NZ624208B2 - A tibial component - Google Patents
A tibial component Download PDFInfo
- Publication number
- NZ624208B2 NZ624208B2 NZ624208A NZ62420812A NZ624208B2 NZ 624208 B2 NZ624208 B2 NZ 624208B2 NZ 624208 A NZ624208 A NZ 624208A NZ 62420812 A NZ62420812 A NZ 62420812A NZ 624208 B2 NZ624208 B2 NZ 624208B2
- Authority
- NZ
- New Zealand
- Prior art keywords
- tibial
- bearing
- spacer bearing
- component
- spacer
- Prior art date
Links
- 230000000399 orthopedic Effects 0.000 claims abstract description 13
- 230000000712 assembly Effects 0.000 claims abstract description 9
- 238000000034 method Methods 0.000 claims abstract description 8
- 210000000988 Bone and Bones Anatomy 0.000 claims abstract description 6
- 238000011065 in-situ storage Methods 0.000 claims abstract description 5
- 210000003127 Knee Anatomy 0.000 claims description 24
- 210000001519 tissues Anatomy 0.000 claims description 3
- 210000000629 knee joint Anatomy 0.000 description 4
- 230000000295 complement Effects 0.000 description 3
- 230000023298 conjugation with cellular fusion Effects 0.000 description 3
- 238000003780 insertion Methods 0.000 description 3
- 230000013011 mating Effects 0.000 description 3
- 238000001356 surgical procedure Methods 0.000 description 3
- 230000021037 unidirectional conjugation Effects 0.000 description 3
- 206010022114 Injury Diseases 0.000 description 2
- 210000002303 Tibia Anatomy 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 230000002950 deficient Effects 0.000 description 2
- 238000005755 formation reaction Methods 0.000 description 2
- 238000011068 load Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000006011 modification reaction Methods 0.000 description 2
- 238000002271 resection Methods 0.000 description 2
- 210000000689 upper leg Anatomy 0.000 description 2
- 210000001264 Anterior Cruciate Ligament Anatomy 0.000 description 1
- 239000004699 Ultra-high molecular weight polyethylene (UHMWPE) Substances 0.000 description 1
- 230000002159 abnormal effect Effects 0.000 description 1
- 210000003484 anatomy Anatomy 0.000 description 1
- 238000004873 anchoring Methods 0.000 description 1
- 230000000875 corresponding Effects 0.000 description 1
- 230000000994 depressed Effects 0.000 description 1
- 230000018109 developmental process Effects 0.000 description 1
- 238000007689 inspection Methods 0.000 description 1
- 230000002980 postoperative Effects 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 239000004544 spot-on Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 230000000007 visual effect Effects 0.000 description 1
- 238000011179 visual inspection Methods 0.000 description 1
Classifications
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
- A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
- A61F2/02—Prostheses implantable into the body
- A61F2/30—Joints
- A61F2/38—Joints for elbows or knees
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
- A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
- A61F2/02—Prostheses implantable into the body
- A61F2/30—Joints
- A61F2/38—Joints for elbows or knees
- A61F2/3868—Joints for elbows or knees with sliding tibial bearing
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
- A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
- A61F2/02—Prostheses implantable into the body
- A61F2/30—Joints
- A61F2/38—Joints for elbows or knees
- A61F2/389—Tibial components
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
- A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
- A61F2/02—Prostheses implantable into the body
- A61F2/30—Joints
- A61F2002/30001—Additional features of subject-matter classified in A61F2/28, A61F2/30 and subgroups thereof
- A61F2002/30316—The prosthesis having different structural features at different locations within the same prosthesis; Connections between prosthetic parts; Special structural features of bone or joint prostheses not otherwise provided for
- A61F2002/30535—Special structural features of bone or joint prostheses not otherwise provided for
- A61F2002/30604—Special structural features of bone or joint prostheses not otherwise provided for modular
- A61F2002/30607—Kits of prosthetic parts to be assembled in various combinations for forming different prostheses
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
- A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
- A61F2/02—Prostheses implantable into the body
- A61F2/30—Joints
- A61F2/30767—Special external or bone-contacting surface, e.g. coating for improving bone ingrowth
- A61F2/30771—Special external or bone-contacting surface, e.g. coating for improving bone ingrowth applied in original prostheses, e.g. holes or grooves
- A61F2002/30878—Special external or bone-contacting surface, e.g. coating for improving bone ingrowth applied in original prostheses, e.g. holes or grooves with non-sharp protrusions, for instance contacting the bone for anchoring, e.g. keels, pegs, pins, posts, shanks, stems, struts
- A61F2002/30884—Fins or wings, e.g. longitudinal wings for preventing rotation within the bone cavity
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
- A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
- A61F2/02—Prostheses implantable into the body
- A61F2/30—Joints
- A61F2/38—Joints for elbows or knees
- A61F2002/3895—Joints for elbows or knees unicompartimental
Abstract
tibial component ( 10 ), suitable for use in an orthopedic prosthesis, which prosthesis having a femoral component and a spacer bearing ( 70 ). The tibial component includes a planar tibial plate ( 15 ) having an upper bearing surface ( 30 ) and a bone connecting surface ( 20 ). The tibial plate is adapted to interchangeably in situ receive anteriorly-loaded spacer bearings for either mobile- or fixed-bearing prosthetic assemblies. The tibial plate further having at least one anteriorly located spacer bearing attachment means for removably securing the spacer bearing to the tibial plate. The interchangeability of the spacer bearing between mobile and fixed assemblies is immediate or subsequent to a revision procedure, without disturbing bone connecting surfaces of the tibial component. s adapted to interchangeably in situ receive anteriorly-loaded spacer bearings for either mobile- or fixed-bearing prosthetic assemblies. The tibial plate further having at least one anteriorly located spacer bearing attachment means for removably securing the spacer bearing to the tibial plate. The interchangeability of the spacer bearing between mobile and fixed assemblies is immediate or subsequent to a revision procedure, without disturbing bone connecting surfaces of the tibial component.
Description
A TIBIAL COMPONENT
FIELD OF THE INVENTION
This invention relates to a tibial component, suitable for use in an orthopedic
prosthesis, and more particularly in a prosthesis for resurfacing chondral surfaces of
the knee joint.
BACKGROUND OF THE INVENTION
Various types of knee prostheses are known and used in the field of orthopedic
surgery in treating a damaged or injured knee. Specifically, the present applicant is
the inventor of ORTHOPEDIC PROSTHESIS described more fully in South African
patent 2011/00697 filed 27 January 2011, and claiming earliest priority 24 July 2008,
corresponding to , as well as South African provisional patent
application 2011/03673 dated 19 May 2011 entitled A SCORING SYSTEM AND
METHOD FOR EVALUATING INJURY TO A JOINT which has matured into South
African patent 2012/06206, each of which descriptions are incorporated herein in
their entirety by reference.
Treatment options available in chondral resurfacing procedures of knee joints are
unicompartmental knee arthroplasty (UKA) and total knee arthroplasty (TKA). In
both UKA and TKA, a typical knee prosthesis comprises a metallic femoral
component, a metallic tibial component and an ultra high molecular weight
polyethylene (UHMWPE) spacer bearing (or bearing insert) disposed therebetween.
The femoral component, as the name suggests, is for fixation to the distal femur and
the tibial component is for fixation to the proximal tibia.
Historically, the use of a fixed spacer bearing, wherein the spacer bearing is fixed to
the tibial component, was the preferred combination. However, developments has
seen a preference shift to a mobile spacer bearing, wherein the spacer bearing is
allowed some degree of movement, in a slidable or partially rotatory fashion relative
to the tibial component. It is now apparent that the selection of a mobile or fixed
spacer bearing depends on the condition of the particular subject’s knee and notably
the degree of laxation of the knee ligamenture, which is adjudged intra-operatively.
Ultimately, the final decision on whether to use a mobile bearing or fixed bearing, as
well as which of UKA or TKA is appropriate, is made intra-operatively. For instance,
a key indicator or contra-indicator as the case may be, would depend on a visual
examination of the anterior cruciate ligament.
Further, UKA is the preferred form of treatment in diseased or injured knees having a
chondral deficiency. In more severe presentations, a TKA is indicated. In either
treatment option (viz. UKA or TKA), there is a preparatory step for prosthesis
insertion that requires bone resection. Patient build and other anatomical
considerations would indicate the selection of a particular size of femoral component
and tibial component. The selection of a suitably sized spacer bearing is properly
determined once the femoral and tibial components are inserted. This determination
is finally done during the surgical procedure, and not before. Also, dependant on a
visual inspection of the internal condition of the particular patient’s knee, either a
mobile or fixed spacer bearing is indicated. A distinct disadvantage may precipitate
where a physician anticipates the use of a mobile spacer bearing, and an in-
procedure inspection of the knee calls for the use of a fixed spacer bearing. In
practice, both options are not readily available to the physician and a postponement
of the operation is likely, as it is neither practical nor possible to include a full range
of both mobile and fixed spacer bearings of different sizes in a single sterile pack.
Such a pack would simply be too costly for most patients, and would represent
wasteful expenditure. Also, fixed spacer bearings are manufactured at the factory
and the bearings are usually not removable from the tibial component. The
Applicant is aware of fixed bearing components that have clip-on spacer bearings. It
use is still limited as explained above.
A further disadvantage with known prostheses may occur in instances where, due to
rotation and flexion forces acting upon the spacer bearing between the femoral
component and the tibial component, these spacer bearings are likely to wear out or
dislocate with injury e.g. ligamentous rupture or in due course through normal use.
Further, and dependant on other loading conditions acting on the spacer bearing, for
instance where an inappropriately sized spacer bearing is utilized, the spacer
bearing can prematurely wear out or succumb to abnormal damage. In such
instance, revision surgery may be indicated, and removal of one or both of the
femoral component and tibial component may be indicated. If the femoral
component and/or tibial component are both in an acceptable condition, such
removal would be disadvantageous in that the patient may be subject to yet further
bone resection, is exposed to the future possibility of aseptic loosening of the
prosthetic components where such components were successfully inserted, and may
prematurely become a candidate for TKA where previously a UKA could have
remained a viable option.
A need thus exists for a knee prosthesis that is capable of uniform application to any
given patient, as well as a knee prosthesis that is minimally invasive, has a greater
longevity, a reduced cost and shorter post-operative recovery time than known
prostheses.
OBJECTS OF THE INVENTION
It is an object of the present invention to provide a tibial component suitable for
universal application in an orthopedic prosthesis that at least partially overcomes the
disadvantages associated with known prostheses.
It is a further object of the present invention to provide a tibial component that is both
new and inventive relative to the prior art.
SUMMARY OF THE INVENTION
According to one aspect of the present invention, there is provided a tibial
component, suitable for use in an orthopedic prosthesis, which prosthesis includes a
femoral component and a spacer bearing, the tibial component comprising:
- a planar tibial plate having an upper bearing surface and a lower attachment
surface; and
- the tibial plate further having at least one spacer bearing attachment means
for removably securing the spacer bearing to the tibial plate.
The spacer bearing may be removably secured to the tibial component in order to
prevent movement of the spacer bearing relative to the tibial component. The
movement aforementioned may be rotational movement, translational movement, or
both.
There is further provided, according to the invention, for the spacer bearing to
include a concave surface for receiving the femoral component. The concavity on
the spacer bearing may define a curvature of substantially 6°. The spacer bearing
may alternatively include a planar surface for receiving the femoral component.
Where the femoral component is brought to bear upon the spacer bearing having a
concave surface, the intended use is for a prosthetic assembly having a mobile
spacer bearing. Where the femoral component is brought to bear upon the spacer
bearing having the planar surface, the intended use is for a prosthetic assembly
having a fixed spacer bearing. It will thus be fully appreciated that the tibial
component is adapted to interchangeably receive spacer bearings for either mobile-
or fixed-bearing prosthetic assemblies.
The invention yet further provides for the orthopedic prosthesis to be particularly
suitable for use in a human subject, and further particularly in a human knee.
The invention further provides for the tibial plate to include a flange located on the
aspect of the tibial plate that is closest to the centerline of the knee. The flange may
preferably be an orthogonal flange and may have an aperture located thereon. The
aperture may be annular or oblique.
There may be further provided, according to the invention, for the attachment to be a
primary attachment. The primary attachment may be in the nature of a screw and
screw-threaded bore for locating and releasibly securing the spacer bearing onto the
orthogonal flange and ultimately onto the tibial plate. Alternatively the primary
attachment may be in the nature of a cantilevered pin having an elongate cylinder
and an arcuate end thereon, defining a cantilevered snap-fit arrangement for
releasibly securing the spacer bearing onto the orthogonal flange and ultimately onto
the tibial plate.
The invention further provides for the primary attachment means to be
complemented by a secondary attachment means. The secondary attachment
means may be in the form of a locating member and a gripping member, each
located on the spacer bearing. The locating member may be posteriorly disposed
and snap-fits over a rim recess, also located on the tibial plate. The gripping
member is located anteriorly and is for frictional engagement with a complementarily
shaped holder, also located on the tibial plate. The locating member, rim access,
gripping member and holder may collectively define the secondary attachment
means.
The invention further extends to an orthopedic prosthesis assembly comprising a
femoral component, a spacer bearing and a tibial component, wherein the tibial
component comprises a planar tibial plate having an upper bearing surface and a
lower attachment surface; and the tibial plate further having at least one spacer
bearing attachment means for removably securing the spacer bearing to the tibial
plate. The spacer bearing may include a concave surface thereon, or alternatively
and a planar surface thereon.
The femoral component may include an elliptical body having an anterior member
and a posterior member, and an internal femoral attachment surface; the femoral
articular bearing surface and the internal femoral attachment surface having a
substantially uniform cross-sectional curvature at any point along the length of the
anterior member, thereby providing an increased radius of the internal femoral
attachment surface and an increased cross sectional line of fixation to bony tissue;
and the internal femoral attachment surface further defining a line of attachment
extending across the substantially outer circumferential edge thereof.
The invention further extends to a revision method of re-surfacing chondral deficient
surface areas in the knee joint, wherein the method is minimally invasive, including
the step of utilizing and inserting an orthopedic prosthesis including a femoral
component substantially as herein described, as well as a tibial component
substantially as herein described, together with optional attachment means
substantially as herein described.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will now be described in greater detail, by way of non-limiting example,
with reference to the following drawings, in which:
FIGURE 1 shows a schematic perspective top view of a tibial component with
engaged spacer bearing, according to one form of the invention;
FIGURE 2 shows a schematic perspective bottom view of the tibial component
with engaged spacer bearing of the invention shown in Figure 1;
FIGURE 3 shows an exploded schematic perspective bottom view of the tibial
component with spacer bearing of the invention shown in Figure 2;
FIGURE 4 shows a semi-exploded schematic perspective top view of the tibial
component with spacer bearing of the invention shown in Figure 1;
FIGURE 5 shows a schematic posterior perspective bottom view of a tibial
component with engaged spacer bearing, according to an alternate
form of the invention;
FIGURE 6 shows a schematic anterior perspective bottom view of a tibial
component with engaged spacer bearing, according to an alternate
form of the invention;
FIGURE 7 shows an exploded schematic perspective bottom view of a tibial
component with spacer bearing, according to the invention shown in
Figure 5; and
FIGURE 8 shows a side-by-side frontal schematic view of the invention in situ in a
human knee.
DETAILED DESCRIPTION OF THE INVENTION
In this specification, terms representative of anatomical references, such as medial,
lateral, superior, inferior, and the like are to be construed as references to both the
prosthesis, its respective parts, and to a patient’s (not shown) natural anatomy.
These terms are well-recognized and understood in the orthopedic and anatomical
sciences and for purposes of this specification are to be given meanings consistent
therewith.
In the drawings, like numerals refer to like parts, unless otherwise indicated.
Referring firstly to Figure 3, and by way of a first non-limiting example of one form of
the invention, reference numeral 10 generally refers to a tibial component 10 suitable
for use in an orthopedic prosthesis (not shown), which prosthesis (not shown)
includes a femoral component as described and exemplified in
and a spacer bearing 90. The tibial component 10 comprises a planar tibial plate 15
having an upper bearing surface 30 and a lower attachment surface 20, and further
has a spacer bearing attachment means for removably securing the spacer bearing
to the tibial plate.
The planar tibial plate 15 is substantially D-shaped when viewed in plan view, the
curved end thereof being disposed laterally (i.e. away from the centerline of the
knee), while the opposite side (i.e. towards the midline) defines a straight edge.
Tibial plate 15 has an upper bearing surface 30 (as can be seen more clearly in
Figure 4) for receiving and engaging the upper surface 90 of spacer bearing 70.
Tibial plate 15 also defines a lower attachment surface 20 for attaching the tibial
component 10 to a tibial plateau of a subject, generally shown in Figure 8.
Tibial component 10 has an orthogonal flange 40 attached to and extending along
the medial edge thereof antero-posteriorly, initially uniform in height posteriorly and
thereafter tapering towards the tibial plate 15 anteriorly. Juxtaposed the taper
apparent on orthogonal flange 40 is aperture 45 located anteriorly.
Lower attachment surface 20 has tibial anchor 25 extending inferiorly from, and
centrally disposed on, lower attachment surface 20. A central, elongate aperture 35
is defined within tibial anchor 25.
Furthermore, lower attachment surface 20 has a raised surface in the form of a rim
22 that extends along the outer circumferential edge thereof. At the posterior end of
tibial component 10, rim 22 terminates in a recessed portion of the raised surface to
define a rim recess 60. Rim recess 60 is for receiving locating member 65 of spacer
bearing 70, in a complementary engaging fashion relative to each other. This is
intended for proper placement of spacer bearing 70 onto tibial component 10 in as
quick and efficient a manner as possible during a resurfacing procedure.
Opposite rim recess 60, and at the anterior aspect of the tibial component 10, is
holder 50 for receiving and removably securing gripping member 55 located on
spacer bearing 70 in a mating engagement. Typically, the mating engagement is a
first cantilevered snap-fit arrangement using a simple angled recess and hook (not
shown). Preferably, the cantilevered snap-fit arrangement is of the permanent type.
On the anterior aspect of orthogonal flange 40 and juxtaposed the taper hereinbefore
described is previously mentioned annular aperture 45, for receiving and anchoring
fastening member 46 extending through bore 100 located on spacer bearing 70. In
one embodiment of the present invention, securement of the fastening member 46
extending through bore 100 from a medially located entrance (not shown) on the
spacer bearing 70, ultimately to partially anchor in annular aperture 45 is by way of a
screw and complementary screw-threaded bore arrangement. The head of the
screw seats in an angled rebate (not shown) extending about the periphery of the
medially located entrance (not shown) on spacer bearing 70. It follows that annular
aperture 45 and bore 100 are co-linearly disposed relative to each other, when
spacer bearing 70 is engaged onto tibial component 10.
Referring next to Figures 3 and 4, spacer bearing 70 includes a body dimensioned to
mirror the plan-view shape of tibial plate 15. The body aforementioned has an
elongate sidewall 105 extending antero-posteriorly, and which terminates at an
anterior end and a posterior end. Elongate sidewall 105 is for abutment with
orthogonal flange 40, in use. The termination ends of sidewall 105 continue, initially
perpendicular relative to the sidewall 105, and thereafter in a curved taper towards
each other to ultimately meet, thereby defining a substantially D-shape in plan view.
In the described embodiment, upper surface 90 of spacer bearing 70 is typically
planar on its surface and the femoral component (not shown) is brought to bear
thereon. The lower surface 80 of spacer bearing 70 is brought to bear on the upper
bearing surface 30 of tibial plate 15. From the anterior end of lower surface 80, grip
formation 50 extends inferiorly. Opposite to the anterior end, and at the posterior
end of lower surface 80, is locating member 65, also extending downwardly and
terminating in an inwardly extending flange 65(a) that seats in rim recess 60.
By way of second, non-limiting example of an alternative form of the present
invention, Figures 5, 6 and 7 show alternative forms of a spacer bearing and
fastening means to the embodiment described above, but which alternative falls
wholly within the scope of the present disclosure. In this example, annular aperture
45 is substituted by oblique aperture 110, which extends obliquely through
orthogonal flange 40 towards the posterior end thereof. Oblique aperture is in co-
linear relation with oblique bore 140 located on spacer bearing 70 and which extends
obliquely from a position located on the anterior aspect of spacer bearing 70, and
terminates on sidewall 105.
Further, according to this alternative example, at the anterior end of orthogonal
flange 40 is linear recess 130 which extends perpendicularly to orthogonal flange 40.
A further substitution in this example relates to securing member 120 as alternative
to fastening member 46. The securing member 120 is an elongate cylinder having
an arcuate end 150 and a pointed locating end 160. The arcuate end 150 terminates
in a second cantilevered snap-fit arrangement using a hook for locating in linear
recess 130.
It is thus readily understood that the combination of fastening member 46 / bore 100
/ annular aperture 45, and (in the alternative) securing member 120 / oblique
aperture 110 / oblique bore 140, are all in the collective representative of the
aforementioned spacer bearing attachment means (unreferenced).
It will be appreciated that the immobility or mobility of spacer bearing 70 in the
alternate example will depend wholly on the use, or non-use, respectively of
alternate fastening member 120. Where a mobile bearing is intended, spacer
bearing 70 has a concave upper bearing surface (having a 6° curvature) for receiving
the femoral component. The spacer bearing attachment means is not utilized and
the spacer bearing 70 is allowed freedom of movement relative to the tibial plate as
is known in the art. Central to both described examples is the immediate
interchangability of a mobile spacer bearing prosthetic assembly to that of a fixed
spacer bearing prosthetic assembly. In the case of the former, this is though the
omission of fastening member 46 or securing member 120, as well as the placement
of spacer bearing 70 onto the tibial component 10 having a concave upper bearing
surface to face and receive a load from the femoral component (not shown). In the
case of the latter, spacer bearing 70 having a planar upper bearing surface is
engaged onto tibial component 10 while, inter alia, fastening means 46 or securing
member 120 is used to secure the spacer bearing 70 onto tibial component 10.
It will also be readily appreciated that the tibial component 10 is particularly suited for
use in a human knee (not shown), the articulation of which is shown generally in
Figure 8. Femur 160 is articulated with tibia 170, and it is envisioned by the
applicant that the tibial component 10 can be used for either the medial knee
compartment or the lateral knee compartment, as depicted more clearly in Figure 8.
In use, a physician will make a small (approximately) 10 centimeter incision at the
appropriate spot on a subject’s knee in order to expose the inner knee articulation.
Once the femoral condyle and tibial plateau (both not shown) have been suitably
prepared by placement of the femoral component (not shown) and tibial component
, respectively on these locations, a suitably sized spacer bearing is selected for
insertion. According to the initial example described hereinabove, the posterior end
of the spacer bearing 70 is advanced onto tibial plate 15 until locating member 65
locates onto rim recess 60. Once located thereon, gripping member 55 is physically
depressed into grip formation 50 and the spacer bearing is thus properly located
onto tibial plate 15, with sidewall 105 in abutment with orthogonal flange 40. A
suitably sized fastening member 46 such as a screw is introduced into
complementary threaded bore 100 from the medially located bore entrance (not
shown) on spacer bearing 70 (having a planar bearing surface) and advanced
through bore 100 to locate and anchor in annular aperture 45. The spacer bearing
70 is now affixed to the tibial component 10 and represents a fixed prosthetic
assembly. The procedure is completed after suturing of the subject’s knee.
Similarly, where a physician opts to use the fastening means represented by the
combination of securing member 120 / oblique aperture 110 / oblique bore 140, in
such instance, the physician advances alternate fastening member 120 through
anteriorly located oblique bore 140 located on spacer bearing 70 (having a planar
upper bearing surface), until the pointed locating end appears visible through oblique
aperture 110. At this point, arcuate end 150 will be flush against the corner defined
by the anterior aspect and sidewall 105, the second cantilevered snap-fit
arrangement having been engaged, thereby securing the spacer bearing 70 onto
tibial component 10. This also represents a fixed bearing arrangement or fixed
prosthetic assembly.
If it is apparent intra-operatively that a mobile spacer bearing arrangement would be
more suitable to the subject’s needs, the spacer bearing 70 having a concave upper
bearing surface is selected is merely placed onto tibial plate 15 in mating
engagement with tibial plate 15. The use of spacer bearing attachment means is
avoided and no limitation in the movement of the spacer bearing 70 relative to the
tibial plate 15 will result. This arrangement thus represents a mobile bearing
prosthetic assembly.
It will yet further be appreciated that the invention extends to the use of a tibial
component 10 as herein described, together with a femoral component defining a
femoral articular bearing surface and a spacer bearing as herein described disposed
therebetween, the femoral component further including an elliptical body having an
anterior member and a posterior member, and an internal femoral attachment
surface, the femoral articular bearing surface and the internal femoral attachment
surface having a substantially uniform cross-sectional curvature at any point along
the length of the anterior member, thereby providing an increased radius of the
internal femoral attachment surface and an increased cross sectional line of fixation
to bony tissue, the resurfacing of chondral deficient surface areas in knee joints.
A person skilled in the art will readily appreciate that a physician would be able to
replace spacer bearing 70 as and when the occasion calls for same, such as when
the spacer bearing is worn or damaged, without disturbing the tibial component or
the femoral component. Also, given the relative ease of insertion of the spacer
bearing into the existing prosthesis, patient exposure is minimized. Furthermore, the
spacer bearing will assume the identity of a readily replaceable part of the
prosthesis, thereby prolonging the life of existing prosthetic devices, and in particular
those prosthetic assemblies associated with UKA procedures.
Although certain forms of the invention only have been described herein, it will be
understood by any person skilled in the art that other modifications or variations of
the invention are possible. For instance, the spacer bearing attachment means need
not be limited to the two examples described herein, and can embody any alternative
and suitable spacer bearing attachment means that achieves the purpose of fixing
the spacer bearing 70 to the tibial component 10. Additionally, preference is given to
the use of the tibial component 10, together with a femoral component that defines a
uniradial curvature. A femoral component having a poly-radial curvature may be
substituted for use, where suitable. Such modifications and/or variations are
therefore to be considered as falling within the spirit and scope of the present
invention as herein described.
Claims (20)
1. A tibial component, suitable for use in an orthopedic prosthesis, which prosthesis includes a femoral component and a spacer bearing, the tibial 5 component comprising: - a planar tibial plate having an upper bearing surface and a lower attachment surface, the tibial plate being adapted to interchangeably in situ receive anteriorly-loaded spacer bearings for either mobile- or fixed-bearing prosthetic assemblies; 10 - the tibial plate further having at least one anteriorly located spacer bearing attachment means for removably securing the spacer bearing to the tibial plate; and - wherein the interchangeability of the spacer bearing between mobile and fixed assemblies is immediate or subsequent to a revision 15 procedure, without disturbing bone connecting surfaces of the tibial component.
2. The tibial component as claimed in claim 1, wherein the spacer bearing is removably secured to the tibial component thereby preventing movement of 20 the spacer bearing relative to the tibial component.
3. The tibial component as claimed in claim 2, wherein the movement of the spacer bearing is rotational movement, translational movement, or a combination of both rotational and translational movement.
4. The tibial component as claimed in claim 1, wherein the spacer bearing includes a concave surface for receiving the femoral component.
5. The tibial component as claimed in claim 4, wherein the concave surface on 5 the spacer bearing defines a curvature of substantially 6°.
6. The tibial component as claimed in claim 1, 2 or 3, wherein the spacer bearing includes a planar surface for receiving the femoral component. 10
7. The tibial component as claimed in claims 4 or 5, wherein the femoral component is brought to bear upon the concave surface of the spacer bearing, for use in a mobile spacer bearing prosthetic assembly.
8. The tibial component as claimed in claim 6, wherein the femoral component is 15 brought to bear upon the planar surface of the spacer bearing, for use in a fixed spacer bearing prosthetic assembly.
9. The tibial component as claimed in any one of the preceding claims, wherein the tibial plate includes an orthogonal flange located on an aspect of the tibial 20 plate that is closest to the centerline of the knee, the orthogonal flange having an annular or obliquely disposed aperture located thereon.
10. The tibial component as claimed in claim 1, wherein the attachment means is a primary attachment, optionally in the form of a screw and screw-threaded bore for locating and releasibly securing the spacer bearing onto the orthogonal flange and ultimately onto the tibial plate.
11. The tibial component as claimed in claim 10, wherein the primary attachment 5 is optionally and alternatively in the form of a cantilevered pin having an elongate cylinder and an arcuate end thereon, defining a cantilevered snap-fit arrangement for releasibly securing the spacer bearing onto the orthogonal flange and ultimately onto the tibial plate. 10
12. The tibial component as claimed in claim 10 or 11, wherein the primary attachment is complemented by a secondary attachment means.
13. The tibial component as claimed in claim 12, wherein the secondary attachment means is collectively defined by a locating member, a rim access, 15 a gripping member and a holder
14. The tibial component as claimed in claim 13, wherein the locating member and a gripping member are each located on the spacer bearing. 20
15. The tibial component as claimed in claim 13, wherein the locating member is posteriorly disposed on the spacer bearing and is for snap-fitting over a rim recess located on the tibial plate.
16. The tibial component as claimed in claim 15, wherein the gripping member is located anteriorly on the spacer bearing and is for frictional engagement with a complementarily shaped holder located on the tibial plate. 5
17. The tibial component as claimed in any of the preceding claims for use in an orthopedic prosthesis assembly comprising a femoral component, a spacer bearing and the tibial component, wherein the tibial component comprises a planar tibial plate having an upper bearing surface and a lower attachment surface, the tibial plate being adapted to interchangeably in situ receive 10 spacer bearings for either mobile- or fixed-bearing prosthetic assemblies; and the tibial plate further having at least one anteriorly located spacer bearing attachment means for removably securing the spacer bearing to the tibial plate. 15
18. The tibial component as claimed in claim 17, wherein the spacer bearing may include a concave surface thereon, or alternatively and a planar surface thereon, further alternatively a combination of planar and concave surfaces located thereon on opposite sides of the spacer bearing. 20
19. The tibial component as claimed in claim 17, wherein the femoral component includes an elliptical body having an anterior member and a posterior member, and an internal femoral attachment surface; the femoral articular bearing surface and the internal femoral attachment surface having a substantially uniform cross-sectional curvature at any point along the length of 25 the anterior member, thereby providing an increased radius of the internal femoral attachment surface and an increased cross sectional line of fixation to bony tissue; and the internal femoral attachment surface further defining a line of attachment extending across the substantially outer circumferential edge thereof.
20. The tibial component as claimed in any one of the preceding claims, for use in in a human subject, and in particular in a human knee.
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
ZA2011/07123 | 2011-09-29 | ||
ZA201107123 | 2011-09-29 | ||
PCT/IB2012/055192 WO2013046170A1 (en) | 2011-09-29 | 2012-09-28 | A tibial component |
Publications (2)
Publication Number | Publication Date |
---|---|
NZ624208A NZ624208A (en) | 2016-01-29 |
NZ624208B2 true NZ624208B2 (en) | 2016-05-03 |
Family
ID=
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