Reinforced Sagittal Saw Cartridge Guide Bar Against Blade Flexure

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Solution Overview

Problem

Surgical sagittal blade cartridges experience flexure when cutting through bone, leading to suboptimal cut surfaces and potential misfitting of artificial implants, due to the lack of rigidity in the guide bar, which cannot be effectively increased without compromising cut smoothness.

Innovation Solution

A surgical sagittal blade cartridge with a guide bar composed of three plates, including a top, bottom, and inner plate with curved sections and tines, providing structural reinforcement to resist deformation and flexure, while maintaining the necessary thickness to prevent skiving or diving.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If the thickness of the guide bar is increased to reduce flexure, then the rigidity of the guide bar is improved, but the smoothness of the cut surface deteriorates

Engineering Contradiction:
Improverigidity of guide barVSAvoidsmoothness of cut surface
Core Design Contradiction:
StrengthVSManufacturing precision

Solution Approach 1:

The guide bar is segmented into three distinct plates (top plate, bottom plate, and inner plate) that are positioned alongside each other rather than increasing the thickness of a single bar. This segmentation provides rigidity through the distributed structural arrangement while maintaining a slender overall profile that does not compromise cut smoothness.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Instead of solving the rigidity problem by increasing thickness in one dimension, the invention transitions to a multi-plate arrangement that distributes structural strength across multiple dimensions. The three plates work together to provide rigidity through their collective arrangement, avoiding the need to increase the thickness of any single plate to a level that would affect cut quality.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Stability of the object's composition

If the guide bar is made more rigid to prevent flexure, then the stability of the cutting path is improved, but the complexity of the guide bar structure increases

Engineering Contradiction:
Improvestability of cutting pathVSAvoidcomplexity of guide bar structure
Core Design Contradiction:
Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The guide bar is divided into three separate plates (top plate, bottom plate, and inner plate) that can be manufactured and assembled independently. This segmentation allows each plate to be optimized for its specific function while maintaining overall structural stability, and the modular nature simplifies manufacturing and assembly processes compared to a monolithic complex structure.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The three plates are combined to work together as a unified guide bar structure. The top plate, bottom plate, and inner plate are positioned and secured relative to each other to provide collective rigidity and stability for the cutting path, achieving enhanced stability through combination rather than through a single complex component.

Inventive Principle:
Principle #5Merging (Combining)

Data Source

PatentEP3294152B1Surgical sagittal blade cartridge with a reinforced guide bar
Publication Date: 2024.10.02 STRYKER EUROPEAN OPERATIONS HOLDINGS LLC
  • EP3294152B1 patent drawingFigure 1
  • EP3294152B1 patent drawingFigure 2
  • EP3294152B1 patent drawingFigure 3

AI summary

A surgical sagittal saw cartridge (60) that includes a guide bar (62) formed form an inner plate and opposed outer plates, the inner plate having a head. The cartridge has a blade that is disposed against the head of the inner plate. The inner plate is formed to have an inner tine and two opposed outer tines. The inner tine is formed to define the head against which the blade is disposed. The outer tines extend forward of the inner tine so as to define a space between the outer tines in which the blade is seated.