Bone Cutting Fixture with Segmented Guide Appendages
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Solution Overview
Problem
Existing surgical cutting guides for preparing the femur for a knee prosthesis often obstruct the view of the cut surfaces due to their large size and material properties, which can be exacerbated by body fluids and light refraction, and they are not lightweight or disposable.
Innovation Solution
A bone cutting fixture assembly with a centrally located, elongated support structure of polymeric material and pairs of blade guide appendages that define four cutting planes, featuring adjustable guide pins and anchor points to securely fix the guide to the femur, minimizing obstruction and allowing for clear visibility during cutting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a massive housing guide structure is used, then the guide provides stable support and guidance, but it obstructs the view of the bone during cutting
Solution Approach 1:
The guide is divided into separate functional components: a minimal support structure for stability and separate guide elements (appendages with guide surfaces) for blade guidance. This segmentation allows the support structure to be minimal and non-obstructive while the guide surfaces provide necessary guidance, resolving the contradiction between stability and visibility.
Solution Approach 2:
The guiding function is extracted from a massive housing structure and implemented through separate guide appendages with guide surfaces. This extraction removes the obstructive housing while preserving the essential guidance function through dedicated guide surfaces that define cutting planes.
2Weight of moving object
If the guide is made from polymeric material, then it is lightweight and inexpensive, but it may obstruct view when covered with body fluids or when light refraction occurs
Solution Approach 1:
The guide structure uses local transparency where visibility is needed (guide surfaces and support structure areas adjacent to the cut) while maintaining structural integrity. The polymeric material is selected to be transparent in critical viewing areas, allowing light transmission despite the material's inherent refraction properties.
3Illumination intensity
If a transparent plastic guide is used, then visibility is improved, but the guide still obstructs view when covered with body fluids
Solution Approach 1:
The guiding function is extracted from a solid transparent housing and implemented through separate guide appendages with guide surfaces. This extraction creates open spaces between components that prevent body fluids from forming continuous obstructive layers, maintaining visibility even when fluids are present.
4Illumination intensity
If the guide structure is minimized to improve visibility, then obstruction is reduced, but the guide may lack sufficient support and stability
Solution Approach 1:
The guide is segmented into a minimal support structure providing stability and separate guide appendages providing guidance. The support structure is minimized to only what is necessary for stability, while the guide surfaces on the appendages provide the required guidance functionality without adding obstructive mass.
Data Source
AI summary
A bone cutting fixture assembly for use as guide for a cutting blade in shaping a distal end of a femur to receive a component of a knee prosthesis is provided. The assembly has a centrally located, elongated support structure, made of a polymeric material, having a trapezoidal cross section, pairs of adjacent blade guide appendages supported therein so as to define four cutting planes, and two outrigger portions extending therefrom defining anchor points in distal ends thereof. The assembly defines a substantially flat support plane and has spaced apart anchor points positioned so as to enable secure fixing of the fixture to a femur by fixing devices.