TECHNICAL FIELD

[0001] The present disclosure relates to surgical devices. More specifically, the present disclosure relates to improved surgical instruments for arthroplasty procedures.

BACKGROUND

[0002] Arthroplasty procedures can be used to relieve pain in or restore function of a joint due to conditions such as osteoarthritis, rheumatoid arthritis, or other joint conditions through minimally invasive or invasive surgery. An arthroplasty procedure can be performed on any joint and may include a partial or total joint replacement with a replacement prosthesis or prostheses. During an arthroplasty procedure, a surgeon may want to measure a size of an opening between two bones of the joint. In addition, the surgeon may also want to measure a balance of the joint in addition to a size of an opening (referred to as a gap) between two bones of the joint. For example, during partial or total knee replacement (TKR) arthroplasty, a surgeon may desire to gauge or measure a displacement between two bones of the joint and a balance of the joint. Taking such measurements during minimally invasive or invasive arthroplasty can be a challenge given forces applied to the joint by ligaments and other soft tissue of or around the joint. Accordingly, a need exists for improved systems and methods to measure the gap and/or angulation between bones in the course of an arthroplasty procedure.

SUMMARY

[0003] The various apparatus, devices, systems, and/or methods of the present disclosure have been developed in response to the present state of the art, and in particular, in response to the problems and needs in the art that have not yet been fully solved by currently available arthroplasty balance gauges or arthroplasty gap gauges. The apparatus, devices, systems, and/or methods of the present disclosure may provide arthroplasty balance, gap gauge, and cutting guide adjustment in a single device that remedy shortcomings of prior art separate arthroplasty balance gauges, arthroplasty gap gauges and/or cutting guides.

[0004] To achieve the foregoing, and in accordance with the disclosure as embodied and broadly described herein, a gap gauge for facilitating an arthroplasty procedure on a first bone and a second bone of a patient may be provided. One general aspect of the gap gauge can include a first plate positionable in contact with the first bone, a second plate positionable in contact with the second bone, wherein the second plate is displaced from the first plate by a displacement. The gap gauge may also include a separator connected to the first plate and the second plate, wherein the separator can be actuated to adjust the displacement, a separation indicator coupled to the separator and configured to indicate the displacement, and a balance indicator connected to at least one of the first plate and the second plate and configured to indicate a balance status between the first plate and the second plate.

[0005] In one aspect, the balance indicator may include a hinge that pivotally connects the second plate to the gap gauge. The hinge may include a pin having a longitudinal axis that is a pivot axis of the second plate. The longitudinal axis may be parallel to an anterior-posterior axis of the patient such that rotation of the second plate about the pivot axis measures one of a varus condition, a balanced condition, and a valgus condition of the first bone relative to the second bone. [0006] In another aspect, the gap gauge may include a support plate connected to a hinge and a separator and the balance indicator may include a lock-out mechanism configured to prevent rotation of one of the first plate and the second plate connected to the balance indicator. The lock-out mechanism may include a set screw having a set configuration and an unset configuration, the set screw may include threads configured to engage threads within an opening. In the set configuration, the set screw may engage the pin of the hinge such that the pin does not rotate in response to a rotational force applied to at least one of the first plate and the second plate. The engaged pin may also prevent rotation of at least one of the first plate and second plate connected to the pin. In the unset configuration, the set screw is disengaged from the pin of the hinge such that the pin rotates in response to a rotational force applied to at least one of the first plate and the second plate. In one aspect, the set screw engages the pin by biasing against a planar surface of a section of the pin, the section of the pin has a D-shaped cross- section.

[0007] In one aspect, the gap gauge may include a first plate shaped to engage a medial condyle and a lateral condyle of the first bone and a second plate shaped to engage a medial condyle and a lateral condyle of the second bone.

[0008] In one aspect, the gap gauge may include a balance gauge, connected to the balance indicator. The balance gauge may be configured to measure the balance status. The gap gauge may include a dial having marks positioned on a face of the dial to indicate a measure of the balance status of the second plate relative to the first plate, and a needle connected to the balance indicator such that rotation of the second plate about a longitudinal axis of the second plate moves the needle to point toward a mark on the face of the dial that reflects the balance status.

[0009] One general aspect can include a gauge that may have a superior plate extending from a superior body, the superior plate shaped to match a resected surface of the femur, an inferior plate extending from an inferior body, the inferior body shaped to match a resected surface of the tibia, wherein the superior plate is displaced from the inferior plate by a displacement. The gauge may also include a shaft along which at least one of the superior body and the inferior body is slidably coupled to permit adjustment of the displacement, a separator connected to the superior body and the inferior body to adjust the displacement, and a balance indicator connected to one of the superior plate and the inferior plate and configured to indicate an orientation of the superior plate relative to the inferior plate.

[0010] In one aspect the balance indicator connects to the superior plate, the superior plate that includes a pivot plate and a support plate and the balance indicator includes a hinge that includes a pin connected to the pivot plate such that a force applied to the pivot plate can rotate the pivot plate about the pin. The support plate couples to the separator such that actuation of the separator moves the support plate vertically relative to the inferior plate. The pin may include a cylindrical structure that has a longitudinal axis, a proximal end, a distal end, and a middle. The proximal end may connect to a balance gauge and the distal end comprises a pivot for the balance indicator. The pivot may be aligned with the longitudinal axis. In one embodiment, the proximal end may include a first D- shaped cross-section, the distal end may include at least one keyed section, and the middle may include a second D-shaped cross-section having a flat part of the second D-shaped cross-section offset 90 degrees from a flat part of the first D-shaped cross-section. The distal end serves as a pivot for the hinge.

[0011] In one aspect, the gap gauge further includes a handle connected to the inferior body, a separation indicator coupled to the separator and configured to indicate the displacement, a lock-out mechanism connected to the superior body and configured to prevent rotation of the superior plate, or a part of the superior plate, connected to the balance indicator, and a spring coupled to the shaft that biases one of the superior body and the inferior body in opposition to movement of the superior plate away from the inferior plate. The separator may include a driver, a cam connected to the inferior body by way of the driver, the cam includes a contacting surface, and a follower connected to the superior body and biased and configured to contact the contacting surface of the cam such that rotation of the cam adjusts the displacement. In one embodiment, the follower slidably contacts the contacting surface. The cam may include a radial cam having a central axis and the contacting surface be a circumference of the radial cam about the central axis.

[0012] In one aspect, the gap gauge may include a balance gauge coupled to the balance indicator. The balance gauge may include a dial having marks positioned on a face to indicate a measure of the orientation of the superior plate relative to the inferior plate. The balance gauge may also include a needle connected to the balance indicator such that rotation of one of the superior plate and the inferior plate about an anterior-posterior axis of the patient moves the needle to point toward a mark on the face of the dial that reflects the orientation.

[0013] One general aspect of the present disclosure can include a method for measuring a gap between a femur and a tibia of a patient. The method may include, inserting a first plate and a second plate of a gap gauge between the femur and the tibia, actuating the first plate and the second plate apart such that the first plate is in contact with a resected surface of the femur and the second plate is in contact with a resected surface of the tibia, reading a separation indicator of the gap gauge to obtain a displacement between the femur and the tibia, and reading a balance indicator of the gap gauge to obtain a balance status between the femur and the tibia.

[0014] In one aspect, the method may also include adjusting a tension applied to the femur and the tibia by one or more of a medial collateral ligament and a lateral collateral ligament, and reading the balance indicator of the gap gauge to obtain an adjusted balance status between the femur and the tibia in response to adjusting the tension.

[0015] In another embodiment, adjusting the tension may also include releasing one or more of the medial collateral ligament and the lateral collateral ligament while the gap gauge remains between the femur and the tibia and remains actuated.

[0016] In another embodiment, adjusting the tension may also include removing the gap gauge from between the femur and the tibia, resecting one or more of the resected surface of the femur and the resected surface of the tibia, re-inserting the first plate and the second plate of the gap gauge between the femur and the tibia, actuating the first plate and the second plate apart such that the first plate is in contact with the resected surface of the femur and the second plate is in contact with the resected surface of the tibia, reading the separation indicator of the gap gauge to obtain the displacement between the femur and the tibia, and reading the balance indicator of the gap gauge to obtain the balance status between the femur and the tibia.

[0017] In one aspect, a gap gauge for facilitating an arthroplasty procedure on a first bone and a second bone of a patient may be provided. One general aspect of the gap gauge can include a first plate positionable in contact with the first bone. The gap gauge also includes a second plate positionable in contact with the second bone, where the second plate is displaced from the first plate by a displacement. The gap gauge also includes a balance indicator configured to indicate a balance status between the first plate and the second plate. The gap gauge also includes a pin guide configured to couple to one of the second plate and the first plate, the pin guide may include a first pin hole configured to guide insertion of a first pin into the second bone. [0018] In one aspect, the pin guide may include an attachment feature configured to removably couple the pin guide to the second plate such that the pin guide guides insertion of the first pin into the second bone according to the balance status between the first plate and the second plate. The pin guide further may include an attachment feature configured to removably couple the pin guide to the second plate such that the pin guide guides insertion of the first pin into the first bone according to the balance status between the first plate and the second plate. [0019] In another aspect, the pin guide may include a second pin hole configured to guide insertion of a second pin into the second bone. In one aspect, the pin guide couples to the first plate and extends from the first plate such that the pin guide guides insertion of the first pin and the second pin into the second bone such that the first pin and the second pin align at an angle relative to the second plate that counters the balance status between the first plate and the second plate.

[0020] In one aspect, the first pin hole guides insertion of the first pin into one of a medial condyle and a lateral condyle of the second bone and the pin guide may include a second pin hole configured to guide insertion of a second pin into the other one of the medial condyle and the lateral condyle of the second bone.

[0021] In another aspect, the pin guide may include: a second pin hole configured to guide insertion of a second pin parallel to the first pin into the second bone and an adjustment feature configured to rotate the first pin hole and the second pin hole together to counter different angular offsets of the balance status.

[0022] In one aspect, the pin guide may include: a base configured to connect to the second plate; an arm that may include the first pin hole; and a mast extending from the base, the mast connecting the arm and the base. The arm may include a second pin hole, the first pin hole and the second pin hole each positioned in the arm on one of a medial side and a lateral side of a knee when the gap gauge is in place relative to the knee.

[0023] In another aspect, the pin guide may include a second pin hole configured to guide insertion of a second pin into the second bone such that the first pin and the second pin align with each other at an orientation relative to the second plate that matches the balance status; and where coupling a cutting guide to the second bone by way of the first pin and the second pin communicates the balance status to the cutting guide.

[0024] In one aspect, a cutting guide may include an alignment feature that may include a plurality of sets of holes, each member (each set) of the sets of holes configured to accept one of the first pin and the second pin. Each set of holes may be configured to adjust for a different angular offset for the balance status.

[0025] In another aspect, the cutting guide may include: a guide feature configured to guide motion of a cutter to resect a bone; an alignment feature configured to accept the first pin and the second pin and position the cutting guide on the bone; and an adjustment feature configured to rotate the guide feature relative to the alignment feature to adjust for different angular offsets from the balance status.

[0026] In one aspect, the first plate and the second plate are sized for insertion between the first bone that may include a tibia and the second bone that may include a femur.

[0027] One general aspect can include a gap measurement and correction assembly for facilitating an arthroplasty procedure on a femur and a tibia of a patient. The gap measurement and correction assembly also includes a gap gauge that may include : a superior plate extending from a superior body ; an inferior plate extending from an inferior body, where the superior plate is displaced from the inferior plate by a displacement; a separator connected to the superior body and the inferior body to adjust the displacement; a balance indicator connected to one of the superior plate and the inferior plate and configured to indicate a nonparallel orientation of the superior plate relative to the inferior plate; and a pin guide configured to guide insertion of a first pin into one of the tibia and the femur of the patient. The gap measurement and correction assembly also includes a cutting guide attachable to one of the tibia and the femur via the first pin, where the cutting guide is configured to guide resection of the one of the tibia or the femur that counters the nonparallel orientation.

[0028] In one aspect, the assembly where the pin guide further may include an attachment feature configured to removably couple the pin guide to the superior plate such that the pin guide guides insertion of the first pin into the femur according to the nonparallel orientation of the superior plate relative to the inferior plate. The pin guide further may include an attachment feature configured to removably couple the pin guide to the superior plate such that the pin guide guides insertion of the first pin into the tibia according to the nonparallel orientation of the superior plate relative to the inferior plate.

[0029] In another aspect, the pin guide is further configured to guide a second pin into the other one of the tibia and the femur of the patient; and where the pin guide further may include an attachment feature configured to removably couple the pin guide to the inferior plate such that the pin guide guides insertion of the first pin and the second pin into the femur such that the first pin and the second pin align at an angle relative to the superior plate that counters the nonparallel orientation of the superior plate relative to the inferior plate.

[0030] In one aspect, the pin guide may include: a base configured to connect to the superior plate; an arm may include a first pin hole; and a mast extending from the base, the mast connecting the arm and the base. The cutting guide may include an alignment feature that may include a plurality of sets of holes each member of the sets of holes configured to accept one of the first pin and a second pin, each set of holes configured to adjust for a different angular offset for the nonparallel orientation.

[0031] In another aspect, the cutting guide may include: a guide feature configured to guide motion of a cutter to resect a bone; an alignment feature configured to accept the first pin and a second pin and position the cutting guide on the bone; and an adjustment feature configured to rotate the guide feature relative to the alignment feature to adjust for different angular offsets from the nonparallel orientation.

[0032] One general aspect can include a method for measuring and correcting imbalance for an arthroplasty procedure on a femur and a tibia of a patient. The method includes inserting a first plate and a second plate of a gap gauge between the femur and the tibia of a knee joint of a patient. The method also includes actuating the first plate and the second plate apart such that the first plate is in contact with a resected surface of the femur and the second plate is in contact with a resected surface of the tibia. The method also includes reading a balance indicator of the gap gauge to obtain a balance status between the femur and the tibia, inserting a first pin through a pin guide of the gap gauge, securing the first pin to one of the femur and the tibia, and coupling a cutting guide to the one of the femur and the tibia using the first pin. The method also includes using the cutting guide to guide resection of one of the femur and the tibia to counter a nonparallel orientation of the first plate relative to the second plate. [0033] These and other features and advantages of the present disclosure will become more fully apparent from the following description and appended claims or may be learned by the practice of the disclosure as set forth hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Exemplaiy embodiments of the disclosure will become more fully apparent from the following description and appended claims, taken in conjunction with the accompanying drawings. Understanding that these drawings depict only exemplary embodiments and are, therefore, not to be considered limiting of the scope of the appended claims, the exemplary embodiments of the present disclosure will be described with additional specificity and detail through use of the accompanying drawings in which:

[0035] Figure 1A is a perspective view of a gap gauge, according to one embodiment of the present disclosure;

[0036] Figure IB is a perspective view of the gap gauge of Figure 1A;

[0037] Figures 1C - II are a top view, bottom view, side views, rear view, and front view of the gap gauge of Figure 1A, according to one embodiment of the present disclosure;

[0038] Figure 2 is an anterior view of a knee joint with the gap gauge of Figure 1 A inserted between two bones;

[0039] Figure 3 is an anterior view of a knee joint with the gap gauge of Figure 1 A inserted between two bones;

[0040] Figure 4 is a posterior view of a knee joint with the gap gauge of Figure 1 A inserted between two bones;

[0041] Figures 5A-5C are rear views of the gap gauge of Figure 1A illustrating different balance status states;

[0042] Figures 6 A-6C are rear views of the gap gauge of Figure 1 A illustrating different displacements;

[0043] Figure 7 is a perspective view of the gap gauge of Figure 1A;

[0044] Figure 8A is a front view of a driver of a gap gauge, according to one embodiment of the present disclosure;

[0045] Figure 8B is a rear view of a driver and cam of a gap gauge, according to one embodiment of the present disclosure;

[0046] Figure 9 illustrates an exploded view of a gap gauge, according to one embodiment of the present disclosure;

[0047] Figure 10A is a perspective view of a pin of the gap gauge of Figure 1A, according to one embodiment of the present disclosure;

[0048] Figures 10B and IOC are side views of the pin of Figure 10A, according to one embodiment of the present disclosure;

[0049] Figures 11 A and 1 IB are perspective views of a lock-out mechanism of a gap gauge, according to one embodiment of the present disclosure; and

[0050] Figure 12 illustrates a flowchart for measuring a gap and/or balance status between a femur and a tibia of a patient, according to one embodiment of the present disclosure.

[0051] It is to be understood that the drawings are for purposes of illustrating the concepts of the disclosure and may not be drawn to scale. Furthermore, the drawings illustrate exemplary embodiments and do not represent limitations to the scope of the present disclosure.

DETAILED DESCRIPTION

[0052] Exemplary embodiments of the present disclosure will be best understood by reference to the drawings, wherein like parts are designated by like numerals throughout. It will be readily understood that the components of the present disclosure, as generally described and illustrated in the Figures herein, could be arranged and designed in a wide variety of different configurations. Thus, the following more detailed description of the embodiments of the apparatus and method, as represented in the Figures, is not intended to limit the scope of the present disclosure, as claimed in this or any other application claiming priority to this application, but is merely representative of exemplary embodiments of the present disclosure.

[0053] Standard medical directions, planes of reference, and descriptive terminology are employed in this specification. For example, anterior means toward the front of the body. Posterior means toward the back of the body. Superior means toward the head. Inferior means toward the feet. Medial means toward the midline of the body. Lateral means away from the midline of the body. Axial means toward a central axis of the body. Abaxial means away from a central axis of the body. Ipsilateral means on the same side of the body. Contralateral means on the opposite side of the body. A sagittal plane divides a body into right and left portions. A midsagittal plane divides the body into bilaterally symmetric right and left halves. A coronal plane divides a body into anterior and posterior portions. A transverse plane divides a body into superior and inferior portions.

[0054] An anterior-posterior axis is an axis perpendicular to the coronal plane. A medial-lateral axis is an axis perpendicular to the median plane. A cephalad-caudal axis is an axis perpendicular to the transverse plane. These descriptive terms may be applied to an animate or inanimate body.

[0055] The phrases "connected to," "coupled to" and "in communication with" refer to any form of interaction between two or more entities, including mechanical, electrical, magnetic, electromagnetic, fluid, and thermal interaction. Two components may be functionally coupled to each other even though they are not in direct contact with each other. The term "abutting" refers to items that are in direct physical contact with each other, although the items may not necessarily be attached together. The phrase "fluid communication" refers to two features that are connected such that a fluid within one feature is able to pass into the other feature.

[0056] The word "exemplary" is used herein to mean "serving as an example, instance, or illustration." Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments. While the various aspects of the embodiments are presented in drawings, the drawings are not necessarily drawn to scale unless specifically indicated.

[0057] The present disclosure discloses a gap gauge for facilitating an arthroplasty procedure on a first bone and a second bone of a patient. During an arthroplasty procedure, a surgeon may need to confirm that the gap between two bones of the joint is of a desired displacement and that the joint has a desired balance (e.g. balanced, varus condition, or valgus condition). Using separate instruments to get either the displacement or the balance status can complicate the procedure and may require more personnel to assist in the procedure. As one instrument is exchanged for another (e.g., an instrument that only measures displacement exchanged for an instrument that only measures balance status), parts of a joint can shift and thus alter a displacement already measured or alter a balance status read using an instrument that cannot provide both displacement measurements and a balance status, or balance measurement in a single instrument. Consequently, a need exists for an improved gap gauge. In particular, a need exists for gap gauge that can provide both a displacement measurement and a balance status (e.g., balance measurement) using a single instrument. Furthermore, the present disclosure provides for a gap gauge that enables a user to optionally disengage/disable a balance indicator or balance gauge 168 during use for that a user can use the same instrument to only measure displacement between two joint bones, if desired.

[0058] Figure 1A is a perspective view depicting one exemplary embodiment of a gap gauge 100 for facilitating an arthroplasty procedure on a first bone and a second bone of a patient. As used herein, an “arthroplasty procedure” refers to a surgical procedure for restoring and/or improving function and/or operation of a joint of a patient. An arthroplasty procedure can be done for a toe joint, ankle joint, knee joint, hip joint, arm joint, elbow joint, finger joint, or the like. In the illustrated embodiment, the first bone can be a femur 102 and the second bone can be a tibia 104. As used herein, a "gap gauge" refers to an apparatus, instrument, structure, device, component, system, assembly, hardware, software, firmware, circuit, module, or logic structured, organized, configured, programmed, designed, arranged, or engineered to measure an attribute, characteristic, state, or condition of another structure or object or set of structures or objects. In one embodiment, the gap gauge is structured, organized, configured, programmed, designed, arranged, or engineered to measure a displacement between two structures.

[0059] As part of an arthroplasty procedure, the gap gauge 100 can be inserted into an opening 106, also referred to as a gap, between the first bone and the second bone. The gap gauge 100 can be used to determine how much displacement exists between the first bone and the second bone within the opening 106. As used herein, an “opening” refers to a gap, a hole, an aperture, a void in a structure, or the like. In certain embodiments, an opening can refer to a structure configured specifically for receiving something and/or for allowing access. The amount of displacement can be referred to herein as measuring a gap, or space, between the first bone and second bone. [0060] In addition, or alternatively, the gap gauge 100 can be used to determine a balance status of a joint 108 that is part of the arthroplasty procedure. The joint 108 can be a toe joint, ankle joint, knee joint, hip joint, arm joint, elbow joint, finger joint, or the like. In the illustrated embodiment, the joint 108 is a knee joint and the first bone is a femur 102 and the second bone is a tibia 104. Gap gauge 100 can be used to determine both displacement within the opening 106 and a balance status using a single device. Alternatively, a user, such as a surgeon, can use the gap gauge 100 to determine displacement or a balance status using a single convenient device with the first bone and second bone in flexion, in extension, or at an angle between flexion and extension.

[0061] Figure 1A illustrates a three-dimensional axis 110. The three-dimensional axis 110 includes a cephalad-caudal axis 112, a medial-lateral axis 114, and an anterior-posterior axis 116. The three-dimensional axis 110 is used to identify how a gap gauge 100 is positioned and/or oriented with respect to an anterior-posterior axis 116 of a patient who is in a reference anatomical position.

[0062] Figure IB is a perspective view of the gap gauge 100 of Figure 1A. Figure IB illustrates the gap gauge 100 without a first bone or second bone shown. The gap gauge 100 may generally include a first plate, a second plate, a separator, a separation indicator, and a balance indicator. In the illustrated embodiment, the first plate may be a superior plate 118 and the second plate may be an inferior plate 120. The illustrated gap gauge 100 also includes a separator 122, a separation indicator 124, and a balance indicator 126.

[0063] In one embodiment, the superior plate 118 is a plate. As used herein, a "plate" refers to aflat structure or a generally flat structure. In certain embodiments, a plate can be configured to support a load. In certain embodiments, a plate may comprise a generally planar structure. A plate can be a separate structure connected to, or integrated with, another structure. Alternatively, a plate can be connected to part of another structure. A plate can be two-dimensional or three-dimensional and can have a variety of geometric shapes and/or cross-sectional shapes, including, but not limited to a rectangle, a square, or other polygon, as well as a circle, an ellipse, an ovoid, or other circular or semi-circular shape. A plate can be made from a variety of materials including, metal, plastic, ceramic, wood, fiberglass, or the like. The inferior plate 120 can also be a plate.

[0064] The superior plate 118 can be positioned opposite the inferior plate 120. The superior plate 118 can be positioned in contact with a first bone (e.g., a femur 102). The inferior plate 120 can be positioned in contact with a second bone (e.g., a tibia 104). The superior plate 118 and inferior plate 120 can be parallel to each other and cooperate to slide into an opening or gap.

[0065] In one embodiment, the superior plate 118 and inferior plate 120 have a structural integrity that permits them to be positioned, (e.g., inserted) between a femur 102 and a tibia 104. When initially positioned between two bones, the superior plate 118 and inferior plate 120 may contact each other as illustrated in FIGURE 1 A. Once positioned between two bones, a user may move the superior plate 118 relative to the inferior plate 120 which adjusts a displacement 128 between the superior plate 118 and the inferior plate 120. When the superior plate 118 and inferior plate 120 contact each other, the displacement 128 may be zero. In one embodiment, the superior plate 118 and inferior plate 120 may be displaced from each other by a displacement 128 when the gap gauge 100 is initially manufactured/assembled.

[0066] As used herein, a "displacement" refers to a vector that measures how much a structure, member, object, component, or part has moved, changed position, from a starting position to an ending position, or measures the distance between two objects. Displacement can be measured using a variety of units of measure including imperial units, metric units, angular units and the like. In certain embodiments, the displacement is measured in millimeters. In one embodiment, the displacement 128 may range from zero to twenty -five or more millimeters.

[0067] A user may adjust the displacement 128. A user may separate the superior plate 118 and the inferior plate 120 by manually pulling them apart and/or the user may use the separator 122 to separate the superior plate 118 and the inferior plate 120. A user may bring the superior plate 118 and the inferior plate 120 together by manually positioning them and/or the user may use the separator 122 to bring the superior plate 118 and the inferior plate 120 together.

[0068] The separator 122 connects to the superior plate 118 and to the inferior plate 120. The separator 122 can adjust the displacement 128. In one embodiment, actuation of the separator 122 adjusts the displacement 128. As used herein, a "separator" refers to an apparatus, instrument, structure, device, component, system, assembly, or module structured, organized, configured, programmed, designed, arranged, or engineered to separate a first structure from another structure. In one embodiment, the separator is structured, organized, configured, programmed, designed, arranged, or engineered to separate a first plate from a second plate and thereby create a distance between the first plate and the second plate. The separator 122 can actively adjust the displacement 128 and/or retain the superior plate 118 and inferior plate 120 in a certain state of separation, thereby maintaining a desired displacement 128.

[0069] The separation indicator 124 indicates the displacement 128 between the superior plate 118 and the inferior plate 120. The separation indicator 124 can be coupled to the separator 122. As used herein, a "separation indicator" refers to an apparatus, device, component, system, assembly, hardware, software, firmware, circuit, module, or logic structured, organized, configured, programmed, designed, arranged, or engineered to indicate a displacement between two or more structures to a user. The separation indicator can include one or more of an audible signal, a tactile signal, a visual signal or indication, and the like. In one embodiment, a visual indicator for the separation indicator may comprise a number or set of numbers that represent a unit of measure for the displacement (or distance) between the two or more structures. Alternatively, or in addition, the separation indicator may comprise a mechanical device, an electromechanical device, an electronic device (analog or digital), and the like. [0070] The balance indicator 126 indicates a balance status. As used herein, a "balance indicator" refers to an apparatus, device, component, system, assembly, mechanism, hardware, software, firmware, circuit, module, or logic structured, organized, configured, programmed, designed, arranged, or engineered to indicate a balance status to a user of a device or apparatus that includes the balance indicator. The balance indicator can include one or more of an audible signal, a tactile signal, a visual signal or indication, and the like. Alternatively, or in addition, the balance indicator may comprise a mechanical device, an electromechanical device, an electronic device (analog or digital), and the like. As used herein, a "balance status" refers to a condition, state, attribute, value, and/or characteristic, of one or more members, components, structures, and/or openings relative to a state of desired, correct, and/or equal proportions between a reference set of one or more members, components, structures, and/or openings and the one or more members, components, structures, and/or openings being evaluated, measured, or examined. In certain embodiments, the balance status can be a binary condition, state, attribute, value, and/or characteristic. For example, a relationship between the one or more structures or openings and a reference set of one or more structures or openings may be either balanced or unbalanced (also referred to as imbalanced).

[0071] Alternatively, or in addition, a balance status can be a condition, state, attribute, value, and/or characteristic within a range of possible conditions, states, attributes, values, and/or characteristics. For example, in one embodiment, a balance status may be measured with respect to a scale or range of degrees between a positive maximum value and a negative minimum value where a balance status of zero on the range represents a balanced state and a non-zero value along the range represents an unbalanced state. In one embodiment, a range used to measure the balance status may extend from -5 degrees to +5 degrees.

[0072] In certain embodiments, a balance status can represent whether, or not, a superior resection of one bone of a joint is parallel to an inferior resection of another bone of the joint. In another embodiment, a balance status can represent a degree to which a superior resection of one bone of a joint is, or is not, parallel to an inferior resection of another bone of the joint. In another embodiment, a balance status can represent how two bones of a joint and space / opening between them relate to a medial collateral ligament and a lateral collateral ligament interact to each other to achieve a desired relationship with the joint.

[0073] In one embodiment, the balance indicator 126 indicates a balance status between the superior plate 118 and the inferior plate 120. Alternatively, or in addition, the balance indicator 126 may indicate abalance status for a joint 108 and/or between a medial collateral ligament and a lateral collateral ligament of a joint 108. Alternatively, or in addition, the balance indicator 126 may indicate a balance status between a first bone and a second bone. In the context of knee arthroplasty, the balance indicator 126 may indicate whether the arthroplasty procedure, if completed with implants on the measured bone surfaces, is likely to be varus, valgus, or balanced. [0074] The balance indicator 126 can be connected to one, or the other, or both, of superior plate 118 and the inferior plate 120. In one embodiment, the balance indicator 126 connects to the superior plate 118. The balance indicator 126 is illustrated as a dashed region of the gap gauge 100 because one or more components or elements in the dashed region can serve as the balance indicator 126 in different embodiments. For example, in one embodiment, a user may observe a non-parallel position of the superior plate 118, or part of the superior plate 118, and such observation may serve as the balance indicator 126.

[0075] Figures 1C - II illustrate a top view (FIGURE 1C), bottom view (FIGURE ID), side views (FIGURE E-G), rearview (FIGURE 1H), and front view (FIGURE II) of one embodiment of a gap gauge 100. FIGURE 1C illustrates an embodiment that includes a lock-out mechanism 130, a pair of grips 132, and a handle 134. As used herein, a "handle" refers to a structure used to hold, control, or manipulate a device, apparatus, component, tool, or the like. A “handle” may be designed to be grasped and/or held in one or more hands of a user.

[0076] In certain embodiments, the lock-out mechanism 130 can be used by a user to disable, prevent, or ton off actuation of the balance indicator 126 to indicate a balance status. As used herein, a "lock-out mechanism" refers to an apparatus, instrument, structure, device, component, system, assembly, hardware, software, firmware, circuit, module, or logic structured, organized, configured, programmed, designed, arranged, or engineered to prevent, mitigate, or stop operation of a balance indicator of a gap gauge such that the balance indicator does not report a balance status when the gap gauge is actuated. In one embodiment, the lock-out mechanism can prevent rotation of a plate connected to the balance indicator of a gap gauge. The pair of grips 132 can be used by a user to position the superior plate 118 relative to the inferior plate 120. For example, a user may grab the pair of grips 132 with one hand and hold the handle 134 with another hand and pull up on the grips 132 to separate the superior plate 118 and the inferior plate 120.

[0077] FIGURE ID illustrates a bottom view of one embodiment of the gap gauge 100. The view shows the inferior plate 120, lock-out mechanism 130, grips 132, and handle 134.

[0078] FIGURE IE illustrates a side view of one embodiment of the gap gauge 100. The view shows the superior plate 118, inferior plate 120, separator 122, a grip 132, and a handle 134. In addition, the illustrated embodiment includes a superior body 136, an inferior body 138, a shaft 140, and a spring 142. As used herein, a "body" refers to a main or central part of a structure. In one embodiment, a body may include a housing or frame or framework for a larger system, component, structure, or device. As used herein, a "spring" refers to an elastic structure that stores mechanical energy. Springs can be made of a variety of elastic material such as spring steel and can be cylindrical and/or helical in shape. Various types of springs can be used including coil springs, torsion springs, and the like. (Search "spring (device)" on Wikipedia.com Nov. 28, 2020. Modified. Accessed Jan. 6, 2020.)

[0079] The superior body 136 provides structural support and integrity forthe gap gauge 100 and may house one or more parts of the gap gauge 100. The inferior body 138 provides structural support and integrity for the gap gauge 100 and may house one or more parts of the gap gauge 100. In one embodiment, the superior plate 118 extends from the superior body 136 and the inferior plate 120 extends from the inferior body 138.

[0080] The shaft 140 may couple or connect the superior body 136 to the inferior body 138. The shaft 140 may slidably couple with the superior body 136 to the inferior body 138. The slidable coupling between the shaft 140, the superior body 136, and the inferior body 138 permits adjustment of the displacement 128.

[0081] In one embodiment, the shaft 140 may fit within an opening in the superior body 136 and pass through the superior body 136 to engage the inferior body 138. In certain embodiments, the shaft 140 can include threads on the outside of one end of the shaft 140. The threads of the shaft 140 may engage threads of an opening in the inferior body 138 to connect the shaft 140 to the inferior body 138. The shaft 140 may include a head 144 on one end opposite an end that includes the threads.

[0082] The opening in the superior body 136 can be sized to accept the shaft 140 and the spring 142 coiled around the outside of the shaft 140. The spring 142 may contact the superior body 136 and the head 144. The shaft 140 and spring 142 cooperated to retain the superior body 136 connected to the inferior body 138. In one embodiment once assembled in the gap gauge 100, the spring 142 may be biased against the head 144 and the superiorbody 136. The spring 142 can bias the superior body 136 in opposition to movement of the superior plate 118 away from the inferior plate 120.

[0083] In certain embodiments, the gap gauge 100 may include a post 146. The post 146 may slidably engage the superior body 136 and be connected to the inferior body 138. In one embodiment, the post 146 may be screwed into an opening in the superior body 136. The post 146 may cooperate with the shaft 140 to maintain movement of the superiorbody 136 along a single axis.

[0084] FIGURE IF illustrates a side view of one embodiment of the gap gauge 100. The side view shows the superior plate 118, inferior plate 120, separator 122, a lock-out mechanism 130, a grip 132, a handle 134, a superior body 136, inferior body 138, a shaft 140, a spring 142, and a post 146.

[0085] FIGURE 1G illustrates a side view of one embodiment of the gap gauge 100. The side view shows the superior plate 118, inferior plate 120, separator 122, a lock-out mechanism 130, a grip 132, a handle 134, a superiorbody 136, inferior body 138, a shaft 140, spring 142, and a post 146.

[0086] FIGURE 1G illustrates the gap gauge 100 with the separator 122 actuate such that the superior plate 118 and inferior plate 120 are displaced from each other by a displacement 128. In one embodiment, the displacement 128 is a measure between an external surface of the superior plate 118 and an external surface of the inferior plate 120. Those of skill in the art will recognize that a displacement can also be a measure between an internal surface of the superior plate 118 and an internal surface of the inferior plate 120 indicated by displacement 128’.

[0087] In the illustrated embodiment, the gap gauge 100 may include a superior plate 118 that includes a pivot plate 148 and a support plate 150. The pivot plate 148 can be connected, or coupled, to the support plate 150 such that the pivot plate 148 can serve as a balance indicator 126. In one embodiment, the pivot plate 148 can pivot about the anterior-posterior axis 116 relative to the support plate 150. As used herein, a "support plate" refers to a plate structured, organized, configured, programmed, designed, arranged, or engineered to support a load. [0088] FIGURE 1H illustrates a rear view of one embodiment of the gap gauge 100. The rear view shows the superior plate 118, inferior plate 120, separation indicator 124, balance indicator 126, grips 132, handle 134, shaft 140, spring 142, pivot plate 148, and support plate 150. In one embodiment, the inferior plate 120 can be a first plate and the superior plate 118 can be a second plate, or vice versa. Furthermore, in certain embodiments, the inferior plate 120 can be a first plate and the pivot plate 148 can be the second plate, or vice versa. In such embodiments, the gap gauge 100 may not include a support plate 150.

[0089] FIGURE 1H illustrates an embodiment of a gap gauge 100 that includes a driver 152 and a fastener 154. The driver 152 serves to actuate the separator 122. The driver 152 can include a circumference having curved slots that facilitate rotating the driver 152. In one embodiment, the driver 152 serves to engage the separator 122 such that a displacement 128 is maintained. As used herein, a "driver" refers to a mechanical piece, component, or structure for imparting motion to another piece, component, or structure ("driver." Merriam-Webster.com. Merriam-Webster, 2021. Web. 6 Jan. 2021. Modified.) In certain embodiments, a driver canbe awheel configured or connected to other parts such that rotation or motion of the driver causes motion of other interconnected or intercoupled parts of a component, system, apparatus, or device.

[0090] The fastener 154 secures the driver 152 to the gap gauge 100. In one embodiment, the fastener 154 is a bolt that screws into the inferior body 138 and permits the driver 152 to rotate freely about the bolt. [0091] FIGURE II illustrates a front view of one embodiment of the gap gauge 100. The front view shows the superiorplate 118, inferior plate 120, grips 132, handle 134, shaft 140, spring 142, pivotplate 148, and support plate 150. In one embodiment, the balance indicator connects to a second plate, such as superior plate 118, and the balance indicator includes a hinge 156 that pivotally connects the superior plate 118 to the gap gauge 100. In one embodiment, the hinge 156 connects to the support plate 150.

[0092] As used herein, a "hinge" refers to an apparatus, instrument, structure, device, component, member, system, assembly, or module structured, organized, configured, designed, arranged, or engineered to connect two structures such that one structure can rotate about a fixed longitudinal axis of the hinge with respect to the other structure. In one embodiment, a hinge may be considered a mechanical bearing that restricts relative movement of the two structures to a desired kind of movement. In certain embodiments, various types of hinges can be used including a barrel hinge, a butt hinge, a butterfly hinge, a case hinge, a concealed hinge, a continuous / piano hinge, a flag hinge, an H hinge, an HL hinge, a pivot hinge, a self-closing hinge, a spring hinge, a living hinge, a coach hinge, a flush hinge, or the like.

[0093] A hinge can include a pin, one or more knuckles (also referred to as loops, joints, nodes, curls, etc.), and one or more leaves. As used herein, a "pin" refers to a cylindrical structure having a cross-sectional diameter small enough to fit within openings of one or more knuckles of a hinge. In certain embodiments, the pin can include a head on one end, the head can be larger than a diameter of the openings of the one or more knuckles such that the head prevents the pin from passing completely through the openings of the one or more knuckles. A pin can be made from a variety of material including metal, plastic, wood, or the like. A leaf is a structure that extends laterally from the one or more knuckles and can be integrated with or connected to a structure that is intended to pivot or rotate about the pin. In certain embodiments, a hinge can include two or more leaves. A leaf can be a planar structure.

[0094] A knuckle is a structure with an opening sized to receive the pin. A knuckle connects to at least one leaf. A knuckle can have a circular longitudinal cross-section and can be cylindrical. In certain embodiments, each leaf includes a knuckle that can be aligned along a longitudinal axis of the hinge. Once the one or more knuckles are aligned along the longitudinal axis of the hinge, the pin can be inserted into openings of the one or more knuckles to secure the leaf / leaves connected to each knuckle.

[0095] FIGURE II includes a front view of one embodiment of a balance indicator 126. In such an embodiment, the superior plate 118 can include a pivot plate 148 coupled to the gap gauge 100 by the hinge 156. In certain embodiments, the hinge 156 may serve both as a hinge and as a balance indicator 126. For example, a user may view the hinge 156 during an arthroplasty procedure and detect that the pivot plate 148 (or the superior plate 118) is oriented non-parallel to an inferior plate 120. In this manner, a user can determine a balance status. [0096] In one embodiment, the hinge 156 can include a pin 158. The pin 158 can couple, or connect, to the pivot plate 148. The pin 158 can connect the support plate 150 and the pivot plate 148. In another embodiment, the hinge 156 may not connect to a support plate 150. The pin 158 has a longitudinal axis 160 that is a pivot axis 162 for the pivot plate 148. A force (e.g., a force in the direction of arrow 164 or arrow 166) applied to the pivot plate 148 can rotate the pivot plate 148 about the pin 158. As used herein, a "pivot axis" refers to an axis about which a structure pivots or rotates.

[0097] During an arthroplasty procedure, a user may align the longitudinal axis of the pin 158, and hence the pivot axis of the pivot plate 148, with an anterior-posterior axis 116 of a patient in order to determine a balance status. Alternatively, or in addition, during an arthroplasty procedure, a user may position the longitudinal axis of the pin 158, and hence the pivot axis of the pivot plate 148, parallel to an anterior-posterior axis 116 of a patient in order to determine, or measure, a varus condition, a balanced condition, or a valgus condition.

[0098] If the pivot plate 148 pivots about the pin 158 in the direction of arrow 164, this may indicate a varus condition of a first bone relative to a second bone. If the pivot plate 148 pivots about the pin 158 in the direction of arrow 166, this may indicate a valgus condition of a first bone relative to a second bone. If the pivot plate 148 does not pivot about the pin 158, this may indicate a balanced condition of a first bone relative to a second bone. [0099] Figures 2 and 3 are anterior views of a knee joint with the gap gauge 100 of Figure 1A inserted between two bones and show a balanced condition and a varus condition, respectively. A figure showing bones of a joint for a valgus condition is not specifically shown; however, those of skill in the art will appreciate that a valgus condition is simply an angle, or orientation, of the bones of FIGURE 3 such that the pivot plate 148 pivots in the direction of arrow 166 rather than arrow 164.

[00100] As used herein, a "valgus condition" refers to a state of a bone or joint having an undesired outward angulation (angled laterally, away from the body's midline) of the distal segment of a bone or joint. For example, in a valgus condition of the knee, the distal part of the leg below the knee is deviated outward, in relation to the femur, resulting in a knock-kneed appearance. The opposite of varus is called valgus. A varus condition at the knee results in a bowlegged appearance with the distal part of the leg deviated inward, in relation to the femur. (Search "valgus deformity" onWikipedia.com Oct 20, 2020. Modified. Accessed Jan. 6, 2020.) A valgus condition can be experienced in a variety of joints, including but not limited to, ankle joints, elbow joints, foot joints, hand joints, hip joints, knee joints, toe joints, wrist joints, and the like. As used herein, a "varus condition" refers to a state of a bone or joint having an undesired inward angulation (medial angulation, that is, towards the body's midline) of the distal segment of a bone or joint. The opposite of varus is called valgus. The terms varus and valgus refer to the direction that the distal segment of the joint points. For example, a varus condition at the knee results in a bowlegged appearance with the distal part of the leg deviated inward, in relation to the femur. In a valgus condition of the knee, the distal part of the leg below the knee is deviated outward, in relation to the femur, resulting in a knock-kneed appearance. (Search "varus deformity" on Wikipedia.com Oct 20, 2020. Modified. Accessed Jan. 6, 2020.) A varus condition can be experienced in a variety of joints, including but not limited to, ankle joints, elbow joints, foot joints, hand joints, hip joints, knee joints, toe joints, wrist joints, and the like. As used herein, a "balanced condition" refers to a state of a bone and/or joint having a desired alignment of the bone or joint with a central axis of a limb or anatomical structure that includes the bone and/or joint. In certain embodiments, a balanced condition refers to a condition of the bone or joint that is not a varus condition and is not a valgus condition.

[00101] FIGURE 2 illustrates a balanced condition for the joint 108. The superior plate 118 and/or pivot plate 148 contacts the femur 102. The inferior plate 120 contacts the tibia 104. The pivot plate 148 is parallel to the inferior plate 120. In the illustrated embodiment, a force, or tension, in the joint 108, or movement in direction of arrow 164 is offset by a force, or tension, in the joint 108 or movement in direction of arrow 166. As used herein, a "tension" refers to a tensile force that is applied across an elongated structure. For example, a ligament such as a lateral collateral ligament may experience tension due to how the ligament is attached to a femur bone and tibia bone and stretched during flexing of the knee joint. [00102] FIGURE 3 illustrates a varus condition for a joint 108. The superior plate 118 and/or pivot plate 148 contacts the femur 102. The inferior plate 120 contacts the tibia 104. The pivot plate 148 is not parallel to the inferior plate 120. A slant in the superior plate 118 and/or pivot plate 148 can be caused by various factors, including but not limited to, an angle at which the femur 102 and/or tibia 104 has been sectioned, forces acting on the joint 108 by soft tissue and/or ligaments, and the like. In the illustrated embodiment, a force, or tension, in the joint 108, or movement in direction of arrow 164 by a surface of the femur 102 or tibia 104 is greater than a force, or tension, in the joint 108 or movement in direction of arrow 166 by a surface of the femur 102 or tibia 104. [00103] Those of skill in the art recognize that a valgus condition can exist in the joint 108 illustrated in FIGURE 3 if the superior plate 118 and/or pivot plate 148 rotates about the longitudinal axis 160 in the direction of arrow 166. Such a slant can be caused by various factors, including but not limited to, an angle at which the femur 102 and/or tibia 104 has been sectioned, forces acting on the joint 108 by soft tissue and/or ligaments, and the like. In such an embodiment, a force, or tension, in the joint 108, or movement in direction of arrow 166 by a surface of the femur 102 or tibia 104 is greater than a force, or tension, in the joint 108 or movement in direction of arrow 164 by a surface of the femur 102 or tibia 104.

[00104] FIGURE 4 is a posterior view of a knee joint with a gap gauge 100 inserted between a femur 102 and a tibia 104. FIGURE 4 illustrates a rear view of the gap gauge 100. FIGURE 4 shows the superior plate 118, inferior plate 120, separation indicator 124, balance indicator 126, grips 132, handle 134, shaft 140, spring 142, pivot plate 148, support plate 150, driver 152, and fastener 154. The illustrated embodiment includes a balance gauge 168. In one embodiment, the balance gauge 168 can include a dial 170 and a needle 172.

[00105] FIGURE 4 illustrates medial condyles 174a, 174b and lateral condyles 176a, 176b of a first bone (e.g., tibia 104) and a second bone (e.g., femur 102). As used herein, a "medial condyle" refers to one of the two projections on the lower extremity, distal end, of femur, the other being the lateral condyle. The medial condyle is larger than the lateral (outer) condyle due to more weight bearing caused by the center of mass being medial to the knee. (Search "medial condyle" on Wikipedia.com May 12, 2020. Modified. Accessed Jan. 6, 2020.) As used herein, a "lateral condyle" refers to one of the two projections on the lower extremity, distal end, of the femur. The other one is the medial condyle. The lateral condyle is prominent and is broader both in its front-to-back and transverse diameters. (Search "lateral condyle" on Wikipedia.com April 17, 2020. Modified. Accessed Jan. 6, 2020.)

[00106] In the illustrated embodiment, the superior plate 118 is positionable to engage, or contact, the femur

102 and the inferior plate 120 is positionable to engage, or contact, the tibia 104. The superior plate 118 can be shaped, or configured, to engage a medial condyle 174b and a lateral condyle 176b of the femur 102. The inferior plate 120 can be shaped, or configured, to engage a medial condyle 174a and a lateral condyle 176a of the tibia 104. One example of a shape suitable of a superior plate 118 for engaging a medial condyle 174b and a lateral condyle 176b of the femur 102 is illustrated in FIGURE 1C. One example of a shape suitable of an inferior plate 120 for engaging a medial condyle 174a and a lateral condyle 176a of the tibia 104 is illustrated in FIGURE ID. Of course, the size and shape of the superior plate 118 and inferior plate 120 can be different depending on the age and size of the patient (e.g., smaller for children and larger for adults).

[00107] The balance gauge 168, in one embodiment, provides a visual indication of a balance status and can provide specific information about a magnitude of imbalance or balance of the joint 108 to a user of the gap gauge 100. As used herein, a "balance gauge" refers to an apparatus, instrument, structure, device, component, system, assembly, hardware, software, firmware, circuit, module, or logic structured, organized, configured, programmed, designed, arranged, or engineered to measure an attribute, characteristic, state, or condition of another structure or object or set of structures or objects. In one embodiment, the balance gauge is structured, organized, configured, programmed, designed, arranged, or engineered to measure a balance status between two or more structures. The balance gauge 168 can be connected to the balance indicator 126 such that movement of the balance indicator 126 is reflected and/or reported by the balance gauge 168. In this manner, the balance gauge 168 can measure the balance status.

[00108] FIGURE 4 illustrates that a user can determine both a displacement, using the separation indicator 124, and a balance status, using the balance indicator 126 and/or the balance gauge 168 in a single view of the gap gauge 100. This can be helpful as other soft tissue or equipment may interfere with determining either, or both, of a displacement and a balance status during an arthroplasty procedure.

[00109] Figures 5A-5C are rear views of an exemplary gap gauge 100 illustrating different balance status states. Figures 5A-5C illustrate a dial 170 and a needle 172 coupled or connected to a balance indicator 126 in order to measure a balance status. As used herein, a dial refers to a face upon which some measurement is registered usually by means of graduations and a pointer, such as a needle ("dial." Merriam-Webster.com. Merriam-Webster, 2021. Web. 6 Jan. 2021. Modified.) As used herein, a “needle” refers to a long thin structure that may include a point at one end and a coupler for connecting the needle to another structure.

[00110] In the illustrated embodiment, the dial 170 includes marks and each mark is positioned on a face of the dial 170. The marks can represent an angle of pivot, or movement, of a superior plate 118 and/or pivot plate 148 about the pin 158. Each mark on the face can represent a different measure of balance status. Alternatively, or in addition, marks positioned on a face of the dial can indicate a measure of the orientation of a superior plate 118 relative to an inferior plate 120.

[00111] In certain embodiments, the face can include numbers that identify different measures of a balance status. In one embodiment, the dial 170 includes marks for angles ranging from -5 degrees to +5 degrees with 0 degrees representing a balanced condition. As the superior plate 118 and/or pivot plate 148 pivot or rotate about the pin 158, the rotation is measured by and conveyed to the balance indicator 126. Movement of the balance indicator 126 transfers to the needle 172 and moves the needle 172 to point toward a mark on the face that reflects the balance status. Rotation of the superior plate 118 or the inferior plate 120, about an anterior-posterior axis 116 of a patient, moves the needle 172 to point toward a mark on the face of the dial that reflects the orientation of the plates.

[00112] FIGURE 5A illustrates an example balance gauge 168 of a gap gauge 100 that can be positioned to contact a first bone (See FIGURE 1 A) and a second bone (See FIGURE 1 A). Where the surfaces of the bones are parallel and/or forces within the joint 108 are balanced (e.g., a balance condition), a needle 172 of the balance gauge 168 may point to a middle mark of the dial 170 indicating a balance condition, no positive or negative degree of rotation about a pivot axis 162.

[00113] FIGURE 5B illustrates an example balance gauge 168 of a gap gauge 100 that can be positioned to contact a first bone (See FIGURE 1 A) and a second bone (See FIGURE 1 A). Where the surfaces of the bones are not parallel and/or forces within the joint 108 are not balanced (e.g., a varus condition or valgus condition depending on which joint is being measured), a needle 172 of the balance gauge 168 may point to a mark (e.g., - 5 degrees) on the left side of the middle mark of the dial 170 indicating an imbalance or non-balanced condition, a positive or negative degree of rotation about a pivot axis 162.

[00114] FIGURE 5C illustrates an example balance gauge 168 of a gap gauge 100 that can be positioned to contact a first bone (See FIGURE 1 A) and a second bone (See FIGURE 1 A). Where the surfaces of the bones are not parallel and/or forces within the joint 108 are not balanced (e.g., a varus condition or valgus condition depending on which joint is being measured), a needle 172 of the balance gauge 168 may point to a mark (e.g., +5 degrees) on the right side of the middle mark of the dial 170 indicating an imbalance or non-balanced condition, a positive or negative degree of rotation about a pivot axis 162.

[00115] Figures 6A-6C are rear views of an exemplary gap gauge 100 illustrating different displacements. Figures 6A-6C illustrate a superior plate 118, inferior plate 120, and separation indicator 124. The superior plate 118 can include a pivot plate 148 and a support plate 150. Figures 6A-6C also illustrate a driver 152 and a fastener 154.

[00116] In the illustrated embodiment, the separation indicator 124 can include a face that may include a number that represents a measure for a displacement between an outer surface of the superior plate 118 and an outer surface of the inferior plate 120. For example, in the illustrated embodiment, a number at the top-most position of the face when viewed as illustrated may represent a current amount of displacement. For example, the “9” may represent a displacement of 9 millimeters. The face on the driver 152 can include a plurality of different marks and/or numbers (e.g., readings) that each may represent a different displacement between the superior plate 118 and inferior plate 120. The fastener 154 may permit the driver 152 to be rotated about a longitudinal axis of the fastener. The driver 152 is rotatable to a plurality of positions and each position may represent a different displacement that corresponds to the number on the face of the driver 152. The illustrated embodiment can include six different displacements and six numbers each representing a different displacement (e.g., 9, 11, 13, 15, 17, and 19).

[00117] FIGURE 6A illustrates an example separation indicator 124 of a gap gauge 100 that can be positioned within an opening 106 between a first bone (See FIGURE 1 A) and a second bone (See FIGURE 1 A). Once positioned, and the separator 122 is actuated to a desired displacement, a user can read the displacement by reading the number in the top-most position on the separation indicator 124. For example, in FIGURE 6A the displacement is nine millimeters. For example, in FIGURE 6B the displacement is fifteen millimeters. For example, in FIGURE 6C the displacement is nineteen millimeters.

[00118] The separator 122 can be actuated to bring the superior plate 118 in contact with a resected surface of a femur 102 and the inferior plate 120 in contact with a resected surface of a tibia 104. As used herein, a "resected surface" refers to an outermost part or layer of a body structure that is exposed after a resection procedure.

[00119] The superior plate 118 can be shaped, or configured, to facilitate contact with a resected surface of the femur 102. The inferior plate 120 can be shaped, or configured, to facilitate contact with a resected surface of the tibia 104. One example of a shape suitable for the superior plate 118 is illustrated in FIGURE 1C. One example of a shape suitable for the tibia 104 is illustrated in FIGURE ID.

[00120] The separator 122 may be actuated by securing the handle 134 with one hand and then rotating the driver 152 to one or more of a plurality of displacement positions. Alternatively, or in addition, actuation of the separator 122 may include securing the gap gauge 100 in position using the handle 134, rotating the driver 152, and/or pulling on the grips 132 to separate the plates 118,120. If the handle 134 is secured, the driver 152 rotated and the grips 132 pulled to separate the plates 118,120 simultaneously or at about the same time an assistant may help with the actuation.

[00121] Figure 7 is a perspective view of an example gap gauge 100. FIGURE 7 illustrates a gap gauge 100 that includes a separator 122 that includes a cam 702 and a follower 704. As used herein, a "cam" refers to a mechanical device structured, organized, configured, programmed, designed, arranged, or engineered to translate motion of one form into motion of another form. For example, a cam can translate rotary motion into linear motion. Similarly, a cam can translate linear motion into rotary motion. A cam can be a rotating or sliding piece in a mechanical linkage used in transforming rotary motion into linear motion. A cam can be a part of a rotating wheel (e.g. an eccentric wheel) or shaft (e.g. a cylinder with an irregular shape) that strikes or moves a lever at one or more points on the rotating wheel's circular path. The cam can be a simple tooth or an eccentric disc or other shape that produces a smooth reciprocating (back and forth) motion in the follower, which is a lever configured to make contact with the cam. (Search "cam" on Wikipedia.com Dec. 26, 2020. Modified. Accessed Jan. 6, 2020.) Various types of cams can be used with the present disclosure. For example, the cam can be a radial cam, a disc cam, a cylindrical cam, or the like.

[00122] As used herein, a "follower" refers to a rigid structure that contacts a cam lobe profile. In one embodiment, the follower may translate motion of the cam to the follower and/or a structure connected to the follower. In certain embodiments, as the cam rotates the follower may slide along a contacting surface of the cam to thereby convert the rotary motion into a linear motion. A follower may also be referred to as a "cam follower" or "track follower." A cam follower is a type of structure, roller, or needle bearing designed to follow and/or contact a cam lobe profile of the cam. (Search "cam follower" on Wikipedia.com Nov. 13, 2020. Modified. Accessed Jan. 6, 2020.)

[00123] Various kinds of followers can be used in the present disclosure. The type and shape of a cam follower may be based on the kind of surface of the follower (referred to as a follower face) that contacts a contacting surface of the cam. In one embodiment, the follower is a stud that comes to a point to form a knife edge follower. Alternatively, or in addition, the follower face can have a variety of other shapes including, but not limited to a flat face, a mushroom face, a cylindrical face, a curved face, a semispherical face, and the like. In addition, the follower can include a roller on the end that contacts the contacting surface of the cam. The roller on the end of the follower can enable the follower to roll and or slide along the contacting surface of the cam.

[00124] In the illustrated embodiment, the cam 702 is connected to, or integrated with, the driver 152. The driver 152 connects to the inferior body 138 by way of the fastener 154. In this manner, the cam 702 connects to the inferior body 138. The cam 702 includes a contacting surface 706. As used herein, a "contacting surface" refers to a surface of a cam that contacts a follower. The orientation, placement, and position of the contacting surface can vary with the type of cam being used. In embodiments that use a radial cam the radial cam can have a central axis 708 and the contacting surface can be a surface of the cam that follows a circumference of the radial cam about the central axis 708.

[00125] Rotation of the driver 152 also rotates the cam 702. Rotation of the cam 702 moves the superior body 136 which adjusts the displacement of the superior plate 118 relative to the inferior plate 120. In one embodiment, the cam 702 is a radial cam and rotates about a common axis, the central axis 708, with the fastener 154. As used herein, a "radial cam" refers to a type of cam in which the cam has a central axis, and the contacting surface follows a circumference of the cam about the central axis. In a radial cam, the follower moves in a linear motion in a direction perpendicular to the central axis. The follower 704 can contact, or rest, on the cam 702.

[00126] The follower 704 is connected to the superior body 136. In one embodiment, the follower 704 may be biased against the contacting surface 706 by the spring 142 around the shaft 140. The follower 704 is sized and shaped to move the superior body 136 along the shaft 140 relative to the inferior body 138 as the follower 704 slides along, or is positioned along, the contacting surface 706. FIGURE 7 illustrates one example embodiment, in which the support plate 150 couples to the separator 122 (e.g., by way of the cam 702, follower 704, and superior body 136) such that actuation of the separator 122 moves the support plate 150 vertically relative to the inferior plate 120.

[00127] FIGURE 7 also illustrates one embodiment of a driver 152 that includes holes 710, or pockets, around the circumference of the driver 152. When the gap gauge 100 is used, a user may insert rods into the holes 710 to provide leverage for rotating the driver 152.

[00128] Figure 8A is a front view of a driver 152 of a gap gauge 100, according to one embodiment of the present disclosure. FIGURE 8 A illustrates the separation indicator 124, the driver 152, the central axis 708, and an opening 802. The opening 802 may be an area between an outer surface of the driver 152 and a head of the fastener 154. The opening 802 may have a polygonal cross-sectional shape. In the illustrated embodiment, the opening 802 is has a hexagon cross-sectional shape. The opening 802 may be sized and configured to receive a shaft or drive head of a separate tool such as a wrench (not shown). A user may use the wrench in the opening 802 to achieve a mechanical advantage in rotating the driver 152 about the central axis 708.

[00129] Figure 8B is a rear view of a driver 152 and cam 702 of a gap gauge 100, according to one embodiment of the present disclosure. FIGURE 8B illustrates that the cam 702 may have an irregular radius that varies about the central axis 708. The length of the radius about the central axis 708 may be designed or engineered to achieve or maintain a desired displacement between the superior plate 118 and inferior plate 120 connected to the cam 702 and the follower 704.

[00130] Figure 9 illustrates an exploded view of an exemplary gap gauge 100, according to one embodiment of the present disclosure. FIGURE 9 illustrates details about how the hinge 156, pin 158, and needle 172 can cooperate to provide a balance indicator 126. In certain embodiments, the balance indicator 126 includes a lock out mechanism 130 that can prevent rotation of the pivot plate 148 relative to the inferior plate 120 and/or the support plate 150 when the lock-out mechanism 130 is in a set configuration.

[00131] FIGURE 9 illustrates a support plate 150 that includes a knuckle 902 and openings 904a, 904b for at least one corresponding knuckle of the pivot plate 148. The knuckle 902 can connect the support plate 150 to the hinge 156 and the pivot plate 148. In such an embodiment, the support plate 150 and the pivot plate 148 can each serve as leaves of the hinge 156. When assembled, one or more knuckles of the pivot plate 148 align with one or more knuckles 902 of the support plate 150 and receive the pin 158. In this manner, the pivot plate 148, the pin 158, and the support plate 150 serve as a hinge to implement one embodiment of a balance indicator 126. [00132] In certain embodiments, the pivot plate 148 may rotate freely about the pin 158. In such an embodiment, the pin 158 may include one or more pins 906. The pins 906 engage the pin 158 and the pivot plate 148 such that rotation of the pivot plate 148 causes rotation of the pin 158. In addition, if the pin 158 is fixed, or prevented from rotating about the pivot axis 162, the pins 906 may also retain the pivot plate 148 from rotating. [00133] The pin 158 can extend within the superior body 136 and couple to the needle 172. In this manner, rotation of the pin 158 causes the needle 172 to move and point in a different direction. In certain embodiments, the pin 158 may pass through a slot in the post 146 to enable both rotation of the pin 158 and movement of the pin 158 away from the inferior body 138 when the gap gauge 100 is used.

[00134] FIGURE 9 illustrates a lock-out mechanism 130 that can include a set screw 908. The set screw 908 has threads that engage with threads of an opening 910 in the superior body 136. Moving the set screw 908 into the opening 910 activates the lock-out mechanism 130 and prevents rotation of the pin 158 and connected pivot plate 148. Moving the set screw 908 out of the opening 910 deactivates the lock-out mechanism 130 and permits rotation of the pin 158 and connected pivot plate 148.

[00135] As used herein, a "set screw" refers to a type of screw generally used to secure a first object within, or against, second object, usually without using a nut. Set screws can be headless, meaning that the screw is fully threaded and has no head projecting past the thread's major diameter. If a set screw does have a head, the thread may extend to the head. A set screw can be driven by an internal-wrenching drive, such as a hex socket (Allen), star (Torx), square socket (Robertson), or a slot. In one embodiment, the set screw passes through a threaded hole in the second object (an outer object) and is tightened against the first object (an inner object) to prevent the inner object from moving relative to the outer object. The set screw can exert a compressional and/or clamping force through an end of the set screw that projects through the threaded hole. (Search "set screw" on Wikipedia.com Aug. 17, 2020. Modified. Accessed Jan. 6, 2020.)

[00136] Figure 10A is a perspective view of a pin 158 of the gap gauge 100 of Figure 1A, according to one embodiment of the present disclosure. The pin 158 may be a cylindrical structure with a longitudinal axis 160. The pin 158 can include a proximal end 1002, a distal end 1004, and a middle 1006. In one embodiment, the proximal end 1002 connects to a balance gauge 168. For example, the proximal end 1002 may include a D-shaped cross section that includes a flat part 1008. In one embodiment, the D-shaped cross-section of the proximal end 1002 may be sized to accept a D -shaped opening in a needle 172 that can be slide over the proximal end 1002 and positioned for a balance indicator 126 and/or a balance gauge 168.

[00137] The distal end 1004 may serve as a pivot for a hinge 156 of the gap gauge 100. Alternatively, or in addition, the distal end 1004 may serve as a pivot for the balance indicator 126. The pivot may align with the longitudinal axis 160. In addition, the distal end 1004 and/or the middle 1006 may include one or more keyed sections 1010. In one embodiment, the keyed sections 1010 may be used for the pins 906 to connect the pin 158 to the pivot plate 148.

[00138] In one embodiment, the middle 1006 may include a section 1012 that includes a planar surface 1014. The planar surface 1014 of the section 1012 may serve as part of the lock-out mechanism 130. For example in one embodiment, the set screw 908 may bias against the planar surface 1014 of the pin 158 to prevent rotation of the pin 158. In the illustrated embodiment, the section 1012 has a D-shaped cross-section. In one embodiment, the D-shaped cross-section of the section 1012 may be offset 90 degrees from a D-shaped cross-section of the proximal end 1002 that includes the flat part 1008. In one example embodiment, the 90-degree offset enables a needle 172 to register/measure no imbalance when the lock-out mechanism 130 is activated to prevent rotation of the pin 158. [00139] Figures 10B and IOC are side views of the pin 158 of Figure 10A, according to one embodiment of the present disclosure. FIGURE 10B illustrates and embodiment of a pin 158 that includes a first section 1016 having a larger diameter than a second section 1018.

[00140] Figures 11A and 11B are perspective views of a lock-out mechanism 130 of a gap gauge 100, according to one embodiment of the present disclosure. FIGURE 11A illustrates the lock-out mechanism 130 when the set screw 908 is in a set configuration. FIGURE 1 IB illustrates the lock-out mechanism 130 when the set screw 908 is in an unset configuration. As used herein, a "set configuration" refers to an arrangement and/or relationship between a set screw and a pin such that the set screw prevents rotation of the pin about a longitudinal axis of the pin. In the set configuration, the set screw 908 has been advanced within the opening 910 to engage the planar surface 1014 of the section 1012.

[00141] As used herein, an "unset configuration" refers to an arrangement and/or relationship between a set screw and a pin such that the set screw permits rotation of the pin about a longitudinal axis of the pin. In the set configuration, the set screw 908 has been retracted within the opening 910 to disengage the planar surface 1014 of the section 1012.

[00142] Figure 12 illustrates a flowchart for a method 1200 for measuring a gap and/or balance status between a femur and a tibia of a patient, according to one embodiment of the present disclosure. In general, the method 1200 may include the use of gap gauge that includes both a separation indicator and a balance indicator 126. In certain embodiments, the gap gauge may also include a balance gauge.

[00143] The method 1200 may begin with a step 1210 in which a first plate (e.g., inferior plate 120) and a second plate (e.g., superior plate 118) of a gap gauge may be inserted between a femur and a tibia. In certain embodiments, the gap gauge may be positioned such that a pivot axis of a hinge may be aligned with an anterior- posterior axis of a patient.

[00144] Once the gap gauge is positioned, the method 1200 may proceed to step 1220 in which the first plate and second plate are actuated apart such that the first plate contacts a resected surface of the femur and the second plate contacts a resected surface of the tibia.

[00145] Once the first plate and second plate have been actuated apart, the method 1200 may proceed to step 1230 in which a separation indicator of the gap gauge may be read to obtain a displacement between the femur and the tibia. Once the displacement has been read, the method 1200 may proceed to step 1240 in which a balance indicator of the gap gauge is read to obtain a balance status between the femur and the tibia.

[00146] A surgeon using the example gap gauge 100 may use the displacement amount and/or the balance status to choose from a set of prosthesis available for an arthroplasty procedure. In one example, a surgeon may choose a different prosthesis than one pre-operatively selected based on the balance status reported/measured by the balance indicator 126 and/or the example balance gauge 168. The different prosthesis may be selected to compensate for the balance status reported/measured by the balance indicator 126 and/or the example balance gauge 168. If a compensating prosthesis is selected, the surgeon may not need to make any changes to the joint 108 to accomplish a desired balance condition.

[00147] In another example, if the balance status indicates a varus condition, a first prosthesis may be selected during the procedure if the balance status indicates a valgus condition, a second prosthesis may be selected during the procedure. Alternatively, or in addition, the displacement and/or balance status may be used by a surgeon to determine whether to do further resection of the femur 102 and/or tibia 104, whether to release one or more of the medial collateral ligament and the lateral collateral ligament, or take other steps of the arthroplasty procedure in an effort to accomplish a desired outcome for the arthroplasty procedure.

[00148] Once the displacement and the balance status has been read, the method 1200 may proceed to step 1250 in which tension applied to the femur and/or the tibia by a medial collateral ligament and/or a lateral collateral ligament is adjusted. Once the tension applied to the femur and/or the tibia is adjusted, the method 1200 may proceed to step 1260 in which the balance indicator of the gap gauge is read to obtain an adjusted balance status between the femur and the tibia in response to adjusting the tension. After reading the adjusted balance, the method 1200 may end with the balance of the joint having the desired balance status.

[00149] Alternatively, or in addition thereto, the method 1200 may proceed to a step in which a tension applied to the femur and the tibia by one or more of a medial collateral ligament and a lateral collateral ligament may be adjusted and the balance indicator of the gap gauge may be read to obtain an adjusted balance status between the femur and the tibia in response to adjusting the tension.

[00150] Alternatively, or in addition thereto, once tension applied to the femur and the tibia by one or more of a medial collateral ligament and a lateral collateral ligament is adjusted, the method 1200 may proceed to a step in which one or more of the medial collateral ligament and the lateral collateral ligament are released while the gap gauge remains between the femur and the tibia and remains actuated.

[00151] Alternatively, or in addition thereto, once tension applied to the femur and the tibia by one or more of a medial collateral ligament and a lateral collateral ligament is adjusted, the method 1200 may proceed to a step in which the gap gauge is removed from between the femur and the tibia. Once the gap gauge is removed from between the femur and the tibia, the method 1200 may proceed to a step in which one or more of the resected surface of the femur and the resected surface of the tibia is resected. Once one or more of the resected surface of the femur and the resected surface of the tibia are resected, the method 1200 may proceed to a step in which the first plate and the second plate of the gap gauge is re-inserted between the femur and the tibia. Once the first plate and the second plate of the gap gauge is re-inserted between the femur and the tibia, the method 1200 may proceed to a step in which the first plate and the second plate are actuated apart such that the first plate is in contact with the resected surface, or further resected surface, of the femur and the second plate is in contact with the resected surface, or further resected surface, of the tibia. Once the first plate and second plate are actuated apart, the method 1200 may proceed to a step in which the separation indicator of the gap gauge is read to obtain the displacement between the femur and the tibia. Once the displacement is obtained, the method 1200 may proceed to a step in which the balance indicator of the gap gauge is read to obtain the balance status between the femur and the tibia. [00152] Any methods disclosed herein comprise one or more steps or actions for performing the described method. The method steps and/or actions may be interchanged with one another. In other words, unless a specific order of steps or actions is required for proper operation of the embodiment, the order and/or use of specific steps and/or actions may be modified.

[00153] Reference throughout this specification to "an embodiment" or "the embodiment" means that a particular feature, structure or characteristic described in connection with that embodiment is included in at least one embodiment. Thus, the quoted phrases, or variations thereof, as recited throughout this specification are not necessarily all referring to the same embodiment.

[00154] Similarly, it should be appreciated that in the above description of embodiments, various features are sometimes grouped together in a single embodiment, Figure, or description thereof for the purpose of streamlining the disclosure. This method of disclosure, however, is not to be interpreted as reflecting an intention that any claim require more features than those expressly recited in that claim. Rather, as the following claims reflect, inventive aspects lie in a combination of fewer than all features of any single foregoing disclosed embodiment. Thus, the claims following this Detailed Description are hereby expressly incorporated into this Detailed Description, with each claim standing on its own as a separate embodiment. This disclosure includes all permutations of the independent claims with their dependent claims.

[00155] Recitation in the claims of the term "first" with respect to a feature or element does not necessarily imply the existence of a second or additional such feature or element. Elements recited in means-plus-function format are intended to be construed in accordance with 35 U.S.C. § 112 Para. 6. It will be apparent to those having skill in the art that changes may be made to the details of the above-described embodiments without departing from the underlying principles set forth herein.

[00156] While specific embodiments and applications of the present disclosure have been illustrated and described, it is to be understood that the scope of this disclosure is not limited to the precise configuration and components disclosed herein. Various modifications, changes, and variations which will be apparent to those skilled in the art may be made in the arrangement, operation, and details of the methods and systems of the present disclosure set forth herein without departing from it spirit and scope.