Surgical Template Segmentation for Knee Replacement Accuracy
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Solution Overview
Problem
Current surgical template systems for total knee replacement surgery face issues such as inaccuracies in placement, complexity, increased procedure time, and cost due to adjustable mechanisms, material shedding, and reduced visibility during bone cuts, particularly with custom molds and soft materials like DuraForm™.
Innovation Solution
A surgical template system comprising a reusable metal tool guide block and patient-specific locating means manufactured using rapid prototyping, where the locating means are designed to conform to the bone's shape, allowing precise placement and reducing material shedding, with separate components for improved accuracy and cost-effectiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If adjustable mechanisms are used in template systems, then adaptability is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The template system is divided into separate components: a reusable guide block and a patient-specific mold. This segmentation allows the guide block to be standardized and simplified while the mold provides patient-specific adaptability, resolving the contradiction between adjustability and complexity.
Solution Approach 2:
The patent employs disposable patient-specific molds that are customized for each patient but used only once. This allows high adaptability for each patient without requiring complex adjustable mechanisms in the reusable guide block, as the customization is achieved through inexpensive single-use molds.
2Manufacturing precision
If custom molds made from soft materials are used, then patient-specific fitting is improved, but material shedding increases
Solution Approach 1:
The system separates the patient-specific mold (which contacts the bone and requires soft material for fitting) from the guide block (which guides the cutting tool). The mold is made from soft material like DuraForm for accurate patient-specific fitting, while the guide block is made from hard metal material that does not shed material during cutting operations.
Solution Approach 2:
The patient-specific mold acts as an intermediary between the bone surface and the guide block. It provides the necessary conformability to the patient's anatomy while the hard metal guide block provides stable tool guidance without shedding, effectively separating the conflicting material requirements.
3Manufacturing precision
If instrument guide blocks are positioned over custom molds, then alignment is improved, but guide aperture distance from bone surface increases reducing accuracy
Solution Approach 1:
The guide block and mold are designed to work together as an integrated system where the mold provides patient-specific alignment and the guide block provides precise tool guidance. The combination achieves both alignment accuracy and cutting accuracy that neither component could achieve alone.
Solution Approach 2:
The mold is created as a patient-specific copy of the bone surface geometry through scanning and rapid prototyping. This accurate geometric copy allows the guide block to be positioned with high precision relative to the bone surface, maintaining guide aperture accuracy despite the intermediate positioning layer.
4Device complexity
If thin instrument guide blocks with shallow guide apertures are used, then device complexity is reduced, but cutting accuracy is reduced
Solution Approach 1:
The system uses composite construction with a hard metal guide block providing deep, precise guide apertures and a separate mold material providing patient-specific fitting. This composite approach allows the guide block to have sufficient thickness for accurate cutting guidance while the overall system remains adaptable to patient anatomy.
Data Source
AI summary
A surgical template system for use in working on a bone comprises: a tool guide block comprising at least one guide aperture for receiving and guiding a tool to work on a bone; locating means comprising a plurality of locating members, each member having a respective end surface for positioning against a surface of the bone; and attachment means for non-adjustably attaching the tool guide block to the locating means such that, when attached, the member end surfaces are secured in fixed position with, respect to each other, for engaging different respective portions of the surface of the bone, and the at least one guide aperture is secured in a fixed position with respect to the end surfaces. Corresponding methods of manufacturing a surgical template system, methods of manufacturing locating means for a surgical template system, methods of fitting a prosthesis to a bone, surgical methods, and surgical apparatus are described.