Knee replacement implants and instruments

Abstract

To provide knee arthroplasty implants, instruments, systems, and methods of implanting the same.SOLUTION: The knee arthroplasty implants may include a femoral implant and a tibial tray implant, each with trabecular surfaces configured to contact bone to provide a scaffold for bone healing and interdigitation. The implants may also include fixation pegs with bulleted profiles to increase the surface area for bone ingrowth. An inserter instrument may include a sliding rack, which is incrementally extended with a rotatable shaft, thereby allowing quick lock and release of various tibia trays.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] TECHNICAL FIELD This application relates generally to knee arthroplasty, and more particularly to knee arthroplasty implants, instruments, and methods for installing knee arthroplasty implants. [Background technology]

[0002] Knee arthroplasty, often referred to as knee replacement, is a surgical procedure used to reconstruct and resurface a knee damaged by, for example, arthritis. Total knee arthroplasty (TKA) devices can replace both the tibiofemoral joint and the patellofemoral joint. The tibiofemoral joint is where the tibia and femur articulate. The patellofemoral joint is where the patella and femur articulate. To replace the tibiofemoral joint, knee arthroplasty can include a femoral implant secured to the distal end of the femur (or thighbone), a tibial tray implant secured to the proximal end of the tibia (or shinbone), an insert disposed therebetween, and an optional patella backing. The femoral and tibial implants cover the ends of the femur and tibia, respectively, which form the knee joint, thereby reconstructing the knee. To replace the patellofemoral joint, knee arthroplasty can include a patellar prosthesis (or implant) to replace the back of the patella and create a replacement articular surface that interfaces with a femoral implant.

[0003] The femoral portion of the procedure can include removing damaged bone and cartilage at the end of the femur and cutting the resurfaced end of the bone to fit the femoral implant. The tibial portion of the procedure can include a planar resection to the proximal tibia, which is replaced with a tibial tray implant. In some cases, the implant may be attached to the bone using bone cement. The implant may include a recess for the cement to fit. However, there are risks associated with bone cement. For example, bone cement can fail by not creating a strong enough bond or can weaken over time, causing the knee replacement to fail, cement fracture, or insufficient cement application. These failures can lead to complications such as inflammation, swelling, and persistent pain. Additionally, cement has its own risks and surgical challenges, such as cement impingement, improper mixing technique, and proper timing of cement mixing and application. There is a need for improved femoral implants and tibial trays that can be implanted without cement, as well as improved instruments configured to implant the components. Summary of the Invention

[0004] To meet this and other needs, knee arthroplasty implants, instruments, systems, and methods for installing them are provided. In particular, the knee arthroplasty implants can include a femoral implant and a tibial tray implant, each having a trabecular bone surface configured to contact bone and provide a scaffold for bone healing and interlocking. The implants can also include fixation pegs with a bullet-like profile to provide primary fixation and increase surface area for bone ingrowth. Specialized instruments can be particularly suitable for installing the implants.

[0005] According to one embodiment, a system for knee arthroplasty includes a femoral implant and a tibial tray implant. The femoral implant has an anterior flange, a pair of posterior condylar flanges, and a distal portion therebetween. The femoral implant has an outer articular surface with a smooth, rounded shape that closely approximates the outer distal femoral surface of a natural human knee, an inner surface shaped to match the resected femur in five resection cuts, and one or more pegs extending from the inner surface. The tibial tray implant has a plate with a peripheral wall defining an insert-receiving space, a distal surface configured to contact the resected tibia, a keel extending from the distal surface, and one or more pegs extending from the distal surface. The inner surface of the femoral implant and the distal surface of the tibial tray define a trabecular bone structure that provides a scaffold for bone healing and interlocking.

[0006] The knee arthroplasty system may include one or more of the following features: The trabecular bone structure may have a grid, lattice, or honeycomb pattern to promote bone ingrowth. The trabecular bone structure may have a porosity ranging from 50 to 80%. The thickness of the trabecular bone structure may be oversized to increase press-fit in the trabecular bone structure area to ensure contact with the resected femur and tibia. The trabecular bone structure may be fabricated by three-dimensional printing. The pegs of the femoral implant and tibial tray implant may each have a bullet-shaped profile with six fins radiating outward from the peg. The inner surface of the femoral implant may include an anterior femoral cut surface, a posterior femoral cut surface, a distal femoral cut surface, an anterior chamfer cut surface, and a posterior chamfer cut surface. The trabecular bone structure may extend along the anterior femoral cut surface, the posterior femoral cut surface, the distal femoral cut surface, the anterior chamfer cut surface, and the posterior chamfer cut surface. The trabecular structure may be surrounded by a solid wall. The femoral and tibial implants may be cementless so that they can be fixed to the bone without cement.

[0007] According to one embodiment, a system for knee arthroplasty includes a tibial tray and an inserter. The tibial tray has a peripheral wall defining an insert-receiving space. The peripheral wall defines a pair of posterior notches and a single anterior notch. The inserter has a body with feet having a pair of fixed posterior tabs, a sliding rack having an anterior tab, and a rotatable shaft for controlling movement of the sliding rack. When the shaft is rotated to translate the sliding rack to an extended position, the posterior tabs are receivable within the posterior notches of the tibial tray and the anterior tab is receivable within the anterior notch of the tibial tray.

[0008] The knee arthroplasty system may include one or more of the following features. The rotatable shaft of the inserter may have a gear with a gear surface at its distal end. The sliding rack may have a linear gear track with teeth that mesh with the gear surface of the rotatable shaft. The foot may be bifurcated by a keyway, and the sliding rack may be receivable within the keyway. The tibial tray may have a kidney shape with an anterior side forming a lateral convex side and a posterior side including a medial concave side separating two lobes, and the foot may have an outer kidney shape that matches the kidney shape of the tibial tray. The tibial tray may include a keel attached to the distal surface of the tibial tray, and the keel may include a pair of coronal fins and a sagittal fin.

[0009] According to one embodiment, a method for implanting a tibial implant may include one or more of the following steps, in any suitable order: (1) positioning fixed posterior tabs on the body of the inserter within corresponding posterior notches in the peripheral wall of the tibial tray; (2) tilting the inserter and / or the tibial tray until the feet of the inserter body are received within the insert-receiving space of the tibial tray; (3) rotating the shaft through the body of the inserter to translate a sliding rack having an anterior tab so that the anterior tab extends into the anterior notch in the tibial tray, thereby locking the inserter to the tibial tray; (4) inserting an impaction cap to seat the tibial tray within the patient's proximal tibia; (5) removing the inserter by rotating the shaft in the opposite direction and withdrawing the sliding rack from the tibial tray; and (6) installing an insert having tabs receivable within the posterior and anterior notches in the tibial tray. The method may also include, before positioning the inserter, resecting the proximal tibia to form a planar resection surface and drilling a cavity in the proximal tibia, the cavity configured to receive the keel of the tibial tray.

[0010] Also provided are kits that include various types and sizes of implants, including femoral implants, tibial trays, and inserts with different anterior-posterior (AP) and / or medial-lateral (ML) aspects, various types and configurations of instruments, including inserter instruments, and other components for performing the procedure. [Brief explanation of the drawings]

[0011] A more complete understanding of the present invention and its attendant advantages and features will be more readily appreciated by reference to the following detailed description when considered in conjunction with the accompanying drawings.

[0012] [Figure 1] FIG. 1 is a perspective view of a femoral implant showing the inner trabecular bone structure according to one embodiment. [Figure 2A]2A and 2B show side and top views, respectively, of the femoral implant of FIG. 1. [Figure 2B] 2A and 2B show side and top views, respectively, of the femoral implant of FIG. 1. [Figure 3A] 1A and 1B show a side view and a close-up view, respectively, of a fixation peg with a bullet-like profile and fins according to one embodiment. [Figure 3B] 1A and 1B show a side view and a close-up view, respectively, of a fixation peg with a bullet-like profile and fins according to one embodiment. [Figure 4] 1 illustrates a perspective view of a tibial tray implant according to one embodiment. [Figure 5] 5 illustrates a bottom view of the tibial tray implant of FIG. 4 showing trabecular bone structure according to one embodiment. [Figure 6A] 1A and 1B show close-up views of the bottom of a tibial tray implant with and without trabecular bone structure, respectively. [Figure 6B] 1A and 1B show close-up views of the bottom of a tibial tray implant with and without trabecular bone structure, respectively. [Figure 7A] 1 illustrates a perspective view of an inserter instrument for installing a tibial tray implant according to one embodiment. [Figure 7B] 1 illustrates a perspective view of an inserter instrument for installing a tibial tray implant according to one embodiment. [Figure 8] 1 shows an exploded view of the inserter instrument. [Figure 9A] 1A-1C show front and side views, respectively, of an inserter instrument mated with a tibial tray implant for implantation, according to one embodiment. [Figure 9B] 1A-1C show front and side views, respectively, of an inserter instrument mated with a tibial tray implant for implantation, according to one embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0013] Embodiments of the present disclosure are generally directed to implants, instruments, systems, and methods for implanting knee replacement implants, including femoral implants and tibial tray implants, for example, during total knee arthroplasty. The total knee arthroplasty system may include a femoral component, a tibial component, and an insert positioned between the femoral and tibial components. The femoral component may be secured to the femur after resurfacing and resecting the end of the bone to fit the femoral implant. The tibial tray implant may be secured to the tibia after a planar resection to the proximal tibia. Specifically, embodiments are directed to cementless femoral and tibial tray implants, each having a trabecular bone structure that interfaces with the bone. The trabecular bone structure may include a porous scaffold configured for bone growth into the structure. As the bone heals, bone grows into the microscopic porous structure, further strengthening implant fixation.

[0014] The implant assembly may be constructed from one or more biocompatible materials. For example, the femoral and tibial implants may be made from metals such as titanium, stainless steel, cobalt chrome, carbon composites, or suitable alloys. The inserts may be made from plastics or polymers such as polyethylene, ultra-high molecular weight polyethylene (UHMWPE), polyetheretherketone (PEEK), or combinations of such materials. In this manner, the components are configured so that the metal articulates with the plastic to provide smooth movement and minimize wear. These materials may be machined or constructed from additive manufacturing, such as three-dimensional (3D) printing, subtractive manufacturing, or hybrid manufacturing processes. While the materials described herein are exemplary, it will be understood that any suitable materials and constructions may be selected for the individual components.

[0015] Although generally described with reference to knee arthroplasty, it should be understood that the implants, instruments, and systems described herein may be applied to other orthopedic locations and applications, such as the spine, including between vertebrae, long bones such as the femur, tibia, humerus, clavicle, fibula, ulna, radius, bones of the foot, bones of the hand, or other suitable bone(s) or joint.

[0016] Additional aspects, advantages, and / or other features of exemplary embodiments of the present invention will become apparent in view of the following detailed description. It will be apparent to those skilled in the art that the described embodiments provided herein are merely exemplary and illustrative, and not limiting. Numerous embodiments and modifications thereof are contemplated as falling within the scope of the present disclosure and equivalents thereto.

[0017] Referring now to the drawings, wherein like reference numerals refer to like elements, FIGS. 1-2B show a femoral implant 10 according to one embodiment. The femoral implant 10 replaces the end of the femur, or thighbone, for example, after resection. The implant 10 curves across the anterior and posterior distal end of the femur, replicating the natural shape of the original femur for proper knee function. In this case, the femoral implant 10 is configured to be secured to the bone without cement, thereby eliminating the need for cement and its associated risks.

[0018] The femoral implant 10 includes an anterior flange 12, a pair of posterior condylar flanges 14, 16, and a distal portion 18 therebetween. The pair of posterior condylar flanges 14, 16 includes a medial condylar portion 14 and a lateral condylar portion 16 configured to mimic the condyles of a natural femur. The medial condylar portion 14 and the lateral condylar portion 16 are spaced apart from one another (e.g., generally along a medial-lateral direction) to define an intercondylar notch 20 therebetween. As best seen in FIG. 2B , the intercondylar notch 20 may be generally rectangular with rounded corners or a rounded rectangle. In the case of a posteriorly stabilized implant, the intercondylar notch 20 can form a box that accepts a stabilizing post or cam. In the case of a posteriorly stabilized implant, the intercondylar box 20 can help stabilize posterior translation of the tibia. In some examples, the intercondylar box 20 can include additional material for migration resistance.

[0019] The outer or lateral articular surface 22 of the implant 10 may form a rounded C-shape that corresponds to the natural distal femoral surface of a human knee. The lateral articular surface 22 may include a lateral condylar surface 24 and a lateral distal surface 26 for cooperation with the corresponding end of the tibia, and a lateral anterior surface 28 for cooperation with the patella. As best seen in FIG. 2B , the lateral anterior surface 28 may be separated by a trochlear groove 29 that closely approximates the anterior distal femoral surface of a natural human knee.

[0020] The femoral implant 10 can be configured to be secured to a resected femur. For example, the femoral component 10 can have an inner or internal surface 30 shaped to match five femoral resection cuts. The five resection bone-interfacing surfaces 30 can include an anterior femoral cut 32, a posterior femoral cut 34, a distal femoral cut 36, an anterior chamfer cut 38, and a posterior chamfer cut 40. The distal femoral cut 36 mates with a resection cut to the distal-most femoral condyle. The distal resection cut can affect mechanical alignment, extension gap, and joint line height. The anterior femoral cut 32 mates with an anterior resection cut to the distal femur that is cut through the trochlear groove. The depth of the anterior resection cut can affect the patellofemoral joint. The posterior femoral cut 34 mates with a posterior resection cut to the distal femur that is cut through the posterior femoral condyle. The posterior resection cuts can affect the flexion gap. The anterior and posterior cuts can be generally parallel and can determine the rotation of the femoral implant. The anterior flange cut 32 and the posterior flange cut 34 can have a taper, such as a 6-degree taper, to press-fit into the resected femur. The anterior chamfer cut 38 is an angled cut connecting the anterior cut 32 and the distal face 36, and the posterior chamfer cut 40 is an angled cut connecting the posterior cut 34 and the distal face 36. These chamfer cuts 38, 40 also mate with corresponding resection cuts on the distal end of the femur. Prior to making the resection cuts, an implant size can be selected to determine the desired resection cut locations to ensure an optimal fit with the interior surface 30 of the implant 10.

[0021] The interior surface 30 defines a trabecular structure 44 that provides a scaffold for bone healing and bone intercalation. As the bone heals, bone grows into the microporous structure, further enhancing fixation, thereby replacing the need for cement. The trabecular structure 44 may comprise, for example, a porous scaffold structure including hexagonal struts with micropores. In some embodiments, the trabecular structure 44 can have a grid, lattice, or honeycomb pattern to promote bone ingrowth. The trabecular structure 44 may comprise a randomized or repeating pattern of open or interconnected pores. The pores may be spherical, partially spherical, or another suitable pore shape or configuration. The trabecular structure 44 can have a suitable porosity (open volume), for example, greater than 50% open, greater than 60% open, or greater than 70% open. In one embodiment, the trabecular structure 44 can have a porosity in the range of approximately 50-80% to maximize the potential for bone ingrowth. The trabecular bone structure 44 can have pore sizes ranging, for example, from about 100 μm to 2 mm in diameter, from about 100 μm to 1 mm, from about 200 to 900 μm, or from about 300 to 800 μm in diameter. Further details regarding suitable porous structures are described, for example, in U.S. Patent No. 10,524,926, which is incorporated herein by reference in its entirety for all purposes.

[0022] The trabecular structure 44 may be fabricated by additive manufacturing, such as three-dimensional (3D) printing, while printing the entire component. Additive manufacturing may include direct metal laser sintering (DMLS), powder bed fusion, vat photopolymerization, material jetting, lamination, extrusion, directed energy deposition, or any other suitable additive manufacturing process. The implant 10 may also be fabricated using a combination of additive manufacturing processes and other manufacturing processes, such as laser etching, ablation, machining, polishing, and chemical processing. The implant 10 may be fabricated entirely via additive processes or may include a hybrid construction by machining a base and then adding the trabecular structure 44 via additive manufacturing.

[0023] The trabecular bone structure 44 may be provided along the interior surface 30 of the implant 10, including the anterior femoral cut surface 32, the posterior femoral cut surface 34, the distal femoral cut surface 36, the anterior chamfer cut surface 38, and the posterior chamfer cut surface 40. The trabecular bone structure 44 may be surrounded by a solid edge, rim, or wall 46. In other words, the periphery of the implant 10 may form a solid wall 46, and the interior region may be filled with the trabecular bone structure 44. The thickness of the trabecular bone structure 44 may be oversized to increase the press-fit in the trabecular bone structure region. As best seen in FIG. 2A , the trabecular bone structure 44 may protrude beyond the wall 46 of the implant 10 to increase contact with the resection cut. This ensures that the trabecular bone structure 44 is always in contact with the resected femur.

[0024] The central portion 48 of the implant 10 can have a solid or smooth area that is free of trabecular bone structure 44. The central portion 48 can extend from the notch 20, along the anterior chamfer 38, and into a small area of ​​the anterior cutting surface 32. The central portion 48 may include a rectangular area with rounded corners or another suitable shape to support the implant 10. A solid central portion 48 can add additional structure to the center of the implant 10, thereby providing additional structural integrity and mechanical stability while maximizing the area of ​​trabecular bone structure 44 to facilitate better integration / incorporation with the adjacent bone.

[0025] The edge or wall 46 of the implant 10 may define one or more recesses 52 configured to mate with, for example, an inserter instrument. Each recess 52 may define a curved indentation for receiving a complementary portion of the instrument. The curved recesses 52 may have, for example, a concave semicircular shape. A pair of recesses 52 may be located along the outer wall 46 on either side of the distal femoral cut 36.

[0026] In addition to the cut bone-interfacing surface 30, the implant 10 may include one or more anchoring projections, fixation spikes, or pegs 60 that can be press-fit into the resected distal surface of the femur. As best seen in the enlarged views of FIGS. 3A-3B, each fixation peg 60 may include a bullet-shaped profile extending perpendicularly from the distal femoral cut surface 36. The bullet-shaped profile may include a pointed or rounded tip 62 that tapers to a wider base 64. The pegs 60 may be solid or hollow (e.g., have a solid or hollow core). In one embodiment, the peg tip 62 may include a curved or hemispherical recess 66, for example, forming a hollow-point (negative cone) end. Each fixation peg 60 may have one or more peripheral ribs or fins 68 disposed about a central fin axis 70. The fins 68 may have rounded, chamfered, sharp, or filleted edges. The fins 68 may include radial protrusions extending outward around the circumference of the peg 60. The fins 68 may radiate outward between the narrow tip 62 and wide base 64 of the peg 60. The fins 68 may be evenly spaced around the peg 60 or configured in other ways. The fins 68 may be configured to minimize bone displacement, minimize the risk of fracture, and / or increase the surface area for bone ingrowth. In one embodiment, the fixation peg 60 has a six-sided fin design, although it will be understood that any suitable number of fins 68 may be selected. The implant 10 may include a pair of fixation pegs 60 located on the distal femoral cut surface 36, although it will be understood that any suitable number and position of pegs 60 may be selected to secure the implant 10 to the bone. The fixation pegs 60 are configured to provide an increased surface area, which contributes to enhanced bone engagement and fixation to the bone.

[0027] The femoral implant 10 can be secured to the femur via the five-section bone-interfacing surface 30, the fixation pegs 60, and the trabecular bone structure 44 to enhance initial and long-term fixation. First, the implant 10 is secured to the femur by the nature of the interfacing surface 30, which can be press-fit onto the resected femur. Initial fixation is also achieved by the press-fit of the fixation pegs 60 into the resected distal surface. The fins 68 also provide a larger surface area for bone engagement over time. In the case of posterior-stabilized implants, the box 20 can add additional strength for migration resistance. Finally, long-term stability may be provided through the trabecular bone structure 44, which provides a scaffold for bone healing and interfitting over time. By providing a cementless implant 10, the implant 10 can be installed without cement, thereby eliminating cement-related complications. Additionally, a cementless procedure may result in shorter procedure times and less surgeon stress.

[0028] 4-6B, a tibial tray implant 110 according to one embodiment is shown. The tibial tray implant 110 replaces the end of the tibia or shin bone, for example, after resection. Similar to the femoral implant 10, the tibial tray implant 110 includes a trabecular bone structure 144 configured to be secured to the bone without cement, thereby eliminating the need for cement and its associated risks. The tibial tray 110 may be initially secured to the bone with one or more keels 130 and pegs 160 to prevent any movement of the tibial tray 110. Sustained stability may be achieved through the trabecular bone structure 144, which acts as a scaffold to support and promote bone regeneration over time.

[0029] The tibial tray 110 may be offered in multiple sizes with different anterior-posterior (AP) and medial-lateral (ML) aspects to fit the patient's anatomy. The tray 110 may include a keel structure 130 on the distal surface 116 of the tray 110, as well as one or more pegs 160 that provide additional support / fixation to the cancellous bone of the tibia. A keel punch may be utilized to create an initial cavity in the cancellous bone of the tibia to allow the keel 130 of the tibial tray 110 to seat within the proximal tibia. One or more additional openings may be formed in the resection to accommodate the pegs 160. After all necessary preparation of the tibia has been performed, the tibial tray 110 is implanted into the resected and drilled proximal tibia. The tibial tray 110 may be snapped into place to ensure proper seating of the tray 110. After the tray 110 is in place and the inserter removed therefrom, an insert (not shown) can be connected to the tray 110 to complete the tibial implant assembly. As with the implant 10, the trabecular bone structure 144 provides a microporous structure for bone ingrowth, thereby providing long-term stability.

[0030] The tibial tray 110 includes a plate 112 having opposing proximal and distal surfaces 114 and 116. The distal surface 116 of the tibial plate 112 is configured to engage the resected surface of the tibia. The tibial plate 112 has a peripheral edge, wall, or lip 118 that defines an insert-receiving space 120 sized and shaped to receive an insert (not shown). The proximal surface 114 of the plate 112 defines the distal or bottom surface of the insert-receiving space 120. The insert-receiving space 120 may be divided into two areas by a raised portion or solid central post 122, which may provide increased fatigue durability.

[0031] The tibial plate 112 includes an anterior side 124 and an opposing posterior side 126. The outer profile of the tibial tray 110 may be rounded or curved. For example, the tibial tray 110 may have a general shape of a long oval with a concave side, such as a kidney bean shape. The anterior side 124 may form an outer convex side as one long side, and the posterior side 126 may include an inner concave side separating two lobes or rounded ends. The central post 122 may extend a distance from a central concave surface on the posterior side 126 toward the anterior side 124, leaving a gap between the two open regions of the insert-receiving space 120. The peripheral wall 118 of the tray 110 may define one or more recesses, pockets, or notches 128 used to receive a portion of an insert to retain the insert within the insert-receiving space 120 of the tibial tray 110. For example, a pair of rearward notches 128 may be provided along the rearward side 126 of wall 118, and a single forward notch 128 (not visible) may be provided along the forward side 126 of wall 118 for mating with an insert and / or inserter instrument such as instrument 200.

[0032] An insert (not shown) seats between the tibial tray 110 and the femoral implant 10 to mimic natural knee motion and provide support as the knee flexes and flexes. The insert can fit within the receiving space 120 to provide an articular or joint surface configured to interface with the femoral implant 10. Further details regarding inserts and tibial tray implants are provided in U.S. Patent Publication No. 2023 / 0270563, which is incorporated herein by reference in its entirety for all purposes.

[0033] The distal surface 116 of the plate 112 defines a trabecular structure 144 that provides a scaffold for bone healing and bone interdigitation. As the bone heals, bone grows into the microporous structure, further strengthening fixation, thereby replacing the need for cement. In one embodiment, the entire bottom surface 116 of the implant 110 includes the trabecular structure 144 to promote bone ingrowth. The trabecular structure 144 may include, for example, a porous scaffold structure including hexagonal struts with micropores. In some embodiments, the trabecular structure 144 can have a grid, lattice, or honeycomb pattern to promote bone ingrowth. The trabecular structure 144 may include a randomized or repeating pattern of open or interconnected pores. The pores may be spherical, partially spherical, or another suitable pore shape or configuration. The trabecular structure 144 can have a suitable porosity (open volume), for example, greater than 50% open, greater than 60% open, or greater than 70% open. In one embodiment, the distal surface 116 can have a porosity ranging from about 50 to 80%. The trabecular structure 144 can have pore sizes ranging from about 100 μm to 2 mm, about 100 μm to 1 mm, about 200 to 900 μm, or about 300 to 800 μm in diameter, for example.

[0034] The trabecular bone structure 144 may be created by additive manufacturing, such as three-dimensional (3D) printing, while printing the entire component. The implant 10 may be manufactured in a fully additive manufacturing process, where all of the implant shape is built on a base plate, post-processed, and removed from the base plate. Alternatively, the implant 10 may be manufactured in a hybrid structure, where the lattice portion of the implant is created by machining from a blank plate or forged blank. The blank is then placed in an additive machine, and both the lattice and the three-dimensional shape are built on the blank. By using additive manufacturing to build the part, a highly porous lattice structure 144 can be constructed, which cannot otherwise be created using traditional manufacturing methods.

[0035] The trabecular structure 144 may form the distal surface 116 of the tray 110. The thickness of the trabecular structure 144 may be oversized, for example, to have a thickness in the range of approximately 1-1.5 mm. As best seen in FIG. 4, the trabecular structure 144 may protrude beyond the plate 112 to increase contact of the trabecular structure 144 with the resection cut. This ensures optimal contact of the trabecular structure 144 with the resected femur to promote bone ingrowth.

[0036] The tibial implant 110 may include a tibial stem or keel 130. The tibial keel 130 is configured to be inserted into a drilled cavity in the resected surface of the proximal end of the patient's tibia. The tibial keel 130 is attached to the distal surface 116 of the tibial plate 112. The tibial keel 130 extends generally distally from the distal surface 116 of the tibial plate 112. The tibial keel 130 may be solid or hollow (e.g., having a solid or hollow core).

[0037] The tibial keel 130 may include one or more fins 132, 134, including a coronal fin 132 and / or a sagittal fin 134. The coronal fins 132 (e.g., two coronal fins 132) may extend outward from the center of the tibial keel 130 in a direction generally parallel to the patient's coronal plane (e.g., a vertical, side-to-side extending plane). The coronal fins 132 may be provided at a slight angle, e.g., about 15 degrees or less, relative to the coronal plane so as to form a slight V-shape. The sagittal fin 134 (e.g., a single sagittal fin 134) may extend outward from the center of the tibial keel 130 in a direction generally parallel to the patient's sagittal plane (e.g., a vertical, anterior-posterior extending plane). The coronal and sagittal fins 132, 134 may taper inward or narrow as the fins 132, 134 extend distally. The width of the sagittal fin 134 may also taper inward (e.g., in a direction generally parallel to the coronal plane) as the fin 134 extends distally. The fins 132, 134 may have rounded edges to improve insertion into the cavity. The distal-most nose or tip 136 of the tibial keel 130 may be tapered or curved, for example, along the coronal and / or sagittal planes. While the nose 136 is shown curved in the coronal plane, it may be obtuse or tapered in both the coronal and sagittal planes. It will be appreciated that other configurations or modifications to the tibial keel 130 may be provided to enhance insertion and retention into the cavity of the proximal tibia.

[0038] Similar to the implant 10, the tibial tray 110 may further include one or more anchoring projections, fixation spikes, or pegs 160. Each peg 160 is configured to be inserted into a corresponding opening in a resection of the patient's proximal tibia to help resist migration. The pegs 160 may be provided on the tray 110 in cementless procedures to provide additional support and / or fixation to the cancellous bone of the tibia. The pegs 1602 extend generally distally from the distal surface 116 of the tibial plate 112. Similar to the pegs 60, the pegs 160 may have a generally bullet shape, or other suitable shapes may be used. The pegs 160 may include one or more peripheral ribs or fins 168, e.g., having rounded, chamfered, sharp, or filleted edges. The fins 168 may be configured to minimize bone displacement, risk of fracture, and / or increase surface area for bone ingrowth. The pegs 160 may be spaced apart from one another around the distal surface 116 of the tibial plate 112. For example, as best seen in FIG. 5 , the pegs 160 may be positioned around the tibial keel 130 with the tibial keel 130 centered between the pegs 160. For example, two pegs 160 may be located toward the anterior side 124 of the implant 110 and two pegs 160 may be located toward the posterior side 126. Any suitable quantity and arrangement of pegs 160 may be provided to achieve the desired support and fixation for the tibial tray 110. The pegs 160 may be substantially identical to one another or may be configured in other ways.

[0039] As shown in FIG. 6B , where the trabecular structure 144 is omitted for clarity, the keel 130 and pegs 160 can extend from the base plate 112. The trabecular lattice structure 144 forms a boundary around the base of the keel 130 and pegs 160 and fills the entire distal surface 116 of the plate 112. The implant 110 may be fabricated by pure additive construction, in which the entire implant 110 is fabricated using a 3D manufacturing method. Alternatively, the implant 110 may be fabricated using hybrid construction, in which the trabecular lattice structure 144, solid keel 130, and pegs 160 are built onto a forged or wrought and machined base plate 112. Regardless of the manufacturing method, the cementless tibial tray implant 110 provides an implant that can be inserted without cement, thereby reducing procedure time, cement-related complications, and stress on the surgeon.

[0040] 7A-9B, an instrument 200 for installing a tibial implant, such as the tibial tray implant 110, is shown, according to one embodiment. The instrument 200 may be used to connect to various sizes of tibial trays 110, allowing for implantation of the tibial tray 110 into the patient. After impaction and implantation, the instrument 200 may then be disengaged from the tibial tray 110. The instrument 200 may be used by a single operator to assist in implanting the tibial tray 110 into the cavity within the tibial soft tissue, thereby allowing for quick locking and release of the tibial tray 110.

[0041] The inserter instrument 10 extends from a proximal end 202 to a distal end 204 along a central longitudinal tool axis 206. The instrument 200 includes a central body or main body 210, an extensible front locking mechanism 212 at the distal end 204, and a fitting cap 214 at the proximal end 202. The main body 210 houses a central shaft 216 for controlling the movement of the front locking mechanism 212. The central shaft 216 incorporates a distal gear face 218 that cooperates with the front locking mechanism 212 and a proximal ratchet tooth 220 that cooperates with a lever mechanism 222. As best seen in the exploded view of FIG. 8 , the components may be welded and pinned together to produce the assembled instrument 200.

[0042] The central body or main body 210 is a hollow member having a base or foot 224 and a neck 226 projecting upwardly or proximally from the foot 224. The neck 226 is a hollow tube sized and dimensioned to receive the central shaft 216 therethrough. The neck 226 and the central through-opening may be generally aligned along the central longitudinal axis 206 of the instrument 200. The neck 226 may define a handle portion having a groove for being grasped by a user, for example. The neck 226 may also define an elongated vertical window 227, which may aid in cleaning or visualization of the central shaft 216.

[0043] The base or foot 224 is configured to engage with the tibial tray 110, thereby controlling movement of the tibial tray 110 during impaction and insertion. The foot 224 is generally sized and shaped to fit within the insert-receiving space 120 in the tibial tray 110. In other words, the outer wall of the foot 224 may have the same kidney shape that generally corresponds to the recess 120 of the tray 110. The foot 224 may be bifurcated by a keyway 228 configured to receive the anterior locking mechanism 212. The foot 224 may include one or more posterior tabs 230 positioned along a posterior portion of the foot 224. The posterior tabs 230 may be fixed to the foot 224. The fixed posterior tabs 230 may be located on two lobes separated by the keyway 228. Each posterior tab 230 may be elongated with a length extending in a direction generally parallel to the patient's coronal plane (e.g., a vertical, side-to-side plane). The fixed posterior tabs 230 are receivable within corresponding posterior pockets or notches 128 in the tibial tray 110. The bottom of the foot 224 may include one or more protectors 232, such as plastic cushions, to prevent metal-to-metal contact between the foot 224 and the implant 110. The protectors 232 may be secured to the bottom of the foot 224 using, for example, respective dowel pins 233.

[0044] The foot 224 houses an expandable anterior locking mechanism 212 that mimics the shape of the tibial tray 110 and is configured to mate with the anterior end 124 of the tibial tray 110. The expandable anterior locking mechanism 212 includes a sliding rack 234 that is configured to slide in an anterior direction when actuated by the central shaft 216. The sliding rack 234 includes a rectangular body having two parallel, straight legs and a horizontal top that resembles the letter U when viewed from the side. The distal end of the sliding rack 234 defines a groove 236 that is sized and dimensioned to mate with the central post 122 of the tibial tray 110. The anterior portion of the sliding rack 234 includes one or more protrusions or tabs 238 that are receivable within a corresponding anterior pocket or notch 128 in the tibial tray 110. As the sliding rack 234 is translated anteriorly, the anterior tab 238 engages the notch 128, thereby securing the instrument 200 to the implant 110. The top of the sliding rack 234 defines a linear gear track 240, which, when actuated by the gear surface 218 on the central shaft 216, translates the sliding rack 234 into and out of engagement with the tibial tray implant 110. The linear gear track 240 may define a plurality of teeth along a linear bar configured to mate with corresponding teeth on the gear surface 218 of the central shaft 216. The sliding rack 234 may be held in place by, for example, an anterior dowel pin 242 and two retaining pins 244.

[0045] The central shaft 216 includes a cylindrical component for transmitting rotational force to the sliding rack 234. The central shaft 216 includes a gear wheel 250 at its distal end having a gear face 218 that includes a plurality of teeth projecting perpendicular to the plane of the gear wheel 250. The gear face 218 may be a type of bevel gear or crown gear configured to mesh with a linear gear track 240. When rotational motion is applied to the central shaft 216, the meshing teeth of the gear face 218 and the linear gear track 240 convert the rotational motion into linear motion, thereby translating the sliding rack 234 to a desired position. The central shaft 216 includes ratchet teeth 220 at its proximal end. The ratchet teeth 220 engage a lever 222 to rotate and lock the central shaft 216 in discrete increments. In this manner, the sliding rack 234 can be extended forward by discrete sizes or increments. In one embodiment, the sliding rack 234 includes a corresponding protector 246 , such as a plastic cushion, to prevent metal-on-metal wear as the sliding rack 234 slides over the central post 122 of the implant 110 .

[0046] The ratchet lever 222 includes a finger having a pawl 260 configured to engage the ratchet teeth 220 on the central shaft 216 and a button 262 for operating the ratchet lever 222. The ratchet lever 222 is secured to the body 210 using a dowel pin 264 about which the ratchet lever 222 pivots. For example, the body 210 may be provided with a recess having two protruding pin holes for receiving the pin 264, thereby pinning the ratchet lever 222 in place to interact with the central shaft 216. A spring 266 provides tension to urge the pawl 260 of the ratchet lever 222 against and maintain engagement with the ratchet teeth 220 on the central shaft 216. When the button 262 is depressed, the pawl 260 disengages from the ratchet teeth 220, thereby allowing the central shaft 216 to move freely. When the pawl 260 is engaged, rotation of the shaft 216 allows incremental movement of the sliding rack 234 .

[0047] The impaction cap 214 includes an impaction handle 270 and a distally protruding shaft 272. The distal end of the shaft 272 mates with the proximal end of the central shaft 216. The top of the central shaft 216 can define, for example, a rectangular protrusion configured to allow the impaction cap 214 to be easily welded onto the central shaft 216. The impaction handle 270 can be graspable and controllable by a user to rotate the central shaft 216. The impaction handle 270 can include a fillet within its shape to allow the instrument 200 to be easily rotated. The impaction handle 270 also provides a large proximal impaction surface to absorb the force or impact of a hammer or mallet.

[0048] As best seen in FIGS. 9A-9B , the instrument 200 can be operated as follows: The mating end of the foot 224 can be positioned within the proximal surface 114 of the tibial tray 110. The operator can position the lower end of the instrument 200 on top of the cementless tibial tray 110, aligning the central island 122 and posterior notch 128 of the tray 110 with the foot 224 of the inserter device 200. Next, the operator can hold the central body 226 and rotate the impaction cap 202, for example, clockwise. The impaction cap 214 can be rotated to rotate the central shaft 216, engaging the gear 218 with the gear rack 240 on the anterior locking mechanism 212 and extending the sliding rack 234 into the anterior groove 128 in the tibial tray 110. The instrument 200 is configured to be placed on various tibial trays 110 and extended in discrete increments until the sliding rack 234 mates with the tibial tray 110. The extension may be locked at discrete distances by ratchet teeth 220 on the top of the central shaft 216 and by engagement with a pawl 260 on the lever 222. When the sliding rack 234 has extended as far as the tibial tray 110 will allow, the instrument 200 is fully locked and held by the ratchet interfaces 220, 260.

[0049] The entire instrument and tibial tray system can then be inserted, tibial tray first, into the patient's soft tissue. During insertion, the operator may impact the impaction cap 214 with a hammer, specialized impactor, or similar device until the tibial tray 110 is in the desired position. The instrument 200 is configured to hold the tibial tray 110 securely in place while the entire system is impacted into the patient's tibia, with the keel 130 and pegs 160 fully seated in the bone and the trabecular surface 144 pressing against the resected tibia.

[0050] The instrument 200 can then be easily released from the tibial tray 110. By depressing the ratchet lever 222, the instrument 200 is unlocked, allowing the impaction cap 214 to be rotated counterclockwise, for example, releasing the inserter 200 from the tibial tray 110 and allowing the implant 110 to be removed without disturbing it. By depressing the lever trigger 262 and rotating the impaction cap 214 in the opposite direction, the locking mechanism 212 collapses, withdrawing the sliding rack 234 and leaving the tibial tray 110 behind. The instrument 200 can quickly lock and release the tibial tray 110 without the use of a hand-tightening mechanism. Additionally, the instrument 200 is configured to interface with implants at a specific extension range, which improves ease of use.

[0051] While the present invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention. Accordingly, it is intended that the present invention cover all modifications and variations of the present invention provided they come within the scope of the appended claims and their equivalents. For example, it is expressly intended that all of the elements of the various devices disclosed above can be combined or modified in any suitable configuration.

Claims

1. 1. A knee arthroplasty implant system comprising: a femoral implant having an anterior flange, a pair of posterior condylar flanges, and a distal portion therebetween, the femoral implant having an outer articular surface having a smooth, rounded shape that closely approximates the outer distal surface of the femur in a natural human knee, an inner surface shaped to match the femur resected in five resection cuts, and one or more pegs extending from the inner surface; a tibial tray implant having a plate with a peripheral wall defining an insert-receiving space, a distal surface configured to contact the resected tibia, a keel extending from the distal surface, and one or more pegs extending from the distal surface; Equipped with The system, wherein the inner surface of the femoral implant and the distal surface of the tibial tray define a trabecular bone structure that provides a scaffold for bone healing and interfitting.

2. The system of claim 1 , wherein the trabecular bone structure has a grid, lattice, or honeycomb pattern to promote bone ingrowth.

3. The system of claim 1 , wherein the trabecular bone structure has a porosity in the range of 50-80%.

4. 10. The system of claim 1, wherein the trabecular bone thickness is oversized for increased press-fit in the trabecular bone region to ensure contact with the resected femur and tibia.

5. The system of claim 1 , wherein the trabecular bone structure is fabricated by three-dimensional printing.

6. The system of claim 1 , wherein the pegs of the femoral implant and the tibial tray implant each have a bullet-shaped profile with six fins radiating outward from the peg.

7. The system of claim 1 , wherein the inner surface of the femoral implant includes an anterior femoral cut surface, a posterior femoral cut surface, a distal femoral cut surface, an anterior chamfer cut surface, and a posterior chamfer cut surface.

8. 8. The system of claim 7, wherein the trabecular bone structure extends along the anterior femoral cut surface, the posterior femoral cut surface, the distal femoral cut surface, the anterior chamfer cut surface, and the posterior chamfer cut surface.

9. The system of claim 1 , wherein the trabecular structure is surrounded by a solid wall.

10. The system of claim 1 , wherein the femoral and tibial implants are cementless and can be fixed to bone without cement.

11. 1. A system for knee arthroplasty, the system comprising: a tibial tray having a peripheral wall defining an insert-receiving space, the peripheral wall defining a pair of posterior notches and a single anterior notch; an inserter having a body with feet having a pair of fixed posterior tabs, a sliding rack having an anterior tab, and a rotatable shaft for controlling movement of the sliding rack, wherein the posterior tabs are receivable within the posterior notch of the tibial tray and the anterior tab is receivable within the anterior notch of the tibial tray when the shaft rotates and the sliding rack translates to an extended position; A system comprising:

12. The system of claim 11 , wherein the rotatable shaft has a gear wheel with a gear face at its distal end.

13. The system of claim 12 , wherein the sliding rack comprises a linear gear track having teeth that mesh with the gear surface of the rotatable shaft.

14. The system of claim 11 , wherein the foot is bifurcated by a keyway, and the sliding rack is receivable within the keyway.

15. 12. The system of claim 11, wherein the tibial tray has a kidney shape with an anterior side forming a lateral convex side and a posterior side including a medial concave side separating two lobes, and the foot section has a lateral kidney shape that matches the kidney shape of the tibial tray.

16. The system of claim 11 , wherein the tibial tray includes a keel attached to a distal surface of the tibial tray, the keel including a pair of coronal and sagittal fins.

17. 1. A method of implanting a tibial implant, the method comprising: Positioning a fixed posterior tab of the inserter body within a corresponding posterior notch in the peripheral wall of the tibial tray; tilting the inserter until a foot of the inserter body is received within the insert-receiving space of the tibial tray; rotating a shaft through the body of the inserter to translate a sliding rack having an anterior tab and extend the anterior tab into an anterior notch in the tibial tray, thereby locking the inserter to the tibial tray; inserting an insertion cap to seat the tibial tray within the patient's proximal tibia; A method comprising:

18. The method of claim 17, further comprising resecting the proximal tibia to form a planar resection surface before positioning the inserter.

19. 18. The method of claim 17, further comprising drilling a cavity in the proximal tibia before positioning the inserter, the cavity configured to receive a keel of the tibial tray.

20. 18. The method of claim 17, further comprising removing the inserter by rotating the shaft in an opposite direction and withdrawing the sliding rack from the tibial tray, and installing an insert having tabs receivable within the posterior and anterior notches in the tibial tray.

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