Tibial spacer blocks and femoral cutting guide
View Patent ↗The present invention relates to one or more tibial spacer blocks used during knee arthroplasty, each configured to be temporarily positioned upon a resected proximal portion of a tibia (essentially mimicking the tibial component of the knee prosthesis), for performing a range of motion analysis and for checking flexion and extension gaps prior to cutting the distal or posterior femur. Preferably, the spacer blocks each include an attachment arrangement configured and arranged to mate with a complementary attachment arrangement of an alignment tower and/or a femoral cutting guide. The alignment tower, which is configured to be used with an alignment rod, is used for verifying the alignment of the limb's mechanical axis when the spacer block is positioned between the tibia and the femur. The femoral cutting guide is used for guiding a cutting member into proper orientation for resecting a distal or posterior portion of a femur.
1. In combination, a tibial component of a knee prosthesis and a system of components used during knee arthroplasty, after resection of a tibia, for guiding a cutting member into proper orientation for resecting a portion of a femur, said combination comprising:
the tibial component having a thickness;
the system comprising:
a femoral cutting guide including a slot configured and arranged to receive a cutting member intended to resect a portion of the femur; and
a plurality of spacer blocks of different predefined thicknesses, each configured to be temporarily positioned upon a resected proximal portion of a tibia during knee arthroplasty, either with or without a modular attachment attached thereto, each of said spacer blocks including:
a main body portion having said predefined thickness defined between substantially parallel distal and proximal surfaces, wherein said predefined thickness of said main body portion of a particular spacer block is approximately equal to said thickness of said tibial component of a knee joint prosthesis;
an attachment arrangement on an anterior side of said main body portion, wherein said attachment arrangement is configured and arranged to mate with a complementary attachment arrangement on said femoral cutting guide; and
an anterior stop projecting from said distal surface of said spacer block, near said anterior side, wherein said anterior stop is configured and arranged to contact an anterior edge of a tibia when said spacer block is positioned upon the resected proximal portion of a tibia in order to prevent movement of said spacer block in a posterior direction.
2. The combination as defined in claim 1 , wherein said slot on said cutting guide is configured and arranged to guide the cutting member for cutting distal portions of medial and lateral condyles.
3. The combination as defined in claim 1 , further comprising:
an alignment tower including a second complementary attachment arrangement, of a similar configuration to said complementary attachment arrangement of said femoral cutting guide, wherein said second complementary attachment arrangement is also configured and arranged to mate with said attachment arrangement of each of said spacer blocks; and
an alignment rod configured to be inserted into a hole within said alignment tower, wherein said alignment rod is used for verifying the alignment of a mechanical axis of a limb when said spacer block is positioned between the tibia and the femur.
4. The combination as defined in claim 1 , wherein:
said attachment arrangement of each of said spacer blocks includes either at least one projection or at least one aperture; and
said complementary attachment arrangement of said femoral cutting guide includes the other of at least one projection or at least one aperture, depending upon a configuration of said attachment arrangement of said spacer blocks, so that said attachment arrangement can mate with said complementary attachment arrangement.
5. The combination as defined in claim 1 , wherein:
said attachment arrangement of said spacer block includes at least one projection; and
said complementary attachment arrangement of said femoral cutting guide includes at least one aperture configured to receive said at least one projection.
6. The combination as defined in claim 5 , wherein when said at least one projection of said spacer block is mated with said at least one aperture of said femoral cutting guide, at least a third of a length of said at least one projection projects outwardly of said at least one aperture.
7. The combination as defined in claim 5 , wherein a proximal surface of said at least one projection of said attachment arrangement of said spacer block is offset with respect to said proximal surface of said main body portion of each of said spacer blocks.
8. The combination as defined in claim 7 , where said offset is approximately 5°.
9. The combination as defined in claim 5 , wherein said at least one projection of said spacer block is of a generally D-shaped cross-section, and said at least one aperture of said femoral cutting guide is of a generally D-shaped cross-section.
10. The combination as defined in claim 5 , wherein said projection of said spacer block includes two concave gripping areas, whereby said two concave gripping areas facilitate gripping of said spacer block.
11. The combination as defined in claim 1 , wherein one of said attachment arrangement of said spacer blocks, said complementary attachment arrangement of said femoral cutting guide, or said slot of said femoral cutting guide is offset to account for posterior tibial slope.
12. The combination as defined in claim 1 , wherein said attachment arrangement of said spacer block is configured and arranged to prevent inverted attachment of said complementary attachment arrangement with said attachment arrangement of said spacer block.
13. The combination as defined in claim 1 , wherein:
said spacer block includes means for temporarily positioning said spacer block upon either a lateral portion or a medial portion of the resected proximal portion of the tibia; and
said spacer block is configured and arranged to be positioned into knee joint spaces in right legs and in left legs.
14. The combination as defined in claim 13 , wherein said means for temporarily positioning said spacer block includes at least one aperture configured to accept a pin for pinning said spacer block into position upon the resected proximal portion of the tibia.
15. The combination as defined in claim 13 , wherein said means for temporarily positioning said spacer block includes said anterior stop projecting from said distal surface of said spacer block.
16. The combination as defined in claim 15 , wherein said means for temporarily positioning said spacer block also includes at least one aperture configured to accept a pin for pinning said spacer block into position upon the resected proximal portion of the tibia.
17. The combination as defined in claim 3 , wherein:
said attachment arrangement of said spacer block includes at least one projection; and
said second complementary attachment arrangement of said alignment tower includes at least one aperture configured to receive said at least one projection of said spacer block.
18. The combination as defined in claim 17 , wherein said at least one projection of said spacer block is of a generally D-shaped cross-section, and said at least one aperture of said alignment tower is of a generally D-shaped cross-section.