CUSTOMIZED TIBIAL TRAYS, METHODS, AND SYSTEMS FOR KNEE REPLACEMENT

A tibial tray for a resurfaced proximal portion of a tibia for a knee replacement for a patient includes, for example, a body having a superior portion, and an inferior tibia-engaging portion having a peripheral inferiorly-extending portion contactable with an underlying cortical bone and/or spaced apart from the underlying inner surface of the cortical of the tibia of the patient. In some embodiments in the total knee replacement, a greater portion of a shearing force acting transversely on the tibial tray and the resected portion of the proximal portion of the tibia of the patient is resisted by the at least one inferiorly-extending wall and the periphery of the resected proximal portion of the tibia compared to a portion of the shearing force being resisted along the center inferior surface of the tibial tray and the resected cancellous bone surface. Methods, robotic systems, and cutting guides are also disclosed.

FIELD OF THE DISCLOSURE

The present disclosure relates generally to surgical implants, methods, and systems for use in repairing knee joints, and more particularly to patient specific surgical procedures and customized tibial trays for use in the replacement of knee joints.

BACKGROUND

Typically, the most common indication for revision surgery of Total Knee Arthroplasties is aseptic loosening (29.8%) and subsidence. Aseptic loosening is also a major cause of post-operative pain. These failures are tied to poor osseointegration, imperfect implant coverage, limited support and shear forces introduced by a flat resection plane.

SUMMARY

Shortcomings of the prior art are overcome and additional advantages are provided through the provision, in one embodiment, of a tibial tray for a resection extending transversely across a proximal portion of a tibia of a patient for use in a total knee replacement. The resected proximal portion of the tibia includes a resected cancellous bone surface, a resected peripheral cortical bone surface, and at least one cavity formed in the underlying periphery of the resected cancellous bone. The tibial tray includes a body comprising a superior portion and an inferior tibia-engaging portion. The superior portion includes a superior surface and a peripheral edge. The inferior tibia-engaging portion includes a peripheral inferior surface supportable on the resected peripheral cortical bone surface, a center inferior surface disposable on the resected center cancellous bone surface, and at least one inferiorly-extending wall spaced inwardly from the peripheral inferior surface and extending around at least a portion of the center inferior surface. The at least one inferiorly-extending wall is receivable in the at least one cavity formed in the periphery of the resected cancellous bone surface. The at least one inferiorly-extending wall includes a first U-shaped wall and a spaced apart second U-shaped wall, the at least one inferiorly-extending wall being receivable in the at least one cavity including a first U-shaped cavity and a spaced apart second U-shaped cavity formed in the periphery of the resected cancellous bone surface.

In another embodiment, a method including, for example, resecting a proximal portion of a tibia of a patient, the resected proximal portion of the tibia having a transverse resected cancellous bone surface, a transverse resected peripheral cortical bone surface, and at least one cavity formed in the underlying periphery of the resected cancellous bone, providing a tibial tray having at least one inferiorly-extending wall spaced inwardly from a peripheral edge of the tibial tray and extending around at least a portion of a center inferior surface, inserting the at least one inferiorly-extending wall in the at least one cavity formed in the underlying periphery of the resected cancellous bone surface, and disposing the center inferior surface against the transverse resected cancellous bone surface, wherein in a total knee replacement, a greater portion of a shearing force acting transversely on the tibial tray and the resected portion of the proximal portion of the tibia of the patient is resisted by the at least one inferiorly-extending wall and the periphery of the resected proximal portion of the tibia compared to a portion of the shearing force being resisted along the center inferior surface of the tibial tray and the resected cancellous bone surface.

In another embodiment, a method for forming a patient specific tibial tray for a total knee replacement of the patient, includes for example, obtaining first data, via at least one processor, representing a proximal portion of the tibia of the patient, the first data corresponding to the proximal portion of the tibia of the patient having an inner cancellous bone, and a peripheral cortical bone having an outer surface and an inner surface, determining, via the at least one processor, second data representing a patient specific resected proximal portion of the tibia of the patient based on the first data, the resected proximal portion of the tibia of the patient having a center cancellous bone surface, a peripheral cortical bone surface, and at least one cavity formed in the underlying periphery of the resected cancellous bone, the at least one cavity having in outer contoured surface portion corresponding to an adjacent inner surface portion of the resected cortical bone, forming, via the at least one processor, the patient specific tibial tray based on the second data, the patient specific tibial tray comprising a body having a superior portion having a superior surface and an inferior tibia-engaging portion, the inferior tibia engaging portion having a center portion contactable with the resected center cancellous bone surface, and at least one inferiorly-extending wall receivable in the at least one cavity, and wherein, in the total knee replacement, a greater portion of a shearing force acting transversely on the patient specific tibial tray and the resected portion of the proximal portion of the tibia of the patient is resistible by the at least one inferiorly-extending wall and the periphery of the resected proximal portion of the tibia compared to a portion of the shearing force being resistible along the center inferior surface of the tibial tray and the resected cancellous bone surface.

Shortcomings of the prior art are overcome and additional advantages are provided through the provision, in one embodiment, of a tibial tray for a resected proximal portion of a tibia of a patient for a knee replacement. The resected proximal portion of the tibia includes a center cancellous bone surface, a peripheral cortical bone surface, and at least one cavity formed in the cancellous bone exposing at least a portion of an underlying inner surface of the cortical bone. The tibial tray includes a body having a superior portion with a superior surface, and an inferior tibia-engaging portion. The inferior tibia-engaging portion includes a center portion having a center surface contactable with the center cancellous bone surface, and a peripheral, inferiorly-extending portion receivable in the at least one cavity formed in the cancellous bone. A surface of the peripheral inferiorly-extending portion is contactable with the exposed underlying inner surface of the cortical bone of the tibia of the patient.

In another embodiment, a method for forming a patient specific tibial tray for a knee replacement for the patient includes, for example, determining a patient specific resected proximal portion of a tibia of the patient, the resected proximal portion of the tibia of the patient having a superior center cancellous bone surface, a peripheral cortical bone surface, and one or more cavities and/or openings in the cancellous bone exposing at least a portion of an underlying inner surface of the cortical bone of the tibia, and forming the patient specific tibial tray comprising a body having an superior portion with a superior surface and an inferior tibia-engaging portion, the inferior tibia engaging portion having a center portion contactable with the cancellous bone surface, and a peripheral, inferiorly-extending portion receivable in the one or more cavities and/or openings and having one or more surfaces contactable with the exposed underlying inner surface of the cortical bone of the tibia of the patient.

In another embodiment, a robotic method for resecting a proximal portion of a tibia of a patient for a knee replacement includes, for example, obtaining, via a processor, first data representing a proximal portion of the tibia of the patient comprising centralized cancellous bone and peripheral cortical bone, determining, via the processor, second data of a patient specific resected proximal portion of the tibia of the patient having a center cancellous bone surface, a peripheral cortical bone surface, and at least one cavity formed in the cancellous bone exposing at least a portion of an underlying inner surface of the cortical bone based on the first data, and forming, via the processor, the tibia of the patent based on the second data of the patient specific resected proximal portion of the tibia, the resected proximal portion of the tibia of the patient having the center cancellous bone surface, a peripheral cortical bone surface, and the at least one cavity exposing the inner surface of the cortical bone of the tibia.

Shortcomings of the prior art are also overcome and additional advantages are provided through the provision, in one embodiment, of a tibial tray for a resected proximal portion of a tibia of a patient for a total knee replacement. The resected proximal portion of the tibia includes a center cancellous bone surface, a peripheral cortical bone surface, and at least one cavity formed in the periphery of the cancellous bone which is spaced apart from the cortical bone exposing an underlying portion of the cancellous bone of the tibia. The tibial tray includes a body having a superior portion with a superior surface, and an inferior tibia-engaging portion. The inferior tibia-engaging portion includes a center portion having a center surface contactable with the center cancellous bone surface, and a peripheral, inferiorly-extending portion receivable in the at least one cavity formed in the cancellous bone surface so that the peripheral inferiorly-extending portion is spaced apart from the underlying inner surface of the cortical bone of the tibia of the patient.

In another embodiment, a method for forming a patient specific tibial tray for a total knee replacement for the patient includes, for example, determining a patient specific resected proximal portion of a tibia of the patient, the resected proximal portion of the tibia of the patient having a superior center cancellous bone surface, a peripheral cortical bone surface, and at least one cavity formed in the periphery of the cancellous bone exposing an underlying portion of the cancellous bone of the tibia, and forming the patient specific tibial tray comprising a body having a superior portion with a superior surface and an inferior tibia-engaging portion, the inferior tibia engaging portion having a center portion contactable with the center cancellous bone surface, and a peripheral, inferiorly-extending portion receivable in the at least one cavity so that the peripheral inferiorly-extending portion is spaced apart from the exposed underlying inner surface of the cortical bone of the tibia of the patient.

In another embodiment, a robotic method for resecting a proximal portion of a tibia of a patient for a total knee replacement includes, for example, obtaining, via a processor, first data representing a proximal portion of the tibia of the patient comprising centralized cancellous bone and peripheral cortical bone, determining, via the processor, second data of a patient specific resected proximal portion of the tibia of the patient having a center cancellous bone surface, a peripheral cortical bone surface, and at least one cavity formed in the periphery of the cancellous bone spaced apart from the cortical bone exposing an underlying portion of the cancellous bone based on the first data, and forming, via the processor, the tibia of the patent based on the second data representing the patient specific resected proximal portion of the tibia, the resected proximal portion of the tibia of the patient having a center cancellous bone surface, a peripheral cortical bone surface, and at least one cavity formed in the periphery of the cancellous bone spaced apart from the cortical bone exposing an underlying portion of the cancellous bone of the tibia.

Shortcomings of the prior art are also overcome and additional advantages are provided through the provision, in one embodiment, of a tibial tray for a resected proximal portion of a tibia of a patient for a total knee replacement. The resected proximal portion of the tibia includes a center cancellous bone surface, a peripheral cortical bone surface, and at least one cavity formed in the periphery of the cancellous bone which is spaced apart from the cortical bone exposing an underlying portion of the cancellous bone of the tibia. The tibial tray includes a body having a superior portion with a superior surface, and an inferior tibia-engaging portion. The inferior tibia-engaging portion includes a center portion having a center surface contactable with the center cancellous bone surface, and a peripheral, inferiorly-extending portion receivable in the at least one cavity formed in the cancellous bone surface so that the peripheral inferiorly-extending outer surface portion corresponds to the contour of the underlying inner surface of the cortical bone of the tibia of the patient. In other embodiments, the peripheral, inferiorly-extending portion includes at least a portion of the peripheral inferiorly-extending outer surface portion extending from a proximal portion of the peripheral, inferiorly-extending portion to a distal portion of the peripheral, inferiorly-extending portion contoured to correspond to a contour of a superior edge portion of the cortical bone along the resection plane so that the at least the portion of the peripheral inferiorly-extending outer surface portion is disposable adjacent to a underlying concave inner surface of the cortical bone.

Shortcomings of the prior art are also overcome and additional advantages are provided through the provision, in one embodiment, of a tibial tray for a resected medial or lateral proximal portion of a tibia of a patient for a partial knee replacement, The resected medial or lateral proximal portion of the tibia has a central cancellous bone surface, a partial peripheral cortical bone surface, and at least one cavity formed in the periphery of the cancellous bone in the resected medial or lateral proximal portion of the tibia. The tibial tray includes a body having a superior portion with a superior surface, and an inferior tibia-engaging portion. The inferior tibia-engaging portion includes a center portion having a center surface contactable with the resected central cancellous bone surface, and a peripheral, inferiorly-extending portion receivable in the at least one cavity formed in the resected cancellous bone surface so that the peripheral inferiorly-extending outer surface portion corresponds to the contour of the underlying inner surface of the cortical bone of the tibia of the patient.

Shortcomings of the prior art are also overcome and additional advantages are provided through the provision, in one embodiment, of a cutting guide for forming at least one cavity in a resected proximal portion of a tibia of a patient for knee replacement. The resected proximal portion of the tibia has a center cancellous bone surface and a peripheral cortical bone surface. The cutting guide includes a planar member having a first planar surface and a second planar surface. The planar member has a peripheral outer edge, a portion of which corresponding to at least a portion of an outer peripheral cortical bone along the resection of the proximal portion of the tibial of the patient, and at least one U-shaped opening extending through the planar member from the first planar surface to the second planar surface and spaced from the peripheral outer edge. The U-shaped opening defines a U-shaped axis, and the U-shaped opening has a constant width normal to the U-shape axis. The U-shaped opening has an inner edge and an outer edge, and the outer edge being parallel to the peripheral outer edge. The cutting guide can further include a milling tool having a proximal diameter sized larger than the width of the opening, and a distal diameter sized for passing through the opening.

Shortcomings of the prior art are also overcome and additional advantages are provided through the provision, in one embodiment, a cutting guide for forming a pair of cavities in a resected proximal portion of a tibia of a patient for total knee replacement, the resected proximal portion of the tibia having a center cancellous bone surface and a peripheral cortical bone surface. The cutting guide includes a planar member having a first planar surface and a second planar surface. The planar member includes a peripheral outer edge corresponding to an outer peripheral cortical bone along the resection of the proximal portion of the tibial of the patient. A pair of U-shaped openings extend through the planar member from the first planar surface to the second planar surface and spaced from the peripheral outer edge. Each of the pair of U-shaped openings define a U-shaped axis, and the U-shaped opening has a constant width normal to the U-shape axis. Each of the pair of the U-shaped openings having an inner edge and an outer edge, and the outer edge is parallel to the peripheral outer edge. The cutting guide can further include a milling tool having a proximal diameter sized larger than the width of opening, and a distal diameter sized for passing through the opening.

DETAILED DESCRIPTION

Generally stated, disclosed herein are resected proximal portions of tibias, tibial trays, and methods and robotic systems for forming the same.

In this detailed description and the following claims, the words proximal, distal, anterior, posterior, medial, lateral, superior, and inferior are defined by their standard usage for indicating a particular part of a bone or implant according to the relative disposition of the natural bone or directional terms of reference.

Positions or directions may be used herein with reference to anatomical structures or surfaces. For example, as the current devices and methods are described herein with reference to use with the bones of the knee, the bones of the knee may be used to describe the surfaces, positions, directions or orientations of the tibial trays, tibial tray installation, and surgical methods. Further, the devices and surgical methods, and the aspects, components, features and the like thereof, disclosed herein are described with respect to one side of the body for brevity purposes. However, as the human body is relatively symmetrical or mirrored about a line of symmetry (midline), it is hereby expressly contemplated that the devices and surgical methods, and the aspects, components, features and the like thereof, described and/or illustrated herein may be changed, varied, modified, reconfigured or otherwise altered for use or association with another side of the body for a same or similar purpose without departing from the spirit and scope of the disclosure. For example, the apparatus and surgical methods, and the aspects, components, features and the like thereof, described herein with respect to a left knee may be mirrored so that they likewise function with a right knee and vice versa.

Referring to the drawings, wherein like reference numerals are used to indicate like or analogous components throughout the several views, and with particular reference to, for example,FIGS. 1, 3, 4, 12-14, 15-21, 22 and 23, 24, and 25therein illustrated are exemplary embodiments of tibial trays installed on a resected proximal portion of a tibia in which portions of the tibial tray are engageable and/or contactable with an underlying inner surface of the cortical bone for use in a knee replacement. As will be appreciated from the description below, the hard cortical bone of the tibia may provide fixation such as press fitting into this dense bone versus conventional tibial trays which rest on top of the hard cortical bone with a keel in the center in the softer cancellous bone. For example, the present disclosure may result in improved fixation of uncemented tibial trays.FIG. 6illustrates a method for use in knee replacement surgery, andFIG. 7illustrates a system for effecting the resecting of the proximal portion of a tibia of a patient and for forming a corresponding, orientated, or matching tibial tray. The methods and systems may be operable for obtaining fully autonomous and automatic resected proximal tibias and corresponding tibial trays from, for example, CT scan data. With reference toFIGS. 26-30, therein illustrated are exemplary embodiments of tibial trays installed on a resected proximal portion of a tibia in which portions of the tibial tray are spaced from and disposed closely adjacent to an underlying inner surface of the cortical bone for use in a knee replacement. As will be appreciated from the description below, the peripheral cancellous bone adjacent to the cortical bone of the tibia may provide fixation to the proximal tibia versus conventional tibial trays which rest on top of the cortical bone with a keel disposed in the center of the softer cancellous bone. For example, the present disclosure may result an in improved fixation of uncemented tibial trays.FIG. 33illustrates a method for use in knee replacement surgery, for example employing the tibial trays ofFIGS. 26-30, which includes effecting the resecting of the proximal portion of a tibia of a patient, and for forming a corresponding, orientated, or matching tibial tray.FIG. 34illustrates a robotic method for use in knee replacement surgery, which includes effecting the resecting of the proximal portion of a tibia of a patient. The methods and systems may be operable for obtaining fully autonomous and automatic resected proximal tibias and corresponding tibial trays from, for example, CT scan data.

In some embodiments, for example, a patient specific tibial tray design may mitigate aseptic loosening and subsidence through a combination of high peripheral surface area contact, underside surface geometry, and patient matched pegs that interface with cortical metaphyseal bone. The present disclosure may solve and/or overcome a primary cause for knee implant failure, namely, aseptic loosening of the tibial component and subsidence.

In some embodiments, the present disclosure is directed to methods for generating a three-dimensional model of a tibia and generating a cut plan for excavating a portion of the tibia with a robot or robotic excavator according to the cut plan to allow for the insertion of a custom tibial tray designed to increase or maximize cortical contact with the periphery of the inner tibial wall.

In some embodiments, a technique of the present disclosure is directed to maximizing cortical contact of a tibial tray along the underlying inner surface of the cortical wall of the tibia. A virtual model of the proximal portion of a tibia bone may be used to determine an improved implant that is designed to achieve a higher level of cortical contact. A processor may be employed and configured to generate an excavation protocol for excavating bone from the tibia such that the amount of bone contact between the bone and the implant is increased, such as 10 percent or greater, compared to convention tibial trays.

FIG. 1illustrates a tibial tray20fitted to a resected proximal portion of a tibia10for a knee replacement, according to an embodiment of the present disclosure. In this illustrated embodiment, at least a portion of the tibial tray20when operably attached to the resected proximal portion of the tibia10interfaces and increases contact with an inner surface or side portion of the cortical bone12of the proximal portion of the tibia10.

For example, the tibial tray20may include a body22having a superior portion24and an inferior tibia-engaging portion26. The superior portion24may include a generally planar superior surface25for supporting a plastic bearing spacer (not shown inFIG. 1). In some embodiments, the surface25includes a peripheral upwardly-extending lip27for attaching via a typical snap fit connection and restraining the plastic bearing spacer.

The tibia engaging portion26may include a center tibia engaging portion30and a peripheral tibia engaging portion40. In this embodiment, the center tibia engaging portion30may include a planar surface contactable with the center cancellous bone surface of the resected proximal portion of the tibia of the patient.

The peripheral tibia-engaging portion40may include at least one inferiorly-extending wall50. The inferiorly-extending wall50may include an inner wall surface52and an outer wall surface54. The inner wall surface52may be disposed normal or at 90 degrees to the superior surface25, or at any suitable angle or angles. The outer wall surface54may be able to be aligned with and abutting or contacting an inner surface13of the cortical bone12.

For example, the outer wall surface54may be disposed at an angle A1, which may be angled at about 25 degrees to about 45 degrees, about 30 degrees to about 40 degrees, about 35 degrees, or other suitable angles relative to the superior surface25of the tibial tray20. The wall50is received in a cavity formed in the resected proximal portion of the tibia10. The cavity may be formed in the cancellous bone, trabecular bone, spongy bone, or light porous bone of the tibia. The wall may increase the contact area with the inner surface13of the cortical bone12. A depth D1of the wall50may extend about 0.5 millimeters (mm) to about 75 mm, about 1 mm to about 50 mm, about 2 mm to about 40 mm, about 4 mm to about 20 mm, exceed 0.5 mm, about 1 mm, about 2 mm, about 3 mm, about 5 mm, about 7 mm, or other suitable depths. In some embodiments, the inferiorly-extending wall50may extend along at least 25 percent of the periphery of the body22, along at least 50 percent of the periphery of the body22, extend along the entire periphery of the body22, or extend along another suitable amount along the periphery of the body22. The width W1of the wall50may be about 5 mm to about 6 mm and is desirably greater than about 0.5 mm and less than about 50 mm. In some embodiments, the peripheral edge29of the tibial tray20may include a lower surface28that extends over the superior cut cortical bone19, e.g., edge18. In some embodiments, the tibial tray20may feature a keel32(shown in dashed lines inFIG. 1) and support pins (not shown inFIG. 1). The access cavity in the proximal portion of the tibia and the tibial tray may be sized and formed manually by a surgeon or as described below, prepared automatically or fully automatically by a robot.

FIG. 2illustrates a superior view of a resected proximal portion of a tibia110of a patient for a knee replacement, according to an embodiment of the present disclosure. In this illustrated embodiment, the resected proximal portion of the tibia110may include a center cancellous surface111, and a cortical bone edge surface118, a first U-shaped cavity115disposed along one side of the proximal portion of the tibia110, and a second U-shaped cavity117disposed along an opposite side of the proximal portion of the tibia110. The cavities115and117may extend into the cancellous bone, trabecular bone, spongy bone, or light porous bone of the proximal portion of the tibia110adjacent to the inner surface of the cortical bone112of the proximal portion of the tibia110. A depth of the cavity may extend about 0.5 millimeters (mm) to about 75 mm, about 1 mm to about 50 mm, about 2 mm to about 40 mm, about 4 mm to about 20 mm, about 1 mm, about 2 mm, about 3 mm, about 5 mm, about 7 mm, or other suitable depth. The width W2of the wall may be about 5 mm to about 6 mm and is desirably greater than about 0.5 mm and less than about 50 mm. A corresponding tibial tray (not shown inFIG. 2) may have a peripheral edge portion of the tibial tray designed such that the outer edge portion approximates the shape of the tibial edge portion along a resection plane parallel to the tibial tray. As described in greater detail below, the proximal portion of the tibia may be resected or resurfaced manually or robotically such as fully automatically to receive a corresponding tibial tray.

FIG. 3illustrates a tibial tray320fitted to a resected proximal portion of a tibia210for a knee replacement, according to an embodiment of the present disclosure. In this illustrated embodiment, at least a portion of the tibial tray320when operably attached to the resected proximal portion of the tibia210interfaces and increases the contact area with an inner side portion of the cortical bone212of the proximal portion of the tibia210.

The tibial tray320may include a body322having a superior portion324and an inferior tibia-engaging portion326. A superior surface325of the superior portion324may be a generally planar surface for supporting a plastic bearing spacer (not shown inFIG. 3). In some embodiments, the superior surface include a peripherally-extending lip for securing the plastic bearing spacer.

The tibia engaging portion326may include a tibia engaging center portion330defining a recess340relative to a peripheral tibia-engaging portion350. The peripheral tibia-engaging portion350may be a wall or a flat portion disposed around some or all of the tibia engaging center portion330and at an elevation different than the tibia engaging center portion330. The peripheral tibia-engaging portion350may be disposed in a cavity formed in the cancellous bone, trabecular bone, spongy bone, or light porous bone of the proximal portion of the tibia adjacent to the inner surface of the cortical bone of the proximal portion of the tibia. The peripheral tibia-engaging portion350may include an inner wall surface352and an outer wall surface354. The inner wall surface352may be disposed normal or at 90 degrees to the superior surface325of the superior portion324. The outer wall surface354may be able to be aligned with and abutting to an inner side surface213of the inner surface of the cortical bone212. A depth D2of the peripheral tibia-engaging portion350may exceed 0.5 mm and may not exceed 75 mm. The geometric resurfacing of the proximal portion of the tibia may result in the superior and inferior portions along a resection plane (excluding a keel and pins) having a depth D3greater than about 0.5 mm and less than about 15 mm. In some embodiments, a tibial tray may feature a keel and support pins. As described in greater detail below, the proximal portion of the tibia210may be resected manually or robotically to receive the corresponding manually or robotically formed tibial tray320.

FIG. 4illustrates a tibial tray420fitted to a resected proximal portion of the tibia410for a knee replacement, according to an embodiment of the present disclosure. In this illustrated embodiment, the tibial tray420is designed to interface with curved surface geometries and support cavities of the resected proximal portion of the tibia410.

For example, a typical proximal portion of the tibia bone may feature a concave minimum near the lateral condyle, a convex maximum near the intercondyle eminence, and a concave minimum near the medial condyle. The resected proximal portion of the tibia410for a knee replacement of the present disclosure may remove the damaged bone from the proximal portion of the tibia while shaping the bone to include a similar general contour of a typical tibia bone. The resurfaced proximal portion of the tibia bone410may feature a concave minimum416near the lateral condyle, a convex maximum417near the intercondyle eminence, and a concave minimum418near the medial condyle. The concave minimum416, the convex maximum417, and/or the concave minimum418may extend into the cancellous bone, trabecular bone, spongy bone, or light porous bone of the proximal portion of the tibia, which lateral portions of the concave minimum416, the convex maximum417, and the concave minimum418may be disposed adjacent to and/or in contact with the underlying inner surface of the cortical bone412of the proximal portion of the tibia410. The tibial tray420may include an inferior tibia-engaging portion having an inferior convex surface426, an inferior convex surface428, and an inferior concave surface427disposed therebetween. The radius of the concave surfaces and the radius of the convex surface may be constant radiuses or have varying curvature. The outer edges of the convex surfaces, when viewed from below, may have an oval or a generally egg-shaped configuration.

The tibial tray420may include one or more pins490designed to interface with the underlying cortical bone412. For example, as shown inFIG. 5, an array of four holes419may be located in each quadrant of the resected proximal portion of the tibia410, which holes419receive pins490(FIG. 4). With reference again toFIG. 4, a bottom portion of the pins490may include an outer cylindrical portion that engages the sides of an opening in the cortical bone412. Such contact area may be with the sides of the opening extending through the cortical bone, including contacting inner edge portions of the openings of the cortical bone, and/or the inner surfaces or surface portions of the cortical bone around the opening in the inner surface of the cortical bone. An inferior edge492of the pins490may be aligned with the outer surface411of the cortical bone412. The periphery of the tibial tray420may define a shelf or lip having a thickness T, for example, of about 4 mm and a width W3of about 2 mm.

The presently disclosed tibial trays may be operable with conventional plastic spacers and femoral components. For example, the superior surface of the presently disclosed tribal trays may include a surface having a general symmetrical or kidney bean shape designed for engagement with a standard plastic spacer component such as in a snap fit manner. A tibial tray with a variable thickness (by way of nonlimiting example, a rim) may exist at the periphery of the tibial tray such that tibial tray coverage is maximized along the resection plane, but such that engagement of a plastic spacer component is not compromised. The thickness of the tibial rim may be about 4 mm. In another embodiment the rim may exceed about 0.5 mm and be less than about 25 mm.

The tibial trays of the present disclosures may include a one-piece, monolithic, or integral body, or may be formed from two or more components. The tibial tray may be made out of a standard metallic implant material, such as titanium, cobalt chrome, or other acceptable stainless steels. In other embodiments, the tibial tray may of the present disclosure may be made out of a plastic or polymeric material.

FIG. 6illustrates a method600for use in knee replacement surgery, according to an embodiment of the present disclosure. In this illustrated embodiment, the method600is operable in providing a customized cut plan of the proximal portion of the tibia for a patient and providing a corresponding customized tibial tray.

The method600may include, for example, at610obtaining first data representing a proximal portion of the tibia of the patient. At620, second data of a patient specific resected proximal portion of the tibia of the patient is determined based on the first data. The resected proximal portion of the tibia of the patient has a superior surface and one or more cavities or openings exposing an inferior portion of an underlying inner surface of the cortical bone of the tibia. At630, a patient specific tibial tray having an inferior surface is determined based on the second data. At640, the patient's tibia is resected based on the second data. At650, the tibial tray is formed based on the second data, and at660, the formed tibial tray is secured onto the formed resected proximal portion of the tibia so that an inferior portion of the tibial tray extends into the one or more cavities and/or openings and contacts the underlying inner surface of the cortical bone of the tibia.

FIG. 7illustrates a block diagram of a system700for implementing, for example, the method600(FIG. 6) for use in knee replacement surgery, according to an embodiment of the present disclosure. In this illustrated system700, for example, at least a portion of a tibial tray when operably attached to a resected proximal portion of the tibia of a patient may interface and increase the contact area with an underlying inner surface of the cortical bone of the proximal portion of the tibia of the patient. System700may generally include a processing unit or processor710, input/output devices720, and memory730.

For example, tibia data702such as first data representing a proximal portion of a tibia of the patient (block610inFIG. 6) may be inputted to system700. Tibia data702may include three-dimensional data obtained by, for example, a Computed Tomography (CT) scan, a Computerized Axial Tomography (CAT) scan, a Magnetic Resonance Imaging (MRI) scan, or other suitable two-dimensional imaging or three dimensional imaging or processing. Such data may be provided directly from an imaging machine or retrievable from a database of stored medical image data. Further input data may include surgeon input704such as a desired general configuration of the tibial tray, desired tibial cuts, and/or other information. The processor710may be a computer operating, for example, WINDOWS, OSX, UNIX or Linux operating system. In some embodiments, the processor710may be a portable or handheld computing device. In other embodiments, the processing unit710may be one or more operably connected processing units, computing devices, servers, linked or operating over one or more networks such a global communications network, e.g., the Internet.

The memory730may include various modules for processing the input data. For example, the memory730may include a tibia cut generator740, a robotic tibia cut plan generator750, and a tibial tray generator760.

The tibia cut generator740may be operable for determining the second data representative of the patient specific resected proximal portion of the tibia of the patient based on the first data (block620,FIG. 6). For example, the second data may be based on the first data, which the first data includes the outer shape of the proximal portion of the tibia, shape of the intercondylar eminence, the lateral condyle, medial condyle, diseased or damaged portions thereof, inner surface of the cortical bone portion, spongy bone portion, and other features. For example, the second data may be identified with sub-voxel (e.g., volumetric pixel data) accuracy of the location of “cortical bone” (e.g., the location of the inner surface of the cortical bone region) relative to “outer surface of the cortical bone” (e.g., the location of the outer surface of the cortical bone region). Using such a high fidelity bone model, suitable programing may be provided for forming a virtual representation of a proposed resected proximal portion of the tibia for receiving a tibial tray that may be generated with a high degree of compatibility with the patient's bone. The resected proximal portion of the tibia of the patient may include a superior surface and one or more openings or cavities exposing an inferior or underlying surface of the cortical bone.

The cut generator740may include various modules such as a resection surface generator742, a cavity generator744, and an optimizing generator746. The resection generator742may allow for a surgeon to indicate, for example, a resection plane or such plane may be automatically generated provided, e.g., by input by a surgeon, or based on or utilizing predetermined data. For example, the resection plane may be determined as disclosed in U.S. patent application Ser. No. 16/153,334, entitled, “Apparatus, Method and System for Providing Customizable Bone Implants”, the entire subject matter of which is incorporated herein by reference. The cavity generator744may include receiving initial inputs from a surgeon such as locations, widths, lengths, depths, or may be based on or utilizing predetermined data. Optimizing generator746may take the inputted or generated configuration of the tibial tray, and virtually test or compare such tibial tray installed in the resected tibia based on forces likely to be experienced. Automatically varying of the dimensions may allow for comparison to previous developed configurations to optimize the configuration of the patient specific resected tibia and the tibial tray. In some embodiments, optimizing generator746may optimize the depth of the walls, the thickness of the walls, and the amount and location of the walls that extend around the tibial tray to result in a reduce removal amount needed of the cancellous bone, thereby causing less trauma to the tibial of the patient. In some embodiments, a suitable module in the memory730may have suitable programming or algorithms for virtually testing a resultant patient specific proximal portion of the tibia and corresponding tibial tray, or for comparison the resultant patient specific proximal portion of the tibia and corresponding tibial tray against exemplary acceptable configurations. Such optimizing techniques are described below.

The robotic tibia cut plan generator750may be operable to determine data or instructions for operating a surgical robot790or other automated device for forming the patient's tibia based on the second data (block640,FIG. 6). In some embodiments, a 3D model of the resected proximal portion of the patient's tibia may be uploaded to the robot and the surgical robot being operable to effect a tibia cut plan to resize the proximal portion of the tibia autonomously, or semi-autonomously to form, for example, a resection and form the one or more cavities or openings or to expose the underlying inner surface or portion of the cortical bone. The data or instructions may be combined with data received by the surgical robot790such as data from local cameras imagers or sensors. A suitable surgical robot may be an LBR iiwa Kuka robot manufactured by KUKA ROBOTICS Corporation of Shelby Township, Mich., and may be operable with one or more bone saws, rasps, saws, drills, and/or other devices.

The tibial tray generator760may be operable to determine a configuration of a patient specific tibial tray having, for example, an inferior surface based on the second data (block630,FIG. 6). For example, the tibial tray generator760may determine the body of the tibial tray having a periphery and inferior surface that matches or corresponds to the resected proximal portion of the tibia. In some embodiments, a 3D model of the tibial tray may be used by a 3D printer795or other manufacturing device known in the art for generating a tibial tray. The 3D printer or manufacturing device may be operable to form the tibial trays, as described above, as a one-piece, monolithic, or integral body, or formed from one or more components, and formed from a standard metallic material, such as titanium, cobalt chrome, or other acceptable stainless steels. Alternative, a prototype or mold may be formed and used for forming by casting or forging the tibial tray implant formed from, for example, a standard metallic material, such as titanium, cobalt chrome, or other acceptable stainless steels.

The technique of the present disclosure may solve the problem by more closely matching the native anatomy of the joint and thereby increasing the surface area contact for osseointegration and reducing shear forces along the implant to bone interface plane. Osseointegration (organic fixation) may occur from cortical contact. For example, the system may introduce patient specific wall, supports, or pegs that interface with the underlying cortical metaphyseal bone to add stability and resist subsidence. By mapping the contours of the metaphyseal bone (the transitional zone at which the diaphysis and epiphysis of a bone come together) such that a tibial tray can be formed and readily inserted.

Programming code or algorithms, such as in the tibia cut generator750, may include the introduction of non-planar shapes to the bottom of the tibial tray that may increase the surface area contact of the resected tibia significantly. By way of example, the surface area of a circle in a plane is characterized by the equation (Area of Circle=πr2). The surface area of a semi-spherical shape approximated by a half-sphere is characterized by the equation (Area of a half-sphere=2πr2). Thus, the introduction of semi-spherical shapes can increase the surface area contact significantly. By way of nonlimiting example, a half-sphere has twice the surface area of a circle of equal radius. The configuration of a normal proximal portion of the tibia is not a flat plane, but the anatomy is characterized by concave and convex geometries, and the tibia cut generator750in determining the resected proximal portion of the tibia may be based on the surface area being non-parallel.

An approximation of these concave and convex surface features900is illustrated inFIG. 9, and a patient specific knee may be designed such as in the tibia cut generator740(FIG. 7) to generally approximate these anatomical surface features. Notably, these surface features may be geometrically approximated such that the minimum height as measured between the lowest and highest members along the resection plane excluding the keel and pins shall exceed about 0.5 mm and the maximum height as measured between the lowest and highest members along the resection plane excluding the keel and pins shall not exceed about 25 mm. It is understood that the medial and lateral condyles and intercodyle eminence may generally approximate regions of local maximum and minimum or minimum and maximum along the resection plane. In some embodiments, programming code or algorithms in the tibia cut generator740(FIG. 7) may determine the resected proximal portion of the tibia based on one or more angled surfaces, and the resulting shear forces. For example, the shear force at any point of the implant to bone contact plane may be characterized by and based on the equation Fx=F cos(theta) where shear force is reduced as theta is increased.A force F is said to have been resolved into two rectangular components if its components are directed along the coordinate axes. introducing the unit vectors i and j along the x and y axes,

FIG. 10illustrates two bone-to-implant interfaces of the support pins and the cortical metaphyseal bone, which may be flat or curved such that the surface area contact is reasonably maximized. Such analysis may be employed in the optimizing generator746(FIG. 7).

In other embodiments, auto-segmentation and implant generation algorithms may be utilized with a surgical robot to introduce pre-planned semi-oblong irregular shapes and cavities into the proximal tibial surface that are designed for engagement with a conforming patient specific tibial tray generated by the algorithms. For example, a pre-operative anatomy of the tibia is characterized by segmentation and implant generation algorithms, which are designed to output a robotic surgical plan and a corresponding patient specific implant. The algorithm outputs may be designed to loosely reconstruct the pre-operative curvature of the native anatomy (geometric approximations of the proximal surface of the tibia, specifically the medial and lateral condyles, intercondyle eminence and medial and lateral curved plateaus) as well as may introduce cavities for pegs of variable length and with high conformity to the underlying bone. The algorithm may map the contours of the metaphyseal bone such that a high conformity implant can be inserted. The surgical robot may prepare these surface features with tissue ablation tooling (for example burrs, sagittal saws, drills, etc.) and the implant may be 3D printed, forged or cast.

The tibial tray may be aligned at the surgeon's discretion and input or by system700. The total knee arthroplasties (TKA) of the present disclosure may be aligned with the tibial component, which is positioned perpendicular to the anatomic axis of the tibia similar to conventional TKAs. For example, the anatomic axis may be colinear with the mechanical axis unless there is some unusual deformity. Alternatively, a so-called kinematic or anatomic technique may be employed in which the goal is to recreate the native sagittal and coronal orientation of the tibial joint surface (e.g., restore the joint surface to where it was before arthritis set in). There is variation in the native alignment of the tibia. The coronal alignment typically averages 3 degrees of varus and the sagittal (posterior slope) averages 7 degrees or so but ranges widely between 0 and 15+. The algorithms in the tibia cut generator may be able to apply either technique.

FIG. 8illustrates a block diagram of a system800for implementing, for example, the method600(FIG. 6) for use in knee replacement surgery, according to an embodiment of the present disclosure.

FIG. 11illustrates a block diagram of a robotic method1200for resecting a tibia of a patient for a knee replacement. The method1200includes, for example, at1210obtaining, via a processor, first data representing a proximal portion of the tibia of the patient. The method further may include at1220determining, via the processor, second data of a patient specific resected proximal portion of the tibia of the patient based on the first data and based on location of an inner surface of the cortical bone of the tibia. The method may also include at1230forming, via the processor, the tibia of the patent based on the second data of the patient specific resected proximal portion of the tibia, the resected proximal portion of the tibia of the patient having one or more cavities and/or openings exposing an inferior portion of an inner surface of the cortical bone of the tibia.

FIGS. 12-14illustrate a tibial tray1320, according to an embodiment of the present disclosure. In this illustrated embodiment, at least a portion of the tibial tray1320when operably attached to a resected proximal portion of a tibia of a patient will interface and increase the contact area with a side portion of an inner surface of the cortical bone of a proximal portion of the tibia. For example, the tibial tray1320may be configured similar to tibial tray20(FIG. 1). In this embodiment, tibial tray1320does not include a keel.

FIGS. 15-19illustrate a tibial tray1420, according to an embodiment of the present disclosure. For example, the tibial tray1420may be configured similar to tibial tray1320(FIGS. 12-14) with the addition of a keel1421(FIGS. 17-20).FIGS. 20 and 21illustrate tibial tray1420disposed on a resected proximal portion of a tibia1410of a patient.

FIGS. 22 and 23illustrate a tibial tray1520, according to an embodiment of the present disclosure. In this illustrated embodiment, at least a portion of the tibial tray1520when operably attached to a resected proximal portion of a tibia of a patient will interface and increase the contact area with an inner surface of an inner surface of the cortical bone of a proximal portion of the tibia. For example, the tibial tray1520may be configured similar to a combination of tibial tray20(FIG. 1) and tibial tray420(FIG. 4). In this embodiment, tibial tray1520may include a tibia engaging portion having peripheral walls and a non-planar center portion. The center portion may be designed to interface with curved surface geometries and support cavities of a resected proximal portion of a tibia. For example, the center portions of the tibial tray may include a convex minimum near the lateral condyle, a concave maximum near the intercondyle eminence, and a convex minimum near the medial condyle. The outer edges of the convex surfaces, as shown inFIG. 23, may have an oval or a generally egg-shaped configuration.

FIG. 24illustrates a tibial tray1620, according to an embodiment of the present disclosure. In this illustrated embodiment, at least a portion of the tibial tray1620when operably attached to a resected proximal portion of a tibia1610of a patient will interface and increase the contact area with an inner surface of a cortical bone of a proximal portion of the tibia. For example, the tibial tray1620may be configured to be received between inner surface portions of the cortical bone. In this embodiment, a resected portion of the patient's tibia may be along a plane P1. Cavities may be provided in the patient's tibia for receiving inferiorly-extending peripheral portions1650of the tibia engaging portion of the tibial tray1620. In this embodiment, the tibial tray does not sit on top of the resected superior edge of the cortical bone of the patient's tibia, but instead extends above the top of the resected superior edge of the cortical bone of the patient's tibia.

FIG. 25illustrates a tibial tray1720, according to an embodiment of the present disclosure. In this illustrated embodiment, at least a portion of the tibial tray1720when operably attached to a resected proximal portion of a tibia1710of a patient will interface and increase the contact area with a side portion of an inner surface of the cortical bone of a proximal portion of the tibia. For example, the tibial tray1620may be configured to be received between inner surface portions of the cortical bone. In this embodiment, a resected portion of the patient's tibia may be along a plane P1. An initial cavity may be formed having an inferior surface disposed along a plane P2, and cavities may be provided in the patient's tibia for receiving inferiorly-extending peripheral portions1750of the tibia engaging portion of the tibial tray1720. In this embodiment, the tibial tray does not sit on top of the resected superior edge of the cortical bone of the patient's tibia, but instead extends generally even with the top of the resected superior edge of the cortical bone of the patient's tibia.

With reference toFIGS. 26-29, therein illustrated are exemplary embodiments of tibial trays installed on a resected proximal portion of a tibia in which portions of the tibial tray are spaced from and disposed closely adjacent to an underlying inner surface of the cortical bone for use in a total knee replacement.

In some embodiments, for example, a patient specific tibial tray design may mitigate aseptic loosening and subsidence through a combination of high underlying peripheral surface area contact and underside surface geometry that interfaces more closely with peripheral cancellous bone adjacent to the cortical bone. The present disclosure may solve and/or overcome a primary cause for knee implant failure, namely, aseptic loosening of the tibial component and subsidence.

In some embodiments, the present disclosure is directed to methods for generating a three-dimensional model of a tibia and generating a cut plan for excavating a portion of the tibia with a robot or robotic excavator according to the cut plan to allow for the insertion of a custom tibial tray designed with one or more peripheral inferiorly-extending portions designed to be spaced from the periphery of the underlying tibial cortical bone.

In some embodiments, a technique of the present disclosure is directed to increasing stability of the tibial tray relative to the resected proximal portion of the tibia by employing one or more peripheral inferiorly-extending portions designed to be spaced from the periphery of the underlying tibial cortical bone. A virtual model of the proximal portion of a tibia bone may be used to determine an improved implant that is designed to achieve a higher level of stability. A processor may be employed and configured to generate an excavation protocol for resecting the proximal tibia and excavating cancellous bone from the tibia such that the amount of contact between the tibia and the implant is increased, by, for example, an amount of 10 percent or greater contact compared to convention tibial trays.

FIG. 26illustrates a tibial tray2020fitted to a resected proximal portion of a tibia2010for a total knee replacement, according to an embodiment of the present disclosure. In this illustrated embodiment, at least a portion of the tibial tray2020when operably attached to the resected proximal portion of the tibia2010includes peripheral inferiorly-extending portions extending onto the cancellous bone2011designed to be offset or spaced from the periphery of the underlying tibial cortical bone2012of the proximal portion of the tibia2010.

For example, as shown inFIG. 27, the tibial tray2020may include a body2022having a superior portion2024and an inferior tibia-engaging portion2026. The superior portion2024may include a generally planar superior surface2025(best shown inFIG. 26) for supporting a plastic bearing spacer (not shown). In some embodiments, the planar superior surface2025includes a peripheral upwardly-extending lip2027(FIG. 26) for attaching via a snap fit connection and restraining the plastic bearing spacer.

With reference still toFIG. 27, the tibia engaging portion2026may include a center tibia engaging portion2030, and a first peripheral tibia engaging portion2040. In this embodiment, the center tibia engaging portion2030may include a contoured surface contactable with the center cancellous bone surface of the resected proximal portion of the tibia of the patient. For example, the center tibia engaging portion may include one or more concave, convex, or planar surfaces contactable with the center cancellous bone surface of the resected proximal portion of the tibia of the patient as similarly described above.

The peripheral tibia-engaging portion2040may include at least one inferiorly-extending wall, and may include a first inferiorly-extending wall2050and a spaced apart second inferiorly-extending wall2051. The first inferiorly-extending wall2050may include an inner wall surface2052and an outer wall surface2054. For example, the walls2052and2054may be U-shaped walls facing each other. The second inferiorly-extending wall2051may include an inner wall surface2053and an outer wall surface2055. The walls2050and2051may be a mirror image of wall2050and may have constant thicknesses, different thickness, varying thickness, or other suitable thicknesses. The inner wall surfaces2052and2053may be disposed normal or at 90 degrees to the superior surface2025, or at any suitable angle or angles. The outer wall surfaces2054and2055may be disposed normal or at 90 degrees to the superior surface2025. In other embodiments, the outer wall surface may be angled relative to the superior surface such as parallel with and spaced from an inner surface2013(FIG. 26) of the cortical bone2012(FIG. 26).

FIG. 28illustrates a superior view of the resected proximal portion of the tibia2010ofFIG. 26of the patient for the total knee replacement, according to an embodiment of the present disclosure. In this illustrated embodiment, the resected proximal portion of the tibia2010may include the cancellous bone2011having a center cancellous surface2015, and the cortical bone2012having a cortical bone edge surface2018. The cancellous bone2011may include a first U-shaped cavity2115disposed along one side such as the medial side of the proximal portion of the tibia2010, and a second U-shaped cavity2117disposed along an opposite side such as the lateral side of the proximal portion of the tibia2010. The first U-shaped cavity2115may include an inner surface2125and an outer surface2126. The second U-shaped cavity2117may include an inner surface2127and an outer surface2128. The cavities2115and2117may extend into the cancellous bone2011(e.g., trabecular bone, spongy bone, or porous bone) of the proximal portion of the tibia2010adjacent to the inner surface2013of the cortical bone2012of the proximal portion of the tibia2010. The walls2050and2051(FIG. 27) are receivable in cavities2115and2017formed in the resected proximal portion of the tibia2010. For example, cavities2115and2017may be sized and configured to correspond to and receive walls2050and2051(FIG. 27) when tibial tray2020is positioned on resected proximal tibia2010,

The inner wall surface2052of the first wall2050may be disposed adjacent to or abut the inner surface2125of the first U-shaped cavity2115, the outer wall surface2054of the first wall2050may be disposed adjacent to or abut the outer surface2126of the first U-shaped cavity2115, the inner wall surface2053of the second wall2051may be disposed adjacent to or abut the inner surface2127of the second U-shaped cavity2117, and the outer wall surface2055of the second wall2051may be disposed adjacent to or abut the outer surface2128of the second U-shaped cavity2117.

With reference again toFIG. 26, a depth D5of the wall2050may extend for example, about 0.5 millimeters (mm) to about 75 mm, about 1 mm to about 50 mm, about 2 mm to about 40 mm, about 4 mm to about 20 mm, exceed 0.5 mm, about 1 mm, about 2 mm, about 3 mm, about 5 mm, about 7 mm, or other suitable depth. A width W5of the wall2050may be, for example, about 5 mm to about 6 mm and is desirably greater than about 0.5 mm and less than about 50 mm. The lower portion of the outer surface2054of the wall2050may be spaced from the inner surface2013of the cortical bone2012a distance L5of, for example, about 0.5 mm, about 1 mm, about 2 mm, between 0.05 mm and about 10 mm, between about 0.5 mm and about 5 mm, between about 1 mm and about 2 mm, or other suitable distance.

With reference again toFIG. 27, in some embodiments, the inferiorly-extending walls2050and2051may extend along, for example, at least 25 percent of the periphery of the body2022, along at least 50 percent of the periphery of the body2022, extend along the entire periphery of the body2022, or extend along another suitable amount along the periphery of the body2022. In some embodiments, a peripheral edge2029of the tibial tray2020may include a lower surface2028that extends over the superior cut cortical bone2018(FIG. 28). In some embodiments, the tibial tray2020may feature a keel (not shown inFIG. 27). The resection of the proximal tibia and access cavities in the cancellous bone in the proximal portion of the tibia and the corresponding tibial tray may be sized and formed manually by a surgeon or as described above, prepared automatically by a robot.

FIG. 29illustrates a tibial tray3020fitted to a resected proximal portion of a tibia3010for a total knee replacement, according to an embodiment of the present disclosure. In this illustrated embodiment, at least a portion of the tibial tray3020, when operably attached to the resected proximal portion of the tibia3010, includes peripheral inferiorly-extending portions extending onto the cancellous bone3011. The peripheral inferiorly-extending portions are designed to be spaced such as offset and parallel to the periphery of the underlying tibial cortical bone3012of the proximal portion of the tibia3010.

For example, as shown inFIG. 30, the tibial tray3020may include a body3022having a superior portion3024and an inferior tibia-engaging portion3026. The superior portion3024may include a generally planar superior surface3025(best shown inFIG. 29) for supporting a plastic bearing spacer (not shown). In some embodiments, the planar superior surface3025includes a peripheral upwardly-extending lip3027(FIG. 29) for attaching via a typical snap fit connection and restraining the plastic bearing spacer.

The tibia engaging portion3026may include a center tibia engaging portion3030and a peripheral tibia engaging portion3040. In this embodiment, the center tibia engaging portion3030may include a contoured surface contactable with the center cancellous bone surface of the resected proximal portion of the tibia of the patient. For example, the center tibia engaging portion may include one or more concave, convex, or planar surfaces contactable with the center cancellous bone surface of the resected proximal portion of the tibia of the patient as similarly described above.

The peripheral tibia-engaging portion3040may include at least one inferiorly-extending wall having portions disposed at different depths. Peripheral tibia-engaging portion3040may include, for example, a first inferiorly-extending wall3050and a spaced apart second inferiorly-extending wall3051. Peripheral tibia-engaging portion3040may further include a connecting inferiorly-extending wall3070, a first inwardly-extending wall3080, and a second inwardly-extending wall3090. The connecting inferiorly-extending wall3080may extend between the first inferiorly-extending wall3050and the spaced apart second inferiorly-extending wall3051. The inwardly facing ends3081and3091of first inwardly-extending wall3080and a second inwardly-extending wall3090, respectively, may define a gap G disposed along the posterior side of the tibial tray3020. The gap G may inhibit the need to sacrifice tendons and ligaments at the posterior side of the proximal tibia.

The first inferiorly-extending wall3050may include an inner wall surface3052and an outer wall surface3054. The second inferiorly-extending wall3051may include an inner wall surface3053and an outer wall surface3055. The walls3050and3051may have generally constant thicknesses being rounded at the inferiormost end.

The inner wall surfaces3052and3053may be disposed normal or at 90 degrees to the superior surface3025, or at any suitable angle or angles. The outer wall surfaces3054and3055may be sized and configured to provide a generally constant space S (FIG. 29) between the outer wall surfaces3054and3055and the adjacent inner surface3013(FIG. 29) of the cortical bone3012(FIG. 29).

With reference again toFIG. 29, the outer surfaces of the walls may be spaced from the inner surface3031of the cortical bone, for example, by a distance L6of about 0.5 mm, about 1 mm, about 2 mm, between 0.05 mm and about 10 mm, between about 0.5 mm and about 5 mm, between about 1 mm and about 2 mm, or other suitable distance.

With reference again toFIG. 30, a depth D6of the walls3050and3051may extend, for example, about 0.5 mm to about 75 mm, about 1 mm to about 50 mm, about 2 mm to about 40 mm, about 4 mm to about 20 mm, exceed about 0.5 mm, about 1 mm, about 2 mm, about 3 mm, about 5 mm, about 7 mm, or other suitable depths. A depth D7of the connecting wall3070and inwardly extending walls3080and3090may extend, for example, about 0.5 mm to about 75 mm, about 1 mm to about 50 mm, about 2 mm to about 40 mm, about 4 mm to about 20 mm, exceed about 0.5 mm, about 1 mm, about 2 mm, about 3 mm, about 5 mm, about 7 mm, or other suitable depths. In some embodiments, the depth D7of the connecting wall3070and inwardly extending walls3080and3090may be, for example, about 20 percent, about 25 percent, about 30 percent, or other suitable percentage of depth D6. A width W6of the walls3050and3051may be, for example, about 5 mm to about 6 mm and is desirably greater than about 0.5 mm and less than about 50 mm. A width W7of the walls3070,3080, and3090may be, for example, about 5 mm to about 6 mm and is desirably greater than about 0.5 mm and less than about 50 mm. In some embodiments width W7may be, for example, less that width W6, such as width W7being half the width compared to width W6.

With reference again toFIG. 29, the resection of the proximal tibia3010and access cavities in the cancellous bone in the proximal portion of the tibia and the corresponding tibial tray3020may be sized and formed manually by a surgeon or as described above, prepared automatically by a robot.

FIGS. 31 and 32illustrate a tibial tray4020(FIG. 31) according to an embodiment of the present disclosure, which may be fitted to a resected proximal portion of a tibia4010(FIG. 32) of a patient for a total knee replacement. In this illustrated embodiment, at least a portion of the tibial tray4020, when operably attached to the resected proximal portion of a tibia4010(FIG. 32) of a patient, includes peripheral inferiorly-extending portions extending onto the cancellous bone4011(FIG. 32) in close proximity to the cortical wall of the resected proximal tibia. The peripheral inferiorly-extending portions may be designed to be spaced such as offset and/or parallel to the periphery of the underlying tibial cortical bone of the proximal portion of the tibia of the patient.

As illustrated inFIG. 31, tibial tray4020may have asymmetrical convex surfaces4030and4031, and asymmetrical peripheral inferiorly-extending portions4052and4053extending from the undersurface of the tibial tray4020to enhance force distribution over the medial and lateral compartments, and may further include a rim4018that extends around some, almost all, or all of the entire periphery of the tibial tray4020. In addition to portions of the tibial tray being asymmetrical, the peripheral inferiorly-extending portion4052may be angled and thinner that the peripheral inferiorly-extending portion4053, which is thicker and aligned more vertically.

In the various embodiments, desirably, the cavities and walls do not penetrate the outer cortical bone. In other embodiments, a portion of the cavities or walls such as the lower portions thereof may contact or extend into the cortical bone.

FIG. 33illustrates a method6000for use in total knee replacement surgery, according to an embodiment of the present disclosure. In this illustrated embodiment, the method5000is operable in providing a customized cut plan of the proximal portion of the tibia for a patient and in providing a corresponding customized tibial tray. The method5000may include, for example, at5100obtaining first data representing a proximal portion of the tibia of the patient. At5200, second data of a patient specific resected proximal portion of the tibia of the patient is determined based on the first data. The resected proximal portion of the tibia of the patient has a superior surface and at least one cavity in the cancellous bone exposing a peripheral underlying portion of the cancellous bone of the tibia of the patient. At5300, a patient specific tibial tray having an inferior surface is determined based on the second data. At5400, the patient's tibia is resected based on the second data. At5500, the tibial tray is formed based on the second data, and at5600, the formed tibial tray is secured onto the resected proximal portion of the tibia so that a peripheral inferior portion of the tibial tray extends into the at least one cavity and is spaced apart from the underlying cortical bone of the tibia of the patient.

FIG. 34illustrates a block diagram of a robotic method6000for resecting a tibia of a patient for a total knee replacement. The method6000includes, for example, at6100obtaining, via a processor, first data representing a proximal portion of the tibia of the patient having centralized cancellous bone and peripheral cortical bone. The method further may include at6200determining, via the processor, second data representing a patient specific resected proximal portion of the tibia of the patient having a center cancellous bone surface, a peripheral cortical bone surface, and at least one cavity formed in the cancellous bone surface spaced apart from the cortical bone exposing a peripheral underlying portion of the cancellous bone of the tibia of the patient based on the first data. The method may also include at6300forming, via the processor, the tibia of the patent based on the second data representing the patient specific resected proximal portion of the tibia, the resected proximal portion of the tibia of the patient having a center cancellous bone surface, a peripheral cortical bone surface, and at least one cavity exposing a peripheral underlying portion of the cancellous bone spaced apart from the underlying inner surface of the cortical bone of the tibia of the patient.

In further embodiments, a patient matched or customized tibial tray may include, for example, inferiorly-extending pegs, flanges, fins, etc. that are positioned at or near the peripheral edge of the tibial tray and which, when installed, is received in one or more cavities or holes in the cancellous bone spaced apart from and in close proximity with the underlying inner surface of the cortical bone in the resected proximal portion of the patient's tibia. An alternative embodiment of the tibial tray may have, for example, asymmetrical convex elements extending from the undersurface of the tray to enhance force distribution over the medial and lateral compartments and a rim that extends around all, almost the entire, or a portion of the peripheral superior surface of the resected cortical bone.

The present disclosure is also directed to methods and systems for generating a three dimensional cut plan for excavating portions of the proximal tibia for a total knee replacement using a robot or robotic excavator according to the cut plan to create cavities that allow for the insertion of the custom tibial trays shown and described in connection withFIGS. 26-30, which may be effected using the system700ofFIG. 7and system800ofFIG. 8, and which may result in increased or maximized stabilization of the tibial tray post-implantation. The robot may employ images or cameras for optical tracking to navigate the anatomy and may actively create the custom cavities, for example, may not need to rely on haptic feedback or a surgeon to execute the cuts.

FIG. 35illustrates a proximal portion of a tibia7000of a patient for a total knee replacement, according to an embodiment of the present disclosure. The lateral portion and/or the medial portion may include a portion of the cortical bone7012that extends inwardly towards the uppermost portion of the tibia7000. For example, as show inFIG. 35, a proximal lateral portion7015of the cortical bone7012of the tibia7000may extend inwardly towards the uppermost portion of the tibia7000resulting in an inner surface7016of the cortical bone7012having an inner concave surface.

As described above, the tibial trays according to the present disclosure for use in a total knee replacement may include one or more inferiorly-extending walls with an outer wall surface and an inner wall surface. The outer wall surface may be configured to correspond and contact an underlying inner surface of the cortical bone or be spaced from and disposed closely adjacent to an underlying inner surface of the cortical bone. It will be appreciated that a tibial tray having an inferiorly-extending wall corresponding to the location of the lateral cortical bone having an inner concave surface7016below a resection plane RP1may result in the one or more inferiorly-extending walls of the tibial tray not being insertable in the resected proximal tibia with one or more cavities for receiving the one or more inferiorly-extending walls.

As shown inFIG. 35, a flat resection plane may be resection plane RP1that is positioned perpendicular to an anatomic axis A of the tibia7000. With reference toFIG. 36, in order for a tibial tray8000to be insertable close proximity to the inner surface of the cortical bone7012(FIG. 35), an angle α between a bottom surface8003of the tibial tray8000, which bottom surface8003rests on the flat resection plane RP1, and an outer surface8054of the one or more inferiorly-extending walls8050must be equal to or greater than 90 degrees. For the tibial tray8000to be insertable the angle β between the bottom surface8003of the tibial tray8000and an inner surface8052of the one or more inferiorly-extending walls8050must be equal to or greater than 90 degrees.

With reference toFIG. 37, in the design and/or fabrication of a tibial tray, for example, using the system700(FIG. 7) or system800(FIG. 8) the method may include algorithms or programing code to maintain the ability to insert a tibial tray8500with the one or more inferiorly-extending walls8550in a resected proximal portion of a tibia. To maintain the ability to insert the tibial tray implant, one of more constraints may be imposed on the design of the outer surface of the one or more inferiorly-extending walls8550of the tibial tray8500. For example, in the design and/or fabrication of the one or more inferiorly-extending walls8550of the tibial tray8500where the cortical bone underlying a resection plane defines an inner concave surface (e.g., inner concave surface7016inFIG. 35), the superior edge7400(FIG. 35) of the cortical bone7012(FIG. 35) along the resection plane RP1(FIG. 35) may define a constraint so that the resulting outer surface8554of the inferiorly-depending wall8550is vertical or extends inwardly. In some embodiments, relative to an anatomic axis A (or other arbitrary axis or vertical reference) of the tibia7000, horizontal distances d1and d2between the outer surface of the inferiorly-extending wall and the anatomic axis A may decrease from the proximal portion of the outer surface of the inferiorly-extending wall to the distal portion of the outer surface of the inferiorly-extending wall.

As shown inFIG. 38, a tibial tray8700may be designed and/or fabricated with constraints on the outer surface of the inferiorly-extending wall8750based on an underlying contoured cortical bone inner surface. For example, an outer surface portion8757of the inferiorly-extending wall8750may be configured to correspond to the shape of the underlying contoured cortical bone inner surface. Outer surface portion8759of the inferiorly-extending wall8750may be constrained by the superior edge7400(FIG. 35) of the cortical bone7012(FIG. 35) along the resection plane RP1(FIG. 35) resulting in the outer surface portion8759having an outer vertical wall surface or a curved outer wall surface perpendicular to the bottom surface of the tibial tray.

In some embodiments, for example, for clinical reasons a resection plane may not be flat, but instead need to be disposed on an angle. If the implant was designed assuming a flat resection plane, but inserted onto an angled resection plane, clinical problems may be introduced. For example, the inferiorly-extending wall may not accurately correspond to the inner surface of a cortical wall and/or may even contact and/or penetrate the cortical bone.

With reference toFIG. 39, in some embodiments, due to clinical reasons such as injury or disease, a resection plane RP2may be required and designed and/or fabricated using the system700(FIG. 7) or system800(FIG. 8) to be on an angle, e.g., a resection plane RP2may be resection plane that is positioned at a non-perpendicular angle to the anatomic axis A of the tibia. To compensate for this approach, a tibial tray9000design process may account for the angle of the resection plane relative to the anatomic axis A of the tibia, which angle may be determined pre-operatively by algorithms or program code and/or by a surgeon. In the event of an angled resection plane, the insertion calculations described above may be employed, but amended to account for the angle θ, between the resection plane RP2and a horizontal plane HP perpendicular to the anatomic axis A of the tibia. For example, angle θ may be added to angle α and angle β.

FIG. 40illustrates a tibial tray10020fitted to a partial resected proximal portion of a tibia10010for a partial knee replacement, according to an embodiment of the present disclosure. As illustrated, such a partial unicompartmental knee replacement (PUKR) replaces only a portion of a proximal portion of a damaged tibia as it leaves intact at least one of the natural bearing surfaces of the knee. For example, the tibial tray10020may replace either an inside (medial) part of a proximal tibia or an outside (lateral) part of a proximal part of a tibia. In this illustrated embodiment, at least a portion of the tibial tray10020when operably attached to the resected proximal portion of the tibia10010interfaces and increases contact with or may be spaced closely to an inner surface or side portion of the cortical bone100012of the proximal portion of the tibia10010.

For example, as shown inFIGS. 41 and 42, the tibial tray10020may include a body10022having a superior portion10024(FIG. 41) and an inferior tibia-engaging portion10026. The body10022may include a peripheral edge10023that corresponds to a portion of the outer surface of the cortical bone along the resected surface of the tibia, and a peripheral edge10024that spans across the center of the resected surface of the tibia. Peripheral edge10024may be disposed across the axis A (FIG. 40) of the tibia or spaced from the axis A (FIG. 40) of the tibia.

The superior portion10024may include a generally planar superior surface10025(FIG. 41) for supporting a plastic bearing spacer (not shown). In some embodiments, the planar superior surface10025may include a peripheral upwardly-extending lip (not shown) for attaching via a snap fit connection and restraining the plastic bearing spacer.

With reference again toFIG. 41, the tibia engaging portion10026may include a center tibia engaging portion10030, and a peripheral tibia engaging portion10040. In this embodiment, the center tibia engaging portion10030may include a surface contactable with a center cancellous bone surface of the resected proximal portion of the tibia of the patient. For example, the center tibia engaging portion may include one or more concave, convex, or planar surfaces contactable with the center cancellous bone surface of the partial resected proximal portion of the tibia of the patient as similarly described above. As illustrated inFIGS. 41 and 42, center tibia engaging portion10030may include a convex surface10031. The convex undersurface may be designed to maximize surface area contact and reduce shear forces along the resection plane.

The peripheral tibia-engaging portion10040may include an inferiorly-extending wall10050. The inferiorly-extending wall10050may include an inner wall surface10052(FIG. 42) and an outer wall surface10054. For example, the wall surfaces10052and10054may be U-shaped walls. The wall10050may have a constant thickness, different thicknesses, varying thicknesses, or other suitable thicknesses. The inner wall surface10052may be disposed normal or at 90 degrees to the superior surface10025, or at any suitable angle or angles. The outer wall surfaces10054may be disposed normal or at 90 degrees to the superior surface10025. In other embodiments, the outer wall surface may be angled relative to the superior surface such as parallel with and spaced from an inner surface10013(FIG. 40) of the cortical bone10012(FIG. 40). As described above, outer wall surface10054may be configured to contact the inner surface of the cortical bone or may be configured to be closely spaced from the inner cortical bone.

As described above, various surgical robot methods may be employed for excavating the one or more cavities in the cancellous bone in the resected proximal portion of the tibia for insertion of the various tibial components as described above.

FIG. 43illustrates a patient specific jig or tibia cavity cutting guide11000with openings11050to accommodate a non-robotic burr or milling tool12000(FIG.44) to allow a surgeon to manually excavate the cavities as described above. For example, cutting guide11000may be used by a surgeon for forming at least one cavity in a resected proximal portion of a tibia of a patient for knee replacement. The resected proximal portion of the tibia includes a center cancellous bone surface and a peripheral cortical bone surface as described above. The cutting guide11000may include a planar member11020having a first planar surface11022and a second planar surface (not shown inFIG. 43).

Planar member11020may include a peripheral outer edge11023, which corresponds to an outer peripheral cortical bone along the resected proximal portion of the tibial of the patient. A pair of U-shaped openings11050extends through the planar member from the first planar surface11022to the second planar surface (not shown) and is spaced from the peripheral outer edge. Each of the pair of U-shaped openings11050defines a U-shaped axis11060, and the U-shaped opening has a constant width W8normal to the U-shape axis. Width W8desirably corresponds to the width of the inferiorly-extending portions of corresponding patient specific tibial tray. Each of the pair of U-shaped openings have an inner edge11061and an outer edge11062. The outer edge11062may be disposed parallel to the peripheral outer edge11023. Cutting guide11000may be, for example, a patient specific cutting guide and which may be effected using the system700ofFIG. 7and system800ofFIG. 8. For example, suitable algorithms and programming code stored in memory730(FIG. 7) along with the patient tibia data702(FIG. 7) and the surgeon input704(FIG. 7) may be operably processed in processor710(FIG. 7) to generate a patient specific cutting guide, which cutting guide may be produced or manufactured using 3D printer795(FIG. 7).

With reference toFIG. 44, the milling tool12000includes a proximal diameter X1sized larger than the width W8(FIG. 43) of U-shaped openings11050, and a distal diameter X2sized for passing through the width W8of the U-shaped openings11050. As such, patient specific tibia cavity cutting guide11000(FIG. 43) with openings11050into which the milling tool12000fits, constrains movement of the milling tool12000in a fixed shape. With reference again toFIG. 43, cutting guide11000may include one or more fixing holes11070to accommodate temporary fixation, e.g., via screws, of the cutting guide to the resected tibia. The periphery of the cutting guide may be sized to match the outer periphery of the resected tibia such that visual alignment and proper placement on the resected tibia is readily performed.

With reference again toFIG. 44, a manual excavation of the cavities for the inferiorly-extending portions of the tibial tray may be made to the proper depth. For example, the cutting portion for of the milling guide12000may be sized to extend a length L that correspond to the depth of the inferiorly-extending portions of the tibial tray and to allow for receipt of the inferiorly-extending portions of the tibial tray when the tibial tray is placed on the resected proximal portion of the patient's tibia.

FIG. 45illustrates a patient specific implant system13000for a total knee replacement, according to an embodiment of the present disclosure. For example, the patient specific implant system13000may include a tibial tray13020, such as configured and manufactured as described above, a spacer13025, a femoral implant component13050, and a patellar implant component13070.

FIG. 46illustrates a patient specific implant system14000for a partial total knee replacement, according to an embodiment of the present disclosure. For example, the patient specific implant system14000may include a partial tibial tray14020, such as configured and manufactured as described above, a spacer14025, and a partial femoral implant component14050.

FIGS. 47-50illustrate a tibial tray15000, according to an embodiment of the present disclosure. For example, the tibial tray15000may be configured similar to tibial tray2020(FIGS. 26-28) with the exception of having a circumferential wall or fin15040. Tibial tray15000may be installed on a resected proximal portion of a tibia in which the circumferential wall or fin15040is disposed closely adjacent to an underlying inner surface of the cortical bone for use in a total knee replacement.

In this illustrated embodiment, the tibial tray15000may include a body15022having a superior portion15024and an inferior tibia-engaging portion15026. The superior portion15024may include a generally planar superior surface15025(best shown inFIG. 48) for supporting a plastic bearing spacer (not shown). In some embodiments, the planar superior surface15025may include a peripheral upwardly-extending lip (not shown) for attaching via a snap fit connection and restraining a plastic bearing spacer.

The inferior tibia-engaging portion15026may include the circumferential wall or fin15040, which when operably attached to the resected proximal portion of a tibia10(FIG. 50) extends into the cancellous bone of the resected tibia. The circumferential wall or fin15040may be designed to be offset or spaced from the periphery of the underlying tibial cortical bone of the proximal portion of the tibia.

As shown inFIG. 47, the tibia engaging portion15026may include a center tibia engaging portion15030, and the single inferiorly-extending circumferential wall or fin15040. In this embodiment, the center tibia engaging portion15030may include a flat surface contactable with the center cancellous bone surface of the resected proximal portion of the tibia of the patient. In other embodiments, the center tibia engaging portion may have a contoured surface as described above.

The single inferiorly-extending circumferential wall or fin15040may include an inner wall surface15051and an outer wall surface15055. For example, the wall may have a cross-sectional kidney shape similar to the superior portion15024. The superior portion15024may have constant thicknesses, different thickness, varying thickness, or other suitable thicknesses. The inner wall surface15051may be disposed normal or at 90 degrees to the superior surface15025, or at any suitable angle or angles. The outer wall surface15055may be disposed normal or at 90 degrees to the superior surface15025. In other embodiments, the outer wall surface may be angled relative to the superior surface such as parallel with and spaced from an inner surface of the cortical bone as shown inFIG. 50. In other embodiments, the outer wall surface15055may be configured to rest against the inner surface of the underlying cortical bone.

With reference again toFIG. 47, in this illustrated embodiment, the wall or fin15040may be circumferential and extend completely around and located towards a periphery of the implant or tibial tray undersurface or inferior surface15030. The outer surface of the circumferential wall or fin may be based on pre-operative imaging data of the inner cortical wall of a patient, specifically to design the implant or tibial tray such that the fin outer wall is a fixed and a constant distance from the mapped inner surface of the cortical wall.

An implant ledge width W9from the location of the mapped inner cortical wall and the location of the outer fin wall can be determined. With reference toFIG. 50, for example, an outer fin wall may be defined having a distance X from the inner cortical wall. A width Y, based on generally accepted pre-operative patient sample data for cortical wall thicknesses may allow designing an implant ledge W9such that the width of the ledge is characterized by the formula:

For example, a distance X from the inner cortical wall to an outer fin wall may be defined as being 3 mm from the inner cortical wall at every point. The thickness of the cortical wall may be based on a patient's age. For example, a cortical wall thickness Y may be 2.2 mm for a certain age as predetermined based on, e.g., Gosman et al. “Development of Cortical Bone Geometry in the Human Femoral and Tibial Diaphysis”,The Anatomical Record,296(5), 774-787, 2013. Thus, a tibial tray may be designed and configured having a ledge width W9of 5.2 mm for example, from the exterior surface of the fin at every point along the periphery. The width Y may be variable based on anatomical observation or further study. For example, further research may find the average resected wall thickness is not uniform. For example, if the medial wall thickness is generally a value different from the lateral thickness, that information may be incorporated into the design of the tibial tray. In other embodiments of the present disclosure, a patient specific design may employ a mapping of the inner cortical wall to design a patient specific tibial tray having a matched wall or fin. An implant ledge width W9may then be determined based on the mapped cortical wall thicknesses and a known distance of the wall or fin from the inner cortical wall.

With reference still toFIG. 50, in a total knee replacement an as indicated by the arrows inFIG. 50, a greater portion of a shearing force acting transversely on the tibial tray and the resected portion of the proximal portion of the tibia of the patient may be resisted by the at least one inferiorly-extending wall and the periphery of the resected proximal portion of the tibia compared to a portion of the shearing force being resisted along the center inferior surface of the tibial tray and the resected cancellous bone surface. In some embodiments, the greater portion may be greater than 50 percent, greater than 60 percent, greater than 70 percent, greater than 80 percent, greater than 90 percent, between 50 percent and 60 percent, between 50 percent and 70 percent, between 50 percent and 80 percent, between 50 percent and 90 percent, between 60 percent and 70 percent, between 70 percent and 80 percent, between 80 percent and 90 percent, between 60 percent and 80 percent, about 60 percent, about 70 percent, about 80 percent, about 90 percent, or other suitable parentage or range of percentages. In the other described and illustrated embodiments of the tibial trays in the present disclosure, such a shearing force may be similarly counteracted in a total knee replacement. Such embodiments may not include a center keel or may include a center keel such as a shallow keel, wherein such shearing force is primarily counteracted along the periphery of the resected proximal portion of the tibia of the patient.

FIGS. 51-56illustrate a bi-cruciate tibial tray16000, according to an embodiment of the present disclosure. For example, in a bi-cruciate retaining knee replacement both the anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL) may be maintained. For example, this may be provided by bone resections and an implant geometry that circumvents these ligaments. The bi-cruciate tibial tray16000may include a circumferential or partially circumferential wall or fin. The lateral, anterior and medial fin walls are designed to abut or to be in close proximity to the inner cortical wall. The posterior portion of the implant undersurface may not feature a rim, or feature a rim that is generally inset from and designed to match the periphery of the posterior implant surface. The posterior implant surface is curved such that the anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL) are maintained. In this illustrated embodiment, the tibial tray16000may include a U-shaped body16022having a U-shaped superior portion16024and a C-shaped inferior tibia-engaging portion16026(best shown inFIGS. 52 and 55). The U-shaped superior portion16024(FIGS. 51 and 54) may define portions (a lateral portion and a medial portion) defining a cavity16021therebetween. The superior portion16024may include a generally planar superior surface16025(best shown inFIGS. 51 and 54) for supporting a plastic bearing spacer (not shown). The superior portion16024may include a raised land or portion16023(best shown inFIG. 51) disposed between lateral portions for the superior portion16024. In some embodiments, the planar superior surface16025may include a peripheral upwardly-extending lip (not shown) for attaching via a snap fit connection and restraining a plastic bearing spacer.

The inferior tibia-engaging portion16026may include the C-shaped wall or fin16040, which when operably attached to the resected proximal portion of a tibia (not shown inFIGS. 51-56) extends into the cancellous bone of the resected tibia. The wall or fin16040may be designed to be offset or spaced from the periphery of the underlying tibial cortical bone of the proximal portion of the tibia.

The single inferiorly-extending C-shaped wall or fin16040may include an inner wall surface16051and an outer wall surface16055. For example, the wall may have a cross-sectional shape similar to the cross-sectional U-shaped superior portion16024along with periphery thereof. The superior portion16024may have constant thicknesses, different thickness, varying thickness, or other suitable thicknesses. The inner wall surface16051may be disposed normal or at 90 degrees to the superior surface16025, or at any suitable angle or angles. The outer wall surface16055may be disposed normal or at 90 degrees to the superior surface16025. In other embodiments, the outer wall surface may be angled relative to the superior surface such as parallel with and spaced from an inner surface of the cortical bone (not shown inFIG. 51-56). In other embodiments, the outer wall surface15055may be configured to rest against the inner surface of the underlying cortical bone. The outer surface of the circumferential wall or fin15055may be based on pre-operative imaging data of the inner cortical wall of a patient, specifically to design the implant such that the fin outer wall is a fixed and a constant distance from the mapped inner surface of the cortical wall.

FIGS. 57-61illustrate a bi-cruciate tibial tray17000, according to an embodiment of the present disclosure. For example, in a bi-cruciate retaining knee replacement both the anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL) may be maintained. For example, this may be provided by bone resections and an implant geometry that circumvents these ligaments. The bi-cruciate tibial tray17000may include a circumferential or partially circumferential wall or fin. The lateral, anterior and medial fin walls are designed to abut or to be in close proximity to the inner cortical wall. The posterior portion of the implant undersurface may: a) not feature a rim; or b) feature a rim that is generally inset from and designed to match the periphery of the posterior implant surface. The posterior implant surface is curved such that the anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL) are maintained.

In this illustrated embodiment, the tibial tray17000may be essentially the same the bi-cruciate tibial tray16000(FIGS. 51-56) with the exception of a wall17040being disposed at an angle relative to a superior surface17025and being spaced from a plurality of inferiorly-extending projections or pins17300. The wall17040and the pins17300may be dispose at a non-perpendicular angle S relative to the superior surface17000and to a medial-lateral direction. For example, angle S may be between about 70 degrees and 80 degrees, or may be about 75 degrees, or other suitable non-perpendicular angle.

During the insertion of a traditional style tibial baseplate with a post and fins, the tibia is subluxed in the anterior direction to a great extent to allow the post and fins to be prepared with a punch used from the superior direction. The tibia must remain subluxed anteriorly in order to place the tibial implant directly onto the resected tibia surface and seated in a directly inferior direction. In the embodiment of the tibial tray17000, the wall and pegs are angled generally in the posterior direction to allow the implant to be inserted from the anterior side on an angle rather than directly down from the superior direction. This may allow the surgeon to sublux the tibia anteriorly less than in some traditional systems in order to insert the tibial baseplate, which may cause less soft tissue damage due to extreme subluxation of the tibia.

FIG. 62illustrates a patient specific jig or tibia cavity cutting guide18000with a series of openings18050to accommodate a non-robotic burr or milling tool12000(FIG. 44) to allow a surgeon to manually excavate the cavities as described above. For example, cutting guide18000may be used by a surgeon for forming at least one cavity such as a continuous cavity in a resected proximal portion of a tibia of a patient for knee replacement. The resected proximal portion of the tibia includes a center cancellous bone surface and a peripheral cortical bone surface as described above. The cutting guide18000may include a planar member18020having a first planar surface18022and a second planar surface (not shown inFIG. 62).

Planar member18020may include a peripheral outer edge18023, which corresponds to an outer peripheral cortical bone along the resected proximal portion of the tibial of the patient. A series curved openings18050extends through the planar member from the first planar surface18022to the second planar surface (not shown) and is spaced from the peripheral outer edge. Each of the openings18050defines an axis18060, and the opening has a constant width W10normal to the axis. The width desirably corresponds to the width of the inferiorly-extending portions of corresponding patient specific tibial tray. Each of the openings have an inner edge18061and an outer edge18062. The outer edge18062may be disposed parallel to the peripheral outer edge18023. The cutting guide18000may include one or more fixing holes18070to accommodate temporary fixation, e.g., via screws, of the cutting guide to the resected tibia. The periphery of the cutting guide may be sized to match the outer periphery of the resected tibia such that visual alignment and proper placement on the resected tibia is readily performed.

Cutting guide18000may be, for example, a patient specific cutting guide and which may be effected using the system700ofFIG. 7and system800ofFIG. 8. For example, suitable algorithms and programming code stored in memory730(FIG. 7) along with the patient tibia data702(FIG. 7) and the surgeon input704(FIG. 7) may be operably processed in processor710(FIG. 7) to generate a patient specific cutting guide, which cutting guide may be produced or manufactured using 3D printer795(FIG. 7).

The cutting guide18000may be operable with a milling tool such as the milling tool12000(FIG. 44). As such, patient specific tibia cavity cutting guide18000with openings18050into which the milling tool12000fits, constrains movement of the milling tool1200in a fixed shape. A manual excavation of the at least one cavity for the inferiorly-extending portions of the tibial tray may be made to the proper depth. For example, the cutting portion for of the milling guide12000(FIG. 44) may be sized to extend a length L (FIG. 44) that correspond to the depth of the inferiorly-extending portion of the tibial tray and to allow for receipt of the inferiorly-extending portion of the tibial tray when the tibial tray is placed on the resected proximal portion of the patient's tibia. As will be appreciated, the cutting guide18000may be removed and the remaining portions between the series of cavities may be removed by aa surgeon to compete the continuous cavity in the resected portion of the proximal portion of the tibia of the patient.

FIG. 63illustrates a block diagram of a method19000for use in a total knee replacement. The method19000includes, for example, at19100resecting a proximal portion of a tibia of a patient, the resected proximal portion of the tibia having a transverse resected cancellous bone surface, a transverse resected peripheral cortical bone surface, and at least one cavity formed in the periphery of the resected cancellous bone, at19200providing a tibial tray having at least one inferiorly-extending wall spaced inwardly from a peripheral edge of the tibial tray and extending around at least a portion of a center inferior surface, at19300inserting the at least one inferiorly-extending wall in the at least one cavity formed in the periphery of the resected cancellous bone surface, at19400disposing the peripheral edge of the tibial tray on the transverse resected peripheral cortical bone surface, and the center inferior surface on the transverse resected cancellous bone surface, and wherein, in the total knee replacement, a greater portion of a shearing force acting transversely on the tibial tray and the resected portion of the proximal portion of the tibia of the patient is resisted by the at least one inferiorly-extending wall and the periphery of the resected proximal portion of the tibia compared to a portion of the shearing force being resisted along the center inferior surface of the tibial tray and the resected cancellous bone surface.

It will be appreciated from the technique of the present disclosure for the tibial trays and the resected proximal portion of the tibia may overcome the problems of conventional non-patient specific tibial trays that are designed to rest on a flat resection plane that minimizes surface area contact and maximizes shear forces, lack redundant modes of support, provide poor implant surface area coverage influencing the risk of subsidence. The patient specific tibial trays and patent specific resected proximal portion of the tibia overcome the problems associated with conventional tibial trays, which conventional tibial trays are designed as geometric approximations of multiple bone models that are manually segmented from large image databases and proportionally constrained and scaled to accommodate a range of sizes and resecting of the proximal portion of the tibia being flat cut often using a sagittal saw.

The technique of the present disclosure may provide increased surface area contact and/or reduced shear forces along the resection plane of the implant-to-bone interface resulting in less failures or loosening by poor alignment and natural lateral loading of the joint.

The algorithms of the present disclosure may be operable to generate a patient specific tibial tray and robotic cut path of the proximal portion of the tibia that solves the primary failures modes of press-fit tibial knee implants by restoring the pre-operative anatomy and specifically 1) maximizing the surface area contact for increased osseointegration, 2) reducing shear forces and localizing forces to either side of the intercondylar eminence, 3) maximizing cortical contact at the periphery of the implant, and 3) minimizing subsidence and increasing stability with patient specific support pins.

A1. A tibial tray for a resected proximal portion of a tibia of a patient for a total knee replacement. The resected proximal portion of the tibia has a center cancellous bone surface, a peripheral cortical bone surface, and at least one cavity formed in the periphery of the cancellous bone spaced apart from the cortical bone exposing an underlying portion of the cancellous bone of the tibia. The tibial tray may include a body having a superior portion with a superior surface, and an inferior tibia-engaging portion. The body may include an inferior tibia-engaging portion having a center portion having a center surface contactable with the center cancellous bone surface, and a peripheral, inferiorly-extending portion receivable in the at least one cavity formed in the cancellous bone surface so that the peripheral inferiorly-extending portion is spaced apart from the underlying inner surface of the cortical bone of the tibia of the patient.

A2. The tibial tray of A1, wherein the inferior tibia-engaging portion comprises a peripheral edge portion having an inferior surface supportable on the peripheral cortical bone surface of the tibia of the patient, and the peripheral, inferiorly-extending portion being disposed inwardly of the peripheral edge portion. A3. The tibial tray of A1 or A2, wherein the center surface of the inferior tibia-engaging portion comprises a non-planar surface. A4. The tibial tray of any of A1 through A3, wherein the inferiorly-extending portion of the inferior tibia-engaging portion is extendable around at least 10 percent of a perimeter of the underlying peripheral inner surface of the cortical bone of the tibia of the patient. A5. The tibial tray of any of A1 through A4, wherein the inferior tibia-engaging portion comprises an inferior convex surface, an inferior concave surface, and/or an inferior convex surface and an inferior concave surface. A6. The tibial tray of any of A1 through A5, wherein the inferior tibia-engaging portion comprises a pair of spaced-apart inferior convex surfaces corresponding in size to a medial condyle and a lateral condyle of the proximal portion of the tibia of the patient. A7. The tibial tray of any of A1 through A6, wherein the peripheral, inferiorly-extending portion comprises a wall spaced apart from the inner surface of the cortical bone. A8. The tibial tray of A7, wherein the wall comprises a surface configured to be spaced apart from the underlying inner surface of the cortical bone, is angled at about 35 degrees relative to the superior surface of the superior portion of the body, and extends about 7 mm below the superior surface of the superior portion of the body. A9. The tibial tray of any of A7 or A8, wherein the wall extends along at least 30 percent of a perimeter of the underlying peripheral cancellous bone of the tibia of the patient. A10. The tibial tray of any of A7 through A9, wherein the wall extends along the entire peripheral portion of the body. A11. The tibial tray of any of A1 through A10, wherein the inferiorly-extending portion comprises a pair of curved walls configured to be spaced apart from the inner surface the cortical bone. A12. The tibial tray of any of A1 through A11, wherein the inferiorly-extending portion comprises a pair of curved walls configured to be spaced apart from the inner surface the cortical bone, and the center surface comprises a pair of spaced-apart inferior convex surfaces corresponding in size to a medial condyle and a lateral condyle of the proximal portion of the tibia of the patient. A13. The tibial tray of any of A1 through A12, wherein the peripheral inferiorly-extending portion defines a constant gap between the peripheral inferiorly-extending portion and an inner surface of the cortical bone. A14. The tibial tray of any of A1 through A13, wherein the center portion of the body comprises an inferiorly-extending keel. A15. The tibial tray of any of A1 through A14, wherein the body comprises a one-piece body.

B1. A method for forming a patient specific tibial tray for a total knee replacement of the patient, the method comprising: determining a patient specific resected proximal portion of a tibia of the patient, the resected proximal portion of the tibia of the patient having a center cancellous bone surface, a peripheral cortical bone surface, and at least one cavity formed in the periphery of the cancellous bone spaced apart from the cortical bone exposing an underlying portion of the cancellous bone of the tibia; and forming the patient specific tibial tray comprising a body having a superior portion having a superior surface and an inferior tibia-engaging portion, the inferior tibia engaging portion having a center portion contactable with the center cancellous bone surface, and a peripheral, inferiorly-extending portion receivable in the at least one cavity so that the peripheral inferiorly-extending portion is spaced apart from the underlying inner surface of the cortical bone of the tibia of the patient.

B2. The method of B1 further comprising, obtaining first data, via a processor, representing a proximal portion of the tibia of the patient, and determining, via the processor, second data corresponding the patient specific resected proximal portion of the tibia of the patient based on the first data, and the forming, via the processor, comprises 3D printing, forging, casting based on the second data. B2. The method of B1, wherein the obtaining first data comprises obtaining CT scan data and/or X-rays, and the determining comprises determining the patient specific resected proximal portion of the tibia of the patient based on the obtained first data. B3. The method of B1 or B2 further comprising, maximizing the size and shape of the inferior tibia-engaging portion based on a depth and an amount extending along the periphery of the underlying cancellous bone. B20. The method of and of B17 through B19 further comprising, reducing shear forces and localized forces based on the implant to bone contact plane based on the equation Fx=F cos(theta).

C1. A tibial tray for a resected proximal portion of a tibia of a patient for a total knee replacement, the resected proximal portion of the tibia having a central cancellous bone surface, a peripheral cortical bone surface, and at least one cavity formed in the periphery of the cancellous bone. The tibial tray comprising a body the body comprising a superior portion with a superior surface; and an inferior tibia-engaging portion. The inferior tibia-engaging portion comprises a center portion having a center surface contactable with the central cancellous bone surface, and a peripheral, inferiorly-extending portion receivable in the at least one cavity formed in the cancellous bone surface so that the peripheral inferiorly-extending outer surface portion corresponds to the contour of the underlying inner surface of the cortical bone of the tibia of the patient.

C2. The tibial tray of C1, wherein the peripheral, inferiorly-extending portion comprises at least a portion of the peripheral inferiorly-extending outer surface portion extending from a proximal portion of the peripheral, inferiorly-extending portion to a distal portion of the peripheral, inferiorly-extending portion contoured to correspond to a contour of a superior edge portion of the cortical bone along the resection plane so that the at least the portion of the peripheral inferiorly-extending outer surface portion is disposable adjacent to a underlying concave inner surface of the cortical bone. C3. The tibial tray of C2, wherein the contour of the at least the portion of the peripheral inferiorly-extending outer surface portion from the proximal portion to the distal portion of the peripheral, inferiorly-extending portion is perpendicular to the resection plane. C4. The tibial tray of C1, wherein the peripheral, inferiorly-extending portion comprises at least a portion of the peripheral inferiorly-extending outer surface portion extending from a proximal portion of the peripheral, inferiorly-extending portion to a distal portion of the peripheral, inferiorly-extending portion having a proximal portion contoured to correspond to a contour of a superior edge portion of the cortical bone along the resection plane, and a distal portion contoured to being disposable inwardly from the contour of the superior edge portion of the cortical bone along the resection plane.

D1. A tibial tray for a resected proximal portion of a tibia of a patient for a knee replacement, the resected proximal portion of the tibia having a center cancellous bone surface, a peripheral cortical bone surface, and at least one cavity formed in the cancellous bone exposing at least a portion of an underlying inner surface of the cortical bone. The tibial tray includes a body comprising a superior portion with a superior surface; and an inferior tibia-engaging portion. The inferior tibia-engaging portion comprises a center portion having a center surface contactable with the center cancellous bone surface, and a peripheral, inferiorly-extending portion receivable in the at least one cavity formed in the cancellous bone surface, a surface of the peripheral inferiorly-extending portion contactable with the exposed underlying inner surface of the cortical bone of the tibia of the patient.

D2. The tibial tray of D1 wherein the inferior tibia-engaging portion comprises: a peripheral edge portion having an inferior surface supportable on the peripheral cortical bone surface of the tibia of the patient, and the peripheral, inferiorly-extending portion being disposed inwardly of the peripheral edge portion. D3. The tibial tray of D1 wherein the center surface of the inferior tibia-engaging portion comprises a non-planar surface. D4. The tibial tray of D1 wherein the surface of the inferiorly-extending portion of the inferior tibia-engaging portion is contactable with at least 10 percent of a perimeter of the underlying peripheral inner surface of the cortical bone of the tibia of the patient. D5. The tibial tray of D1 wherein the inferior tibia-engaging portion comprises an inferior convex surface, an inferior concave surface, and/or an inferior convex surface and an inferior concave surface. D6. The tibial tray of D1 wherein the inferior tibia-engaging portion comprises a pair of spaced-apart inferior convex surfaces corresponding in size to a medial condyle and a lateral condyle of the proximal portion of the tibia of the patient. D7. The tibial tray of D1 wherein the peripheral, inferiorly-extending portion comprises a wall contactable against the exposed inner surface of the cortical bone. D8. The tibial tray of D7 wherein the wall comprises the surface contactable with the exposed underlying inner surface of the cortical bone and is angled at about 35 degrees relative to the superior surface of the superior portion of the body and extending about 7 mm below the superior surface of the superior portion of the body. D9. The tibial tray of D7 wherein the wall extends along at least 30 percent of a perimeter of the underlying peripheral inner surface of the cortical bone of the tibia of the patient. D10. The tibial tray of D7 wherein the wall extends along the entire center portion of the body. D11. The tibial tray of D1 wherein the inferiorly-extending portion comprises a pair of curved walls contactable against spaced apart portions of the inner surface the cortical bone. D12. The tibial tray of D1 wherein the inferiorly-extending portion comprises a pair of curved walls contactable against spaced apart portions of the inner surface the cortical bone, and the center surface comprises a pair of spaced-apart inferior convex surfaces corresponding in size to a medial condyle and a lateral condyle of the proximal portion of the tibia of the patient. D13. The tibial tray of D1 wherein the inferiorly-extending portion comprises at least one inferiorly-extending pin extendable through an aperture in the inner cortical bone and having an edge alignable with an outer surface of the cortical bone. D14. The tibial tray of D1 wherein the center portion of the body comprises an inferiorly-extending keel. D15. The tibial tray of D1 wherein the body comprises a one-piece body.

E1. A method for forming a patient specific tibial tray for a knee replacement of the patient, the method comprising: determining a patient specific resected proximal portion of a tibia of the patient, the resected proximal portion of the tibia of the patient having a superior center cancellous bone surface, a peripheral cortical bone surface, and one or more cavities and/or openings in the cancellous bone exposing at least a portion of an underlying inner surface of the cortical bone of the tibia; and forming the patient specific tibial tray comprising a body having an superior portion having a superior surface and an inferior tibia-engaging portion, the inferior tibia engaging portion having a center portion contactable with the cancellous bone surface, and a peripheral, inferiorly-extending portion receivable in the one or more cavities and/or openings and having one or more surfaces contactable with the exposed underlying inner surface of the cortical bone of the tibia of the patient.

E2. The method of E1 further comprising obtaining first data, via a processor, representing a proximal portion of the tibia of the patient, and determining, via the processor, second data corresponding the patient specific resected proximal portion of the tibia of the patient based on the first data, and the forming, via the processor, comprises 3D printing, forging, casting based on the second data. E3. The method of E2 wherein the obtaining first data comprises obtaining CT scan data and/or X-rays, and the determining comprises determining the patient specific resected proximal portion of the tibia of the patient based on the obtained first data. E4. The method of E2 further comprising maximizing the one or more surfaces of the inferior tibia-engaging portion based on a depth and an amount of the surface extending along the perimeter of the underlying inner surface portion of the cortical bone. E5. The method of E2 further comprising reducing shear forces and localized forces based on the implant to bone contact plane based on the equation Fx=F cos(theta).

As may be recognized by those of ordinary skill in the art based on the teachings herein, numerous changes and modifications may be made to the above-described and other embodiments of the present invention without departing from the scope of the invention. The implants and other components of the devices and/or apparatus as disclosed in the specification, including the accompanying abstract and drawings, may be replaced by alternative component(s) or feature(s), such as those disclosed in another embodiment, which serve the same, equivalent or similar purpose as known by those skilled in the art to achieve the same, equivalent or similar results by such alternative component(s) or feature(s) to provide a similar function for the intended purpose. In addition, the devices and apparatus may include more or fewer components or features than the embodiments as described and illustrated herein. Accordingly, this detailed description of the currently-preferred embodiments is to be taken as illustrative, as opposed to limiting the invention.

The invention has been described with reference to the preferred embodiments. It will be understood that the architectural and operational embodiments described herein are exemplary of a plurality of possible arrangements to provide the same general features, characteristics, and general apparatus operation. Modifications and alterations will occur to others upon a reading and understanding of the preceding detailed description. It is intended that the invention be construed as including all such modifications and alterations.