News Column

"Medical Reamers and Methods of Forming the Same" in Patent Application Approval Process

July 25, 2014



By a News Reporter-Staff News Editor at Health & Medicine Week -- A patent application by the inventors Sidebotham, Christopher G. (Mendham, NJ); Roitburg, Leon (East Hanover, NJ); Lewis, Randall J. (Bethesda, MD), filed on October 28, 2013, was made available online on July 10, 2014, according to news reporting originating from Washington, D.C., by NewsRx correspondents (see also Patents).

This patent application has not been assigned to a company or institution.

The following quote was obtained by the news editors from the background information supplied by the inventors: "Cutting tools, such as medical reamers used by surgeons, generally have a cutting surface that is able to cut and/or remove material from an object. For example, in many different disciplines in orthopedics cutting tools are used for machining bone in the preparation of artificial joints including hips, knees, elbows and shoulders, and also in the repair of long bone fractures. The design and method of manufacturing cutting surfaces of cutting tools can affect the efficiency, functional life of the spherical reamer and cost in manufacturing. Accordingly, improvements relating to design and manufacturing methods are desirable."

In addition to the background information obtained for this patent application, NewsRx journalists also obtained the inventors' summary information for this patent application: "In some embodiments, improved cutting tools and methods of manufacturing the same are provided.

"In certain implementations, the cutting tools comprise medical reamers, including acetabular reamers, long bone cylindrical reamers, long bone tapered reamers, patella reamers and glenoid reamers along with the design of different cutting teeth in specific zones of the reamers and the improved method of making these reamers and their cutting edges.

"In some implementations, a cutting tool is provided with a cutting surface on a first side of the cutting tool and an attachment member on a second side of the cutting tool. The cutting surface can include a plurality of cutting edges and the attachment member can be configured to be coupled to a powered driving member (e.g., a drill). The cutting tool comprises an axis of rotation and the cutting surface defines a plurality of latitude lines. The plurality of cutting edges can be oriented at varying orientation angles relative to the latitude lines.

"In some implementations, the plurality of cutting edges can be in three different zones and respective cutting edges in the different zones have different characteristics. The different zones can comprise a polar zone, a transition zone, and an equatorial zone. Respective cutting edges can define a cutting angle between the cutting edge and a first side of the cutting tool, and the cutting angle between cutting edges in the polar zone can be larger than those defined by cutting edges in the transition zone, and the cutting angle between cutting edges in the transition zone can be larger than those defined by cutting edges in the equatorial zone. In some implementations, the tooth height can be the same (i.e., substantially the same) regardless of the cutting angle.

"In some implementations, the orientation angles vary depending on whether the respective cutting edges are in the polar zone, the transition zone, or the equatorial zone, and the orientation angle of respective cutting edges in the equatorial zone is greater than the orientation angle of respective cutting edges in the transition zone, and the orientation angle of respective cutting edges in the transition zone is greater than the orientation angle of respective cutting edges in the polar zone.

"In some implementations, the thickness of the side wall is less than 0.040 inches, or in some cases, between 0.022 inches and 0.40 inches. Openings can be provided adjacent respective cutting edges, the respective openings defining a funnel angle that is between 20 and 40 degrees. In some cases, the funnel angle can be between 25 and 35 degrees.

"In some implementations, the cutting surface is a panel and the cutting tool comprises a plurality of separate panels. The cutting tool can include a frame member (e.g., a center support and a base) and the plurality of separate panels can be coupled to the frame member.

"In another implementation, a method for forming a cutting tool is provided. The method can include forming a plurality of panels from one or more flat sheets of metal and coupling the plurality of panels to a frame member to form the cutting tool. The plurality of panels can be formed with a plurality of cutting edges and a plurality of openings adjacent respective cutting edges. When coupled to the frame member, the plurality of panels can define a plurality of latitude lines about the axis of rotation of the cutting tool and the plurality of formed cutting edges have orientation angles relative to the latitude lines that vary. In some cases, respective panels can have cutting edges with orientation angles that vary along the respective panel.

"In certain implementations, the act of forming a plurality of panels comprises stamping the one or more flat sheets of metal to form a plurality of cavities and punching holes at or adjacent to the plurality of cavity to provide bone-chip-receiving openings. The act of forming the plurality of cavities can include forming a plurality of 'V'-shaped cavities.

"In certain implementations, the act of forming the plurality of panels can include stamping the one or more panels to create a desired height of the cutting edges and to provide a desired curvature of the one or more panels.

"In certain implementations, the act of coupling the plurality of panels to the frame member can include forming a frame member that comprises a center support, a base, and a form dome, and securing the plurality of panels to the center support, the base, and the form dome. In some cases, the act of securing the plurality of panels to the center support, the base, and the form dome can be performed by laser welding or other types of welding. The act of coupling the plurality of panels to the frame member can also include placing the plurality of panels into an injection molding tool and injection molding the frame member around the plurality of panels to create the frame member.

"In some implementations, the act of forming a plurality of panels from one or more flat sheets of metal can include forming the plurality of cutting edges with different zones that have cutting edges with different characteristics, the different zones comprising a polar zone, a transition zone, and an equatorial zone. Respective cutting edges can define a cutting angle between the cutting edge and a first side of the cutting tool, and the cutting angle between cutting edges in the polar zone are larger than those defined by cutting edges in the transition zone, and the cutting angle between cutting edges in the transition zone are larger than those defined by cutting edges in the equatorial zone.

"In certain implementations, the act of punching holes at or adjacent to the plurality of cavity comprises forming bone-chip-receiving openings with a funnel angle that is between 20 and 40 degrees. In addition, in some cases, the one or more flat sheets of metal have a thickness less than 0.040 inches.

"In certain implementations, the method includes determining an effective functional life of the cutting tool.

"In other embodiments, a cutting tool is provide that has a cutting surface on a first side of the cutting tool, the cutting surface comprising a plurality of cutting edges, and an attachment member on a second side of the cutting tool, the attachment member being configured to be coupled to a powered driving member. A plurality of cutting edges are provided in at least three different zones and respective cutting edges in the different zones have different characteristics.

"The foregoing and other objects, features, and advantages of the invention will become more apparent from the following detailed description, which proceeds with reference to the accompanying figures.

BRIEF DESCRIPTION OF THE DRAWINGS

"FIG. 1 illustrates an acetabular reamer, the use of the reamer to prepare the acetabulum, and a press-fit acetabular implant positioned as part of a total hip procedure.

"FIG. 2A illustrates an acetabular reamer with a hollow spherical cutter. FIG. 2B illustrates axial force applied by a surgeon, by pushing the cutter into the acetabulum and a second torsional force exerted by the power reaming tool. FIG. 2C illustrates the acetabular implant in position as part of a total hip procedure.

"FIG. 3A illustrates a cutting tool composed of a sharp tooth edge, a specific tooth elevation, specific cutting angle, a specific tooth orientation to the axis of rotation and a peripheral opening around the cutting edge providing an improved flow path for the bone debris. FIG. 3B illustrates a bone chip opening. FIG. 3C illustrates a funnel angle for bone debris.

"FIG. 4A illustrates a manufacture of cutting teeth geometry by forming a sheet. FIG. 4B illustrates cutting tooth geometry of the sheet. FIG. 4C illustrates a cutting tooth height set.

"FIG. 5A illustrates a novel cutting tool having a plurality of teeth, with one row of teeth shown for clarity. FIG. 5B illustrates the cutting edge orientation to latitude lines.

"FIG. 6 illustrates a novel cutting tool having a plurality of teeth.

"FIG. 7A illustrates an acetabulum undersized to a reamer. FIG. 7B illustrates a schematic view of cutting teeth zones. FIG. 7C illustrates a primarily side cutting reaming action. FIG. 7D illustrates a transition from side cutting to end cutting. FIG. 7E illustrate a primarily end cutting action.

"FIG. 8A illustrates a schematic view of cutting teeth zones and their general functions. FIG. 8B illustrates the cutting teeth of the equatorial zone. FIG. 8C illustrates the cutting teeth of the transitional zone. FIG. 8D illustrates the cutting teeth of the polar zone.

"FIG. 9 illustrates a schematic view of cutting forces applied by a cutting tool.

"FIG. 10A illustrates frictional forces associated with bone chips created by a cutting tool with a first thickness. FIG. 10B illustrates frictional forces associated with bone chips created by a cutting tool with a second thickness.

"FIG. 11A illustrates stamping a flat sheet forming panels with multiple teeth designs. FIG. 11B illustrates punching holes in the sheet. FIG. 11C illustrates stamping tooth height and forming a panel curvature.

"FIG. 12 illustrates a formed dome of a reamer.

"FIG. 13 illustrates a formed center support of a reamer.

"FIG. 14 illustrates a form base of a reamer.

"FIG. 15A illustrates an assembly of panels of a reamer. FIG. 15B illustrates an assembled reamer.

"FIG. 16A illustrates stamped cutting panels of a spherical reamer. FIG. 16B illustrates an injection molding tool for creating plastic framing. FIG. 16C illustrates a finished reamer.

"FIG. 17A illustrates a cylindrical reamer stamped panel. FIG. 17B illustrates a molded plastic frame. FIG. 17C illustrates another stamped panel. FIG. 17D illustrates a finished reamer.

"FIG. 18 illustrates the results of an exemplary test procedure.

"FIG. 19 illustrates the results of an exemplary test procedure.

"FIG. 20 illustrates an exemplary test procedure.

"FIG. 21 illustrates an exemplary cutting tool of at least some of the disclosed embodiments, which is a spherical reamer.

"FIG. 22 illustrates an exemplary cutting tool of at least some of the disclosed embodiments, which is a long bone tapered reamer.

"FIG. 23 illustrates an exemplary cutting tool of at least some of the disclosed embodiments, which is a cylindrical reamer.

"FIG. 24 illustrates an exemplary cutting tool of at least some of the disclosed embodiments, which is a patellar reamer."

URL and more information on this patent application, see: Sidebotham, Christopher G.; Roitburg, Leon; Lewis, Randall J. Medical Reamers and Methods of Forming the Same. Filed October 28, 2013 and posted July 10, 2014. Patent URL: http://appft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&u=%2Fnetahtml%2FPTO%2Fsearch-adv.html&r=1806&p=37&f=G&l=50&d=PG01&S1=20140703.PD.&OS=PD/20140703&RS=PD/20140703

Keywords for this news article include: Patents, Bone Research.

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Source: Health & Medicine Week


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