Prosthesis (i.e. – artificial body members) – parts thereof – or ai – Implantable prosthesis – Bone
Reexamination Certificate
2000-09-26
2002-08-06
Smith, Jeffrey A. (Department: 3732)
Prosthesis (i.e., artificial body members), parts thereof, or ai
Implantable prosthesis
Bone
C623S020140
Reexamination Certificate
active
06428577
ABSTRACT:
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not applicable.
REFERENCE TO A “MICROFICHE APPENDIX”
Not applicable.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to orthopaedic prosthetic devices, and more particularly to an improved rotating platform, mobile knee prosthesis that incorporates anterior stabilization along with the ability to constrain the movement of the articular surface from rotation and translation, to rotation only.
2. General Background of the Invention
Femoral rollback is believed to improve range of motion and extensor mechanism leverage so as to improve efficiency and more accurately replicate natural kinematics. Conventional mobile bearing designs may lack the desired effect of femoral rollback, particularly in the absence of the posterior cruciate ligament.
Posterior Stabilized (PS) fixed bearing designs provide femoral rollback by articulating a cam on the femoral component with a post on the tibial articular insert during flexion. However, PS fixed bearing designs do not have the advantages of mobile bearing designs with regards to enhanced range of motion, reduced rehabilitation time, improved patellofemoral alignment, increased contact area, and reduced bone-implant interface shear forces.
In fixed bearing designs, excessive wear of the PS post can occur during articulation with the femoral cam. Internal-external rotation of the femoral component reduces the PS post-femoral cam congruency which increases contact stresses. The increased contact stresses can lead to excessive polyethylene wear and component failure. Allowing the PS post to rotate within a fixed articular insert will maintain femoral cam-PS post congruency during internal/external rotation of the femoral component.
Further, in any type of posterior stabilized design (fixed bearing or mobile bearing), one of the most problematic failure modes of the polyethylene is the fracture of the central post of the insert. This failure can be attributed to “notching” the anterior side of the central post with the anterior most inner-condylar area of the femoral component. Thus, any mechanism to reduce the probability for impingement of the femoral component against the anterior side of the tibial central post in hyper-extension would reduce the probability for tibial insert post failure due to “notching” and ultimately breaking.
Previous rotating platform designs have incorporated rotating only, or rotation and translation through the use of different prostheses. An example of a prosthesis that rotates and translates is shown in British publication 2219942, entitled “Knee Prosthesis”. U.S. Pat. No. 5,906,643 provides a tibial baseplate with a post that protrudes through a meniscal component and articulates with a cam on a femoral component. The post is an integral part of the tibial baseplate.
U.S. Pat. No. 5,879,392 provides a tibial baseplate with a fixed post that extrudes through the stem of the tibial baseplate and through the bearing component and articulates with a recess within the femoral component.
EP 0 916 321 A2 provides a femoral component with transverse flanges on the medial and lateral surfaces of the posterior stabilized box that articulate with projections from the medial and lateral surfaces of the post.
WO 95/35484 provides a bearing component with a post that articulates with a recess within the femoral component. The bearing component is limited in rotational, anterior, and posterior movement with respect to the tibial component.
The following patents relate to other orthopedic prosthetic devices, many of the listed patents pertaining to a knee prosthesis:
Patent #
Issue Date
Title
3,899,796
08/19/75
Metacarpophalangeal Joint
4,016,606
04/12/77
Knee Joint Prosthesis
4,094,017
06/13/78
Knee Joint Prosthesis With Patellar-Femoral
Contact
4,216,549
08/12/80
Semi-Stable Total Knee Prosthesis
4,224,697
09/30/80
Constrained Prosthetic Knee
4,257,129
03/24/81
Prosthetic Knee Joint Tibial Implant
4,340,978
07/27/82
New Jersey Meniscal Bearing Knee Replacement
4,673,407
06/16/87
Joint-Replacement Prosthetic Device
4,822,366
04/18/89
Modular Knee Prosthesis
4,936,853
06/26/90
Modular Knee Prosthesis
4,950,297
08/21/90
Knee Prosthesis
4,959,071
09/25/90
Partially Stabilized Knee Prosthesis
5,007,933
04/16/91
Modular Knee Prosthesis System
5,032,132
07/16/91
Glenoid Component
5,071,438
12/10/91
Tibial Prosthesis With Pivoting Articulating
Surface
5,116,375
05/26/92
Knee Prosthesis
5,271,747
12/21/93
Meniscus Platform for an Artificial Knee Joint
5,282,868
02/01/94
Prosthetic Arrangement for a Complex Joint,
Especially Knee Joint
5,314,483
05/24/94
Meniscus Platform for an Artificial Knee Joint
5,344,460
09/06/94
Prosthesis System
5,370,699
12/06/94
Modular Knee Joint Prosthesis
5,387,240
02/07/95
Floating Bearing Prosthetic Knee
5,395,401
03/07/95
Prosthetic Device for a Complex Joint
5,404,398
04/11/95
Prosthetic Knee With Posterior Stabilized
Femoral Component
5,413,604
05/09/95
Prosthetic Knee Implant for an Anterior Cruciate
Ligament Deficient Total Knee Replacement
5,413,608
05/09/95
Knee Joint Endoprosthesis for Replacing the
Articular Surfaces of the Tibia
5,549,686
08/27/96
Knee Prosthesis Having a Tapered Cam
5,609,639
03/11/97
Prosthesis for Knee Replacement
5,658,342
08/19/97
Stabilized Prosthetic Knee
5,702,466
12/30/97
Rotational and Translational Bearing Combination
in Biological Joint Replacement
5,782,925
07/21/98
Knee Implant Rotational Alignment Apparatus
5,871,543
02/16/99
Tibial Prosthesis With Mobile Bearing Member
5,871,545
02/16/99
Prosthetic Knee Joint Device
5,935,173
08/10/99
Knee Prosthesis
GENERAL DISCUSSION OF THE PRESENT INVENTION
The present invention has as an object a tibial prosthesis and mating articular insert with specially configured stabilization posts. The invention enables for the surgeon to convert a mobile bearing articular surface from a fixed to a rotating only or translating only. The prosthesis can also provide both rotation and translation simultaneously.
These conversions are accomplished with special locking members or plugs that connect to the tibial base special plate. The plugs can be secured to the base plate with a taper lock or a threaded connection for example.
A post on the proximal tibial base plate can be positioned with an offset with respect to an oval hole in the articular insert to provide anterior stabilization in the total knee prosthesis.
The prosthesis of the present invention will be used as part of a total knee surgery when the surgeon chooses to use a prosthesis that incorporates a particular, selected relative motion between tibial tray and tibial insert.
This present invention consists of a posterior stabilized “PS” post which is secured to the mobile bearing tibial baseplate allowing only rotational movement. The PS post captures a bearing component to the tibial baseplate through an elongated slot in the bearing component. The elongated slot in the bearing component allows it to translate anteriorly and posteriorly with respect to the posterior stabilized post. The bearing component may also rotate with respect to the tibial baseplate in conjunction with the PS post. The bearing component has two concave surfaces that are articulate with the convex surfaces of the femoral component, and that are roughly congruent with the convex surfaces of the femoral component at zero degrees of flexion or full extension. The PS post articulates with a recess or cam of the femoral component to provide femoral rollback.
In addition to the above described design, the PS post should allow for posterior translation, in addition to rotational movement. This posterior movement would allow the post to translate instead of impinging upon the inner-condylar notch area of the femoral component in hyper-extension.
The PS post has a flat distal surface that articulates with the tibial baseplate. A T-slot is located on the distal end and articulates with a T-post on the tibial baseplate. A through hole in the PS post is located such that a rotation peg can capture the PS post to t
Brosnahan Robert
Carson Christopher Patrick
Evans David Lee
Marik Greg
Pothier Albert J.
Garvey, Jr. Charles C.
Garvey, Smith, Nehrbass & Doody LLC
Proddy Michael B.
Smith Jeffrey A.
Smith & Nephew Inc.
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