Instrumentation for long stem surgery

• US 5,282,803 A
• Filed: 03/30/1992
• Issued: 02/01/1994
• Est. Priority Date: 03/07/1991
• Status: Expired due to Term

• Current Assignee: Smith & Nephew Richards Incorporated (Smith & Nephew PLC)
• Original Assignee: Smith & Nephew Richards Incorporated (Smith & Nephew PLC)
• Inventors: Lackey, Jennifer J.
• Primary Examiner(s): Brown, Michael A.
• Application Number:
  US07/859,884
• Time in Patent Office: 673 Days
• Field of Search: 606/79, 606/80, 606/78, 606/62, 606/57, 606/96, 606/86, 606/87, 606/88, 623/16, 623/17
• US Class Current: 606/80
• CPC Class Codes: A61B 17/155 Cutting femur
• CPC Class Codes: A61B 17/1764 for the knee

Abstract

A method and apparatus for installing a knee prosthetic component on a patient'"'"'s tibia includes the selection by a surgeon of one of a plurality of reamers, each of the reamers having a different cutting size diameter such as for example between ten and twenty-two millimeters of cutting diameter. The reamer is initially selected as a very small reamer and the surgeon places progressively larger cutting diameter reamers in the patient'"'"'s intermedullary canal until resistance or until the reamer becomes stuck. When the surgeon finds a reamer that is sized so that it will ream and cut cortical bone preferably a full three hundred and sixty degrees (360°), the patient'"'"'s intramedullary canal is cut and reamed into a depth which corresponds to the length of the stem portion of the femoral prosthetic component. Instrumentation is installed on the upper generally cylindrically shaped portion of the reamer as soon as cutting and reaming is completed and without removal of the reamer from the intermedullary canal. This insures that cutting instrumentation will be properly oriented with regard to the hole that is cut and reamed to prepare the intermedullary canal.

Claims

1. A method of implanting a knee prosthesis component having a stem that registers with the patient'"'"'s leg bone intramedullary canal comprising the steps of:

a) using a rotary reamer of a first smaller diameter with a distal end portion having a cutting portion that defines a cutting diameter during use, the reamer being selected from a group of reamers, each of an increasingly larger external diameter to preliminarily ream the intramedullary canal of a patient'"'"'s leg bone to a preselected diameter, and beginning at the knee joint area;

b) using progressively larger diameter reamers to ream the intramedullary canal of the patient'"'"'s leg bone until a reamer is selected that has a sufficiently large external cutting diameter that the reamer distal end portion is cutting cortical bone to define a prepared bore that will abut the stem of the selected knee prosthesis component during use;

c) installing cutting instrumentation on the selected reamer as the reamer occupies the intramedullary canal and the distal end portion fits against the bore, wherein the reamer defines a reference axis for the cutting instrumentation;

d) cutting the leg bone at the knee joint area using the cutting instrumentation supported by the selected reamer; and

e) placing the stem of a selected knee prosthesis component in the patient'"'"'s intramedullary canal wherein the stem fits the prepared bore.

2. The method of claim 1 wherein the reamer is step "d" has a lower distal cutting end portion positioned in the intramedullary canal at the bore and an upper, non-cutting end portion that supports the instrumentation.

3. The method of claim 1 wherein a plurality of reamers of different diameters are sequentially placed in the intramedullary canal beginning with a small reamer having a smaller diameter and inserting progressively larger reamers until a reamer is selected that is capable of reaming three hundred sixty degrees (360°

) of cortical bone tissue at the distal end of the reamer.

4. The method of claim 3 wherein the smallest diameter reamer is ten (10) millimeters or less in diameter.

5. The method of claim 1 wherein in step "a" the reamer has upper and lower end portions, and the lower end of the reamer extends into the intramedullary canal, and the upper end portion remains exposed and externally of the intramedullary canal.

6. The method of claim 1 wherein in step "c" the cutting instrumentation provides one or more flat cutting reference surfaces and in step "d", cuts are made by abutting a selected reference surface with a cutting blade.

7. The method of claim 1 wherein in step "d", the reamer is advanced sufficiently into the intramedullary canal to create a rotational frictional resistance between the reamer and the cortical bone tissue during reaming.

8. The method of claim 1 wherein in step "b" the cutting instrumentation is supported upon the reamer at spaced apart locations.

9. The method of claim 1 wherein a smaller of the reamers is of a cutting diameter of ten (10) millimeters.

10. A cutting instrumentation system for use in preparing a patient'"'"'s bone tissue at the patient'"'"'s knee joint area for a knee prosthesis, and wherein the bone tissue has a proximal bone tissue surface that is generally transverse to the patient'"'"'s intramedullary canal, comprising;

a) a plurality of elongated rotary reamers, each having an upper proximal end portion and a lower distal end portion having a rotary cutting element thereon, wherein each respective reamer has a rotary cutting element of a progressively larger cutting diameter;

b) an instrumentation assembly having means thereon for supporting the assembly during use upon a selected reamer at its upper end portion and in a position externally of the patient'"'"'s intramedullary canal so that the instrumentation assembly is referenced upon the reamer; and

c) the instrumentation assembly with an opening that closely fits the reamer to fix the angle of the cutting block relative to the reamer, the cutting block surrounding the reamer during use and providing a surface portion including a cutting block that closely fits the patient'"'"'s proximal bone tissue surface at the knee joint area;

d) the block having a cutting guide surface thereon for referencing a cutting blade so that selected bone tissue cuts can be made adjacent the knee joint area of the patient.

11. The cutting instrumentation of claim 10 wherein the cutting guide surfaces are generally flat.

12. The cutting instrumentation of claim 10 further comprising a prosthesis having a stem and a transverse table attached to the upper end of the stem defining an angle therewith, and wherein the cutting block has a flat planar cutting guide surface that intersects the reamer linear axis at said angle.

13. The cutting instrumentation of claim 12 wherein the stem is of a generally uniform cylindrically-shaped cross section.

14. The cutting instrumentation of claim 10 wherein said plurality of elongated reamers include a smaller reamer having a cutting diameter of about ten (10) millimeters, and a plurality of larger cutting diameter reamers.

15. The cutting instrumentation of claim 14 wherein the plurality of reamers have cutting diameters of between ten (10) and twenty-two (22) millimeters.