Patent Publication Number: US-10786331-B2

Title: Automated implant identification system and method with combined machine-readable and human-readable markers

Description:
BACKGROUND 
     Modern surgical procedures involve the use of a wide variety of supplies and implants, such as screws, plates, Kirschner wires (K-wires), anchors, and drill bits. It is critical to track and create a record of the type and quantity of the supplies used both inside and outside of the field during a particular surgical procedure for a variety of reasons, such as billing, quality assurance, accurate patient records, and determining the type and quantity of supplies that need to be reordered and restocked. Creating such an accurate record while a surgery is being performed is complicated by a variety of factors, including the wide variety of supplies that are used, difficulty of tracking what is used inside the sterile field, the lack of space on the tray to print the corresponding part number of each distinct screw type, the small size of such supplies, and the difficulty of distinguishing similar supplies from each other, all in real-time while the surgery is being performed. Traditional manual methods for tracking such supply usage, such as visually identifying the supplies that are used and writing down the type and quantity of such supplies on paper or manually recording such supplies in a database, tend to be slow, tedious, and error-prone. Errors in the record of the type and quantity of supplies and implants used can have a variety of negative consequences, including failure of the hospital to be reimbursed for all of the supplies that were used, failure to reorder the correct supplies, lag time in ordering restock supplies in a timely fashion, and errors in the patient&#39;s surgical history which can contribute to suboptimal care for the patient in the future. 
     What is needed, therefore, are improved techniques for tracking the type and quantity of supplies used during surgery. 
     SUMMARY 
     A tray includes a plurality of rows, each of which includes a plurality of slots. Each row contains a plurality of screws. Different rows may contain screws of different types, e.g., lengths. Each of one or more rows contains a machine-readable object (e.g., peg) containing both: (1) machine-readable data representing one or more properties of the objects in the corresponding rows, and (2) human-readable indicia representing one or more properties of the objects in the corresponding rows. Removal of an object from a row is performed by reading data from the machine-readable object in the row and using that data to modify (e.g., decrement or increment) a count of the type of object contained in that row. 
     Other features and advantages of various aspects and embodiments of the present invention will become apparent from the following description and from the claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an illustration of a surgical plating tray according to one embodiment of the present invention. 
         FIG. 2  is an illustration of a peg according to one embodiment of the present invention. 
         FIG. 3  is a flowchart of a method performed by one embodiment of the present invention to load a tray with objects and corresponding machine-readable objects. 
         FIG. 4  is a flowchart of a method performed by one embodiment of the present invention to track the removal of objects from the tray. 
         FIG. 5  is an illustration of a surgical plating tray according to another embodiment of the present invention. 
         FIG. 6  is an illustration of a peg according to another embodiment of the present invention. 
         FIG. 7  is an illustration of a surgical asset tray according to one embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIG. 1 , a surgical plating tray  100  (also referred to in the art as a “set,” “module,” or “caddie”) is shown according to one embodiment of the present invention. For ease of illustration, the tray  100  shown in  FIG. 1  is designed solely to hold surgical screws. In practice, the tray  100  may hold other kinds of surgical supplies, such as any of the other kinds of surgical supplies described herein. As another example, in practice the tray  100  may be part of a larger tray which contains other components for holding other kinds of surgical supplies. 
     As shown in  FIG. 1 , the surgical plating tray  100  includes a plurality of rows  102   a - e.  In the particular example of  FIG. 1 , the tray  100  includes exactly five rows. This is merely an example, however, and does not constitute a limitation of the present invention. More generally, trays implemented according to embodiments of the present invention may include any number of rows. A tray may have an entire module dedicated solely to holding screws, and another module dedicated solely to holding another type of supply, such as plates. As another example, a tray may include a module which holds multiple types of supplies, e.g., both screws and plates. These and other types of trays all fall within the scope of embodiments of the present invention. Similarly, the precise spacing, orientation, and arrangement of the rows shown in  FIG. 1  is merely illustrative and not limiting of the present invention. 
     Furthermore, the tray  100  illustrated in  FIG. 1  includes a plurality of slots  104   a - e  at the tops of corresponding rows  102   a - e,  respectively. In the particular example shown in  FIG. 1 , slots  104   a ,  104   c ,  104   d , and  104   e  contain screw length markers on which numbers are printed. Such numbers indicate the length of screw contained in the corresponding row. For example, the number  3  on the screw length marker in slot  104   a  indicates that screws of  3  mm in length are contained in corresponding row  102   a . Similarly, the number  4  on the screw length marker in slot  104   c  indicates that screws of 4 mm length are contained in corresponding row  102   c ; the number  4  on the screw length marker in slot  104   d  indicates that screws of 4 mm in length are contained in corresponding row  102   d ; and the number  5  on the screw length marker in slot  104   e  indicates that screws of 5 mm in length are contained in corresponding row  102   e . As these examples illustrate, the number printed on a particular screw length marker in a particular row indicates the length of the screws that are contained in that particular row. 
     In the example of  FIG. 1 , the absence of a screw length marker in a slot indicates that the corresponding row does not contain any screws. For example, the absence of a screw length marker in slot  104   b  indicates that corresponding row  102   b  does not contain any screws. 
     Everything described above in connection with the slots  104   a - e  and the screw length markers contained in the slots  104   a - e  is merely an example and does not constitute a limitation of the present invention. For example, some or all of the slots  104   a - e  may be omitted from the tray  100 . Similarly, some or all of the screw length markers may be omitted from the tray  100 . Some or all of the screw length markers may contain indicia other than numbers, such as letters, words, bar codes, QR codes, color codes, or any other indicia. Some or all of the screw length markers may be located at positions other than the tops of their corresponding rows, such as in the middle or the bottom of their corresponding row. The screw length markers shown in the slots  104   a - e  of  FIG. 1  may be made of any material(s) and be of any shape(s) and/or size(s). The length of screws in the tray may alternatively be indicated by direct part marking on the actual tray  100  itself, rather than by using screw length markers inserted into the tray. 
     Each of the rows  102   a - e  may include a plurality of corresponding slots, which are adapted to receive and hold screws (e.g., surgical screws) and other objects (such as the screw length markers shown in  FIG. 1 ). The slots within a particular row may be arranged in a linear or substantially linear arrangement. Each of the rows  102   a - e  includes a “topmost” slot at one end of the row and a “bottommost” slot at the other end of the row, although the designation of one end of the row as “topmost” and the other end of the row as “bottommost” is arbitrary and used herein only for ease of reference. More generally, the “topmost” slot refers to the slot at one end of a row and the “bottommost” slot refers to the slot at the other end of the row. For example, in the embodiment illustrated in  FIG. 1 , slots  104   a - e  will be referred to herein as the “topmost” slots of their corresponding rows  102   a - e  for ease of explanation, although those slots may just as easily be defined as the “bottommost” slots of their corresponding rows  102   a - e.    
     The slots in the tray  100  may be adapted to receive and hold screws and/or other objects in any of a variety of ways. For example, in the embodiment illustrated in  FIG. 1 , each of the slots includes a lower lip, below the exterior surface of the slot, having a surface with an opening having a smaller diameter than the cross-section of the exterior surface of the slot, thereby forming an interior surface on which the head of a screw, peg, or other object may rest when inserted into the slot. For example, referring to  FIG. 2 , a peg  200  is shown. The peg (also referred to herein as a “pin”) includes a relatively short cylindrical head  202  coupled to a relatively long cylindrical shaft  204 . In the particular embodiment shown in  FIG. 2 , the lower portion of the head  202  is beveled at its point of connection to the shaft. The particular shapes and sizes of the head  202  and shaft  204  shown in  FIG. 2 , including the bevel, are merely examples and do not constitute limitations of the present invention. 
     The peg  200  may, for example, be implemented as disclosed in U.S. Pat. No. 9,313,558, entitled, “Tagging of Metal Pins for Mounted Objects with Light-Activated Microtransponders,” issued on Apr. 12, 2016, and incorporated by reference herein in its entirety. As disclosed therein, a pin may have a transponder affixed thereto. The transponder may be a very small, light-triggered transponder (referred to as an “MTP” or “p-Chip”). MTPs are generally sided, in that the photocell/RF circuitry is formed on one face, and the other major face is generally silicon—and can be a product of height reduction by back grinding. The circuitry face is generally protected by a passivation layer, such as of silicon dioxide, silicon nitride or mixtures, or multiple such layers. 
     The peg  200  is an elongated object, and may be made, for example, of metal, plastic, or wood, one end of which has a bulky, often oval shape, called the head of the pin  200 , the other end of which may be sharpened. The diameter of the bulky end is typically larger than the diameter of the elongated portion of the peg  200 . The axis of the peg  200  goes through the center points of the cross-sections of the elongated portion of the peg  200 . 
     When an object, such as the peg  200 , is inserted into one of the slots in the tray  100 , such as any one of slots  104   a - e  or  106   a - e,  the shaft  204  of the peg  200  may extend into the cylindrical cavity of the slot, below the exterior surface of the slot, and further below the interior surface described above with the narrower cavity. As the peg  200  is further inserted into the slot, the head  202  of the peg  200  will eventually make contact with the protruding interior surface of the slot, thereby preventing the peg  200  from being inserted further into the slot. The result, as illustrated by various pins and screws in the tray  100  of  FIG. 1 , is that the peg  200  is held in place within its slot, with the upper surface of the peg  200  being level with, or slightly above or below the upper surface of the slot. 
     In the embodiment illustrated in  FIG. 1 , the screw length markers in slots  104   a ,  104   c ,  104   d , and  104   e  may include shafts (not shown), coupled to the undersides of the numbered surfaces of the screw length markers, which may be the same as or similar to the pin shaft  204  shown in  FIG. 2 . As a result, the screw length markers may be inserted into and held in place by the slots of the tray  100  in the same or similar manner as the peg  200  of  FIG. 2 . 
     In the example described above and illustrated in  FIGS. 1 and 2 , the slots in the tray  100  are adapted to hold pins and other objects in place using a combination of the interior lip and gravity. This is merely an example and does not constitute a limitation of the present invention. In other embodiments, one or more slots may be adapted to hold pins and other objects in place using other means, such as suction, friction, and/or adhesion. 
     In the particular example shown in  FIG. 1 , the slots have a circular cross-section, although this is not a limitation of the present invention. The slots may, for example, have square, hexagonal, octagonal, or other cross-sections. 
     In the embodiment shown in  FIG. 1 , within each of the rows  102   a - e,  the slots that are below the screw length marker in that row are typically used to hold screws. For example, in row  102   a , slots  106   a  and  110   a - h  typically are used to hold screws of the type indicated by the number or other indicia on the screw length marker in the topmost slot  104   a  of that row  102   a . In embodiments of the present invention, one or more of the slots in a row may be used to contain a machine-readable object, such as a machine-readable pin, which contains data representing information about one or more of the screws (or other supplies) in that row, such as the type of such screws. 
     For example, in  FIG. 1 , slot  106   a  includes a machine-readable object  108   a , such as a machine-readable pin, which may be designed in accordance with  FIG. 2  and the above-referenced U.S. Pat. No. 9,313,558. Similarly, in the example of  FIG. 1 , slots  106   c  and  106   e  also include such machine-readable objects (e.g., pins). 
     In the particular example of  FIG. 1 , machine-readable objects are contained within one or more of the slots  106   a - e  which are immediately below the topmost slots of rows  102   a - e.  For example, machine-readable object  108   a  is contained within slot  106   a , which is immediately below topmost slot  104   a . Such slots, which are immediately below the topmost slots of each row, are referred to herein as “next topmost slots.” This, however, is merely an example and does not constitute a limitation of the present invention. Machine-readable objects may be contained within any slot(s) in any row, such as the topmost slot, the middle slot, the bottommost slot, or any combination thereof. As merely one example, machine-readable objects may be contained within the topmost slots of one or more of the rows  102   a - e.  For example, the screw length markers shown in  FIG. 1  may be machine-readable, using the mechanisms disclosed in U.S. Pat. No. 9,313,558 and/or other mechanisms, thereby eliminating the need to include both the screw length markers and additional machine-readable objects in the tray  100 . Instead, in such embodiments, the screw length markers may perform the dual function of providing human-readable indicia of the screws contained within the rows  102   a - e  and providing machine-readable data representing information about the screws contained within the rows  102   a - e.    
     Machine-readable objects implemented according to embodiments of the present invention may be clearly visually discernible from the screws or other objects in the same row. For example, in the embodiment illustrated in  FIG. 1 , the machine-readable pins  108   a - c  have heads with an upper surface that is flat and shiny, making them easy to locate visually. Furthermore, the screws in the tray  100  have Phillips-style heads, which are not flat and which therefore stand out visually from the flat heads of the machine-readable pins  108   a - c.  More generally, pins implemented according to embodiments of the present invention may have one or more visual characteristics which are distinct from one or more visual characteristics of the corresponding screws (or other supplies), thereby causing them to be easily discernible visually from the corresponding screws. 
     In general, a machine-readable object contained within any one of the rows  102   a - e  may contain a non-transitory storage medium which contains data representing information about one or more properties of one or more of the objects (e.g., screws) that are contained within that row. Examples of such storage media include, for example, radio frequency identification (RFID) tags, light-triggered transponders, integrated circuits (chips), bar codes, and QR codes. The non-transitory storage medium contained in a machine-readable object may use any mechanism to store data. The data contained within a non-transitory storage medium may represent any of a variety of information about the objects contained within the same row as the non-transitory storage medium, such as their manufacturer, model number, part number, stock keeping unit (SKU), length, width, or any combination thereof. Additionally or alternatively, the data contained with a non-transitory storage medium may represent a link or a pointer to any such information, such as an index into a database containing information about the objects contained within the same row as the non-transitory storage medium. 
     As described above, the data contained within a non-transitory storage medium may be machine-readable. Such data may or may not be human-readable. For example, a non-transitory storage medium may be or include an RFID tag, in which case the data on such a tag may be readable by a machine and not be a human. In some embodiments, however, a non-transitory storage medium and/or a supply (e.g., screw) may include human-readable indicia representing some or all of the same information as represented by the machine-readable data stored on the non-transitory medium. Examples of such indicia include printed symbols (e.g., numbers and/or letters) representing a manufacturer, model number, part number, stock keeping unit (SKU), length, width, or any combination thereof of the supply (e.g., screw). The inclusion of such human-readable indicia may eliminate the need for the human-readable screw length markers described above and shown in  FIG. 1 . Furthermore, note that some indicia, such as numbers and bar codes, may be both machine-readable and human-readable. Furthermore, the screw length markers may include, instead of or in addition to human-readable indicia representing screw lengths, human-readable indicia representing any one or more of the other properties listed above. 
     A non-transitory storage medium may be contained within or otherwise coupled to or associated with a machine-readable object in any of a variety of ways. For example, a non-transitory storage medium may be affixed to the head  202  of the peg  200  shown in  FIG. 2 , such as by using tape or other adhesive means to affix the non-transitory storage medium to the upper surface of the head  202  of the peg  200 . The non-transitory storage medium may, for example, be contained within a cavity  206  of the head  202  of the peg. A cap (not shown) may be secured over the cavity  206 , such as by welding or heatstaking it over the cavity  206 , thereby enclosing the non-transitory storage medium inside the cavity. The cap may, for example, be transparent or translucent. 
     In the particular example shown in  FIG. 1 , row  102   a  contains: (1) machine-readable object  108   a  (e.g., pin) in slot  106   a ; and (2) screws in slots  110   a - d  and  110   f - h.  Machine-readable object  108   a  includes a non-transitory storage medium containing data representing information about the screws (if any) contains in the slots  110   a - h  of row  102   a.    
     In addition, note that the next topmost slot  106   b  of the row  102   b  that is adjacent and immediately to the right of row  102   a  does not contain a machine-readable object (e.g., pin). In fact, row  102   b  does not contain any machine-readable object at all. In some embodiments of the present invention, a single machine-readable object may be contained within a particular row to indicate that the particular row, and any rows immediately subsequent to that row on the right which do not contain any machine-readable objects, contains objects (e.g., screws) which are described by the data on the machine-readable object in the particular row. For example, in  FIG. 1 , the fact that row  102   a  contains a machine-readable object  108   a  and that the immediately adjacent row  102   b  to the right of row  102   a  does not contain any machine-readable objects means that the machine-readable object  108   a  in row  102   a  contains data representing information describing any and all objects in both rows  102   a  and  102   b . More generally, the machine-readable object in a particular row may contain data representing information describing objects in that particular row and in all subsequent rows to the right up to but not including the next row that contains a machine-readable object. In the example of  FIG. 1 , row  102   c  contains a machine-readable object  108   b  in row  102   c ; therefore, the machine-readable object  108   a  in row  102   a  contains data representing information about objects in rows  102   a  and  102   b  but not  102   c.    
     The scheme described above for using a single machine-readable object to describe objects in multiple rows is merely an example and not a limitation of the present invention. As an alternative, for example, machine-readable objects may be contained in each and every row containing objects about which information is desired. 
     Returning to the particular example shown in  FIG. 1 , row  102   c  contains: (1) machine-readable object  108   b  (e.g., pin) in slot  106   c ; and (2) screws in various slots. Machine-readable object  108   b  includes a non-transitory storage medium containing data representing information about the screws (if any) contained in the slots of row  102   c . Note that because row  102   d  does not contain a machine-readable object, then according to the scheme described above, the data contained on the storage medium of machine-readable object  108   b  represents information describing any and all objects in both rows  102   c  and  102   d.    
     Finally, in the particular example shown in  FIG. 1 , row  102   e  contains: (1) machine-readable object  108   c  (e.g., pin) in slot  106   e ; and (2) screws in various slots. Machine-readable object  108   c  includes a non-transitory storage medium containing data representing information about the screws (if any) contained in the slots of row  102   e.    
     As described above, different rows in the tray  100  may contain objects (e.g., screws) having properties that differ from each other. For example, each row may contain objects that share the same or substantially the same properties as each other (e.g., manufacturer, model number, part number, stock keeping unit (SKU), length, and/or width), but different rows may contain objects whose properties differ from the properties of objects contained in other rows. For example, in the embodiment illustrated in  FIG. 1 , the objects contained in rows  102   a  and  102   b  may have the same or substantially the same properties as each other, the objects contained in rows  102   c  and  102   d  may have the same or substantially the same properties as each other, and the objects contained in row  102   e  may have the same or substantially the same properties as each other, but the properties of the objects contained in rows  102   a - b  may differ from the properties of the objects contained in rows  102   c - d  and  102   e , the properties of the objects contained in rows  102   c - d  may differ from the properties of the objects contained in rows  102   a - b  and  102   e , and the properties of the objects contained in row  102   e  may differ from the properties of the objects contained in rows  102   a - b  and  102   c - d.    
     Because the machine-readable object in each row contains a storage medium containing data representing information about the objects in that row, the data contained on the machine-readable objects in different rows in the tray  100  may differ from each other to reflect the differences in properties of the corresponding objects. For example, assume that the objects in a particular row A of the tray  100  have a first set of properties, that the objects in another particular row B of the tray  100  have a second set of properties, and that the first and second set of properties differ from each other. As a result, the machine-readable object corresponding to (e.g., contained within the same row as) the objects in row A will contain data representing the first set of properties and the machine-readable object corresponding to (e.g., contained within the same row as) the objects in row B will contain data representing the second set of properties. Because the first and second sets of properties differ from each other, the data contained in the two machine-readable objects will also differ from each other. This may be true not only for two machine-readable objects in the tray  100 , but for any number of machine-readable objects in the tray  100 . 
     In the embodiment illustrated in  FIG. 1 , assets (e.g., screws) in a particular row are identified by both a human-readable marker (e.g., screw length markers) in one slot in the row and a machine-readable object in another slot in the same row. For example, row  102   a  in  FIG. 1  contains both: (1) a human-readable marker, with the number “ 3 ” printed on it, in slot  104   a , and (2) a machine-readable object  108   a , in slot  106   a , containing machine-readable data representing one or more properties (e.g., length) of assets in row  102   a . This scheme has a variety of advantages described herein. However, this scheme requires the use of two slots (e.g., slots  104   a  and  106   a  in row  102   a ) in a row to store information about assets in that row. Alternative embodiments of the present invention will now be described in which both human-readable data descriptive of assets in a row and machine-readable data descriptive of assets in the same row may be stored in a single slot in that row. A benefit of such embodiments is that they free up slots for use in storing surgical assets rather than objects containing data descriptive of surgical assets. This can be particularly advantageous in connection with small trays having few slots and/or situations in which it is desirable to pack trays with surgical assets as densely as possible in order to hold as many surgical assets in the available space as possible. 
     Referring to  FIG. 5 , a surgical plating tray  500  (also referred to in the art as a “set”) is shown according to one embodiment of the present invention. The tray  500  of  FIG. 5  is similar in a variety of ways to the tray  100  of  FIG. 5 . Any aspect of the tray  100  of  FIG. 1  that is not explicitly described herein in connection with  FIG. 5  should be assumed to be equally applicable to  FIG. 5 . For example, any description herein of the tray  100 ; rows  102   a - e;  slots  104   a - e,    106   a - e,  and  110   a - h;  and machine-readable objects  108   a - c  in connection with  FIG. 1  should be assumed to be equally applicable to those elements in  FIG. 5  unless explicitly stated otherwise herein. 
     In the embodiment shown in  FIG. 5 , as in the case of  FIG. 1 , within each of the rows  102   a - e,  the slots that are below the screw length marker in that row are typically used to hold screws. For example, in row  102   a , slots  106   a  and  110   a - h  typically are used to hold screws of the type indicated by the number or other indicia on the screw length marker in the topmost slot  104   a  of that row  102   a . As described elsewhere herein, each screw length marker in  FIG. 5  may alternatively contain any human-readable indicia (e.g., numbers, letters, and/or other human-readable characters) representing one or more characteristics of assets (e.g., screws) that are in the same row as the screw length marker (or a subsequent row). As a result, the term “screw length marker” should be understood to refer herein more generally to any object having human-readable indicia thereon, whether or not such indicia represents a length of a screw or other object. As a result, the term “human-readable asset identifier” may be used interchangeably herein with “screw length marker.” 
     As further described above, in embodiments of the present invention, one or more of the slots in a row may be used to contain a machine-readable object, such as a machine-readable pin, which contains data representing information about one or more of the screws (or other assets) in that row, such as the type of such screws. 
     In the embodiment of  FIG. 5 , a single object includes both the human-readable indicia and human-readable object described herein. As a result, such a single object may be contained within a single slot in the tray  500 . 
     For example, in  FIG. 5 , slot  104   a  includes a machine-readable object  508   a , such as a machine-readable pin, which may be designed in accordance with  FIG. 2  and the above-referenced U.S. Pat. No. 9,313,558. Similarly, in the example of  FIG. 5 , slots  104   c  and  104   e  also include such machine-readable objects (e.g., pins). 
     The machine-readable object  508   a  also includes (e.g., on its top surface) human-readable indicia which, in the particular example of  FIG. 5 , is a printed number  3 . As a result, the machine-readable object  508   a  performs the functions of both the machine-readable objects and human-readable indicia (e.g., screw length markers) disclosed herein. As shown in  FIG. 5 , the machine-readable object  508   a  is contained within a single slot  104   a  in the tray  500 . As a result, it is not necessary in the embodiment of  FIG. 5  to use two slots of the tray  500  to implement the functions of the machine-readable object and the human-readable indicia. As shown in  FIG. 5 , in contrast to  FIG. 1 , the slot  106   a  is empty and may be used to store a screw or other surgical asset. 
     Similarly, the machine-readable object  508   b  (in slot  104   c ) includes (e.g., on its top surface) human-readable indicia which, in the particular example of  FIG. 5 , is a printed number  4 . Similarly, the machine-readable object  508   c  (in slot  104   e ) includes (e.g., on its top surface) human-readable indicia which, in the particular example of  FIG. 5 , is a printed number  5 . Note that slots  106   c  and  106   e  in the tray  500  of  FIG. 5  are empty, as the result of the dual-use nature of the machine-readable objects  508   b  and  508   c , in comparison to the tray  100  of  FIG. 1 . 
     As in the case of the machine-readable objects in the tray  100  of  FIG. 1 , the machine-readable objects  508   a - c  in the tray  500  of  FIG. 5  contained within any one of the rows  102   a - e  may contain a non-transitory storage medium which contains data representing information about one or more properties of one or more of the objects (e.g., screws) that are contained within that row. Examples of such storage media include, for example, radio frequency identification (RFID) tags, light-triggered transponders, integrated circuits (chips), bar codes, and QR codes. The non-transitory storage medium contained in a machine-readable object may use any mechanism to store data. The data contained within a non-transitory storage medium may represent any of a variety of information about the objects contained within the same row as the non-transitory storage medium, such as their manufacturer, model number, part number, stock keeping unit (SKU), length, width, or any combination thereof. 
     Machine-readable objects suitable for use with the tray  500  of  FIG. 5  may be implemented in any of a variety of ways to enable data to be read by machine from such machine-readable objects and for humans to read the human-readable indicia on such objects. For example, the human-readable indicia on a particular machine-readable object may be located on that object (e.g., on its top surface) so that it does not overlap with, occlude, or otherwise interfere with the reading, by machine, of the machine-readable data on that object. For example, the human-readable indicia may occupy one portion of a surface of the machine-readable object, while the machine-readable storage medium may occupy another, non-overlapping, portion of the same surface of the machine-readable object. As another example, the machine-readable storage medium may overlap (e.g., be on top of), in whole or in part, with the human-readable indicia on the same machine-readable object, but be transparent or sufficiently transparent to enable the human-readable indicia to be read by a human. As yet another example, the human-readable indicia may cover, in whole or in part, the machine-readable storage medium on the same machine-readable object, but the machine-readable storage medium may be of a kind which may be read by machine even when it is partially or entirely occluded. 
     The method  300  of  FIG. 3  and the method  400  of  FIG. 4 , described above in connection with the tray  100  of  FIG. 1 , are equally applicable to the tray  500  and machine-readable objects  508   a - c  of  FIG. 5 . For example, any reference in  FIGS. 3 and 4  and the accompanying text herein to a machine-readable object may refer to any of the machine-readable objects  508   a - c  of  FIG. 5 , and any reference in  FIGS. 3 and 4  and the accompanying text herein to a screw length marker or other human-readable indicia may refer to any of the machine-readable objects  508   a - c  of  FIG. 5  because such objects include human-readable indicia in addition to machine-readable data. 
     Referring to  FIG. 6 , a peg  600  (also referred to herein as a “pin”) is shown according to another embodiment of the present invention. The peg  600  of  FIG. 6  may have any of the properties described herein in connection with the peg  200  of  FIG. 2  and any other peg disclosed herein, even if such properties are not explicitly disclosed herein in connection with the peg  600  of  FIG. 6 . As merely one example, the head  602  of the peg  600  may include a machine-readable object and/or human readable indicia of any of the kinds disclosed herein. 
     Recall that the peg  200  of  FIG. 2  has a relatively long cylindrical shaft  204 . In contrast, the peg  600  of  FIG. 6  has an expandable and compressible base member  604  in place of the shaft  204 . In the particular embodiment shown in  FIG. 6 , the base member  604  includes a first leg  606   a  and a second leg  606   b , which are integrally formed with and connected at a top portion  608  of the base member  604 . The connection of the legs  606   a - b  to the top portion  608  is sufficiently elastic to enable the legs  606   a - b  to be compressed towards each other under pressure (possibly so far as to touch each other), and is such that when the legs  606   a - b  are compressed towards each other, they provide opposing outward restorative forces away from each other and against an inner surface of a slot into which the peg  600  is inserted. 
     The peg  600  also includes a first snap member  610   a , which is coupled to (and which may be formed integrally with) the first leg  606   a ; and a second snap member  610   b , which is coupled to (and which may be formed integrally with) the second leg  606   b . The first snap member  610   a  has a lip  612   a  at its top surface, which extends outwardly from, and is coupled to (and possibly integrally formed with) the bottom of the first leg  606   a . Similarly, the second snap member  610   b  has a lip  612   b  at its top surface, which extends outwardly from, and is coupled to (and possibly integrally formed with) the bottom of the second leg  606   b.    
     In the particular example illustrated in  FIG. 6 , the inner surface of the first leg  606   a  aligns with (and may be formed integrally with) the inner surface of the first snap member  610   a , such that the two surfaces are aligned with each other in the same plane to form a single continuous surface. Similarly, in the particular example illustrated in  FIG. 6 , the inner surface of the second leg  606   b  aligns with (and may be formed integrally with) the inner surface of the second snap member  610   b , such as the two surfaces are aligned with each other in the same plane to form a single continuous surface. 
     The net effect of the structure of the peg  600  is that when the peg  600  is inserted into a slot (such as any of the slots  104   a - e,    106   a - e,  or  110   a - h ) in the surgical tray  100  or the surgical tray  500 , the inner surface of the slot may compress the legs  606   a - b  and the snap members  610   a - b  towards each other as the peg  600  is inserted into the slot. Then, when the lips  612   a - b  extend below a lower surface of the slot, the outward restorative forces exerted by the legs  606   a - b  and snap members  610   a - b  may cause the legs  606   a - b  and snap members  610   a - b  to move outwards, thereby causing the lips  612   a - b  to extend (i.e., snap) beyond the diameter of the lower surface of the slot. As a result, if an attempt is then made to pull the peg  600  back upward through the slot, the lips  612   a - b  will make contact with the lower surface of the slot, thereby preventing the peg  600  from being pulled further upward. 
     In this way, the structure of the peg  600 , particularly the snap members  610   a - b,  provides a mechanism for locking the peg  600  into a slot so that the peg  600  cannot fall out of the slot once snapped into place. To remove the peg  600  from the slot, it is necessary to provide inward force against the snap members  610   a - b  so that the move towards each other sufficiently to enable the lips  612   a - b  to fit within the slot, at which point the peg  600  may be pulled upward and pulled through the slot and removed from the tray. 
       FIG. 7  shows a surgical asset tray  700  according to another embodiment of the present invention. The tray  700  includes a plurality of asset wells  702   a - h  and a corresponding plurality of slots  704   a - h  containing a corresponding plurality of pegs  706   a - h.  The particular number, shape, and locations of wells, slots, and pegs shown in  FIG. 7  are merely examples and do not constitute limitations of the present invention. Furthermore, the number of wells may be different from the number of slots. For example, some wells but not others may have corresponding slots. Similarly, the number of slots may be different from the number of pegs. For example, not all slots may contain pegs. 
     The tray  700  also includes a plurality of human-readable asset identifiers  708   a - g  corresponding to wells  702   a - g.  In the particular example of  FIG. 7 , well  702   h  does not have a corresponding human-readable asset identifier. This is merely an example, however, and not a limitation of the present invention. Any one or more of the wells in a tray may have a corresponding human-readable asset identifier. 
     In the particular example in  FIG. 7 , wells  702   a - b  and  702   d - h  contain corresponding surgical assets  710   a - b  and  710   d - h,  such as surgical plates of various kinds. More generally, the wells  702   a - b  and  702   d - h  may contain any kind(s) of surgical assets. In the particular example in  FIG. 7 , well  702   c  does not contain any surgical assets, but this is merely an example and does not constitute a limitation of the present invention. More generally, any one or more of the wells in a tray may contain one or more surgical assets. 
     Note that the wells  702   a - h  may be, but need not be, arranged in rows. For example, wells  702   a ,  702   b , and  702   h  are of different sizes and do not align with each other on their right or left edges. As another example, the centers of wells  702   c  and  702 g do not align with each other. More generally, the wells  702   a - h  may be arranged in any layout in the tray  700  of  FIG. 7 , whether or not such a layout contains any rows. 
     In the particular example of  FIG. 7 , each of the human-readable asset identifiers  708   a - h  corresponds to a single corresponding one of the wells  702   a - h,  and contains a human-readable identifier (e.g., set of human-readable characters, such as letters and/or numbers) which describes one or more properties of surgical assets contained in (or suitable for being contained in) the corresponding well. For example, the human-readable asset identifier  708   a  corresponding to the well  702   a  and contains an asset identifier (“ 398   905 ”) describing properties of the surgical assets  710   a  contained in the well  702   a  (such as by representing a pointer to or index into a database or other dataset containing data representing such properties). A human-readable asset identifier may, but need not be, located in proximity to its corresponding well. For example, a human-readable asset identifier may, but need not be, located adjacent to its corresponding well (e.g., no more than ⅛ inch, no more than ¼ inch, no more than ½ inch, no more than ¾ inch, or no more than 1 inch), whereby it is obvious from visual inspection that the human-readable asset is associated with its corresponding well. 
     Similarly, in the particular example of  FIG. 7 , each of the pegs  706   a - g  corresponds to a single corresponding one of the wells  702   a - g,  and contains a non-transitory storage medium of any of the kinds described herein, containing data representing one or more properties of surgical assets contained in (or suitable for being contained in) the corresponding well, in any of the ways disclosed herein. For example, the peg  706   a  corresponding to the well  702   a  may contain a non-transitory storage medium describing properties of the surgical assets  710   a  contained in the well  702   a  (such as by representing a pointer to or index into a database or other dataset containing data representing such properties). A peg may, but need not be, located in proximity to its corresponding well. For example, a peg may, but need not be, located adjacent to its corresponding well (e.g., no more than ⅛ inch, no more than ¼ inch, no more than ½ inch, no more than ¾ inch, or no more than 1 inch), whereby it is obvious from visual inspection that the peg is associated with its corresponding well. 
     In summary, the tray  700  of  FIG. 7  includes a plurality of asset wells  702   a - h  and a corresponding plurality of slots  704   a - h  containing a corresponding plurality of pegs  706   a - h.  The tray  700  also includes a plurality of human-readable asset identifiers  708   a - g  corresponding to wells  702   a - g.  The wells  702   a - b  and  702   d - h  contain corresponding surgical assets  710   a - b  and  710   d - h,  such as surgical plates of various kinds. Each of the human-readable asset identifiers  708   a - h  corresponds to a single corresponding one of the wells  702   a - h,  and contains a human-readable identifier which describes one or more properties of surgical assets contained in (or suitable for being contained in) the corresponding well. Each of the pegs  706   a - g  corresponds to a single corresponding one of the wells  702   a - g,  and contains a non-transitory storage medium containing data representing one or more properties of surgical assets contained in (or suitable for being contained in) the corresponding well. 
     As a result, when any of the an asset is removed from one of the wells  702   a - g,  the non-transitory storage medium on the corresponding one of the pegs  706   a - g  may be read by a machine to identify properties of the removed asset, such as by using any of the techniques disclosed herein. For example, the method  300  of  FIG. 3  may be used in connection with the tray  700  of  FIG. 7 , with the following modifications:
         In operation  312 , the first machine-readable object may be inserted into a first slot that corresponds to (e.g., is in proximity and/or adjacent to) a well that stores or is suitable for storing objects of the first type, whether or not the first slot and the well are in the same row as each other.   In operation  314 , the second machine-readable object may be inserted into a second slot that corresponds to (e.g., is in proximity and/or adjacent to) a well that stores or is suitable for storing objects of the second type, whether or not the second slot and the well are in the same row as each other.   In operation  316 , screws (or other surgical assets) of the first type are stored in the well that corresponds to (e.g., is in proximity and/or adjacent to) the first machine-readable object.   In operation  318 , screws (or other surgical assets) of the second type are stored in the well that corresponds to (e.g., is in proximity and/or adjacent to) the second machine-readable object.       

     Similarly, the method  400  of  FIG. 4  may be used in connection with the tray  700  of  FIG. 7 , with the following modifications:
         In operation  402 , an object may be removed from a particular well W in the tray, regardless of whether the well is in a row of the tray.   In operation  404 , a machine-readable object O that corresponds to (e.g., is in proximity to) well W is identified.       

     Otherwise, the methods  300  and  400  of  FIGS. 3 and 4 , respectively, may be applied to the tray  700  of  FIG. 7 . 
     As the above description illustrates, one embodiment of the present invention is directed to a tray, or a portion thereof for containing screws and/or object objects, in which one or more machine-readable objects containing machine-readable data have been inserted into slots in the tray, such that the locations of the slots in which the machine-readable objects have been inserted correspond to properties of the objects (e.g., screws) which are in the same rows as the machine-readable objects. 
     Another embodiment of the present invention is directed to a method for configuring a tray of the kind described above. Referring to  FIG. 3 , a flowchart is shown of such a method  300  according to one embodiment of the present invention. The method  300  includes selecting a tray having a plurality of rows, where each of the plurality of rows includes a plurality of slots ( FIG. 3 , operation  302 ). A first set of object properties is identified, such as a set of properties of a first kind of object (e.g., screw). The first set of properties may include any one or more of the kinds of properties described above. A first machine-readable object is selected (e.g., a pin containing a chip) ( FIG. 3 , operation  304 ), and data representing (or pointing to) some or all of the first set of object properties is stored in the first machine-readable object ( FIG. 3 , operation  306 ). As described above, the data stored on the first machine-readable object may, for example, be an index into a database containing some or all of the first set of object properties. 
     A second set of object properties is identified, such as a set of properties of a second kind of object (e.g., screw). The second set of properties may include any one or more of the kinds of properties described above. The second set of properties may differ from the first set of properties in whole or in part. For example, the second set of properties may include a SKU or length that differs from the SKU or length of the first set of properties. A second machine-readable object is selected (e.g., a pin containing a chip) ( FIG. 3 , operation  308 ), and data representing some or all of the second set of object properties is stored in the second machine-readable object ( FIG. 3 , operation  310 ). 
     Note that operations  308  and  310  effectively repeat operations  304  and  306 , but for a second object and second machine-readable object. Operations  304  and  306  may be repeated for any additional number of object types and corresponding machine-readable objects. 
     The first machine-readable object is inserted into the tray in a slot (e.g., the topmost or next topmost slot) of a row in which objects (e.g., screws) of the type represented by the data in the first machine-readable object are stored, or will be stored ( FIG. 3 , operation  312 ). Similarly, the second machine-readable object is inserted into the tray in a slot (e.g., the topmost or next topmost slot) of a row in which objects (e.g., screws) of the type represented by the data in the second machine-readable object are stored, or will be stored ( FIG. 3 , operation  314 ). Note that operation  314  effectively repeats operation  312 , but for a second machine-readable object. Operation  312  may be repeated for any additional number of machine-readable objects. 
     One or more objects (e.g., screws) of the type represented by the data in the first machine-readable object are inserted into the same row in the tray as the first machine-readable object ( FIG. 3 , operation  316 ). One or more objects (e.g., screws) of the type represented by the data in the second machine-readable object are inserted into the same row in the tray as the second machine-readable object ( FIG. 3 , operation  318 ). Note that operation  318  effectively repeats operation  316 , but for a second machine-readable object and corresponding type of object. Operation  316  may be repeated for any additional number of machine-readable objects and corresponding types of objects. 
     The result of performing method  300  is to populate a tray, such as the tray shown in  FIG. 1 , with machine-readable objects and corresponding types of objects (e.g., screws) in the same rows as those machine-readable objects, so that the removal of such objects from the tray may be detected, such as in the manner described below in connection with  FIG. 4 . 
     The order of the steps shown in  FIG. 3  is merely an example and does not constitute a limitation of the present invention. The steps of method  300  may be performed in orders other than the order shown in FIG. 3 . For example, steps  316  and  318  may be performed before steps  312  and  314 . As another example, steps  306 ,  306 ,  308 , and  310  may be performed after steps  316  and  318 . 
     Embodiments of the present invention include methods for reading data from machine-readable objects (such as the machine-readable objects  108   a - c  shown in  FIG. 1 ) to track the removal of objects (e.g., screws) from a tray (e.g., tray  100 ). For example, referring to  FIG. 4 , a flowchart is shown of a method  400  for tracking the removal of objects from a tray (e.g., tray  100 ) according to one embodiment of the present invention. 
     An object (e.g., screw) is removed from a particular row R of the tray  100  ( FIG. 4 , operation  402 ). The machine-readable object in row R is identified ( FIG. 4 , operation  404 ). For example, if slot  110   a  were removed from row  102   a , then machine-readable object  108   a  may be identified as the machine-readable object in the same row as slot  110   a.    
     One or more units of data are read from the identified machine-readable object  108   a  ( FIG. 4 , operation  406 ). Such data may be read in any of a variety of ways. For example, a wand may be positioned (e.g., by a human operator) over the surface of the machine-readable object, thereby causing the wand to read some or all of the data from the machine-readable object. The wand or other reading device may be triggered to read data from the machine-readable object in response to input from the human operator, such as the pressing of a button. 
     A computer (not shown) may automatically identify the type (e.g., length) of the removed object based on the data read from the machine-readable object ( FIG. 4 , operation  408 ). For example, if the data read from the machine-readable object include data which expressly specifies a type of the removed object, then the computer may identify the type of the removed object as the type expressly specified by the read data. As another example, the computer may derive the type of the removed object from the data read from the machine-readable object. For example, if the data read from the machine-readable object specifies a length of the removed object, then the computer may derive the type of the removed object from the specified length, such as by using a table or other data structure to correlate the specified length with an object type (e.g., part number or SKU). 
     The method  400  decrements a stored count of the identified object type ( FIG. 4 , operation  410 ). For example, the computer may include a database or other data structure containing counts of various types of objects. As a particular example, such a data structure may begin with a count, for each of the object types initially stored in the tray  100 , of the number of objects of that type initially stored in the tray. For example, in the embodiment shown in  FIG. 1 , if rows  102   a  and  102   b  initially contain, in aggregate, ten screws of length  3 , then the data structure stored in the computer may initially contain data indicating that the tray  100  contains ten screws of length  3 . In this example, in operation  410 , the computer may decrement that count in response to determining that a screw was removed from row  102   a  or  102   b.    
     In addition to or instead of decrementing the stored count of the identified object type, the method  400  may increment a count of the number of objects of the identified object type that have been removed from the tray  100 . For example, the computer may initially contain data indicating that zero objects of each object type have been removed from the tray, such as when the method  300  of  FIG. 3  is performed to initially load the tray. Then, as each object is removed from the tray  100 , the method  400  may increment a count of the number of objects of that type that have been removed from the tray  100 . 
     Operations  402 - 410  may be repeated for any number of objects removed from the tray  100 . The function performed by the method  400  is to maintain an accurate count of the number of objects removed from the tray. 
     The specific examples of ways in which machine-readable objects and human-readable indicia may be coupled to an asset tray are merely examples and do not constitute limitations of the present invention. For example, although in certain embodiments disclosed herein, machine-readable objects are inserted into slots in a tray, this is merely an example and not a limitation of the present invention. Machine-readable objects may be coupled to a tray in any of a variety of ways, such as by affixing the machine-readable objects to the tray (e.g., using tape), such as to a surface of the tray near the corresponding assets. Human-readable objects may similarly be affixed to the tray (e.g., using tape), such as by affixing such human-readable objects to a surface of the tray near the corresponding assets. 
     Furthermore, both machine-readable objects and human-readable indicia may take any of a variety of forms, such as forms other than the various pegs disclosed herein. For example, a machine-readable object or human-readable indicia may be implemented within a thin disc, such as by sandwiching the machine-readable object or human-readable indicate between two layers of film, the bottom of which may be adhesive so that the disc may easily be affixed to a surface of the tray. 
     In certain embodiments disclosed herein, assets are shown as being inserted into slots in a tray. In other embodiments disclosed herein, assets are shown as being located within wells in a tray. Such embodiments may be combined with each other in any of a variety of ways. For example, in any embodiment disclosed herein in which one or more assets are placed within a slot, one or more of such assets may alternatively be placed within a well. Conversely, in any embodiment disclosed herein in which one or more assets are placed within a well, one or more of such assets may alternatively be placed within a slot. 
     Embodiments of the present invention have a variety of advantages. For example, by enabling the removal of objects (e.g., screws) from the tray to be tracked by reading machine-readable data from machine-readable objects in the tray, and thereby automatically updating a count of such removed objects in a computer, embodiments of the present invention decrease the effort, increase the speed, and increase the accuracy of such tracking in comparison to prior art object removal tracking methods. In particular, embodiments of the present invention eliminate the need for any human operator to write down or manually enter data specifying the objects removed from the tray  100 . This significantly decreases the complexity of the tracking process and enables such tracking to be performed nearly instantly after an object has been removed from the tray. Furthermore, objects and trays often do not have part numbers written on them. As a result, enabling such information to be read automatically from the objects and/or trays increases the accuracy of recording the parts that were used. 
     Other industries, and even departments within hospitals other than the surgical department, consider scanning at the point of use to be the gold standard for supply chain accuracy and management because of the wide range of benefits that it provides. Such scanning at the point of use, however, has not been implemented or even possible until the advent of the present invention, which uses a combination of novel and nonobvious technical means to enable screws and other supplies to be scanned at the point of use, e.g., during surgical procedures in the sterile field at the time at which such supplies are used. Embodiments of the present invention take all of the advantages of scanning at the point of use and apply them to the surgical context. 
     It is to be understood that although the invention has been described above in terms of particular embodiments, the foregoing embodiments are provided as illustrative only, and do not limit or define the scope of the invention. Various other embodiments, including but not limited to the following, are also within the scope of the claims. For example, elements and components described herein may be further divided into additional components or joined together to form fewer components for performing the same functions. 
     Any of the functions disclosed herein may be implemented using means for performing those functions. Such means include, but are not limited to, any of the components disclosed herein, such as the computer-related components described below. 
     The techniques described above may be implemented, for example, in hardware, one or more computer programs tangibly stored on one or more computer-readable media, firmware, or any combination thereof. The techniques described above may be implemented in one or more computer programs executing on (or executable by) a programmable computer including any combination of any number of the following: a processor, a storage medium readable and/or writable by the processor (including, for example, volatile and non-volatile memory and/or storage elements), an input device, and an output device. Program code may be applied to input entered using the input device to perform the functions described and to generate output using the output device. 
     Embodiments of the present invention include features which are only possible and/or feasible to implement with the use of one or more machines, such as computers, computer processors, and/or other elements of a computer system. Such features are either impossible or impractical to implement mentally and/or manually. For example, embodiments of the present invention read data from a machine-readable object, such as by using a wand to read data from a chip. This function cannot be performed by a human manually or mentally. 
     Any claims herein which affirmatively require a computer, a processor, a memory, or similar computer-related elements, are intended to require such elements, and should not be interpreted as if such elements are not present in or required by such claims. Such claims are not intended, and should not be interpreted, to cover methods and/or systems which lack the recited computer-related elements. For example, any method claim herein which recites that the claimed method is performed by a computer, a processor, a memory, and/or similar computer-related element, is intended to, and should only be interpreted to, encompass methods which are performed by the recited computer-related element(s). Such a method claim should not be interpreted, for example, to encompass a method that is performed mentally or by hand (e.g., using pencil and paper). Similarly, any product claim herein which recites that the claimed product includes a computer, a processor, a memory, and/or similar computer-related element, is intended to, and should only be interpreted to, encompass products which include the recited computer-related element(s). Such a product claim should not be interpreted, for example, to encompass a product that does not include the recited computer-related element(s). 
     Each computer program within the scope of the claims below may be implemented in any programming language, such as assembly language, machine language, a high-level procedural programming language, or an object-oriented programming language. The programming language may, for example, be a compiled or interpreted programming language. 
     Each such computer program may be implemented in a computer program product tangibly embodied in a machine-readable storage device for execution by a computer processor. Method steps of the invention may be performed by one or more computer processors executing a program tangibly embodied on a computer-readable medium to perform functions of the invention by operating on input and generating output. Suitable processors include, by way of example, both general and special purpose microprocessors. Generally, the processor receives (reads) instructions and data from a memory (such as a read-only memory and/or a random access memory) and writes (stores) instructions and data to the memory. Storage devices suitable for tangibly embodying computer program instructions and data include, for example, all forms of non-volatile memory, such as semiconductor memory devices, including EPROM, EEPROM, and flash memory devices; magnetic disks such as internal hard disks and removable disks; magneto-optical disks; and CD-ROMs. Any of the foregoing may be supplemented by, or incorporated in, specially-designed ASICs (application-specific integrated circuits) or FPGAs (Field-Programmable Gate Arrays). A computer can generally also receive (read) programs and data from, and write (store) programs and data to, a non-transitory computer-readable storage medium such as an internal disk (not shown) or a removable disk. These elements will also be found in a conventional desktop or workstation computer as well as other computers suitable for executing computer programs implementing the methods described herein, which may be used in conjunction with any digital print engine or marking engine, display monitor, or other raster output device capable of producing color or gray scale pixels on paper, film, display screen, or other output medium. 
     Any data disclosed herein may be implemented, for example, in one or more data structures tangibly stored on a non-transitory computer-readable medium. Embodiments of the invention may store such data in such data structure(s) and read such data from such data structure(s).