Cannulated Reamer With Offset Guide Surface For Femoral Joint Reshaping
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Solution Overview
Problem
Existing bone shaping systems obstruct the view of the femoral lobe during cutting and may damage the femoral stem, lacking controlled cutting and heat management for preparing the joint for a prosthetic cap.
Innovation Solution
A cannulated reamer system with a central guide and bar structure that includes an offset surface to prevent damage and a reamer handle to manage heat, allowing for controlled reshaping and heat dissipation away from the operative site.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a reamer is placed over the femoral lobe for cutting, then controlled reshaping of the femoral joint is enabled, but the tool obstructs the view of the femoral lobe
Solution Approach 1:
The reamer is divided into functionally distinct segments: a cutting form for reshaping the femoral lobe and a separate holder for support and heat management. The cutting form includes a central guide that can be cannulated to allow visualization, separating the cutting function from the support function to enable both controlled reshaping and improved visibility.
Solution Approach 2:
A central guide structure acts as an intermediary between the cutting form and the holder. This guide can be cannulated to allow visual access to the femoral lobe while maintaining the structural integrity needed for controlled cutting. The guide mediates between the need for tool support and the need for visualization.
2Manufacturing precision
If the reamer is supported directly at the cutting site, then controlled cutting is achieved, but heat is generated at the operative site causing tissue damage
Solution Approach 1:
The support and heat management functions are extracted from the cutting form and placed in the holder. The holder provides structural support and stability for controlled cutting, while being cannulated to allow heat to pass through to a heat sink, thereby removing the harmful heat generation from the operative site.
Solution Approach 2:
The holder acts as an intermediary that receives the cutting form and provides support while managing heat. The cannulated structure of the holder allows thermal energy to be conducted away from the cutting site to a heat sink, mediating between the heat generated during cutting and the surrounding tissue.
3Stability of the object's composition
If the reamer is made robust for controlled cutting, then cutting stability is improved, but the device complexity increases
Solution Approach 1:
The device is segmented into modular components: a cutting form, a central guide, and a holder. Each component has a specific function, allowing the system to achieve stability through proper component integration rather than through overall complexity. The bayonet mounting mechanism provides simple yet effective connection between components.
Solution Approach 2:
Multiple functions are merged into the holder: structural support, heat management through cannulation, and positioning of the cutting form. This consolidation reduces the number of separate components needed while maintaining cutting stability, thereby reducing overall device complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables precise and controlled reshaping of the femoral joint while preventing damage to the femoral stem and reducing heat-related tissue damage by moving heat generation away from the cutting site.
Implementation Method 1
pushed against the head by a helical spring
Implementation Method 2
The offset surface is preferably polished to reduce friction during relative rotational movement between this surface and the surface referenced to the bone
Implementation Method 3
controls heat by moving any points of heat generation from the reamer to the holder, and thus away from the operative site
Data Source
AI summary
A reamer system is provided which includes a cannulated reamer handle, and a corresponding cannulated reamer, which, when assembled and operated over a drill pin secured in a manner axially aligned with the stem of the femoral joint, enables the accurate and controlled reshaping of the femoral joint. The reamer is made up of a cutting form and a central guide, in which the guide is supported at the center of the cutting form by a bar structure. The bar structure includes portions which connect to and extend radially between the central guide and a peripheral edge of the cutting form. Optionally, the central guide includes a surface offset from a plane of the bar structure to a degree which enables that surface to contact an associated surface referenced to the bone, in order to prevent the cutting form from plunging so far over the bone as to potentially damage the femoral stem. This offset surface is preferably polished to reduce friction during relative rotational movement between this surface and the surface referenced to the bone. The offset surface is an axially perpendicular surface of a boss through which the drill pin is guided.