502  can result in an increased height of the coupling  308 . In one embodiment, the angle α 1 , α 2  can be about 30° which can result in a coupling  308  with an appropriate size and weight (e.g., a light weight coupling  308  that can be used for coupling a light weight navigational array to an object). A length of the lines of contact  303 ,  305  can contribute to the stability of the coupling  308 , however, manufacturing the cylindrical surface  404  and/or the prismatic surface  502  may become more difficult as a length of the surface  404 ,  502  increases. 
       FIGS.  12 ,  13 , and  13 A  illustrate how the pin  412  can be configured to compensate for variation in the alignment of the first component  310  and the second component  312  in the coupling  308 . In some instances, the cylindrical surface  404  and the prismatic surface  502  may not be fully or perfectly aligned in the mated configuration, due to, for example, frictional forces between the components and/or tolerance variations. The pin  412  can be configured to account for and limit positional error between the two components, such that the coupling  308  can maintain a stable and reliable connection between the first component  310  and the second component  312 . 
     As will be discussed in detail below, the pin  412  can be configured to account for tolerance-based variations in the alignment of the first component  310  and the second component  312  such that, notwithstanding these variations, two lines of contact between the cylindrical surface  404  and the prismatic surface  502  can be maintained in the coupling  308 . Further, the distal end  412   d  of the pin  412  can provide an additional point of contact between the first component  310  and the second component  312  when the first component  310  and the second component  312  are not in a perfect alignment. The additional point of contact can limit the degree to which the second component  312  can tilt relative to the first component  310 . The reduced diameter portion  1004  of the pin  412  can compensate for tolerance variations (i.e., tilting or other variation from ideal relative positioning) in the alignment of the first component  310  and the second component  312  such that a first line of contact  303  and a second line of contact  305  can be maintained in the coupling  308 . Accordingly, the coupling  308  can provide precise attachment and orientation of a first object (e.g., the instrument adapter  302 ) associated with the first component  310  and a second object (e.g., the navigation array  304 ) associated with the second component  312 . 
       FIG.  12    shows the first component  310  and the second component  312  perfectly aligned in the mated configuration of the coupling  308 . In some embodiments, perfect or ideal alignment can be evidenced from the back surface  432  of the first component  310  extending parallel to the back surface  520  of the second component  312 . To help achieve perfect or parallel alignment between the first and second components  310 ,  312 , it can be beneficial to have extended contact area between the handle  418  and the first component  310 . Such extended contact can provide good leverage for the handle  418  to bring the components  310 ,  312  into parallel alignment. For example, a diameter  1104  of a contact area between the planar surface  424  of the handle  418  and the back surface  432  of the first component  310  can extend across a width the first component  310  (i.e., across the Y-axis of the first component  310 ). In some embodiments, the diameter  1104  can extend across an entire or substantially an entire width of the back surface  432  of the first component  310 . 
     A clearance  1102  can extend between the pin  412  and the inner surface  517  of the second opening  516 . In the ideal parallel alignment, the clearance  1102  can extend between the pin  412  and the inner surface  517  along a full length of the second opening  516  (i.e., from the proximal end  516   p  to the distal end  516   d  of the second opening  516 ). The clearance  1102  can be small between the distal end  412   d  of the pin  412  and the inner surface  517  of the second opening  516  such that the two components can slide past one another but there is negligible play between the components. As will be discussed in detail below, the clearance  1102  can widen along the reduced diameter portion  1004  of the pin  412 . In some embodiments, such as the perfectly aligned configuration of  FIG.  12   , the screw  410  can successfully bring the first component  310  and the second component  312  into parallel alignment and restrict movement in all six degrees of freedom without the pin  412  contacting the second component  312 . 
     In contrast to the coupling illustrated in  FIG.  12   , in some instances, alignment between the first component  310  and the second component  312  can be imperfect after the screw  410  engages with the first opening  514  to secure the first and second components  310 ,  312 .  FIG.  13    shows the coupling  308  in one such instance, with the first component  310  and the second component  312  in a non-parallel alignment due to, for example, friction between the two components and/or tolerance variations. Note that the scale in these figures is exaggerated and the degree of tilting or misalignment between components can be small, e.g., so small that it does not impact the ability of threads formed on the screw  410  and the opening  514  to properly engage. As illustrated, the second component  312  can be tilted relative to the first component  310  such that the back surface  520  of the second component  312  extends at an oblique angle relative to the back surface  432  of the first component  310 . An outline  1202  of a parallel- or perfectly-aligned second component  312  is shown for comparison. An additional point of contact  1204  can occur between the distal end  412   d  of the pin  412  and the second component  312 . Accordingly, a tilting of the second component  312  can be restricted to the point at which the inner surface  517  of the second opening  516  contacts the distal end  412   d  of the pin  412 . The point of contact  1204  can thus constrain the orientation of the second component  312  relative to the first component  310  to a known and predictable configuration, and can provide stability to the coupling  308 . 
     As discussed above, the clearance  1102  can widen between the reduced diameter portion  1004  of the pin  412  and the inner surface  517  of the second opening  516 . The clearance  1102  can allow two lines of contact  303 ,  305  to be maintained between the second component  312  and the first component  310  despite the non-parallel alignment of the components. More particularly, because the reduced diameter portion  1004  of the pin  412  aligns with a substantial portion of the opening  516  in the second component  312 , including the proximal end  516   p  of the second opening  516 , a portion of the sidewall of the second opening  516  can extend into the clearance  1102  in the non-parallel alignment without contacting the pin  412 . Such a configuration can allow the second component  312  to maintain contact with and move along the cylindrical surface  404  of the first component  310 . For example, in the orientation illustrated in  FIG.  13   , the two lines of contact  303 ,  305  can be maintained despite the tilting of the second component  312 . The prismatic surface  502  (i.e., the sidewalls  508 ,  510 ) can translate along and maintain contact with the cylindrical surface  404 . As such, the reduced diameter portion  1004  of the pin  412 , and the resulting clearance  1102 , can add stability to the coupling  308  by allowing for two lines of contact (e.g., lines of contact  303 ,  305 ) to be maintained between the first component  310  and the second component  312  despite a non-parallel or non-ideal alignment of the first and second components. Accordingly, even without parallel or ideal alignment, the coupling  308  in the secured position can limit relative motion between the first component  310  and the second component  312  in all six degrees of freedom. 
     With reference to  FIG.  13 A , which shows a portion of  FIG.  13    within the area D in greater detail, an alternative pin with a straight profile  1206  (i.e., an alternative/straight pin without a reduced diameter portion) could result in a loss of contact between the first component  310  and the second component  312  in the non-parallel or non-ideal alignment. This is because the straight profile  1206  of a pin would create an area of conflict  1208  between the pin and the second component  312  when the second component  312  is tilted relative to the first component  310 . This can result in a loss of at least one line of contact between the first component  310  and the second component  312  and can negatively impact the stability of the coupling  308 . For example, a second point of contact  1210  can occur between the straight profile  1206  of the alternative pin and the second component  312 . This contact can pivot the second component  312  away from the first component  310  and result in a loss of contact between the prismatic surface  502  and the cylindrical surface  404 . 
       FIG.  14    illustrates the coupling  308  with the first component  310  seated within the second component  312 . The screw  410  and the pin  412  of the first component  310  can be received within the first and second openings  514 ,  516  of the second component  312 , respectively. While not visible, the cylindrical surface  404  of the first coupling component  310  can be seated within a recess formed by the prismatic surface  502  of the second coupling component  312 . The distal surface  1002  of the pin  412  can be flush with the back surface  520  of the second component  312 . The distal surface  421  of the screw  410  can be flush with the back surface  520  of the second component  312 . In some embodiments, the distal surface  421  of the screw  410  being flush with the back surface  520  of the second component  312  can indicate that the screw  410  is not threadably engaged with the opening  516 . Accordingly, the first component  310  and the second component  312  can be seated, but not yet fully mated or secured. In the seated configuration, relative motion between the first component  310  and the second component  312  can be limited, but not yet blocked, in one or more degree of freedom, e.g., by one or more of the contact between the cylindrical surface  404  and the prismatic surface  502 , the pin  412  received within the second opening  516  and the screw  410  received within the first opening  514 . 
       FIG.  15   . Illustrates the coupling  308  with the first component  310  mated with or secured to the second component  312 . The screw assembly  414  can be actuated to drive the screw  410  to mate the first component  310  with the second component  312 . For example, a user can rotate the handle  418  in a first direction to drive the screw  410  within the first opening  514 . In some embodiments, the distal end  420   d  of the screw  410  can extend past the back surface  520  of the second component  312 . This can indicate that the screw  410  has been driven to threadably engage with the first opening  514 . In some embodiments, the entirety of the unthreaded distal end  420   d  of the screw  410  can protrude from the first opening  514 . This can serve as a visual indication that an entire length of the threaded portion  422  of the screw  410  is engaged with the threaded inner surface  518  of the first opening  514 . The distal surface  1002  of the pin  412  can remain flush with the back surface  520  of the second component  312  when the first component  310  and the second component  312  are mated. As discussed above, in such a mated configuration, the screw  410  and pin  412  can block relative movement between the first component  310  and the second component  312  in all six degrees of freedom, such that there is negligible play between the components  310 ,  312 . In some embodiments, the first component  310  and the second component  312  can have a matching outer perimeter. Matching outer perimeters of the first and second components  310 ,  312  can produce a continuous and smooth profile of the coupling  308  and allow for quick visual confirmation that the components are properly aligned with one another. 
     To decouple the first component  310  from the second component  312 , the handle  418  can be driven or rotated in a second direction such that the screw  410  disengages from the first opening  514 . More particularly, as the screw  410  is rotated in the second direction, the threaded portion  422  of the screw  410  can move proximally through the opening  514  such that a proximal end  422   p  of the threaded portion  422  can exit the threaded surface  518  of the first opening  514 . The first component  310  and the second component  312  can be completely decoupled when the distal end  422   d  of the threaded portion  422  exits the threaded surface  518  of the first opening  514 . The first component  310  can then be moved away from the second component  312 . 
     Generally, the first component  310  and the second component  312  can be manufactured from a hard metal, such as steel, titanium, or the like to reduce wear and allow reuse of the instruments or objects on which the components are formed or disposed. In other embodiments certain polymers or other materials may also be appropriate for use in forming the first and second components  310 ,  312 . 
     The coupling  308  can be used to couple a first object associated with the first coupling component  310  to a second object associated with the second coupling component  312 . The coupling  308  can be used with any of a variety of instruments or objects. For example, in some embodiments, the first object can be an instrument adapter (e.g., instrument adapter  302 ) configured to receive an instrument (e.g., instrument  306 ) therein, and the second object can be a navigation array (e.g., navigation array  304 ). A position and orientation of the coupling components  310 ,  312  with respect to the navigation array (e.g., navigation array  304 ) can be known, such that the position and orientation of the instrument  306  attached to the array  304  by the coupling  308  (e.g., instrument  306  placed within instrument adapter  302 ) can be determined from the position and orientation of the array  304 . In alternative embodiments, the first object can be an instrument such that the instrument may be directly coupled to a navigation array  304  via a coupling  308  without the need for an instrument adapter  302 . While reference is made herein to the instrument adapter  302  as the first object associated with the first coupling component  310  and to the navigation array  304  as the second object associated with the second coupling component  312 , in other embodiments the instrument adapter  302  can be associated with the second coupling component  312  while the navigation array  304  can be associated with the first coupling component  310 . 
       FIGS.  16 - 21    illustrate embodiments of the instrument adapter  302  associated with the first coupling component  310  and the navigation array  304  associated with the second coupling component  312 . The first component  310  and the second component  312  can be identical to that of the first component and the second component described in detail above, with reference to  FIGS.  3 - 15   . Accordingly, a detailed description of their structure, operation, and use is omitted from the description of  FIGS.  16 - 21    for the sake of brevity. 
       FIGS.  16  and  17    show an embodiment of a navigation array  304  that can be used with the coupling  308  of the present disclosure. The navigation array  304  can include a frame  602  with the second component  312  formed thereon, e.g., integrally formed in the frame  602  or attached thereto. The frame  602  can include one or more branches  604 . Each branch  604  can have an attachment feature  606  that can receive a sphere-shaped fiducial or other marker for use with a navigation system. The attachment feature(s)  606  can be arranged in predetermined positions and orientations with respect to one another and/or the frame  602 . The attachment features  606  can be positioned such that, in use, markers attached thereto can be placed within a field of view of a navigation system and can be identified in images captured by the navigation system. By way of non-limiting example, markers can include infrared reflectors, LEDs, and so forth. The branches  604  and/or attachment features  606  can be arranged on a navigation array  304  with different positions and/or orientations to that of the illustrated navigation array  304 . For example, while the navigation array  304  illustrated in  FIGS.  16  and  17    has three branches  604  with each branch having a single attachment feature  606 , a navigation array  304  can have a greater or fewer number of branches and/or attachment features. The navigation array  304  can include an inertial measurement unit (IMU), an accelerometer, a gyroscope, a magnetometer, other sensors, or combinations thereof. In some embodiments, the sensors can transmit position and/or orientation information to a navigation system, e.g., to a processing unit of the navigation system. 
     In the navigation array  304  illustrated in  FIGS.  16  and  17   , a coupling component (e.g., the first or second component described above) can be disposed on a lower surface or lower portion of the array. For example, the second component  312  of the coupling  308  can be integrally formed with or attached to a lower portion of the navigation array  304 . Accordingly, in some embodiments, the navigation array  304  can function as the second object to be coupled to a first object by the coupling  308 .  FIG.  16    shows a front side of the navigation array  304  with the second component  312  formed at the lower portion of the frame  602 . In other embodiments, the second component  312  can be disposed at a different location relative to the navigation array  304 . The prismatic surface  502  of the second component  312  can be formed on the front side of the navigation array  304 .  FIG.  17    illustrates a back side of the navigation array  304  with the second component  312  formed at the lower portion of the frame  602 . As can be seen, the identification pin  802  of the second coupling component  312  can be visible on the back side of the navigation array  304 . 
       FIGS.  18 - 21    show various views of an embodiment of an instrument adapter  302  associated with the first coupling component  310 . The instrument adapter  302  can include an arm  320  with an instrument ring  322  at a first end thereof. Additional details about the instrument ring  322  can be found in U.S. Patent Application Publication No. 2018/0344301, filed on May 31, 2017, and entitled “Coupling Devices for Surgical Instruments and Related Methods” to Wehrli et al., which is hereby incorporated by reference in its entirety. The instrument ring  322  can be configured to securely receive an instrument therein. 
     The first coupling component  310  can be attached to or formed on a second end of the arm  320 , where the second end is opposite the first end of the arm.  FIG.  19    illustrates a side view of the instrument adapter  302 . As can be seen in  FIG.  19   , the first component  310  can be integrally formed with the adapter  302 . In other embodiments, the first component  310  can be welded, threaded, glued, or otherwise attached to the instrument adapter  302 . The screw  410  and the pin  412  can extend parallel to a longitudinal axis of the arm  320  of the instrument adapter  302 . In other words, the screw  410 , the pin  412 , and the arm  320  can each extend parallel to and along the X-axis. In other embodiments, the instrument adapter  302  can have a different geometric configuration such that the instrument arm  320  can extend at an oblique angle relative to the screw  410  and the pin  412 . 
       FIG.  20    illustrates the instrument adapter  302  with the first component  310  in a perspective view, with the back surface  432  of the first component  310  visible.  FIG.  21    shows the instrument adapter  302  with a front view of the first component  310  (i.e., a view showing a ZY plane, with the X-axis extending into the page). As shown, a longitudinal axis of the first cylindrical surface  404  (i.e., the Z-axis) can be disposed perpendicular to a longitudinal axis of the adapter arm  320 , which extends into the page in the view of  FIG.  21   . In other embodiments, the first component  310  can be disposed in a different positional relationship with respect to the adapter arm  320 , and, more broadly, to the instrument adapter  302  and/or an instrument disposed therein. 
       FIGS.  22 - 26    illustrate an embodiment of a method of using the coupling  308  to attach a first object to a second object, e.g., an instrument to a navigation array. Except as indicated below, the steps of the described method can be performed in various sequences, and one or more steps can be omitted or added. Additionally, the instruments illustrated in the drawings are merely examples and alternative embodiments of the instruments, e.g., different first and/or second objects, etc., can be used in conjunction with the steps described below. A detailed description of every sequence of steps is omitted here for the sake of brevity. 
     In use, the first component  310  and the second component  312  can be coupled to one another to lock all degrees of freedom between the first object (e.g., an instrument adapter  302 ) and the second object (e.g., the navigation array  304 ) and to position the first object and the second object in a known and fixed relative position and orientation. As will be described in detail below, the first component  310  can be aligned with the second component  312 . The first component  310  can then be brought into contact with the second component  312  such that the first component  310  is seated or placed against the second component  312 . The first component  310  and the second component  312  can then be mated or secured to complete the coupling of the first object to the second object. 
     As shown in  FIGS.  22  and  23   , the first component  310  can be aligned with the second component  312 . More particularly, the screw  410  extending from the first coupling component  310  can be aligned with the first opening  514  of the second component  312 . The pin  412  extending from the first component  310  can be aligned with the second opening  516  of the second component  312 . Proper orientation of the second object  304  and, more particularly, of the second coupling component  312  can be visually confirmed, for example, by confirming that the identification pin  802  is visible on a lower portion of the back surface  520  of the second component  312 . 
     Next, the first component  310  and the second component  312  can be moved together such that the cylindrical surface  404  of the first coupling component  310  can be placed or seated against the prismatic surface  502  of the second coupling component  312 .  FIGS.  24  and  25    illustrate the first component  310  seated against the second component  312 . The screw  410  can be received within the first opening  514  and the pin  412  can be received within the second opening  516 . As described above in greater detail with reference to  FIG.  14   , in the seated configuration, the distal surface  1002  of the pin  412  and the distal surface  421  of the screw  410  can be flush with the back surface  520  of the second component  312 . In some embodiments, this can evidence that the threaded portion  422  of the screw  410  is not fully threadably engaged with the first opening  514 . As can be seen in  FIG.  25   , the screw assembly  414  and, more particularly, the planar surface  424  of the handle  418  can be a distance away from the back surface  432  of the first component  310 . A portion of the screw post  420  can extend proximally from the back surface  432  of the first component  310  between the handle  418  and the back surface. In some such embodiments, with the first component  310  seated against the second component  312 , the planar surface  424  of the handle  418  can be parallel to but removed from the back surface  432  of the first component. 
     Once the first component  310  is placed against the second component  312 , a force can be applied to couple the first component  310  with the second component  312 . In some embodiments, the handle  418  can be rotated in the first direction to drive the screw  410  in the first direction. Rotating the screw  410  in the first direction can move the screw distally through the first opening  514 . The threaded portion  422  of the screw  410  can threadably engage with the threaded inner surface  518  of the first opening  514 . Driving the screw  410  can mate the first component  310  to the second component  312 , thereby securing the first component  310  against the second component  312 . In some embodiments, the handle  418  can be rotated in the first direction until the planar surface  424  abuts the back surface  432  of the first component  310 . More particularly, driving the screw  410  can pull and lock the cylindrical surface  404  securely against the prismatic surface  502  of the second coupling component  312 . As discussed above, in some instances securing the first component  310  and the second component  312  can result in a perfectly aligned configuration of the first and second components  310 ,  312 , while, in other instances, the first component  310  and the second component  312  may be secured in an imperfect alignment. Regardless, after securing the coupling  308 , the first component  310  and the second component  312  can be in a known position and orientation with negligible play or relative movement therebetween. 
     In some embodiments, relative movement between the first component  310  and the second component  312  can be restricted in all six degrees of freedom when an entire length of the threaded portion  422  (i.e., from the proximal end  422   p  of the threaded portion to the distal end  422   d  of the threaded portion) is engaged with corresponding threads of the threaded inner surface  518  of the first opening  514 . A length of the threaded portion  422  of the screw  410  can be selected to achieve various functions during coupling. For example, the length can be selected such that the distal end  422   d  of the threaded portion  422  engages threads of the threaded inner surface  518  of the first opening  514  when the first coupling component  310  is seated within the second coupling component  312 . In such arrangements, engagement of the threads can provide mechanical advantage to help draw the coupling components  310 ,  312  together during coupling and to urge the coupling components apart during decoupling. 
       FIGS.  26 - 30    show various views of the navigation array  304  coupled to the instrument adaptor  302  with the coupling  308  in the fully mated or secured position. The unthreaded distal end  420   d  of the screw  410  can extend beyond the back surface  520  of the second component  312 . In some embodiments, this can serve as a visual confirmation that the first component  310  and the second component  312  have been coupled such that relative movement between the two components is sufficiently blocked or restricted. The planar surface  424  of the screw assembly  414  can bear against the back surface  432  of the first component  310  to press the first component  310  into the second component  312 . 
     As discussed in detail above, rotating the screw  410  can engage the threaded inner surface  518  of the first opening  514  of the second coupling  312 , and can block relative motion between the first component  310  and the second component  312  along and about the X-axis and the Y-axis. Relative rotation about the Z-axis can also be blocked. To the extent that relative movement between the first component  310  and the second component  312  exists due to frictional forces once the screw  410  has engaged with the threaded surface  518  of the first opening  514 , the pin  412  received within the second opening  516  can further limit such relative motion along the Z-axis, as described above. 
     Moreover, the first component  310  and the second component  312  can be coupled in a known position and/or orientation such that the associated first object (e.g., the instrument adapter  302 ) and the associated second object (e.g., the navigation array  304 ) exist in a known position and/or orientation relative to one another. As such, the navigation array  304  can be used with the navigation system  307  to accurately and precisely locate and navigate the instrument adapter  302  and/or the instrument  306  disposed therein. While the description provided for herein discusses an instrument adapter  302  associated with a component of the coupling  308 , an instrument can be directly associated with a component of the coupling  308  without the use of an instrument adapter. In other words, a first component  310  or a second component  312  of the coupling  308  can be attached to or otherwise disposed on an instrument. In this manner, the instrument can be directly coupled to a navigation array  304  (or other object) using the coupling  308 . 
     Decoupling the first component  310  from the second component  312  can be achieved by disengaging the screw  410  from the threaded inner surface  518  of the first opening  514 . In some embodiments, this can include rotating the handle  418  in the second direction to rotate the screw  410  in the second direction. More particularly, as the screw  410  is rotated in the second direction, the threaded portion  422  of the screw  410  can move proximally through the opening  514  such that a proximal end of the threaded portion  422  can exit the threaded surface  518  of the first opening  514 . The first component  310  and the second component  312  can be completely decoupled when the distal end  422   d  of the threaded portion exits the threaded surface  518  of the first opening  514 . The first component  310  can then be moved away from the second component  312 . In some embodiments, decoupling the first component  310  and the second component  312  can include inserting an instrument through one or more of the openings  430  in the handle  418  of the screw assembly  414  and rotating the instrument thereby increasing the torque applied to the handle  418 . 
       FIGS.  31 - 33    illustrate an alternative embodiment of a coupling  1308 . Except as indicated below, the structure, operation, and use of this embodiment is similar or identical to that of the coupling  308  described above. Accordingly, a detailed description of said structure, operation, and use is omitted here for the sake of brevity. 
     The coupling  1308  can include a first component  1310  associated with a first object (e.g., an instrument adapter  1302 ) and a second component  1312  associated with a second object (e.g., a navigation array  1304 ). With reference to  FIG.  31   , the first coupling component  1310  can include a cylindrical surface  1404 , a screw  1410 , and a pin  1412 . The screw  1410  can extend from a planar inlay  1416  of the cylindrical surface  1404 . The planar inlay  1416  can be configured such that it spans only a region of the cylindrical surface that surrounds the screw  1410  extending therefrom. As such, the pin  1410  can extend from a convex portion of the cylindrical surface  1404 . 
       FIGS.  32  and  33    show the first object (e.g., instrument adapter  1302 ) coupled to the second object (e.g., navigation array  1304 ) by the coupling  1308 . In similar manner as to the coupling  308 , described above, the first component  1310  can be coupled to the second component  1312  to restrict relative motion in all six degrees of freedom such that there is negligible play between the first component  1310  and the second component  1312 . Accordingly, the instrument adapter  1302  and the navigation array  1304  can be coupled in a known orientation by the coupling  1308 . An instrument  1306  can be received within the instrument adapter  1302  such that the position of the instrument  1306  can be accurately and precisely tracked using the navigation array  1304 . 
     As evident from the foregoing, in at least some embodiments, the systems and methods disclosed herein can provide a coupling with a fully defined interface for coupling an instrument and/or an instrument adapter and a navigation array with minimal play and unique orientation for accurate and precise navigation of surgical instruments. 
     Although specific embodiments are described above, it should be understood that numerous changes may be made within the spirit and scope of the concepts described. Accordingly, it is intended that this disclosure not be limited to the described embodiments, but that it have the full scope defined by the language of the following claims. The above embodiments describe a coupling  308  that couples a navigation array to an instrument or an instrument adapter. While this is one contemplated use, the methods and devices of the present disclosure can be equally adapted for use with other objects. As such, the devices and components described herein can be formed in a variety of sizes and materials appropriate for use in various applications. 
     One skilled in the art will appreciate further features and advantages based on the above-described embodiments. Accordingly, the disclosure is not to be limited by what has been particularly shown and described. All publications and references cited herein are expressly incorporated herein by reference in their entirety.