Distal femoral cutting guide apparatus with anterior or posterior referencing for use in knee joint replacement surgery

• US 5,417,694 A
• Filed: 11/08/1993
• Issued: 05/23/1995
• Est. Priority Date: 11/08/1993
• Status: Expired due to Term

• Current Assignee: Smith & Nephew Richards Incorporated (Smith & Nephew PLC)
• Original Assignee: Smith & Nephew Richards Incorporated (Smith & Nephew PLC)
• Inventors: Marik, Gregory C., Lackey, Jennifer J., Elliott, M. Scott
• Primary Examiner(s): ASCHENBRENNER, PETER
• Application Number:
  US08/149,053
• Time in Patent Office: 561 Days
• Field of Search: 606/79, 606/80, 606/81, 606/82, 606/84, 606/86, 606/87, 606/88, 606/96, 606/102, 606/62-65
• US Class Current: 606/88
• CPC Class Codes: A61B 17/155 Cutting femur

Abstract

A distal femoral cutting instrument includes an intramedullary rod for referencing the patient'"'"'s intramedullary canal. A valgus block with a flat reference surface mounts to the intramedullary rod at a bore of the valgus block. The bore of the block has a slant with respect to the flat reference surface on the valgus block. The reference surface defines a line that is normal to the mechanical axis of the patient while the bore of the valgus block tracks the patient'"'"'s biomechanical axis. A distal femoral cutting block removably attaches to the valgus block and provides a flat cutting guide surface for shaping the patient'"'"'s distal femur. The valgus block, intramedullary rod, and a stylus (for connecting the valgus block and cutting together) are removed as a unit before shaping of the distal femur. An indexing system includes a gauge having a series of openings corresponding to "anterior" referencing and to "posterior" referencing. During anterior referencing, the gauge allows the surgeon to select the next smaller size prosthesis if the size falls in between available sizes. In posterior referencing, the gauge allows the surgeon to select the next larger size prosthesis if the gauge measures a size that falls in between available sizes.

Claims

1. A distal femoral cutting instrument for preparing a patient'"'"'s distal femur to receive a femoral prosthesis, the femur having anterior and posterior distal femoral surfaces, comprising:

a) an intramedullary rod for referencing the patient'"'"'s intramedullary canal by aligning the rod with the patient'"'"'s intramedullary canal;

b) a valgus block having a plurality of flat surfaces and including at least anterior and posterior parallel flat surfaces and a distal flat surface perpendicular to the anterior and posterior surfaces;

c) a bore in the valgus block that extends between two of the flat surfaces, forming an acute angle therewith, said bore being sized and shaped to register upon the intramedullary rod;

d) a distal femoral cutting block that removably attaches to the valgus block, the cutting block having a flat surface for guiding a blade or saw during cutting of the distal femur;

e) the cutting block including means thereon for affixing the distal femoral cutting block to the anterior cortical bone of the patients femur;

f) gauge means forming a sliding connection with the distal femoral cutting block for measuring the thickness of the patient'"'"'s distal femur between the anterior and posterior surfaces thereof;

g) indexing means on the gauge means for indicating the thickness of the patient'"'"'s distal femur, said indexing means including independent anterior and posterior referencing indicia, allowing the surgeon to measure the distal femur using either an the anterior or posterior referencing indicia.

2. The apparatus of claim 1 wherein the rod has an elongated linear axis.

3. The apparatus of claim 1 further comprising a stylus member that forms a removable connection between the valgus block and the distal femoral cutting block, the stylus comprising a flanged member with connection means thereon for removably attaching the member to the valgus block and to the cutting block.

4. The apparatus of claim 1 wherein the gauge means comprises a pair of movably connected gauge members that slide relative to one another.

5. The apparatus of claim 5 wherein the gauge means comprises a pair of gauge members that slidably engage one another.

6. The apparatus of claim 6 wherein each of the gauge members has a shoulder for engaging the anterior and posterior distal femoral surfaces during use.

7. The apparatus of claim 7 wherein the gauge members have means for affixing the position of the gauge members relative to one another and at a selected location on the distal femur.

8. A method of shaping the distal femur of a patient to receive a femoral prosthesis that is selected from a group of prostheses having anterior/posterior sizes that are differently sized in known dimensional increments and wherein the patient'"'"'s distal femur has an anterior and posterior portions, comprising the steps of:

a) surgically placing one end of an elongated intramedullary rod in the patient'"'"'s intramedullary canal at the distal femur;

b) referencing a cutting block with the intramedullary rod by affixing the block to the rod, the block having a cutting block body portion with a transverse reference surface for guiding a cutting instrument during cutting of the distal femur;

c) affixing the cutting block body to the anterior portion of the patient'"'"'s distal femur;

d) removing at least the rod and a portion of the cutting block assembly to expose the distal femur so that a transverse cut can be made through the distal femur;

e) cutting the distal femur by guiding a cutting instrument with the transverse reference surface;

f) measuring the thickness of the distal femur between its anterior and posterior surface portions with an adjustable gauge that includes an anterior cortical cutting guide and indicia for indicating the size of a femoral prosthesis that will fit the patient'"'"'s distal femur once shaping is completed;

g) selecting either an anterior or a posterior referencing surgical technique if the measured dimension falls in between available sizes;

h) selecting an anterior referencing technique by selecting the next smallest size prosthesis if the measured dimension is in between available prosthesis sizes;

i) selecting a posterior referencing technique by selecting the next largest size prosthesis if the measured dimension is in between available prosthesis sizes;

j) means for affixing the referencing means in a position that selects the next largest or the next smallest size prosthesis if the indicated size falls in between available prosthesis sizes;

k) affixing the gauge in a desired position using either anterior or posterior referencing to affix the cutting guide to the anterior cortical cutting guide gauge in either the next largest or next smallest prosthesis size if the gauge dimension falls in between sizes;

l) selecting a cutting block with cutting guide surfaces thereon for making distal femoral and transfer cuts that correspond to the prosthesis of the size selected.

9. The method of claim 8 further comprising the step of securing the cutting block to the rod at an opening in the cutting block.

10. The method of claim 8 further comprising the step of removing the valgus block and intramedullary rod from the patient'"'"'s distal femur after the cutting block body has been secured to the distal femur.

11. The method of claim 8 further comprising the step of connecting the cutting block assembly to the valgus block with a stylus.

12. The method of claim 11 further comprising the step of removing the rod, stylus and valgus block from the distal femur.

13. A distal femoral cutting instrument for preparing a patient'"'"'s distal femur to receive a femoral prosthesis, the femur having anterior and posterior distal femoral surfaces, comprising:

a) an intramedullary rod for referencing the patient'"'"'s intramedullary canal by aligning the rod with the patient'"'"'s intramedullary canal;

b) a valgus block having a plurality of flat surfaces and including at least anterior and posterior parallel flat surfaces and a distal flat surface perpendicular to the anterior and posterior surfaces;

c) a bore in the valgus block that extends between two of the flat surfaces, forming an acute angle therewith, said bore being sized and shaped to register upon the intramedullary rod;

d) a distal femoral cutting block that removably attaches to the valgus block, the cutting block having a flat surface for guiding a blade or saw during cutting of the distal femur;

e) the cutting block including means thereon for affixing the distal femoral cutting block to the anterior cortical bone of the patients femur;

f) gauge means forming a sliding connection with the distal femoral cutting block for measuring the thickness of the patient'"'"'s distal femur between the anterior and posterior surfaces thereof;

g) indexing means on the gauge means for indicating the thickness of the patient'"'"'s distal femur, said indexing means including independent anterior and posterior referencing indicia, allowing the surgeon to measure the distal femur using either an the anterior or posterior referencing indicia.

14. A method of shaping the distal femur of a patient to receive a femoral prosthesis that is selected from a group of prostheses having anterior/posterior sizes that are differently sized in known dimensional increments and wherein the patient'"'"'s distal femur has an anterior and posterior portions, comprising the steps of:

a) surgically placing one end of an elongated intramedullary rod in the patient'"'"'s intramedullary canal at the distal femur;

b) referencing a cutting block with the intramedullary rod by affixing the block to the rod, the block having a cutting block body portion with a transverse reference surface for guiding a cutting instrument during cutting of the distal femur;

c) affixing the cutting block body to the anterior portion of the patient'"'"'s distal femur;

d) removing at least the rod and a portion of the cutting block assembly to expose the distal femur so that a transverse cut can be made through the distal femur;

e) cutting the distal femur by guiding a cutting instrument with the transverse reference surface;

f) measuring the thickness of the distal femur between its anterior and posterior surface portions with an adjustable gauge that includes an anterior cortical cutting guide and indicia for indicating the size of a femoral prosthesis that will fit the patient'"'"'s distal femur once shaping is completed;

g) selecting either an anterior or a posterior referencing surgical technique if the measured dimension falls in between available sizes;

h) selecting an anterior referencing technique by selecting the next smallest size prosthesis if the measured dimension is in between available prosthesis sizes;

i) selecting a posterior referencing technique by selecting the next largest size prosthesis if the measured dimension is in between available prosthesis sizes;

j) means for affixing the referencing means in a position that selects the next largest or the next smallest size prosthesis if the indicated size falls in between available prosthesis sizes;

k) affixing the gauge in a desired position using either anterior or posterior referencing to affix the cutting guide to the anterior cortical cutting guide gauge in either the next largest or next smallest prosthesis size if the gauge dimension falls in between sizes;

l) selecting a cutting block with cutting guide surfaces thereon for making distal femoral and transfer cuts that correspond to the prosthesis of the size selected.