JP2024522198A - Arthrogenesis balance and gap gauge - Google Patents

Abstract

A gap gauge for facilitating arthroplasty of a first bone and a second bone of a patient is disclosed. The gap gauge may include a first plate positionable in contact with the first bone and a second plate positionable in contact with the second bone. The second plate may be 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, 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. The balance indicator may be configured to indicate a balance status between the first plate and the second plate. The separator may be actuated to adjust the displacement.

Description

The present disclosure relates to surgical devices. More specifically, the present disclosure relates to improved surgical instruments for joint arthroplasty.

Arthroplasty can be used to relieve joint pain or restore joint function due to conditions such as osteoarthritis, rheumatoid arthritis, or other joint conditions through minimally invasive or invasive surgery. Arthroplasty can be performed on any joint and can include partial or complete joint replacement with a replacement prosthesis or prosthesis. During arthroplasty, the surgeon may want to measure the size of the opening between the two bones of the joint. In addition, the surgeon may also want to measure the balance of the joint in addition to the size of the opening (called the gap) between the two bones of the joint. For example, during a partial or total knee replacement (TKR), the surgeon may want to measure or measure the displacement between the two bones of the joint and the balance of the joint. Making such measurements during minimally invasive or invasive arthroplasty can be a challenge considering the forces applied to the joint by the ligaments of the joint and other soft tissues around the joint. Thus, there is a need for improved systems and methods for measuring the gap and/or angle between bones during the course of arthroplasty.

The various apparatus, devices, systems, and/or methods of the present disclosure have been developed in response to the current state of the art, and in particular in response to problems and needs in the art that have not yet been fully addressed 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 remedies shortcomings of the separate arthroplasty balance gauges, arthroplasty gap gauges, and/or cutting guides of the prior art.

To achieve the above, and in accordance with the present disclosure as embodied and broadly described herein, a gap gauge may be provided for facilitating arthroplasty of a first bone and a second bone of a patient. One general aspect of the gap gauge may include a first plate positionable in contact with the first bone and a second plate positionable in contact with the second bone, the second plate being 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, the separator being operable 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.

In one aspect, the balance indicator may include a hinge pivotally connecting the second plate to the gap gauge. The hinge may include a pin having a longitudinal axis that is the pivot axis of the second plate. The longitudinal axis may be parallel to the anterior-posterior axis of the patient such that rotation of the second plate about the pivot axis measures one of a varus, balanced, and valgus condition of the first bone relative to the second bone.

In another aspect, the gap gauge may include a support plate connected to the hinge and the separator, and the balance indicator may include a lockout mechanism configured to prevent rotation of one of the first and second plates connected to the balance indicator. The lockout mechanism may include a set screw having a set configuration and an unset configuration, and the set screw may include threads configured to engage with threads in the opening. In the set configuration, the set screw may engage with a 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 and second plates. The engaged pin may also prevent rotation of at least one of the first and second plates 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 and second plates. In one aspect, the set screw engages the pin by biasing a planar surface of a section of the pin, and the section of the pin has a D-shaped cross-section.

In one aspect, the gap gauge can include a first plate shaped to engage the medial and lateral condyles of a first bone and a second plate shaped to engage the medial and lateral condyles of a second bone.

In one aspect, the gap gauge may include a balance gauge connected to a balance indicator. The balance gauge may be configured to measure a balance status. The gap gauge may include a dial having markings disposed on a face of the dial to indicate a measurement of a 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 toward the marking on the face of the dial reflecting the balance status.

One general aspect may include an upper plate extending from the upper body, the upper plate shaped to match the resection surface of the femur, and a lower plate extending from the lower body, the lower plate shaped to match the resection surface of the tibia, the upper plate being displaced from the lower plate by the displacement. The gauge may also include a shaft to which at least one of the upper body and the lower body is slidably coupled to allow adjustment of the displacement, a separator connected to the upper body and the lower body to adjust the displacement, and a balance indicator connected to one of the upper plate and the lower plate and configured to indicate an orientation of the upper plate relative to the lower plate.

In one aspect, the balance indicator connects to an upper plate, the upper plate including a pivot plate and a support plate, and the balance indicator includes a hinge including 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 lower plate. The pin can include a cylindrical structure having a longitudinal axis, a proximal end, a distal end, and a center. The proximal end can connect to the balance gauge, and the distal end includes a pivot for the balance indicator. The pivot can be aligned with the longitudinal axis. In one embodiment, the proximal end can include a first D-shaped cross-section, the distal end can include at least one keyed cross-section, and the center can include a second D-shaped cross-section where the flat portion of the second D-shaped cross-section is offset 90 degrees from the flat portion of the first D-shaped cross-section. The distal end serves as the pivot for the hinge.

In one aspect, the gap gauge further includes a handle connected to the lower body, a separation indicator coupled to the separator and configured to indicate the displacement, a lockout mechanism connected to the upper body and configured to prevent rotation of the upper plate or a portion of the upper plate connected to the balance indicator, and a spring coupled to the shaft to bias one of the upper body and the lower body against movement of the upper plate away from the lower plate. The separator may include a driver, a cam connected to the lower body via the driver, the cam having a contact surface, and a follower connected to the upper body and biased and configured to contact the contact surface of the cam such that rotation of the cam adjusts the displacement. In one embodiment, the follower slidably contacts the contact surface. The cam may include a radial cam having a central axis, the contact surface being a circumference of the radial cam about the central axis.

In one aspect, the gap gauge may include a balance gauge connected to a balance indicator. The balance gauge may include a dial having markings disposed on a face to indicate a measure of the orientation of the upper plate relative to the lower plate. The balance gauge may also include a needle connected to the balance indicator such that rotation of one of the upper and lower plates about the patient's anterior-posterior axis moves the needle to point toward a marking on the face of the dial reflecting the orientation.

One general aspect of the present disclosure may include a method for measuring a gap between a patient's femur and tibia. 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 such that the first plate contacts the resected surface of the femur and the second plate contacts the 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.

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

In another embodiment, adjusting the tension may also include releasing one or more of the medial and lateral collateral ligaments while the gap gauge remains between the femur and tibia and activated.

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 femoral resection surface and the tibia resection surface, reinserting 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 so that the first plate contacts the femoral resection surface and the second plate contacts the tibia resection surface, 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.

In one aspect, a gap gauge for facilitating arthroplasty of a first bone and a second bone of a patient may be provided. One general aspect of the gap gauge may 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, the second plate displaced from the first plate by the 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 the first pin into the second bone.

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 a balance status between the first plate and the second plate. The pin guide may further 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 a balance status between the first plate and the second plate.

In another aspect, the pin guide can include a second pin hole configured to guide insertion of the second pin into the second bone. In one aspect, the pin guide is coupled to 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 are angled relative to the second plate to counterbalance the balance status between the first plate and the second plate.

In one aspect, the first pin hole can guide insertion of a first pin into one of the medial and lateral condyles of the second bone, and the pin guide can include a second pin hole configured to guide insertion of a second pin into the other of the medial and lateral condyles of the second bone.

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 a second bone and an adjustment feature configured to rotate the first and second pin holes together to counter different angular offsets of the balance status.

In one aspect, the pin guide may include a base configured to connect to the second plate, an arm that may include a first pin hole, and a mast extending from the base and connecting the arm and the base. The arm may include a second pin hole, and when the gap gauge is in position relative to the knee, the first pin hole and the second pin hole are each located in the arm on one of the medial and lateral sides of the knee.

In another aspect, the pin guide may include a second pin hole configured to guide insertion of the second pin into the second bone such that the first pin and the second pin are aligned with each other in an orientation relative to the second plate consistent with the balance status, and the balance status is communicated to the cutting guide by coupling the cutting guide to the second bone via the first pin and the second pin.

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

In another aspect, the cutting guide may include a guide mechanism configured to guide movement of the cutter to resect the bone, an alignment mechanism configured to receive the first and second pins and position the cutting guide over the bone, and an adjustment mechanism configured to rotate the guide mechanism relative to the alignment mechanism to adjust for different angular offsets from the balance status.

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

One general aspect may include a gap measuring and correction assembly for facilitating arthroplasty of a patient's femur and tibia. The gap measuring and correction assembly may also include a gap gauge that may include an upper plate extending from the upper body, a lower plate extending from the lower body, where the upper plate is displaced from the lower plate by a displacement, a separator connected to the upper body and the lower body to adjust for the displacement, a balance indicator connected to one of the upper plate and the lower plate and configured to indicate a non-parallel orientation of the upper plate relative to the lower plate, and a pin guide configured to guide insertion of a first pin into one of the patient's tibia and femur. The gap measuring and correction assembly may also include a cutting guide attachable to one of the tibia and femur via the first pin, the cutting guide configured to guide resection of one of the tibia or femur against the non-parallel orientation.

In one aspect, the assembly may further include an attachment feature configured to removably couple the pin guide to the upper plate such that the pin guide guides insertion of the first pin into the femur according to the non-parallel orientation of the upper plate relative to the lower plate. The pin guide may further include an attachment feature configured to removably couple the pin guide to the upper plate such that the pin guide guides insertion of the first pin into the tibia according to the non-parallel orientation of the upper plate relative to the lower plate.

In another aspect, the pin guide is further configured to guide the second pin into the other one of the patient's tibia and femur, and the pin guide may further include an attachment feature configured to removably couple the pin guide to the lower 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 are aligned at an angle relative to the upper plate counter to the non-parallel orientation of the upper plate relative to the lower plate.

In one aspect, the pin guide may include a base configured to connect to the top plate, an arm that 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 mechanism including a plurality of sets of holes, each member of the set of holes configured to receive one of the first pin and the second pin, and each set of holes configured to accommodate a different angular offset for non-parallel orientation.

In another aspect, the cutting guide may include a guide mechanism configured to guide movement of the cutter to resect the bone, an alignment mechanism configured to receive the first and second pins and position the cutting guide over the bone, and an adjustment mechanism configured to rotate the guide mechanism relative to the alignment mechanism to adjust for different angular offsets from a non-parallel orientation.

One general aspect may include a method for measuring and correcting imbalance for a patient's femoral and tibial arthroplasty. The method includes inserting a first plate and a second plate of a gap gauge between the femur and the tibia of the patient's knee joint. The method also includes actuating the first plate and the second plate apart so that the first plate contacts the resected surface of the femur and the second plate contacts the 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, fixing the first pin to one of the femur and the tibia, and coupling a cutting guide to one of the femur and the tibia using the first pin. The method also includes using the cutting guide to guide the resection of one of the femur and the tibia to counter the non-parallel orientation of the first plate relative to the second plate.

These and other features 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 herein.

Exemplary embodiments of the present disclosure will become more fully apparent from the following description and the appended claims, taken in conjunction with the accompanying drawings. With the understanding that these drawings depict only exemplary embodiments and therefore should not be considered as limiting the scope of the appended claims, exemplary embodiments of the present disclosure will be described with additional specificity and detail through the use of the accompanying drawings:

FIG. 1A is a perspective view of a gap gauge according to one embodiment of the present disclosure. FIG. 1B is a perspective view of the gap gauge of FIG. 1A. FIG. 1C is a top view of the gap gauge of FIG. 1A according to one embodiment of the present disclosure. FIG. 1D is a bottom view of the gap gauge of FIG. 1A according to one embodiment of the present disclosure. FIG. 1E is a side view of the gap gauge of FIG. 1A according to one embodiment of the present disclosure. FIG. 1F is a side view of the gap gauge of FIG. 1A according to one embodiment of the present disclosure. FIG. 1G is a side view of the gap gauge of FIG. 1A according to one embodiment of the present disclosure. FIG. 1H is a rear view of the gap gauge of FIG. 1A according to one embodiment of the present disclosure. FIG. 1I is a front view of the gap gauge of FIG. 1A according to one embodiment of the present disclosure. FIG. 2 is an anterior view of a knee joint with the gap gauge of FIG. 1A inserted between two bones. FIG. 3 is an anterior view of a knee joint with the gap gauge of FIG. 1A inserted between two bones. FIG. 4 is a posterior view of a knee joint with the gap gauge of FIG. 1A inserted between two bones. 5A is a rear view of the gap gauge of FIG. 1A showing different balance status conditions. 5B is a rear view of the gap gauge of FIG. 1A showing different balance status conditions. 5C is a rear view of the gap gauge of FIG. 1A showing different balance status conditions. FIG. 6A is a rear view of the gap gauge of FIG. 1A showing different displacements. FIG. 6B is a rear view of the gap gauge of FIG. 1A showing different displacements. FIG. 6C is a rear view of the gap gauge of FIG. 1A showing different displacements. FIG. 7 is a perspective view of the gap gauge of FIG. 1A. FIG. 8A is a front view of a driver of a gap gauge according to one embodiment of the present disclosure. FIG. 8B is a rear view of a driver and cam of a gap gauge according to one embodiment of the present disclosure. FIG. 9 illustrates an exploded view of a gap gauge according to one embodiment of the present disclosure. 10A is a perspective view of a pin of the gap gauge of FIG. 1A according to one embodiment of the present disclosure. FIG. 10B is a side view of the pin of FIG. 10A according to one embodiment of the present disclosure. FIG. 10C is a side view of the pin of FIG. 10A according to one embodiment of the present disclosure. FIG. 1A is a perspective view of a lockout mechanism of a gap gauge according to one embodiment of the present disclosure. FIG. 11B is a perspective view of a lockout mechanism of a gap gauge according to one embodiment of the present disclosure. FIG. 12 illustrates a flow chart for measuring the gap and/or balance status between a patient's femur and tibia, according to one embodiment of the present disclosure.

It should be understood that the drawings are intended to illustrate the concepts of the present disclosure and may not be drawn to scale. Moreover, the drawings depict illustrative embodiments and are not intended to represent limitations on the scope of the present disclosure.

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

Standard medical orientations, 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 the central axis of the body. Abaxial means away from the central axis of the body. Ipsilateral means the same side in relation to the body. Contralateral means the opposite side in relation to the body. The sagittal plane divides the body into left and right portions. The midsagittal plane divides the body into symmetrical right and left halves. The coronal plane divides the body into anterior and posterior portions. The cross section divides the body into upper and lower parts.

The anterior-posterior axis is the axis perpendicular to the coronal plane. The medial-lateral axis is the axis perpendicular to the midplane. The craniocaudal axis is the axis perpendicular to the transverse plane. These descriptive terms may be applied to animate or inanimate bodies.

The phrases "connected," "coupled," and "in communication" refer to any form of interaction between two or more things, including mechanical, electrical, magnetic, electromagnetic, fluid, and thermal interaction. Two components can be functionally coupled to one another even if they are not in direct contact with one another. The term "abutting" refers to things that are in direct physical contact with one another, but the things are not necessarily attached together. The phrase "fluid communication" refers to two features that are connected such that fluid in one feature can flow into the other feature.

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. Various aspects of the embodiments are presented in drawings, but the drawings are not necessarily drawn to scale unless specifically indicated.

The present disclosure discloses a gap gauge for facilitating joint arthroplasty of a first and second bone of a patient. During joint arthroplasty, a surgeon may need to ensure that the gap between the two bones of the joint is at the desired displacement and that the joint has the desired balance (e.g., balanced, varus, or valgus foot). Using separate instruments to obtain either the displacement or the balance status may complicate the procedure and may require more personnel to assist with the procedure. When one instrument is replaced with another instrument (e.g., an instrument that measures only displacement replaced with an instrument that measures only balance status), the site of the joint may shift the displacement and thus change the displacement already measured or change the balance status read using an instrument that cannot provide both displacement measurement and balance status, or balance measurement with a single instrument. Thus, there is a need for an improved gap gauge. In particular, there is a need for a gap gauge that can provide both displacement measurement and balance status (e.g., balance measurement) using a single instrument. Additionally, the present disclosure provides a gap gauge that allows the user to optionally disable/disable the balance indicator or balance gauge 168 during use so that the user can use the same instrument to measure only the displacement between the two articular bones, if desired.

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

As part of the joint arthroplasty, the gap gauge 100 can be inserted into an opening 106, also referred to as a gap, between a first bone and a second bone. The gap gauge 100 can be used to determine how much displacement exists between the first bone and the second bone in the opening 106. As used herein, "opening" refers to a gap, a hole, an opening, a void in a structure, and the like. In certain embodiments, an opening can refer to a structure that is specifically configured to receive something and/or allow access. The amount of displacement can be referred to herein as measuring the gap or space between the first bone and the second bone.

Additionally or alternatively, the gap gauge 100 can be used to determine the balance status of a joint 108 that is part of an arthroplasty. The joint 108 can be a toe joint, ankle joint, knee joint, hip joint, arm joint, elbow joint, finger joint, etc. In the illustrated embodiment, the joint 108 is a knee joint, the first bone is the femur 102, and the second bone is the tibia 104. The gap gauge 100 can be used to determine both the displacement and balance status in the opening 106 using a single device. Alternatively, a user, such as a surgeon, can use the gap gauge 100 to determine the displacement or balance status for a first bone and a second bone in flexion, extension, or an angle between flexion and extension, using a single convenient device.

FIG. 1A shows three-dimensional axes 110. The three-dimensional axes 110 include a cranio-caudal axis 112, a medial-lateral axis 114, and an anterior-posterior axis 116. The three-dimensional axes 110 are used to identify how the gap gauge 100 is positioned and/or oriented relative to the anterior-posterior axis 116 of a patient in a reference anatomical position.

FIG. 1B is a perspective view of the gap gauge of FIG. 1A. FIG. 1B shows the gap gauge 100 without the 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 an upper plate 118 and the second plate may be a lower plate 120. The illustrated gap gauge 100 also includes a separator 122, a separation indicator 124, and a balance indicator 126.

In one embodiment, the upper plate 118 is a plate. As used herein, "plate" refers to a flat or generally flat structure. In certain embodiments, the plate can be configured to support a load. In certain embodiments, the plate can include a generally planar structure. The plate can be a separate structure connected to or integrated with another structure. Alternatively, the plate can be connected to a portion of another structure. The plate can be two or three dimensional and can have a variety of geometric and/or cross-sectional shapes, including, but not limited to, rectangular, square, or other polygonal, as well as circular, elliptical, oval, or other circular or semicircular shapes. The plate can be made from a variety of materials, including metal, plastic, ceramic, wood, fiberglass, and the like. The lower plate 120 can also be a plate.

The upper plate 118 can be positioned opposite the lower plate 120. The upper plate 118 can be positioned in contact with a first bone (e.g., the femur 102). The lower plate 120 can be positioned in contact with a second bone (e.g., the tibia 104). The upper plate 118 and the lower plate 120 are parallel to one another and can cooperate to slide into an opening or gap.

In one embodiment, the upper plate 118 and the lower plate 120 have structural integrity that allows them to be positioned (e.g., inserted) between the femur 102 and the tibia 104. When initially positioned between the two bones, the upper plate 118 and the lower plate 120 may contact one another as shown in FIG. 1A. Once positioned between the two bones, a user may move the upper plate 118 relative to the lower plate 120 which adjusts the displacement 128 between the upper plate 118 and the lower plate 120. When the upper plate 118 and the lower plate 120 contact one another, the displacement 128 may be zero. In one embodiment, the upper plate 118 and the lower plate 120 may be displaced from one another by the displacement 128 when the gap gauge 100 is initially manufactured/assembled.

As used herein, "displacement" refers to a vector that measures the movement or change in position of a structure, member, object, component, or part from a start position to an end position, or the distance between two objects. Displacement can be measured using a variety of units of measurement, including imperial, metric, angular, etc. In a particular embodiment, displacement is measured in millimeters. In one embodiment, displacement 128 can range from 0 to 25 or more millimeters.

The user can adjust the displacement 128. The user can separate the upper plate 118 and the lower plate 120 by manually pulling them apart, and/or the user can separate the upper plate 118 and the lower plate 120 using the separator 122. The user can also bring the upper plate 118 and the lower plate 120 together by manually positioning them, and/or the user can bring the upper plate 118 and the lower plate 120 together using the separator 122.

The separator 122 is connected to the upper plate 118 and the lower 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, "separator" refers to an apparatus, instrument, structure, device, component, system, assembly, or module that is structured, organized, configured, programmed, designed, arranged, or designed to separate a first structure from another structure. In one embodiment, the separator is structured, organized, configured, programmed, designed, arranged, or designed to separate a first plate from a second plate, thereby creating a distance between the first plate and the second plate. The separator 122 can actively adjust the displacement 128 and/or hold the upper plate 118 and the lower plate 120 in a particular separation state, thereby maintaining a desired displacement 128.

The separation indicator 124 indicates the displacement 128 between the top plate 118 and the bottom 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 that is structured, organized, configured, programmed, designed, arranged, or designed to indicate to a user the displacement between two or more structures. The separation indicator can include one or more of an audible signal, a tactile signal, a visual signal or display, or the like. In one embodiment, the visual indicator of the separation indicator can include a number or set of numbers that represents a unit of measure of the displacement (or distance) between the two or more structures. Alternatively or additionally, the separation indicator can include a mechanical device, an electromechanical device, an electronic device (analog or digital), or the like.

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 that is structured, organized, configured, programmed, designed, arranged, or designed to indicate a balance status to a device or a user of an apparatus that includes the balance indicator. The balance indicator may include one or more of an audible signal, a tactile signal, a visual signal or display, and the like. Alternatively, or in addition, the balance indicator may include a mechanical device, an electromechanical device, an electronic device (analog or digital), and the like. As used herein, a "balance status" refers to a state, condition, attribute, value, and/or characteristic of one or more members, components, structures, and/or openings relative to a desired, correct, and/or equal proportion state between a reference set of one or more members, components, structures, and/or openings and one or more members, components, structures, and/or openings being evaluated, measured, or inspected. In certain embodiments, the balance status may be a binary condition, state, attribute, value, and/or characteristic. For example, the relationship between one or more structures or openings and a criteria set of one or more structures or openings may be either balanced or unbalanced (also referred to as unbalanced).

Alternatively, or in addition, the balance status may 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, the balance status may be measured on a scale or range of degrees between a positive maximum and a negative minimum value, with a balance status of zero on the range representing a balanced state and non-zero values along the range representing an unbalanced state. In one embodiment, the range used to measure the balance status may extend from -5 degrees to +5 degrees.

In certain embodiments, the balance status can represent whether the upper resection of one bone of a joint is parallel to the lower resection of another bone of the joint. In another embodiment, the balance status can represent the degree to which the upper resection of one bone of a joint is parallel or not parallel to the lower resection of another bone of the joint. In another embodiment, the balance status can represent how the two bones of a joint and the space/opening between them interact with each other in relation to the medial and lateral collateral ligaments to achieve a desired relationship with the joint.

In one embodiment, the balance indicator 126 indicates a balance status between the upper plate 118 and the lower plate 120. Alternatively or additionally, the balance indicator 126 may indicate a balance status of the joint 108 and/or a balance status between the medial collateral ligament and the lateral collateral ligament of the joint 108. Alternatively or additionally, the balance indicator 126 may indicate a balance status between a first bone and a second bone. In a knee arthroplasty setting, the balance indicator 126 may indicate whether the arthroplasty is likely to be varus, valgus, or balanced when completed with an implant on the measured bone surface.

The balance indicator 126 can be connected to one or the other or both of the upper plate 118 and the lower plate 120. In one embodiment, the balance indicator 126 is connected to the upper plate 118. In a different embodiment, the balance indicator 126 is shown as a dashed area of the gap gauge 100 because one or more components or elements within the dashed area can function as the balance indicator 126. For example, in one embodiment, a user can observe a non-parallel position of the upper plate 118, or a portion of the upper plate 118, and such observation can function as the balance indicator 126.

1C-1I show top (1C), bottom (1D), side (1E-G), rear (1H), and front (1I) views of one embodiment of a gap gauge 100. FIG. 1C shows an embodiment including a lockout 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, etc. A "handle" may be designed to be grasped and/or held in one or more hands of a user.

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

FIG. 1D shows a bottom view of one embodiment of the gap gauge 100. The view shows the bottom plate 120, the lockout mechanism 130, the grip 132, and the handle 134.

FIG. 1E shows a side view of one embodiment of the gap gauge 100. The view shows the top plate 118, the bottom plate 120, the separator 122, the grip 132, and the handle 134. In addition, the illustrated embodiment includes an upper body 136, a lower body 138, a shaft 140, and a spring 142. As used herein, "body" refers to the main or central part of a structure. In one embodiment, the body may include a housing or a frame or framework for a larger system, component, structure, or device. As used herein, "spring" refers to a resilient structure that stores mechanical energy. Springs can be made of various resilient materials, such as spring steel, and can be cylindrical and/or helical. Various types of springs can be used, such as coil springs, torsion springs, etc. (Wikipedia.com, searched for "spring (device)" on November 28, 2020. Modified. Retrieved January 6, 2020)
The upper body 136 provides structural support and integrity to the gap gauge 10 and may house one or more portions of the gap gauge 100. The lower body 138 provides structural support and integrity to the gap gauge 10 and may house one or more portions of the gap gauge 100. In one embodiment, the upper plate 118 extends from the upper body 136 and the lower plate 120 extends from the lower body 138.

The shaft 140 can couple or connect the upper body 136 to the lower body 138. The shaft 140 can be slidably coupled to the upper body 136 and the lower body 138. The slidable coupling between the shaft 140, the upper body 136, and the lower body 138 allows for adjustment of the displacement 128.

In one embodiment, the shaft 140 can fit within an opening in the upper body 136 and pass through the upper body 136 to engage the lower body 138. In a particular embodiment, the shaft 140 can include threads on the outside of one end of the shaft 140. The threads on the shaft 140 can engage with threads on an opening in the lower body 138 to connect the shaft 140 to the lower body 138. The shaft 140 can include a head 144 on an end opposite the end that includes the threads.

The opening in the upper body 136 can be sized to receive the shaft 140 and the spring 142 wound around the outside of the shaft 140. The spring 142 can contact the upper body 136 and the head 144. The shaft 140 and the spring 142 cooperate to hold the upper body 136 connected to the lower body 138. In one embodiment, once assembled into the gap gauge 100, the spring 142 can be biased against the head 144 and the upper body 136. The spring 142 can bias the upper body 136 against movement of the upper plate 118 away from the lower plate 120.

In certain embodiments, the gap gauge 100 may include a post 146. The post 146 may be slidably engaged with the upper body 136 and connected to the lower body 138. In one embodiment, the post 146 may be threaded into an opening in the upper body 136. The post 146 may cooperate with the shaft 140 to maintain movement of the upper body 136 along a single axis.

FIG. 1F shows a side view of one embodiment of the gap gauge 100. The side view shows the upper plate 118, the lower plate 120, the separator 122, the lockout mechanism 130, the grip 132, the handle 134, the upper body 136, the lower body 138, the shaft 140, the spring 142, and the post 146.

FIG. 1G shows a side view of one embodiment of the gap gauge 100. The side view shows the upper plate 118, the lower plate 120, the separator 122, the lockout mechanism 130, the grip 132, the handle 134, the upper body 136, the lower body 138, the shaft 140, the spring 142, and the post 146.

FIG. 1G shows the gap gauge 100 in which the separator 122 operates such that the upper plate 118 and the lower plate 120 are displaced relative to one another by a displacement 128. In one embodiment, the displacement 128 is a measure between the outer surface of the upper plate 118 and the outer surface of the lower plate 120. Those skilled in the art will recognize that the displacement can also be a measure between the inner surface of the upper plate 118 and the inner surface of the lower plate 120 as indicated by a displacement 128'.

In the illustrated embodiment, the gap gauge 100 may include an upper plate 118 that includes a pivot plate 148 and a support plate 150. The pivot plate 148 may be connected or coupled to the support plate 150 such that the pivot plate 148 may function as a balance indicator 126. In one embodiment, the pivot plate 148 may pivot about a fore-aft axis 116 relative to the support plate 150. As used herein, a "support plate" refers to a plate that is structured, organized, configured, programmed, designed, arranged, or engineered to support a load.

1H shows a rear view of one embodiment of the gap gauge 100. The rear view shows the upper plate 118, the lower plate 120, the separation indicator 124, the balance indicator 126, the grip 132, the handle 134, the shaft 140, the spring 142, the pivot plate 148, and the support plate 150. In one embodiment, the lower plate 120 can be the first plate and the upper plate 118 can be the second plate, or vice versa. Furthermore, in certain embodiments, the lower plate 120 can be the first plate and the pivot plate 148 can be the second plate, or vice versa. In such an embodiment, the gap gauge 100 may not include the support plate 150.

1H shows an embodiment of the gap gauge 100 including a driver 152 and a fastener 154. The driver 152 functions to actuate the separator 122. The driver 152 can include a circumference with a curved slot that facilitates rotation of the driver 152. In one embodiment, the driver 152 functions to engage the separator 122 such that the 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 modified 1/6/2021.) In certain embodiments, the driver can be a wheel configured or connected to other parts such that rotation or motion of the driver causes motion of other interconnected or interconnected parts of a component, system, apparatus, or device.

The fastener 154 secures the driver 152 to the gap gauge 100. In one embodiment, the fastener 154 is a bolt that threads into the lower body 138 and allows the driver 152 to rotate freely around the bolt.

FIG. 1I shows a front view of one embodiment of the gap gauge 100. The front view shows the top plate 118, the bottom plate 120, the grip 132, the handle 134, the shaft 140, the spring 142, the pivot plate 148, and the support plate 150. In one embodiment, the balance indicator connects to a second plate, such as the top plate 118, and the balance indicator includes a hinge 156 that pivotally connects the top plate 118 to the gap gauge 100. In one embodiment, the hinge 156 is connected to the support plate 150.

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

A hinge may include a pin, one or more knuckles (also called 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 the opening of one or more knuckles of the hinge. In certain embodiments, the pin may include a head at one end, which may be larger than the diameter of the opening of the knuckle or knuckles such that the head prevents the pin from passing completely through the opening of the knuckle or knuckles. The pin may be made from a variety of materials, such as metal, plastic, wood, etc. A leaf is a structure that extends laterally from the knuckle or knuckles and may be integrated with or connected to a structure intended to pivot or rotate around the pin. In certain embodiments, a hinge may include two or more leaves. The leaf may be a planar structure.

A knuckle is a structure having an opening sized to receive a pin. The knuckle connects to at least one leaf. The 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 the longitudinal axis of the hinge. Once the knuckle or knuckles are aligned along the longitudinal axis of the hinge, a pin can be inserted into the opening of the knuckle or knuckles to secure the leaf/leaves connected to each knuckle.

1I includes a front view of one embodiment of the balance indicator 126. In such an embodiment, the upper plate 118 may include a pivot plate 148 coupled to the gap gauge 100 by a hinge 156. In certain embodiments, the hinge 156 may function as both a hinge and a balance indicator 126. For example, a user may view the hinge 156 during arthroplasty and detect that the pivot plate 148 (or the upper plate 118) is oriented in a direction that is not parallel to the lower plate 120. In this manner, the user may determine the balance status.

In one embodiment, the hinge 156 can include a pin 158. The pin 158 can be coupled or connected 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 be connected to the support plate 150. The pin 158 has a longitudinal axis 160 that is a pivot axis 162 for the pivot plate 148. A force applied to the pivot plate 148 (e.g., a force in the direction of arrow 164 or arrow 166) can cause the pivot plate 148 to rotate about the pin 158. As used herein, "pivot axis" refers to the axis about which a structure pivots or rotates.

During arthroplasty, the user may align the longitudinal axis of the pin 158, and therefore the pivot axis of the pivot plate 148, with the anterior-posterior axis 116 of the patient to determine balance status. Alternatively, or in addition, during arthroplasty, the user may position the longitudinal axis of the pin 158, and therefore the pivot axis of the pivot plate 148, parallel to the anterior-posterior axis 116 of the patient to determine or measure varus, balanced, or valgus conditions.

If the pivot plate 148 pivots about the pin 158 in the direction of the arrow 164, this may indicate a varus condition of the first bone relative to the second bone. If the pivot plate 148 pivots about the pin 158 in the direction of the arrow 166, this may indicate a valgus condition of the first bone relative to the second bone. If the pivot plate 148 does not pivot about the pin 158, this may indicate a balanced condition of the first bone relative to the second bone.

2 and 3 are anterior views of a knee joint with the gap gauge 100 of FIG. 1A inserted between two bones, showing balanced and varus conditions, respectively. A diagram showing the bones of the joint for the valgus condition is not specifically shown, but one skilled in the art will understand that the valgus condition is simply the angle or orientation of the bones in FIG. 3 such that the pivot plate 148 pivots in the direction of arrow 166 rather than arrow 164.

As used herein, "valgus condition" refers to a bone or joint condition having an undesirable outward angle (angle away from the midline of the body) of the distal segment of the bone or joint. For example, in a valgus knee condition, the distal portion of the leg below the knee deviates outward relative to the femur, resulting in a knock knee appearance. The opposite of varus is called valgus. A valgus knee condition results in a bow leg appearance with the distal portion of the leg deviating inward in relation to the femur. (Searched Wikipedia.com for "Valgus deformity" on October 20, 2020. Modified. Accessed January 6, 2020) Valgus conditions can be experienced in various joints, including but not limited to the ankle joint, elbow joint, foot joint, wrist joint, hip joint, knee joint, toe joint, wrist joint, etc. As used herein, a "varus condition" refers to a condition of a bone or joint having an undesirable medial angle (i.e., an inward angle toward the midline of the body) of the distal segment of the bone or joint. The opposite of varus is called valgus. The terms "varus" and "valgus" refer to the direction in which the distal segment of the joint points. For example, a varus condition of the knee results in a bow leg appearance with the distal portion of the leg deviating inward in relation to the femur. For example, in a valgus condition of the knee, the distal portion of the leg below the knee deviates outward in relation to the femur, resulting in a knock knee appearance. (Searched Wikipedia.com for "varus defect" on October 20, 2020. Modified. Accessed January 6, 2020) Varus conditions can be experienced in various joints, including but not limited to the ankle joint, elbow joint, ankle joint, wrist joint, hip joint, knee joint, toe joint, wrist joint, etc. As used herein, a "balanced state" refers to a state of a bone and/or joint in which the bone or joint has a desired alignment with the central axis of the limb or anatomical structure that contains the bone and/or joint. In certain embodiments, a balanced state refers to a state of a bone or joint that is not in varus and not in valgus.

2 shows a balanced state of the joint 108. The upper plate 118 and/or pivot plate 148 contact the femur 102. The lower plate 120 contacts the tibia 104. The pivot plate 148 is parallel to the lower plate 120. In the illustrated embodiment, a force or tension in the joint 108 or movement in the direction of arrow 164 is countered by a force or tension in the joint 108 or movement in the direction of arrow 166. As used herein, "tension" refers to a tensile force applied across an elongated structure. For example, a ligament such as the lateral collateral ligament may experience tension due to the way the ligament is attached to the femur and tibia and stretches during flexion of the knee joint.

3 illustrates a varus state of the joint 108. The upper plate 118 and/or pivot plate 148 contact the femur 102. The lower plate 120 contacts the tibia 104. The pivot plate 148 is not parallel to the lower plate 120. The tilt of the upper plate 118 and/or pivot plate 148 can be caused by a variety of factors, including, but not limited to, the angle at which the femur 102 and/or tibia 104 are cut, forces acting on the joint 108 by soft tissues and/or ligaments, etc. In the illustrated embodiment, the force or tension within the joint 108 or the movement of the surface of the femur 102 or tibia 104 in the direction of arrow 164 is greater than the force or tension within the joint 108 or the movement of the surface of the femur 102 or tibia 104 in the direction of arrow 166.

Those skilled in the art will recognize that a valgus condition may exist in the joint 108 shown in FIG. 3 when the top plate 118 and/or pivot plate 148 rotate about the longitudinal axis 160 in the direction of arrow 166. Such tilting may be caused by a variety of factors, including, but not limited to, the angle at which the femur 102 and/or tibia 104 are cut, forces acting on the joint 108 by soft tissues and/or ligaments, etc. In such an embodiment, the force or tension within the joint 108, or the movement by the surface of the femur 102 or tibia 104 in the direction of arrow 166 is greater than the force or tension within the joint 108, or the movement by the surface of the femur 102 or tibia 104 in the direction of arrow 164.

Figure 4 is a posterior view of a knee joint with the gap gauge 100 inserted between the femur 102 and the tibia 104. Figure 4 shows a rear view of the gap gauge 100. Figure 4 shows the upper plate 118, the lower plate 120, the separation indicator 124, the balance indicator 126, the grip 132, the handle 134, the shaft 140, the spring 142, the pivot plate 148, the support plate 150, the driver 152, and the 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.

FIG. 4 shows the 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, "medial condyle" refers to one of two processes at the distal end of the femur, the other being the lateral condyle. The medial condyle is larger than the lateral (outer) condyle due to the increased weight bearing caused by the center of mass being on the inside of the knee. (Wikipedia.com searched for "medial condyle" on May 12, 2020. Modified. Accessed January 6, 2020) As used herein, "lateral condyle" refers to one of two processes at the distal end of the femur, the other being the medial condyle. The lateral condyle is prominent and wider in both its anterior-posterior and lateral diameters. (Searched for "lateral condyle" on Wikipedia.com on April 17, 2020. Updated. Accessed January 6, 2020)
In the illustrated embodiment, the upper plate 118 is positionable to engage or contact the femur 102 and the lower plate 120 is positionable to engage or contact the tibia 104. The upper plate 118 can be shaped or configured to engage the medial condyle 174b and the lateral condyle 176b of the femur 102. The lower plate 120 can be shaped or configured to engage the medial condyle 174a and the lateral condyle 176a of the tibia 104. An example of a suitable shape for the upper plate 118 to engage the medial condyle 174b and the lateral condyle 176b of the femur 102 is shown in FIG. 1C. An example of a suitable shape for the lower plate 120 to engage the medial condyle 174a and the lateral condyle 176a of the tibia 104 is shown in FIG. 1D. Of course, the size and shape of the upper plate 118 and the lower plate 120 can vary depending on the age and size of the patient (e.g., smaller for a child and larger for an adult).

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

FIG. 4 shows that a user can determine both the displacement using the separation indicator 124 and the 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 useful because other soft tissue or instruments may interfere with the determination of either or both of the displacement and balance status during arthroplasty.

5A-5C are rear views of an exemplary gap gauge 100 showing different balance status conditions. 5A-5C show a dial 170 and a needle 172 coupled or connected to the balance indicator 126 to measure balance status. As used herein, a dial refers to a dial on which some measurements are registered, usually by a scale and a pointer such as a needle. ("Dial." Merriam-Webster.com. Merriam - Webster, 2021. Web modified 06 Jan 2021.) 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.

In the illustrated embodiment, the dial 170 includes markings, each marking located on a face of the dial 170. The markings may represent a pivot angle or movement of the top plate 118 and/or the pivot plate 148 about the pin 158. Each marking on the face may represent a different measure of balance status. Alternatively, or in addition, the marks located on the face of the dial may indicate a measure of the orientation of the top plate 118 relative to the bottom plate 120.

In certain embodiments, the dial can include numbers that identify different measurements of balance status. In one embodiment, the dial 170 includes markings for angles ranging from -5 degrees to +5 degrees, with 0 degrees representing a balanced state. As the top 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. The movement of the balance indicator 126 is transferred to the needle 172, which moves the needle 172 to point toward the mark on the dial that reflects the balance status. Rotation of the top plate 118 or the bottom plate 120 about the patient's anterior-posterior axis 116 moves the needle 172 to point toward the mark on the dial that reflects the orientation of the plate.

5A illustrates an exemplary balance gauge 168 of the gap gauge 100 that can be positioned to contact a first bone (see FIG. 1A) and a second bone (see FIG. 1A). When the bone surfaces are parallel and/or the forces in the joint 108 are balanced (e.g., balanced), the needle 172 of the balance gauge 168 may point to a center mark on the dial 170, indicating a balanced condition, or may point to a positive or negative degree of rotation about the pivot axis 162.

5B illustrates an exemplary balance gauge 168 of the gap gauge 100 that can be positioned to contact a first bone (see FIG. 1A) and a second bone (see FIG. 1A). If the bone surfaces are not parallel and/or the forces in the joint 108 are not balanced (e.g., a varus or valgus condition, depending on which joint is being measured), the needle 172 of the balance gauge 168 may point to a mark to the left of the center mark on the dial 170 (e.g., −5 degrees) to indicate an imbalanced or unbalanced condition, a positive or negative degree of rotation about the pivot axis 162.

5C illustrates an exemplary balance gauge 168 of the gap gauge 100 that can be positioned to contact a first bone (see FIG. 1A) and a second bone (see FIG. 1A). If the bone surfaces are not parallel and/or the forces in the joint 108 are not balanced (e.g., a varus or valgus condition depending on which joint is being measured), the needle 172 of the balance gauge 168 may point to a mark to the right of the center mark on the dial 170 (e.g., +5 degrees) to indicate an imbalanced or unbalanced condition, a positive or negative degree of rotation about the pivot axis 162.

Figures 6A-6C are rear views of an exemplary gap gauge 100 showing different displacements. Figures 6A-6C show the top plate 118, the bottom plate 120, and the separation indicator 124. The top plate 118 can include a pivot plate 148 and a support plate 150. Figures 6A-6C also show a driver 152 and a fastener 154.

In the illustrated embodiment, the separation indicator 124 may include a dial that may include a number representing a measure of displacement between the outer surface of the upper plate 118 and the outer surface of the lower plate 120. For example, in the illustrated embodiment, the number at the topmost position of the dial when viewed as illustrated may represent the current amount of displacement. For example, a "9" may represent a displacement of 9 millimeters. The dial on the driver 152 may include a number of different marks and/or numbers (e.g., readings) each of which may represent a different displacement between the upper plate 118 and the lower plate 120. The fastener 154 may allow the driver 152 to rotate about the longitudinal axis of the fastener. The driver 152 may be rotatable to a number of positions, each of which may represent a different displacement corresponding to a number on the dial of the driver 152. The illustrated embodiment may include six different displacements and six numerical values (e.g., 9, 11, 13, 15, 17, and 19), each of which may represent a different displacement.

Figure 6A shows an example separation indicator 124 of a gap gauge 100 that can be positioned in the opening 106 between a first bone (see Figure 1A) and a second bone (see Figure 1A). Once positioned and the separator 122 is actuated to a desired displacement, a user can read the displacement by reading the numerical value at the top position of the separation indicator 124. For example, in Figure 6A, the displacement is 9 millimeters. For example, in Figure 6B, the displacement is 15 millimeters. For example, in Figure 6C, the displacement is 19 millimeters.

The separator 122 can be actuated to bring the upper plate 118 into contact with the resected surface of the femur 102 and the lower plate 120 into contact with the resected surface of the tibia 104. As used herein, "resected surface" refers to the outermost portion or layer of a body structure exposed after a resection procedure.

The upper plate 118 can be shaped or configured to facilitate contact with the resected surface of the femur 102. The lower plate 120 can be shaped or configured to facilitate contact with the resected surface of the tibia 104. An example of a suitable shape for the upper plate 118 is shown in FIG. 1C. An example of a suitable shape for the tibia 104 is shown in FIG. 1D.

The separator 122 may be actuated by fixing the handle 134 with one hand and then rotating the driver 152 to one or more of a plurality of displacement positions. Alternatively, or additionally, actuation of the separator 122 may include using the handle 134 to fix the gap gauge 100 in place, rotating the driver 152, and/or pulling the grip 132 to separate the plates 118, 120. When the handle 134 is fixed, the driver 152 is rotated and the grip 132 is pulled to separate the plates 118, 120 simultaneously or nearly simultaneously, an assistant can assist in actuation.

FIG. 7 is a perspective view of an exemplary gap gauge 100. FIG. 7 shows the gap gauge 100 including a separator 122 including a cam 702 and a follower 704. As used herein, a "cam" refers to a mechanical device that is structured, organized, configured, programmed, designed, arranged, or designed to convert one form of motion into another form of motion. For example, a cam can convert rotary motion into linear motion. Similarly, a cam can convert linear motion into rotary motion. A cam can be a rotating or sliding part in a mechanical linkage used in converting rotary motion into linear motion. A cam can be a rotating wheel (e.g., an eccentric wheel) or a part of a shaft (e.g., an irregularly shaped cylinder) that strikes or moves a lever at one or more points on the circular path of a rotating wheel. A cam can be a simple tooth or eccentric disk or other shape that creates a smooth reciprocating motion (back and forth) in a follower, which is a lever configured to contact the cam. (Searched Wikipedia.com for "cam" on December 26, 2020. Modified. Retrieved January 6, 2020.) Various types of cams can be used in this disclosure. For example, the cam can be a radial cam, a disk cam, a cylindrical cam, etc.

As used herein, a "follower" refers to a rigid structure that contacts the cam lobe profile. In one embodiment, the follower can translate the motion of the cam to the follower and/or the structure connected to the follower. In certain embodiments, as the cam rotates, the follower may slide along the contact surface of the cam, thereby converting the rotational motion to linear motion. A follower may also be referred to as a "cam follower" or a "track follower." A cam follower is a type of structure, roller, or needle bearing designed to follow and/or contact the cam lobe profile of a cam. (Wikipedia.com search for "CAM follower" on November 13, 2020. Modified. Accessed January 6, 2020)

Various types of followers can be used in the present disclosure. The type and shape of the cam follower can be based on the type of surface of the follower (referred to as the follower face) that contacts the contact 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 additionally, the follower face can have a variety of other shapes, including, but not limited to, a flat surface, a mushroom surface, a cylindrical surface, a curved surface, a hemispherical surface, and the like. Additionally, the follower can include a roller on the end that contacts the contact surface of the cam. The roller on the end of the follower can allow the follower to roll or slide along the contact surface of the cam.

In the illustrated embodiment, the cam 702 is connected to or integral with the driver 152. The driver 152 connects to the lower body 138 via fasteners 154. In this manner, the cam 702 connects to the lower body 138. The cam 702 includes a contact surface 706. As used herein, "contact surface" refers to the surface of the cam that contacts the follower. The orientation, arrangement, and location of the contact surface may vary depending on the type of cam used. In an embodiment using a radial cam, the radial cam may have a central axis 708 and the contact surface may be a surface of the cam that follows the circumference of the radial cam about the central axis 708.

Rotation of the driver 152 also rotates the cam 702. Rotation of the cam 702 moves the upper body 136 which adjusts the displacement of the upper plate 118 relative to the lower plate 120. In one embodiment, the cam 702 is a radial cam and rotates with the fastener 154 about a common axis, a central axis 708. As used herein, "radial cam" refers to a type of cam where the cam has a central axis and the contact surface follows the 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 the cam 702 or rest on the cam 702.

The follower 704 is connected to the upper body 136. In one embodiment, the follower 704 may be biased against the contact surface 706 by a spring 142 around the shaft 140. The follower 704 is sized and shaped to move the upper body 136 along the shaft 140 relative to the lower body 138 as the follower 704 slides or is positioned along the contact surface 706. FIG. 7 shows an example embodiment in which the support plate 150 is coupled to the separator 122 (e.g., via the cam 702, follower 704, and upper body 136) such that actuation of the separator 122 moves the support plate 150 vertically relative to the lower plate 120.

FIG. 7 also shows one embodiment of the 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 a rod into the holes 710 to provide leverage for rotating the driver 152.

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

FIG. 8B is a rear view of the driver 152 and cam 702 of the gap gauge 100 according to one embodiment of the present disclosure. FIG. 8B illustrates that the cam 702 may have an irregular radius that varies about a 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 upper plate 118 and the lower plate 120 connected to the cam 702 and the follower 704.

Figure 9 illustrates an exploded view of an exemplary gap gauge 100, according to one embodiment of the present disclosure. Figure 9 illustrates details of 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 lockout mechanism 130 that can prevent rotation of the pivot plate 148 relative to the lower plate 120 and/or the support plate 150 when the lockout mechanism 130 is in a set configuration.

9 shows the support plate 150 including 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 function as a leaf 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 function as a hinge for mounting one embodiment of the balance indicator 126.

In certain embodiments, the pivot plate 148 may be free to rotate about the pin 158. In such embodiments, the pin 158 may include one or more pins 906. The pins 906 engage the pins 158 and the pivot plate 148 such that rotation of the pivot plate 148 causes rotation of the pins 158. Additionally, the pins 906 may also hold the pivot plate 148 against rotation if the pins 158 are fixed or prevented from rotating about the pivot axis 162.

The pin 158 can extend into the upper body 136 and be coupled to the needle 172. In this manner, rotation of the pin 158 causes the needle 172 to move and point in different directions. In certain embodiments, the pin 158 can pass through a slot in the post 146 to allow both rotation of the pin 158 and movement of the pin 158 away from the lower body 138 when the gap gauge 100 is in use.

FIG. 9 shows the lockout mechanism 130, which may include a set screw 908. The set screw 908 has threads that engage with threads of an opening 910 in the upper body 136. Moving the set screw 908 into the opening 910 activates the lockout mechanism 130 and prevents rotation of the pin 158 and connected pivot plate 148. Moving the set screw 908 out of the opening 910 stops the lockout mechanism 130 and allows rotation of the pin 158 and connected pivot plate 148.

As used herein, a "set screw" refers to a type of screw commonly used to secure a first object in or against a second object, usually without the use of a nut. A set screw can be headless, meaning that the thread is fully threaded and the head does not protrude beyond the major diameter of the thread. If the set screw has a head, the threads may extend to the head. A set screw can be driven with an internal wrench drive, such as a hex socket (Allen), star (Torx), square socket (Robertson), or slotted. In one embodiment, the set screw passes through a threaded hole in a second object (the outer object) and tightens against a first object (the inner object) to prevent the inner object from moving relative to the outer object. A set screw can exert a compressive and/or clamping force through the end of the set screw that protrudes through the threaded hole. (Searched Wikipedia.com for "set screw" on August 17, 2020. Modified. Accessed January 6, 2020)

10A is a perspective view of the pin 158 of the gap gauge 100 of FIG. 1A according to one embodiment of the present disclosure. The pin 158 may be a cylindrical structure having a longitudinal axis 160. The pin 158 may include a proximal end 1002, a distal end 1004, and a center 1006. In one embodiment, the proximal end 1002 is connected to the balance gauge 168. For example, the proximal end 1002 may include a D-shaped cross-section including a flat portion 1008. In one embodiment, the D-shaped cross-section of the proximal end 1002 may be sized to receive a D-shaped opening in a needle 172 that can slide over the proximal end 1002 and be positioned for the balance indicator 126 and/or the balance gauge 168.

The distal end 1004 may function as a pivot for the hinge 156 of the gap gauge 100. Alternatively, or additionally, the distal end 1004 may function as a pivot for the balance indicator 126. The pivot may be aligned with the longitudinal axis 160. Additionally, the distal end 1004 and/or the center 1006 may include one or more keyed sections 1010. In one embodiment, the keyed sections 1010 may be used by the pin 906 to connect the pin 158 to the pivot plate 148.

In one embodiment, the center 1006 may include a section 1012 that includes a flat 1014. The flat 1014 of the section 1012 may function as part of the lockout mechanism 130. For example, in one embodiment, the set screw 908 may be biased against the flat 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 the D-shaped cross-section of the proximal end 1002 that includes the flat portion 1008. In one exemplary embodiment, the 90 degree offset allows the needle 172 to not register/measure an imbalance when the lockout mechanism 130 is activated to prevent rotation of the pin 158.

Figures 10B and 10C are side views of the pin 158 of Figure 10A according to one embodiment of the present disclosure. Figure 10B shows an embodiment of the pin 158 including a first section 1016 having a larger diameter than the second section 1018.

11A and 11B are perspective views of the lockout mechanism 130 of the gap gauge 100 according to one embodiment of the present disclosure. FIG. 11A shows the lockout mechanism 130 when the set screw 908 is in a set configuration. FIG. 11B shows the lockout mechanism 130 when the set screw 908 is in an unset configuration. As used herein, "set configuration" refers to the arrangement and/or relationship between the set screw and the pin such that the set screw prevents rotation of the pin about its longitudinal axis. In the set configuration, the set screw 908 is advanced within the opening 910 and engaged with the flat 1014 of the section 1012.

As used herein, "unset configuration" refers to the arrangement and/or relationship between the set screw and the pin such that the set screw allows rotation of the pin about the longitudinal axis of the pin. In the set configuration, the set screw 908 is retracted within the opening 910 to disengage the flats 1014 of the section 1012.

FIG. 12 illustrates a flow chart for a method 1200 for measuring the gap and/or balance status between a patient's femur and tibia, according to one embodiment of the present disclosure. In general, the method 1200 may include the use of a 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.

The method 1200 may begin at step 1210, where a first plate (e.g., lower plate 120) and a second plate (e.g., upper plate 118) of the gap gauge may be inserted between the femur and the tibia. In certain embodiments, the gap gauge may be positioned such that the pivot axis of the hinge may be aligned with the anterior-posterior axis of the patient.

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

Once the first plate and the second plate are actuated apart, the method 1200 may proceed to step 1230 where a separation indicator of the gap gauge may be read to obtain the displacement between the femur and the tibia. Once the displacement is read, the method 1200 may proceed to step 1240 where a balance indicator of the gap gauge is read to obtain a balance status between the femur and the tibia.

A surgeon using the exemplary gap gauge 100 may use the displacement and/or balance status to select from a set of available prostheses for joint arthroplasty. In one example, the surgeon may select a different prosthesis than was selected preoperatively based on the balance status reported/measured by the balance indicator 126 and/or the exemplary 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 exemplary balance gauge 168. If a compensating prosthesis is selected, the surgeon may not need to make any changes to the joint 108 to achieve the desired balance state.

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 the surgeon to determine whether to perform further resections of the femur 102 and/or tibia 104, whether to release one or more of the medial and lateral collateral ligaments, or whether to take other steps of the arthroplasty procedure to achieve a desired outcome for the arthroplasty procedure.

Once the displacement and balance status are read, method 1200 may proceed to step 1250 where the tension applied to the femur and/or tibia by the medial and/or lateral collateral ligaments is adjusted. Once the tension applied to the femur and/or tibia is adjusted, method 1200 may proceed to step 1260 where the balance indicator of the gap gauge is read to obtain an adjusted balance status between the femur and tibia in response to the tension adjustment. After reading the adjusted balance, method 1200 may end with the balance of the joint having the desired balance status.

Alternatively, or in addition, method 1200 may proceed to a step in which tension applied to the femur and tibia by one or more of the medial and lateral collateral ligaments may be adjusted and the balance indicators of the gap gauges may be read to obtain an adjusted balance status between the femur and tibia in response to the tension adjustment.

Alternatively, or in addition, once the tension applied to the femur and tibia by one or more of the medial and lateral collateral ligaments has been adjusted, method 1200 may proceed to a step in which one or more of the medial and lateral collateral ligaments are released and the gap gauge remains between the femur and tibia and remains actuated.

Alternatively, or in addition, once the tension applied to the femur and tibia by one or more of the medial and lateral collateral ligaments is adjusted, the method 1200 may proceed to removing the gap gauge 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 resecting one or more of the femoral and tibial resection surfaces. Once one or more of the femoral and tibial resection surfaces are resected, the method 1200 may proceed to reinserting the first and second plates of the gap gauge between the femur and the tibia. Once the first and second plates of the gap gauge are reinserted between the femur and the tibia, the method 1200 may proceed to actuating the first and second plates apart such that the first plate contacts the resected or further resected surface of the femur and the second plate contacts the resected or further resected surface of the tibia. Once the first and second plates are actuated apart, the method 1200 may proceed to reading a separation indicator of the gap gauge to obtain a displacement between the femur and the tibia. Once the displacement is obtained, the method 1200 may proceed to reading a balance indicator of the gap gauge to obtain a balance status between the femur and the tibia.

Any method disclosed herein includes one or more steps or actions for carrying out the described method. The steps and/or actions of the method may also be interchanged with one another. In other words, unless a particular order of steps or actions is required for proper operation of an embodiment, the order and/or use of certain steps and/or actions may be modified.

Throughout this specification, references to "an embodiment" or "the embodiment" mean that a particular feature, structure, or characteristic described in connection with that embodiment is included in at least one embodiment. Thus, references or variations thereof recited throughout this specification do not necessarily all refer to the same embodiment.

Similarly, in the above description of the embodiments, it should be understood that various features may be grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure. However, this method of disclosure should not be interpreted as reflecting an intention that any claim requires more features than are expressly recited in that claim. Rather, as the following claims reflect, inventive aspects lie in combinations of fewer than all of the features of a single disclosed feature described above. Thus, the claims following the 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 and their dependent claims.

The term "first" in a claim referring to a feature or element does not necessarily imply the presence of a second or additional such feature or element. Elements described in means-plus-function form are intended to be construed in accordance with 35 U.S.C. § 112. 6. It will be apparent to those skilled in the art that changes can be made in the details of the above-described embodiments without departing from the underlying principles described herein.

Although specific embodiments and applications of the present disclosure have been illustrated and described, it should be understood that the scope of the disclosure is not limited to the detailed configuration and components disclosed herein. Various modifications, changes and variations that are 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 described herein without departing from the spirit and scope of the technology.

Claims (40)

1. A gap gauge for facilitating joint arthroplasty of a first bone and a second bone of a patient, comprising:
a first plate positionable in contact with the first bone;
a second plate positionable in contact with a second bone, the second plate being displaced from the first plate by a displacement;
a separator connected to the first plate and the second plate, the separator being actuable to adjust the displacement;
a separation indicator coupled to the separator and configured to indicate a displacement;
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. The gap gauge of claim 1, wherein the balance indicator is connected to the second plate, and the balance indicator includes a hinge that pivotally connects the second plate to the gap gauge. The gap gauge of claim 2, wherein the hinge includes a pin having a longitudinal axis that is a pivot axis of the second plate, the longitudinal axis being parallel to the 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. The gap gauge of claim 3, further comprising a support plate connected to the hinge and the separator, and the balance indicator including a lockout mechanism configured to prevent rotation of one of the first plate and the second plate connected to the balance indicator. the lockout mechanism further includes a set screw having a set configuration and an unset configuration, the set screw including threads configured to engage threads in an aperture, wherein in the set configuration, the set screw engages 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;
5. The gap gauge of claim 4, wherein 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. The gap gauge of claim 5, wherein the set screw engages the pin by biasing it against a planar surface of a section of the pin, the section of the pin having a D-shaped cross-section. the first plate is shaped to engage the medial and lateral condyles of the first bone;
The gap gauge of claim 1 , wherein the second plate is shaped to engage the medial and lateral condyles of the second bone. The gap gauge of claim 1, further comprising a balance gauge connected to the balance indicator, the balance gauge configured to measure a balance status. The gap gauge is
9. The gap gauge of claim 8, comprising: a dial having markings disposed on a face of the dial to indicate a measurement of the balance status of the second plate relative to the first plate; and a needle connected to a balance indicator such that rotation of the second plate about a longitudinal axis of the second plate moves the needle toward the marking on the face of the dial that reflects the balance status. 1. A gap gauge for facilitating joint arthroplasty of a first bone and a second bone of a patient, comprising:
an upper plate extending from the upper body, the upper plate being shaped to conform to a resected surface of the femur;
a lower plate extending from the lower body, the lower plate being shaped to conform to a resected surface of the tibia, the upper plate being displaced from the lower plate by a displacement;
a shaft to which at least one of the upper body and the lower body is slidably coupled to allow for adjustment of displacement;
a separator connected to the upper body and the lower body to adjust the displacement;
a balance indicator connected to one of the upper plate and the lower plate and configured to indicate an orientation of the upper plate relative to the lower plate. The gap gauge of claim 10, wherein the balance indicator connects to the top plate, the top plate including a pivot plate and a support plate, the balance indicator includes a hinge including the pin connected to the pivot plate such that a force applied to the pivot plate can rotate the pivot plate about the pin, and the support plate couples to the separator such that actuation of the separator moves the support plate vertically relative to the bottom plate. The gap gauge of claim 11, wherein the pin includes a cylindrical structure having a longitudinal axis, a proximal end, a distal end, and a center, the proximal end connects to the balance gauge, and the distal end includes a pivot for the balance indicator, the pivot being aligned with the longitudinal axis. The gap gauge of claim 12, wherein the proximal end includes a first D-shaped cross-section, the distal end includes at least one keyed cross-section, the center includes a second D-shaped cross-section with a flat portion of the second D-shaped cross-section offset 90 degrees from the flat portion of the first D-shaped cross-section, and the distal end includes a pivot for the hinge. The gap gauge is
a handle connected to the lower body;
a separation indicator coupled to the separator and configured to indicate the displacement;
a lockout mechanism connected to the upper body and configured to prevent rotation of the upper plate or a portion of the upper plate connected to the balance indicator;
a spring coupled to the shaft biasing one of the upper body and the lower body against movement of the upper plate away from the lower plate, the separator further comprising:
Driver and
a cam connected to the lower body via the driver and including a contact surface;
a follower connected to the upper body and configured and biased to contact a contact surface of the cam such that rotation of the cam regulates displacement. The gap gauge of claim 14, wherein the cam includes a radial cam having a central axis, and the contact surface is a circumference of the radial cam centered on the central axis. The balance indicator further includes a balance gauge connected to the balance indicator, the balance gauge comprising:
a dial having markings disposed on a surface thereof to indicate a measure of the orientation of the upper plate relative to the lower plate;
11. The gap gauge of claim 10, including a needle connected to the balance indicator such that rotation of one of the upper and lower plates about the patient's anterior-posterior axis moves the needle to point toward the mark on the face of the dial that reflects the direction. 1. A method for measuring a gap between a patient's femur and tibia, comprising:
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 such that the first plate contacts the resected surface of the femur and the second plate contacts the 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. 18. The method of claim 17, further comprising adjusting tension applied to the femur and the tibia by one or more of a medial collateral ligament and a lateral collateral ligament, and reading a balance indicator of a gap gauge to obtain an adjusted balance status between the femur and the tibia in response to adjusting the tension. 19. The method of claim 18, wherein adjusting the tension includes 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 activated. Adjusting the tension includes:
removing a gap gauge from between the femur and the tibia;
resecting one or more of the femoral resection surface and the tibial resection surface;
reinserting 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 contacts the resected surface of the femur and the second plate contacts the resected surface of the tibia;
reading the separation indicator of the gap gauge to obtain a displacement between the femur and the tibia;
20. The method of claim 18, comprising reading the balance indicator of the gap gauge to obtain a balance status between the femur and the tibia. 1. A gap gauge for facilitating joint arthroplasty of a first bone and a second bone of a patient, comprising:
a first plate positionable in contact with the first bone;
a second plate positionable in contact with the second bone, the second plate displaced from the first plate by a displacement;
a balance indicator configured to indicate a balance status between the first plate and the second plate;
a pin guide configured to couple to one of the second plate and the first plate, the pin guide including a first pin hole configured to guide insertion of a first pin into the second bone;
and a gap gauge. 22. The gap gauge of claim 21, wherein the pin guide includes 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 a balance status between the first plate and the second plate. 22. The gap gauge of claim 21, wherein the pin guide further includes 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 a balance status between the first plate and the second plate. the pin guide includes a second pin hole configured to guide insertion of a second pin into the second bone;
22. The gap gauge of claim 21, wherein the pin guide is coupled to 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 are angled relative to the second plate to counter a balance status between the first plate and the second plate. 22. The gap gauge of claim 21, wherein the first pin hole guides insertion of the first pin into one of the medial and lateral condyles of the second bone, and the pin guide includes a second pin hole configured to guide insertion of a second pin into the other of the medial and lateral condyles of the second bone. the pin guide includes 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 account for different angular offsets of balance status. The pin guide is
a base configured to connect to the second plate;
an arm that may include the first pin hole;
22. The gap gauge of claim 21 including a mast extending from the base, the mast connecting the arm and the base. 28. The gap gauge of claim 27, wherein the arm includes a second pin hole, and the first pin hole and the second pin hole are each disposed within the arm on one of the medial and lateral sides of the knee when the gap gauge is in position relative to the knee. the pin guide includes a second pin hole configured to guide insertion of the second pin into the second bone such that the first pin and the second pin are aligned with one another in an orientation relative to the second plate consistent with a balance status;
22. The gap gauge of claim 21, wherein the balance status is communicated to a cutting guide by coupling the cutting guide to the second bone via the first pin and the second pin. The gap gauge of claim 29, wherein the cutting guide includes an alignment mechanism including a plurality of sets of holes, each element of the set of holes configured to receive one of the first pin and the second pin, and each set of holes configured to adjust for a different angular offset of the balance status. The cutting guide comprises:
a guide mechanism configured to guide movement of the cutter to resect bone;
an alignment mechanism configured to receive the first pin and the second pin and to position the cutting guide over a bone;
and an adjustment mechanism configured to rotate the guide mechanism relative to the alignment mechanism to adjust for different angular offsets from the balance status. 22. The gap gauge of claim 21, wherein the first plate and the second plate are sized for insertion between the first bone, which includes a tibia, and the second bone, which includes a femur. 1. A gap measurement and correction assembly for facilitating femoral and tibial arthroplasty of a patient, comprising:
an upper plate extending from the upper body;
a lower plate extending from the lower body, the upper plate being displaced from the lower plate by displacement;
a separator connected to the upper body and the lower body to adjust the displacement;
a balance indicator connected to one of the upper plate and the lower plate and configured to indicate a non-parallel orientation of the upper plate relative to the lower plate;
a pin guide configured to guide insertion of a first pin into one of the tibia and the femur of the patient;
a cutting guide attachable to one of the tibia and the femur via the first pin, the cutting guide configured to guide a resection of one of the tibia or the femur in the opposing non-parallel direction;
The assembly containing: The assembly of claim 33, further comprising an attachment feature configured to removably couple the pin guide to the upper plate such that the pin guide guides insertion of the first pin into the femur according to a non-parallel orientation of the upper plate relative to the lower plate. The assembly of claim 33, wherein the pin guide further includes an attachment feature configured to removably couple the pin guide to the upper plate such that the pin guide guides insertion of the first pin into the tibia according to a non-parallel orientation of the upper plate relative to the lower plate. the pin guide is further configured to guide a second pin into the other one of the tibia and the femur of the patient;
34. The assembly of claim 33, wherein the pin guide further includes an attachment feature configured to removably couple the pin guide to the lower 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 are aligned at an angle relative to the upper plate opposite a non-parallel orientation of the upper plate relative to the lower plate. The pin guide is
a base configured to connect to the top plate;
an arm including a first pin hole;
34. The assembly of claim 33 including a mast extending from the base, the mast connecting the arm and the base. The assembly of claim 33, wherein the cutting guide may include an alignment feature including a plurality of sets of holes, each element of the set of holes configured to receive one of the first pin and the second pin, and each set of holes configured to accommodate a different angular offset for non-parallel orientation. The cutting guide comprises:
a guide mechanism configured to guide movement of the cutter to resect bone;
an alignment mechanism configured to receive the first pin and the second pin and to position the cutting guide over the bone;
an adjustment mechanism configured to rotate the guide mechanism relative to the alignment mechanism to adjust for different angular offsets from the non-parallel orientation. 1. A method for measuring and correcting imbalances for femoral and tibial arthroplasty of a patient, comprising:
inserting a first plate and a second plate of a gap gauge between the femur and the tibia of the patient's knee joint;
actuating the first plate and the second plate apart such that the first plate contacts the resected surface of the femur and the second plate contacts the resected surface of the tibia;
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;
coupling a cutting guide to one of the femur and the tibia using the first pin;
using the cutting guide to guide resection of one of the femur and the tibia to counter a non-parallel orientation of the first plate relative to the second plate;
The method includes:

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