Surgical Cutting Tool with Segmented Blades for Bone Seating

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Solution Overview

Problem

Conventional surgical cutting tools for preparing seating surfaces in natural bone for prosthetic joint implants suffer from manufacturing inaccuracies, costly production, and inefficiencies leading to uneven cutting surfaces, which can result in improper affixation and performance issues of the implant components.

Innovation Solution

A surgical cutting tool with a cutting blade construct and arbor design, where cutting blades are made of metal and arbor is of synthetic polymeric material, allowing for precise cutting with curved edges that follow a contour configuration matching the implant component, ensuring a smooth and accurate seating surface preparation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If conventional domed sheet metal construction with punched cutting teeth is used, then manufacturing cost is reduced, but manufacturing precision and cutting accuracy deteriorate

Engineering Contradiction:

Improvemanufacturing costVSAvoidcutting accuracy

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent applies the disposable principle by making the cutting head an expendable component that is replaced after a limited number of uses or when cutting performance degrades. This allows each cutting head to be optimized for precision with sharp cutting edges without concern for long-term durability, while the overall system remains cost-effective through controlled replacement rather than expensive maintenance or re-sharpening of permanent tools.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

2Productivity

If cutting teeth are arranged in staggered pattern on hemispherical shell, then bone removal capability is improved, but cutting surface smoothness deteriorates

Engineering Contradiction:

Improvebone removal capabilityVSAvoidcutting surface smoothness

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The patent applies segmentation by dividing the cutting function into multiple discrete cutting teeth arranged in staggered patterns around the cutting envelope. Each tooth independently engages the bone, and their staggered arrangement ensures continuous cutting action while distributing bone removal across multiple small cuttings rather than large chunks, thereby maintaining both productivity and surface smoothness.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent applies spheroidality by arranging cutting teeth along a hemispherical cutting envelope that matches the desired seating surface geometry. The curved arrangement of teeth follows the spherical path, ensuring that each tooth cuts along the correct contour while the collective action of all teeth produces a smooth, continuous spherical seating surface despite the discrete nature of individual tooth engagement.

Inventive Principle:

Principle #14Spheroidality (Curvature)

3Strength

If rim is left uninterrupted for structural integrity, then tool strength is improved, but cutting surface area is reduced

Engineering Contradiction:

Improvetool structural integrityVSAvoidcutting surface area

Core Design Contradiction:

StrengthVSArea of stationary object

Solution Approach 1:

The patent applies segmentation by dividing the rim into multiple discrete segments rather than leaving it as an uninterrupted continuous structure. These segmented rim sections provide sufficient structural support for tool strength while creating gaps that allow cutting teeth to extend to the full equatorial circumference, maximizing the cutting surface area and eliminating the undersized ledge problem.

Inventive Principle:

Principle #1Segmentation

4Ease of manufacture

If reamer diameter varies from nominal dimension, then manufacturing tolerance is relaxed, but seating surface accuracy deteriorates

Engineering Contradiction:

Improvemanufacturing toleranceVSAvoidseating surface accuracy

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent applies the disposable principle where each cutting head is manufactured as a precision component with accurate dimensional control, then used for a limited number of procedures before replacement. This allows tight manufacturing tolerances to be applied economically to each individual head, ensuring high seating surface accuracy, while the overall cost is managed through controlled disposal rather than expensive long-term maintenance.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Data Source

PatentUS7837686B1Surgical cutting tool

Publication Date: 2010.11.23 HOWMEDICA OSTEONICS CORP

AI summary

A surgical cutting tool for cutting a seating surface of curved contour configuration in natural bone for receiving a component of a prosthetic implant at an implant site. The tool has cutting blades in a cutting blade construct placed within an arbor such that the cutting blades are supported by the arbor circumferentially spaced from one another, with cutting edges of the cutting blades exposed for cutting the seating surface. Stabilizers along the arbor stabilize the tool during a cutting operation, while channels in the arbor along the cutting blades carry away cut bone. The cutting blades are essentially flat, are economically manufactured from flat stock, are provided with a predetermined thickness and a cutting blade radius, and include cutting edges placed within the cutting blade construct circumferentially forward of the cutting blade radius to establish a gap between the cutting blade radius and a corresponding radius of the seating surface for providing an effective cutting profile along each cutting edge.