Patent Application
20080058945
1. Field of the Invention
The invention relates to orthopedic joint replacement and, more particularly, to a prosthetic device for use in orthopedic joint replacement for resurfacing an articular surface of a bone and a system and method for implanting the same.
2. Description of Related Art
As shown in
One disadvantage of conventional TKA systems is that the incision must be large enough to accept implantation of the femoral component 500 and the tibial component 502. Another disadvantage is that the femoral component 500 and the tibial component 502 have standard, fixed geometries and are available in a limited range of sizes. As a result, the surgeon may be unable to achieve a fit that addresses each patient's unique anatomy, ligament stability, and kinematics. Additionally, because conventional implant geometry is fixed, the surgeon may be forced to remove healthy as well as diseased bone to accommodate the implant. Thus, conventional TKA systems lack the flexibility to enable the surgeon to select implant components that are customized to accommodate a patient's unique anatomy and/or disease state.
In an effort to overcome disadvantages of conventional TKA systems, modular TKA knee prostheses comprising multiple components that are inserted separately and assembled within the surgical site have been developed. An example of a modular system is described in U.S. patent application Ser. No. 11/312,741, filed Dec. 30, 2005, published as Pub. No. US 2006/0190086, and hereby incorporated by reference herein in its entirety. One disadvantage of such systems is that the modular components, although inserted separately, are connected together inside the patient's body. Thus, the modular components mimic a conventional TKA system, and, as a result, have limitations similar to those of a conventional TKA system. Additionally, because the modular components are fixed together, the components are dependent upon one another in that the selection and placement of one modular component is determined (or constrained by) the selection and placement of another modular component. For example, each modular component must include a connection mechanism (e.g., pins, screws, etc.) designed to mate with a corresponding connection mechanism on another modular component. Because the two components must mate together, the selection and placement of a component is determined and constrained by the selection and placement of the mating component. As a result, the degrees of freedom, interchangeability, and design variability of each modular component are restricted and the final geometry of the assembled component is fixed. Thus, conventional modular implants do not enable the surgeon to vary the placement or geometry of each modular component to best suit each patient's unique anatomy, ligament stability, kinematics, and disease state.
Conventional knee arthroplasty systems exist that include multiple unconnected components 600 (e.g., a bicondylar knee arthroplasty system as shown in
Another disadvantage of such conventional systems is that the unconnected components 600 require accurate alignment relative to one another. A unicondylar implant (i.e., encompassing only a medial or a lateral compartment of the joint) may perform well because the biomechanics of the joint are not governed soley by the implant but also by the intact articular surfaces of the healthy condyle and by the intact ligaments. For a bicondylar implant (shown in
In view of the foregoing, a need exists for techniques and implants that enable individual components of a prosthetic device to be selected and implanted in one, two, or three compartments of a joint with a high degree of accuracy and in any combination that enables the surgeon to vary the geometry and configuration of the implant to create a customized prosthetic device tailored to the patient's unique anatomy, ligament stability, kinematics, and disease state.
An aspect of the present invention relates to a method of implanting a prosthetic device configured to form at least a portion of a joint. The method includes selecting a first component of the prosthetic device configured to be implanted in a body, determining a placement at which the first component will be fixed relative to a bone of the body, selecting a second component of the prosthetic device configured to be implanted in the body, and determining a placement at which the second component will be fixed relative to the bone. The determination of the placement of the second component is not constrained by a connection to the first component.
Another aspect of the present invention relates to a prosthetic device configured to form at least a portion of a joint. The prosthetic device includes a plurality of components configured to be implanted in a body. Each of the plurality of components is configured to be fixed relative to a bone of the body. Each of the plurality of components is also configured such that a placement at which the component will be fixed relative to the bone is not constrained by a connection to another of the components
Yet another aspect of the present invention relates to a prosthetic device. The prosthetic device includes a plurality of segmented components configured to form at least a portion of a joint. Each of the plurality of segmented components is configured such that a placement of one of the segmented components in the joint is not constrained by a connection to another of the segmented components.
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain principles of the invention.
FIGS. 3(a)-3(d) are perspective views of a conventional posterior stabilized total knee arthroplasty system.
FIGS. 9(a)-9(c) are perspective views of the component of
FIGS. 21(a)-21(c) are cross-sectional sagittal views illustrating lowpoints of a medial tibial component and a lateral tibial component of an embodiment of a prosthetic device according to the present invention.
Presently preferred embodiments of the invention are illustrated in the drawings. An effort has been made to use the same or like reference numbers throughout the drawings to refer to the same or like parts.
The distal end of the femur 230 is conceptually divided into a lateral (i.e., outside) condyle region A, a central (or patellofemoral) region C (which contains a patellar groove 232 having an inverted U-shape), and a medial condyle (i.e., inside) region E. Similarly, the proximal end of the tibia 240 is conceptually divided into lateral B, central D, and medial F regions, which correspond, respectively, to the lateral A, central C, and medial E regions of the femur 230. Finally, the space between the patella 250 and the femur 230 or the tibia 240 (depending on the bending state of the leg) defines a patellar region G.
The prosthetic device 5 includes a plurality of components configured to be implanted in a body of a patient to form at least a portion of a joint, such as a knee joint as shown in
The components of the prosthetic device 5 are preferably segmented components. As shown in FIGS. 5(a) and 5(b), a segmented component is an individual component implanted in the joint as an independent, self-contained, stand-alone component that is not physically constrained by any other segmented component (as used herein, the term physically constrained means that the components are linked through a physical connection and/or physical contact in such a manner that the link between the components imposes limitations on the positioning or placement of either of the components). Thus, the components 10, 11, 12, 13, and 14 are all segmented components. Although a segmented component is an independent, stand-alone component, a segmented component itself may be formed by joining multiple components together (e.g., via mechanical joint, bonding, molding, etc.). For example, the segmented component 11 may be a medial tibial component formed by connecting a modular tibial baseplate 11a and a modular tibial insert 11b to form the independent, stand-alone medial tibial component 11. Although formed from multiple pieces, the tibial component 11 is a segmented component according to the present invention because, when implanted in the joint, it is not physically constrained by any other segmented component of the prosthetic device 5, such as the component 13 (shown in
One advantage of a prosthetic device having unconnected and/or physically separated components is that the surgeon does not have to consider whether a particular component is designed to mate with other components of the prosthetic device 5. Instead, the surgeon can select each component based on how that particular component will fit to the specific patient anatomy and the expected performance in the specific region of the joint in which it will be implanted. As a result, the surgeon can create a customized prosthetic device, for example, by selecting each component to have the performance characteristics (e.g., size, geometry, conformity, orientation, angle, etc.) best suited for the particular portion of the joint in which it will be installed. In contrast, with conventional modular implants, the surgeon must use modular components that have corresponding connection mechanisms. Thus, the surgeon may be limited to the implant manufacturer's predetermined component combinations and/or forced to select components having less desirable performance characteristics just to ensure that the components can be successfully mated together.
Another advantage of a prosthetic device having unconnected and/or physically separated components is that the position of each component on the bone is not constrained or hindered by the position of any other component on the bone. Thus, a pose (i.e., position and orientation) or placement at which each component is fixed relative to the bone is not constrained by a connection to or contact with another component. As a result, the degrees of freedom available when positioning a component are not limited or restricted by any other component. As a result, the surgeon has freedom to customize the placement (e.g., alignment, orientation, rotation, translation, etc.) of each component of the prosthetic device to meet the specific needs of the patient (e.g., based on unique anatomy, ligament stability, kinematics, and/or disease state). In contrast, conventional TKA implants include monolithic components having fixed geometry. Similarly, conventional modular implants include modular pieces that are fixed together after insertion into the body resulting in fixed geometry. Because the geometry is fixed, the surgeon does not have the freedom to independently position each modular piece.
Another advantage of a prosthetic device having unconnected and/or physically separated components is that the configuration of the prosthetic device 5 is variable. For example, because the components do not constrain one another, the combinations of components forming the prosthetic device 5 can be varied (e.g., mixed and matched) to include any number, type, and/or combination of components appropriate for a particular patient. The appropriate number, type, and/or combination of components may be determined based on patient specific factors such as, for example, the patient's unique anatomy, ligament stability, kinematics, and/or disease state. Thus, by varying the number, type, and/or combination of components, the surgeon can customize the prosthetic device 5 to target osteoarthritic disease by joint compartment. In contrast, with conventional TKA systems, there are typically up to eight different implant sizes offered for each component, and the average size increment is between 3-5 mm. These implants may have a fixed ratio between the anterior-posterior and the medial-lateral dimensions with other implant geometry being accordingly constrained. Because each patient's bone generally does not perfectly match the TKA implant size offering, the surgeon must compromise by downsizing or upsizing the component. Additionally, conventional TKA designs require the removal of a significant amount of bone to eliminate variations in the patient's joint geometry and ensure that one of the available implants will fit. As a result, ligament balance could be slightly looser or tighter than desired, or certain compartments could be overstuffed (i.e., more metal or plastic added than bone removed). In addition, the generally symmetric condyles of the femoral TKA component and the generally symmetric condyles of the tibial TKA component may not perfectly fit the patient's natural asymmetric anatomy. Another problem is that the kinematics of the joint following a TKA procedure are typically different from the natural kinematics. Thus, although the patient experiences significant improvement (e.g., reduced pain, increased range of motion, etc.), full function of the joint is not restored. In contrast, the present invention advantageously provides a segmented implant system with components having multiple sizes, shapes, geometries, and conformities to enable construction of a prosthetic device 5 customized to a particular patient's unique anatomy, ligament stability, kinematics, and/or disease state.
In operation, to target a patient's unique disease state, the surgeon can configure the prosthetic device 5 to address disease in any compartment of the joint. Specifically, the surgeon can mix and match the components of the prosthetic device 5 to provide the desired coverage. For example, the prosthetic device 5 may include components configured for implantation on a first compartment of a knee joint (e.g., a medial compartment), components configured for implantation on a second compartment of the knee joint (e.g., a lateral compartment), and/or components configured for implantation on a third compartment of the knee joint (e.g., a central compartment). As a result, the prosthetic device 5 can be configured as a unicompartmental, bicompartmental, or tricompartmental implant. Thus, the surgeon can vary an arrangement of the components to form a prosthetic device customized to the patient's unique anatomy, disease state, ligament stability, and kinematics.
In one embodiment, the components of the prosthetic device 5 are configured to form a tricompartmental implant. In this embodiment, the prosthetic device 5 includes at least three segmented components each configured to be fixed relative to a corresponding bone of the joint. The tricompartmental implant may be cruciate retaining (shown in
The tricompartmental cruciate retaining embodiment of
As with other components of the prosthetic device 5, the component 15 may be made of one or more pieces. In one embodiment, as shown in
Structurally, the parts 24a and 24b may be connected to form a single segmented component 14a. Alternatively, the parts 24a and 24b may be individual segmented components that are not connected to and/or not in contact with any other component of the prosthetic device 5 when implanted in the joint. For example, in one embodiment, the first and second parts 24a and 24b may be configured such that a placement at which one of the first and second parts 24a and 24b will be fixed relative to the central region C of the first bone 1 is not constrained by a connection to the other of the first and second parts 24a and 24b. In this embodiment, as shown in
One advantage of the posterior stabilized embodiment of the present invention is that the patellofemoral component (e.g., the component 14a, the first and second parts 24a and 24b) is a segmented component that is independent of the medial and lateral femoral components 10 and 12. Similarly, the central tibial component 15 is a segmented component that is independent of the medial and lateral tibial components 11 and 13. As a result, the posterior stabilized patellofemoral component and the central tibial component can be used alone to address disease in the central compartment of the joint or in combination with the medial and/or lateral components of the prosthetic device 5. Thus, the surgeon can vary the combination of components to form an implant customized to the patient's unique anatomy, disease state, ligament stability, and kinematics. In contrast, a conventional PS implant (shown in FIGS. 3(a)-3(d)) is available only as a TKA system with femoral and tibial components each having invariable fixed geometry and covering, respectively, an entire distal surface of the femur and an entire proximal surface of the tibia.
In another embodiment, the components of the prosthetic device 5 are configured to form a unicompartmental implant. For example, in reference to FIGS. 5(a) and 11, for a cruciate retaining embodiment, a unicompartmental implant may be formed by including only (a) the components 10 and 11 (medial compartment), (b) the components 12 and 13 (lateral compartment), (c) the component 14 (central compartment), or (d) the first part 24a (central compartment). Additionally, if the patella P has significant osteoarthritis, the surgeon may decide to resurface the patella P. In such cases, (c) and (d) may include a patellar component. Because the components are segmented, the unicompartmental embodiment can easily be converted into a bicompartmental or tricompartmental embodiment. For example, a bicompartmental implant may be formed by combining any two of (a), (b), and (c) or (d) above. For example,
Similarly, in reference to
In one embodiment, the prosthetic device 5 is a bicompartmental implant that includes a first segmented component configured to be fixed relative to a central portion of a bone (e.g., a femur or a tibia) of the joint and a second segmented component configured to be fixed relative to at least one of a medial portion and a lateral portion of the bone. Thus, in this embodiment, the prosthetic device 5 encompasses the central compartment of the joint and either the medial or lateral compartment of the joint. For example, for a femoral portion of a cruciate retaining embodiment, the components 10 and 14 may be implanted on the first bone 1 (as shown in
The components of the prosthetic device 5 may be made of any material or combination of materials suitable for use in an orthopedic implant. Suitable materials include, for example, biocompatible metals (e.g., a cobalt-chromium alloy, a titanium alloy, or stainless steel); ceramics (e.g., an alumina or zirconia-based ceramic); high performance polymers (e.g., ultra-high molecular weight polyethylene); a low friction, low wear polymer/polymer composite; and/or a polymer composite as described in U.S. patent application Ser. No. 10/914,615, U.S. patent application Ser. No. 11/140,775, and/or International Application No. PCT/US2005/028234 (International Pub. No. WO 2006/020619), each of which is hereby incorporated by reference herein in its entirety.
The components of the prosthetic device 5 may be implanted in the joint in any known manner, for example, using an adhesive, a cement, an intramedullary rod, a press fit, a mechanical fastener, a projection (e.g., stem, post, spike), and the like. Fixation may also be accomplished via biological or bone in-growth. To promote biological in-growth, the components of the prosthetic device 5 may be coated with hydroxyapatite (HA), have a porous texture (e.g., beads, etc.), include one or more surfaces made from a porous metal (e.g., TRABECULAR METAL™ currently produced by Zimmer, Inc.), and/or include one or more surfaces having a cellular engineered structure (e.g., TRABECULITE™ currently produced by Tecomet). In one embodiment, each component of the prosthetic device 5 is implanted using the fixation device best suited for the compartment in which the component will be implanted. For example, the fixation device for a particular component may be selected based on bone quality at the specific site of implantation. For example, if the implantation site has a dense healthy bone, the surgeon may select an implant with a porous coating or porous metal to allow for bone in-growth fixation. The selection of one fixation device or method for one compartment of the joint does not determine the fixation device or method for another compartment. Thus, the components of the prosthetic device 5 may be implanted with similar or different fixation methods and devices.
In one embodiment, the prosthetic device 5 includes a fixation device configured to be inserted into an intramedullary canal of a bone. For example, the component may include a projection or intramedullary canal fixation post 26 as shown in
As shown in
Additionally, in a natural joint, the sagittal shape of the medial tibial plateau has a lowpoint or sulcus L located at approximately a midpoint of the plateau in an anterior-posterior (front-back) direction. At full extension, the femur F rests in the sulcus L as shown in
Advantageously, the present invention can be adapted to address these problems. For example, the ability to select from a variety of segmented components, to mix and match the components, and to place the components as desired (i.e., without physical constraints imposed by other components), the surgeon can configure the prosthetic device 5 to correspond to the natural geometry of a healthy joint so that the resulting knee kinematics more closely mirror normal joint motion. Thus, rather than a limited number of components available in fixed configurations as with conventional TKA and connected modular implant systems, a variety of segmented components (e.g., of various sizes, geometries, conformities, etc.) can be designed and varied by the surgeon to create a prosthetic device having a precise fit for each patient.
For example, the components of the prosthetic device can be configured such that at least one of a geometry, a conformity, and a configuration of the prosthetic device 5 can be varied during implantation by varying at least one of a placement and a selection of one or more of the components. Because the components are unconnected and/or not in contact with one another, constraints on the surgeon's ability to select and place the components as desired are reduced. Thus, selection parameters (e.g., size, shape, geometry, conformity) and placement parameters (e.g., orientation, position, alignment) of one component are not determinative of the selection and/or placement parameters of another component during implantation (as used herein, the term determinative means that the selection or placement parameters of one component necessarily require particular selection or placement parameters of another component). As a result, the surgeon can alter the geometry, conformity, and/or configuration of the prosthetic device 5 to meet the customized needs of the patient by varying the components he selects and/or his placement of those components. As a result, the selection and placement of each component can be tailored to create a customized prosthetic device 5 that meets the patient's unique needs in each region of the joint.
With regard to placement, each component can be implanted in the joint with the orientation, position, and alignment best suited to the patient's unique anatomy, ligament stability, kinematics, and/or disease state. For example, in one embodiment, the components of the prosthetic device 5 may include a first component and a second component configured to be positioned relative to the bone such that an alignment of the first component is not determinative of an alignment of the second component during implantation. For example, during implant planning and placement, the component 10 (shown in FIGS. 5(a) and 5(b)) can be aligned based on the patient's needs in the medial compartment of the joint. Similarly, the components 12 and 14 can be aligned based on the patients needs in the lateral and central compartments, respectively. Because the components are segmented, each can be independently aligned. As a result, the alignment of one component does not depend on and is not constrained by the alignment of another component. Accordingly, during implant planning and placement, the surgeon has the freedom to vary the alignment and other placement parameters of each component to best suit the needs of the patient in the area of the joint where the component is being implanted. In this manner, the implanted components of the prosthetic device 5 enable optimal restoration of joint kinematics based on patient anatomy and previous joint function. Additionally, in situations where the patient has an existing deformity that requires surgical intervention and correction through implants, the ability to align components as desired enables optimal balancing of the joint after deformity correction.
In one embodiment, the degrees of freedom of a first component of the prosthetic device are not determinative of the degrees of freedom of a second component of the prosthetic device. As a result, the surgeon has maximum flexibility when planning implant placement and when installing each component of the prosthetic device 5 in the joint. Because the components of the prosthetic device 5 are not connected to and/or in contact with other components of the prosthetic device 5 when implanted in the joint, each component can be independently positioned in one or more degrees of freedom. In a preferred embodiment, the components can be independently positioned in six degrees of freedom. For example, as shown in FIGS. 23(a) and 23(b), the medial tibial component 32 can be oriented independently of the lateral tibial component 34 by an angle θ1 and an angle θ2. The distance d between the medial and lateral components 32 and 34 can also be adjusted. The medial and tibial components can be independently positioned with potentially different placements in the anterior-posterior, medial-lateral, and superior-inferior directions. Similarly, the components can be oriented with potentially different rotations in varus/valgus, internal/external, and flexion/extension (or posterior slope). The ability to vary the distance d between the components enables adjustment to unique patient geometry, or even to account for variations existing between male and female morphology, as well as between different populations (e.g., Asian, European, African, and others). The slope of the components defined by the angles θ1 and θ2 may be used by the surgeon to adjust the implant slope to an angle that he believes will result in better implant stability and or life depending on the existing precondition of ligaments.
Although FIGS. 23(a) and 23(b) illustrate tibial components, femoral components of the prosthetic device 5 can also be independently positioned in one or more (e.g., six) degrees of freedom. In one embodiment, a distance x (shown in
With regard to selection, each component can be selected to have the size, shape, geometry, and conformity best suited to the patient's unique anatomy, ligament stability, kinematics, and/or disease state and based on the surgical outcome desired by the surgeon for the patient. Conformity refers to the fit between components, such as the manner in which an articular surface of a femoral component fits or conforms to a corresponding articular surface of a tibial component. The degree of conformity depends on the shape of each articular surface and/or how the surfaces are placed relative to one another when implanted in the joint. For example, conformity may be represented by a ratio of a radius of a femoral articular surface to a radius of the corresponding tibial articular surface (e.g., 1:1.05). In one embodiment, the conformity of the prosthetic device 5 in the medial compartment can be different from the conformity in the lateral compartment. This can be accomplished by providing the surgeon with a selection of segmented components with a range of geometries (e.g., profiles, contours, dimensions, slopes, etc.). The surgeon then selects and installs components that provide the desired conformity in the medial compartment and components that provide the desired conformity in the lateral compartment.
For example, in one embodiment, the prosthetic device 5 can be configured to have a first component including a first contour and a second component including a second contour. Each contour may be comprised of one or more radii and may also include substantially straight sections. As shown in
For example, the surgeon may choose components that create a prosthetic device 5 that is highly conforming in the medial compartment and mildly conforming or flat in the lateral compartment. Conversely, the prosthetic device 5 may be constructed to be mildly conforming in the medial compartment and highly conforming in the lateral compartment. Alternatively, the medial and lateral compartments may have a similar degree of conformity. In one embodiment, a medial contour is substantially concave. In another embodiment, a lateral contour is substantially less concave than a medial contour. In another embodiment, a medial contour is substantially concave, and a lateral contour is substantially flat. In another embodiment a medial contour is substantially concave, and a lateral contour is substantially convex. In a preferred embodiment, a medial contour includes a portion having a radius of between about 20 mm to about 75 mm concave. In another embodiment, a medial contour includes a portion having a radius of between about 20 mm to about 75 mm concave, and a lateral contour includes at least one of the following: (a) a portion having a radius of between about 76 mm to about 200 mm concave, (b) a portion having a radius that is greater than the medial radius, (c) a portion having a radius of between about 76 mm concave and 200 mm convex, (d) a portion having a radius that is substantially flat, and (e) a portion having a radius that is substantially flat to about 200 mm convex.
Although the embodiment of FIGS. 15(a) and 15(b) illustrates sagittal conformities, other conformities, such as coronal conformities may be adjusted in a similar manner. For example,
The ability to vary curvature between components is advantageous. For example, in one embodiment, the shape of the surface of the tibial component can be curved to allow for controlled internal/external rotation of the femur during ROM. In another embodiment, the shape of the curve on the medial and lateral components can be selected from different components having different curves to allow for constrained motion or less constrained motion based on parameters selected by the surgeon to fit the patient anatomy and needs. In another embodiment, the coronal curvature is substantially conforming to the curvature of the femur, while the sagittal curvature is less conforming to enable additional medial-lateral stability of the joint and correct for deficient collateral ligaments. In another embodiment, the coronal curvature is mildly conforming, while the sagittal curvature is highly conforming to correct for deficient function of the cruciate ligaments that may not be severe enough to require a posterior stabilized implant.
In addition to being able to vary conformities of the prosthetic device 5, medial and lateral tibial lowpoints can be varied to meet the unique stability needs of the patient and/or to match the femoral components. For example, as shown in
In one embodiment, the prosthetic device 5 includes a first component having a first contour with a first lowpoint and a second component having a second contour with a second lowpoint. The first and second lowpoints may have similar or different anterior-posterior (front-back) locations. In one embodiment, at least one of the first and second lowpoints (e.g., a medial lowpoint of a tibial sagittal contour) is substantially located in an anterior-posterior midplane W.
Another advantage of the segmented components of the present invention is the ability to vary tibial insert thickness to thereby adjust a height of the insert. For example, by providing tibial components of varying thicknesses and/or by placing the tibial components at different elevations on the bone, different insert heights (e.g., h1, h2, h3, h4, h5, h6, h7, h8, etc.) can be achieved in the medial and lateral comportments as shown in
To install the prosthetic device 5 in the patient, the surgeon preferably uses a computer aided surgery (CAS) system to accomplish surgical planning and navigation. For example, a CAS system may be used by the surgeon during bone preparation to achieve the desired bone resection. Preferably, the CAS system is a robotic surgical navigation system that enables the surgeon to achieve sufficient accuracy, predictability, and repeatability in planning the placement of the components of the prosthetic device 5 and in preparing the bone to receive the components. In contrast, conventional freehand and jig-based bone preparation methods may not be able to achieve sufficiently tight tolerances to enable successful installation of the prosthetic device 5.
For example, whereas conventional TKA systems comprise solid parts having fixed geometry and conventional modular systems comprise modular components that are joined together inside the body resulting in fixed geometry, the components of the prosthetic device 5 are individually positioned segmented components. Altering the placement parameters of one or more of the components results in alterations in the geometry of the prosthetic device 5. As a result, the geometry and configuration of the prosthetic device 5 are variable depending on the surgeon's placement of the segmented components relative to the patient's anatomy and/or relative to one another. To ensure that a desired placement of each component is achieved and that desired geometric relationships (e.g., distance, orientation, alignment, etc.) with the patient's anatomy and among the segmented components are established, each segmented component must be installed (or positioned) in the joint with a high degree of accuracy. Achieving the requisite accuracy requires significant surgical skill as well as specialized instruments and technology. Because surgeons have different skill levels and experience, operative results among patients may not be sufficiently predictable and/or repeatable using conventional freehand and jig-based bone preparation methods. Accordingly, in a preferred embodiment, the components of the prosthetic device 5 are configured to be fixed relative to a corresponding bone of the joint that includes at least one robotically prepared surface. The surface of the bone may be prepared, for example, as described in U.S. patent application Ser. No. 11/357,197, filed Feb. 21, 2006, published as Pub. No. US 2006/0142657, and incorporated by reference herein in its entirety. Additionally, relative positioning of the segmented components may be achieved, for example, using the features and techniques described in U.S. patent application Ser. No. 11/617,449, filed Dec. 28, 2006, and hereby incorporated by reference herein in its entirety.
In one embodiment, the surface of the bone is prepared using a robotic surgical navigation system 300 known as the Haptic Guidance System™ (HGS) manufactured by MAKO Surgical Corp. and shown in
The virtual boundary may represent, for example, a cutting boundary defining a region of bone to be removed or a virtual pathway for guiding the surgical tool to a surgical site without contacting critical anatomical structures. The virtual boundary may be defined by a haptic object, and the haptic guidance may be in the form of force feedback (i.e., force and/or torque) that is mapped to the haptic object and experienced by the surgeon as resistance to further tool movement in the direction of the virtual boundary. Thus, the surgeon may feel the sensation that the tool has encountered a physical object, such as a wall. In this manner, the virtual boundary functions as a highly accurate virtual cutting guide. In one embodiment, the surgical navigation system 300 includes a visual display showing the amount of bone removed during the cutting operation as shown in
In addition to bone preparation, a CAS system enables the surgeon to customize the placement of the components to construct a prosthetic device tailored to the specific needs of the patient based on the patient's unique anatomy, ligament stability, kinematics, and/or disease state. Implant planning may be accomplished preoperatively or intraoperatively and may be evaluated and adjusted in real time during execution of the surgical procedure. In a preferred embodiment, implant planning is accomplished using the surgical navigation system 300 known as the Haptic Guidance System™ (HGS) manufactured by MAKO Surgical Corp. and as described in U.S. patent application Ser. No. 11/357,197, filed Feb. 21, 2006, published as Pub. No. US 2006/0142657, and incorporated by reference herein in its entirety. For example, the surgeon may use the surgical planning features of the surgical navigation system 300 to plan the placement of each component relative to a preoperative CT image (or other image or model of the anatomy). The software enables the surgeon to view the placement of each component relative to the anatomy and to other components. The software may also be configured to illustrate how the components will interact as the joint moves through a range of motion. Based on the component placement selected by the surgeon, the surgical navigation system 300 software generates one or more haptic objects, which create one or more virtual boundaries representing, for example, a portion of bone to be removed or critical anatomy to be avoided. During surgery, the haptic object is registered to the patient's anatomy. By providing force feedback, the surgical navigation system 300 enables the surgeon in interact with the haptic object in the virtual environment. In this manner, the surgical navigation system 300 haptically guides the surgeon during bone preparation to sculpt or contour the appropriate location of the bone so that a shape of the bone substantially conforms to a shape of a mating surface of a component of the prosthetic device 5.
In a preferred embodiment, the surgical navigation system 300 is used by the surgeon to preoperatively plan implant placement using computer simulation tools to determine whether the preoperative plan will result in the desired clinical results. Then, during surgery, the surgeon may query the soft tissue and ligaments during range of motion using appropriate instrumentation and sensors as is well known. This information may be combined with the computer simulation information of the surgical navigation system 300 to adjust the implant planning and suggest to the surgeon potential changes and adjustments to implant placement that may achieve the desired clinical outcomes.
According to one embodiment, a surgical method of implanting the prosthetic device 5 comprises steps S1 to S4. In step S1, the surgeons selects a first component configured to be implanted in a body. In step S2, the surgeon determines a placement at which the first component will be fixed relative to a bone of the body. In step S3, the surgeon selects a second component configured to be implanted in the body. In step S4, the surgeon determines a placement at which the second component will be fixed relative to the bone. The determination of the placement of the second component is not constrained by a connection to the first component. The method of this embodiment may further include one or more of steps S5 to S11.
In step S5, at least one of a geometry, a conformity, and a configuration of the prosthetic device is varied by varying at least one of the selection of the first component, the selection of the second component, the placement of the first component, and the placement of the second component. In step S6, the first and second components are placed relative to the bone where an alignment of the second component is not determinative of an alignment of the first component, the degrees of freedom of the second component are not determinative of the degrees of freedom of the first component, and/or the selection of the first component is not determinative of the selection of the second component. In step S7, the first and second components are implanted so that they are not connected. In step S8, the first and second components are implanted so that they are not in contact. In step S9, the first component and the second component are each affixed only to an anatomy (e.g., bone) of the patient and not to one another. The first and second components may be affixed to the anatomy in any known manner such as a press fit, a fastener, an intramedullary rod, cement, an adhesive, biological in-growth, and the like. In step S10, the surgeon selects a third component configured to be implanted in the body. In step S11, the surgeon determines a placement at which the third component will be fixed relative to the bone. The surgeon's determination of the placement of the third component is not constrained by a connection of the third component to the first component or the second component. Additionally, the selection of the first component and the selection of the second component are not determinative of the selection of the third component.
The surgical method described is intended as an exemplary illustration only. In other embodiments, the order of the steps of the method may be rearranged in any manner suitable for a particular surgical application. Additionally, other embodiments may include all, some, or only portions of the steps of the surgical method and may combine the steps of the method with existing and/or later developed surgical approaches.
Thus, according to embodiments of the present invention, an orthopedic joint prosthesis and techniques that enable customization of implant fit and performance based on each patient's unique anatomy, ligament stability, kinematics, and/or disease state are provided.
Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. It is intended that the specification and examples be considered as exemplary only.
| Number | Date | Country | |
|---|---|---|---|
| 60781909 | Mar 2006 | US | |
| 60781867 | Mar 2006 | US | |
| 60781910 | Mar 2006 | US |
