Knee Prosthesis
A knee joint prosthesis assembly can include a femoral component that has a medial and a lateral condyle portion connected by a patellar track portion. The femoral component can form an opening between the medial and lateral condyles. A tibial component can have a medial portion that includes a first engagement structure and a lateral portion that includes a second engagement structure. A medial bearing can have a third engagement structure formed thereon that selectively engages the first engagement structure. A lateral bearing separately formed and independent from the medial bearing can have a fourth engagement structure formed thereon that selectively engages the second engagement structure.
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This application claims the benefit and priority of 61/181,938, filed May 28, 2009. The entire disclosure of the above application are incorporated herein by reference.
FIELDThe present disclosure relates to a knee joint prosthesis including a tibial tray component having independent and selectively attachable bearings including fixed and mobile bearings that can be secured to medial and lateral sides of the tibial tray according to the needs of a particular patient.
BACKGROUNDThis section provides background information related to the present disclosure which is not necessarily prior art.
A knee joint prosthesis can generally comprise a femoral component and a tibial component. The femoral component and the tibial component can be designed to be surgically attached to the distal end of the femur and the proximal end of the tibia, respectively. The femoral component can further be designed to cooperate with the tibial component in simulating the articulating motion of an anatomical knee joint. In many examples, the tibial component can further include a bearing component that includes articulation surfaces on the medial and lateral side for cooperating with a medial and lateral condyle portion of the femoral component. In some examples, the bearing component can be fixed relative to the tibial component. In other examples, the bearing component can be a mobile bearing component that has at least a portion that can move relative to the tibial component during articulation of the femoral component.
SUMMARYThis section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features.
A knee joint prosthesis assembly can include a femoral component that has a medial and a lateral condyle portion connected by a patellar track portion. The femoral component can form an opening between the medial and lateral condyles. A tibial component can have a medial portion that includes a first engagement structure and a lateral portion that includes a second engagement structure. A medial bearing can have a third engagement structure formed thereon that selectively engages the first engagement structure. A lateral bearing separately formed and independent from the medial bearing can have a fourth engagement structure formed thereon that selectively engages the second engagement structure.
According to additional features, the medial and lateral condyles of the femoral component can be configured to articulate along complementary bearing surfaces of the medial and lateral bearings. The medial and lateral bearings can both be configured to be fixed relative to the tibial component. According to other features, one of the medial and lateral bearings can be fixed relative to the tibial component and the other of the medial and lateral bearings can be a mobile bearing component. In other configurations, both of the medial and lateral bearings can be mobile bearing components that have respective portions that slidably advance along an opposing surface of the tibial component. One of the medial and lateral condyle portions that articulates on the mobile bearing component can have a spherical, convex articulations surface.
According to other features, the mobile bearing component can include a fixed portion that has the third or fourth engagement structure that is configured to statically engage the tibial component and a mobile bearing portion that is configured to slidably advance along the opposing surface of the tibial component. The fixed portion can define a pocket that receives and confines the mobile bearing portion therewithin. The mobile bearing portion can be formed of a polymeric material and can include a metallic layer of material disposed around a perimeter thereof. A locking bar can be provided that selectively locates between the tibial component and the medial and lateral bearings. The locking bar can cooperate with the first, second, third and fourth engagement structures and can secure the medial and lateral bearings to the tibial component.
A method of implanting a knee prosthesis can include providing a kit of tibial trays, medial bearings and lateral bearings. The tibial trays can include a bicruciate retaining tray and a posterior cruciate retaining tray. The medial and lateral bearings can include a plurality of fixed and mobile medial and lateral bearings. The patient's proximal tibia and distal femur can be accessed. The proximal and distal femur and at least one of an anterior cruciate ligament and posterior cruciate ligament can be assessed. A bicruciate retaining or posterior cruciate retaining tibial tray can be selected from the kit based on the assessing. The selected tibial tray can be secured to the proximal tibia. The desirability of a fixed or mobile bearing can be determined for the medial and lateral sides of the selected tibial tray based on the assessing. The medial and lateral bearings can be intraoperatively and independently selected from the kit. The selected medial and lateral bearings can be secured to the selected tibial tray.
Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.
The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure.
Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings.
DETAILED DESCRIPTIONExample embodiments will now be described more fully with reference to the accompanying drawings.
With initial reference to
The respective components of the knee prosthesis assembly 10 can be patient specific, such that each component can be constructed for optimal features for a given patient. For example, the bone interface margins of the femoral component 12 and tibial tray 14 can be patient specific for optimized bone coverage. In addition, the overall size, such as anterior-posterior dimensions and bone cut geometry can be determined and used for manufacturing the components of the knee prosthesis assembly 10. Moreover, some articulation features can be determined and used as criteria for forming the components of the knee prosthesis assembly 10. In sum, each of the components of the knee prosthesis assembly 10 can be a patient-specific implant, a semi-custom implant or an off-the-shelf or standard production implant. A custom-made implant is a patient-specific, one-of-a-kind implant specifically made for a particular patient, and consequently there is no inventory associated with such implant. Standard or off-the shelf implants are available and stocked in a number of sizes, typically six or more, and a number of configurations or types, including bilateral or unilateral implants, constrained, semi-constrained, mobile, etc. Because of the variety of sizes and configurations that are kept in stock to be accommodated by different patients, a large inventory of standard implants is created, and several molds for each type and size of implant may be used. Semi-custom implants can provide an intermediate solution between custom-made and off-the-shelf implants. Semi-custom implants reduce the size of inventory and molds required for production, while allowing some degree of patient-specific customization. Additional description of patient-specific implants and semi-custom implants and their implementations may be found in copending patent application Ser. No. 12/103,824, filed Apr. 16, 2008 and entitled: Method and Apparatus for Manufacturing an Implant, the disclosure of which is hereby incorporated by reference.
With additional reference to
The femoral component 12 can include a bone contacting or inferior surface 34 (
With reference now to
With reference to
With reference to
During use, the medial and lateral condyle portions 20 and 22 of the femoral component 12 can articulate on the first and second bearing surfaces 102 and 120 of the respective medial floating bearing 16 and lateral fixed bearing 18. As can be appreciated, the lateral fixed bearing 18 is static relative to the tibial tray 14 during articulation of the femoral component 12. The medial floating bearing 16 is free to slide along the highly polished tibial bearing surface 70 of the medial portion 60 of the tibial tray 14. The medial floating bearing 16 is bound on an inboard side by the rail 72.
While the embodiment shown in the figures includes a floating bearing provided on a medial side and a fixed bearing provided on a lateral side, the location of these bearings can be swapped. Similarly, both of the medial and lateral sides can be formed with floating bearings or fixed bearings. Turning now to
With reference now to
The femoral component 12 can be generally formed similar to the femoral component 12 described in detail above. Again, the medial condyle portion 20 can have a spherical, convex articulation surface that can cooperate with the mobile bearing components 316 as will be described herein. It is appreciated that a similar spherical, convex articulation surface can be provided on the lateral condyle portion 22 in the event that a mobile bearing component is desired on the lateral portion 322 of the tibial tray 314.
The mobile bearing component 316 can generally include a fixed portion 330 and a mobile bearing portion 332 (
The mobile bearing portion 332 can have an outer perimeter surface 350 that substantially matches a profile of the surrounding wall 336, however, is reduced in size so as to be stepped inwardly relative to the surrounding wall 336 (see also
The fixed bearing component 318 can generally include a superior surface 360 that substantially conforms to and provides a surface contact with the profile of the lateral condyle portion 22 of the femoral component 12. A channel 362 can be formed along an anterior inferior surface 364 and that generally tapers anteriorly. A groove 368 can be formed around a posterior edge of the fixed bearing component 318. The fixed bearing component 318 can have an inner wall 369 that cooperates with the U-shaped profile of the tibial tray 314 to accommodate a host or reconstructed ACL.
The tibial tray 314 can generally include a locating tab 370 formed on an anterior edge of the medial portion 320 and a locating tab 372 formed on an anterior edge of the lateral portion 322. A slot 374 can be defined through the tibial tray 314 between the medial and lateral portions 320 and 322. The slot 374 can be configured to accommodate and provide clearance for a host ACL and/or PCL or a reconstructed ACL and/or PCL. A retaining rail 375 can be formed around a posterior edge of the medial portion 320. The retaining rail 375 can include a lip 376 and a groove 378. A retaining rail 380 can be formed around a posterior edge of the lateral portion 322 of the tibial tray 314. The retaining rail 380 can generally include a lip 382 and a groove 384. An inferior surface 386 of the tibial tray 314 can be generally smooth, but may also incorporate a series of round grooved pegs. The inferior surface 386 can be configured to be cemented or press-fit onto the proximal tibia. The tibial tray 314 can be generally manufactured of cobalt-chromium-molybdenum alloy or other suitable biocompatible materials.
Attaching the mobile bearing component 316 to the medial portion 320 of the tibial tray 314 will now be described according to one example. At the outset, the surgeon can select a given medial bearing component 316 from a plurality of medial bearing components (see also kit 600,
Connection of the fixed bearing component 318 to the lateral portion 322 of the tibial tray 314 is similarly carried out. Initially, the inferior surface 364 of the fixed bearing component 318 is located onto the lateral portion 322 of the tibial tray 314. Next, the fixed bearing component 318 is slidably advanced posteriorly, such that the channel 362 slidably accommodates the locating tab 372 while the groove 368 locates under the lip 380. The fixed bearing component 318 is adapted to be statically secured relative to the lateral portion 322 of the tibial tray when assembled.
With reference now to
The tibial tray 414 can include a medial portion 436, a lateral portion 438, posterior engagement tabs 440, an anterior engagement bridge 442 and anterior engagement tabs 443. The anterior engagement bridge 442 can include a track 444 formed thereon. The anterior engagement bridge 442 can provide an increased thickness to the tibial tray 414 at the connection between the medial and lateral portion 436 and 438, respectively to increase durability. A wall 446 can be formed on the anterior engagement bridge 442 adjacent to the track 444. The tibial tray 414 can have inferiorly extending posts 450.
The locking bar 420 can generally include a body 454 having a finger 456 extending therefrom. A catch 458 can be formed on a terminal end of the finger 456. The locking bar 420 can be formed of biocompatible metallic material, such as titanium for example. The body 454 can further include a leading end 460 and a trailing end 462.
Attaching the respective first and second bearing components 416 and 418 to the tibial tray 414 according to one example of the present teachings will now be described. Once a surgeon has selected a first and second bearing component 416 and 418 that satisfies the given needs of a particular patient (see also kit 600,
With reference now to
Turning now to
As used herein, the terms superior, superiorly, superior direction are used to generally refer to the anatomical meaning, such as higher in place or position or generally situated above. Similarly, the terms inferior, inferiorly, inferior direction are used to generally refer to the anatomical meaning, such as lower in place or position or generally situated below.
The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.
Claims
1. A knee joint prosthesis assembly comprising:
- a femoral component having a medial and a lateral condyle portion connected by a patellar track portion, the femoral component forming an opening between the medial and lateral condyles;
- a unitary tibial component having a medial portion that includes a first engagement structure and a lateral portion that includes a second engagement structure;
- a medial bearing having a third engagement structure formed thereon that selectively engages the first engagement structure; and
- a lateral bearing separately formed and independent from the medial bearing and having a fourth engagement structure formed thereon that selectively engages the second engagement structure.
2. The knee joint prosthesis of claim 1 wherein the medial and lateral condyles of the femoral component are configured to articulate along complementary bearing surfaces of the medial and lateral bearings.
3. The knee joint prosthesis of claim 2 wherein the medial and lateral bearings are both configured to be fixed relative to the tibial component.
4. The knee joint prosthesis of claim 2 wherein one of the medial and lateral bearings is fixed relative to the tibial component and the other of the medial and lateral bearings is a mobile bearing component wherein at least a portion of the mobile bearing is configured to slidably advance along an opposing surface of the tibial component.
5. The knee joint prosthesis of claim 2 wherein both of the medial and lateral bearings are mobile bearing components that have respective portions that slidably advance along an opposing surface of the tibial component.
6. The knee joint prosthesis of claim 4 wherein a condyle portion of the medial and lateral condyle portions that articulates on the mobile bearing component has a spherical, convex articulation surface.
7. The knee joint prosthesis of claim 4 wherein the mobile bearing component includes a fixed portion having the third or fourth engagement structure that is configured to statically engage the tibial component and a mobile bearing portion that is configured to slidably advance along the opposing surface of the tibial component.
8. The knee joint prosthesis of claim 7 wherein the fixed portion defines a pocket that receives and confines the mobile bearing portion therewithin.
9. The knee joint prosthesis of claim 8 wherein the mobile bearing portion is formed of a polymeric material and includes a metallic layer of material disposed around a perimeter thereof.
10. The knee joint prosthesis of claim 1, further comprising:
- a locking bar that selectively locates between the tibial component and the medial and lateral bearings, the locking bar cooperating with the first, second, third and fourth engagement structures and securing the medial and lateral bearings to the tibial component.
11. The knee joint prosthesis of claim 1 wherein the tibial component is U-shaped and is adapted to accommodate an anterior cruciate ligament.
12. The knee joint prosthesis of claim 1 wherein the tibial component has an inferiorly extending stem.
13. The knee joint prosthesis of claim 1, further comprising a plurality of fixed and mobile medial bearings and a plurality of separate fixed and mobile lateral bearings, wherein the plurality of medial and lateral bearings have distinct thicknesses in a superior/inferior direction.
14. A method of implanting a knee prosthesis, the method comprising:
- providing a kit of tibial trays, medial bearings and lateral bearings, the tibial trays including a bicruciate retaining tray and a posterior cruciate retaining tray, the medial and lateral bearings including a plurality of fixed and mobile medial and lateral bearings;
- accessing a patient's proximal tibia and distal femur;
- assessing the proximal and distal femur and at least one of an anterior cruciate ligament and posterior cruciate ligament;
- selecting one of a bicruciate retaining or posterior cruciate retaining tibial tray from the kit based on the assessing;
- securing the selected tibial tray to the proximal tibia;
- determining whether a fixed or mobile bearing is desired for a medial and lateral side of the selected tibial tray based on the assessing;
- intraoperatively and independently selecting a medial and a lateral bearing from the kit of bearings; and
- securing the selected medial and lateral bearings to the selected tibial tray.
15. The method of claim 14 wherein selecting the tibial tray comprises selecting the bicruciate retaining tray having a U-shaped slot and wherein securing the bicruciate tibial tray comprises locating an anterior cruciate ligament through the U-shaped slot.
16. The method of claim 14 wherein securing the selected medial and lateral bearings comprises aligning respective engagement structures on the selected tibial tray with complementary engagement structures formed on the medial and lateral bearings and, further comprising:
- slidably advancing a locking bar into contact with the respective engagement structures on the tray and the complementary engagement structures on the medial and lateral bearings.
17. A knee joint prosthesis assembly comprising:
- a unitary tibial component having a medial portion that includes a first engagement structure and a lateral portion that includes a second engagement structure;
- a medial bearing having a third engagement structure formed thereon that selectively engages the first engagement structure;
- a lateral bearing separately formed and independent from the medial bearing and having a fourth engagement structure formed thereon that selectively engages the second engagement structure; and
- a locking bar that selectively locates between the tibial component and the medial and lateral bearings, the locking bar cooperating with the first, second, third and fourth engagement structures and securing the medial and lateral bearings to the tibial component.
Type: Application
Filed: May 27, 2010
Publication Date: Dec 2, 2010
Applicant: Biomet Manufacturing Corp. (Warsaw, IN)
Inventors: Robert Metzger (Wakarusa, IN), James G. Lancaster (Winona Lake, IN)
Application Number: 12/788,961
International Classification: A61F 2/38 (20060101);