Orthopaedic Impactor Body with Polymer Envelope
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Solution Overview
Problem
Current surgical impactors for hip operations are expensive, cumbersome, and have limited design freedom due to their stainless steel construction, with complex kinematic chain guidance complicating cleaning and sterilization, and lack cost-effectiveness and ergonomic design.
Innovation Solution
A biocompatible impactor body with a metallic frame partially covered by a polymer envelope, providing mechanical strength and shock resistance while reducing weight and manufacturing costs, and featuring a U-shaped polymer chute for kinematic chain guidance with minimal friction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the impactor body is made of stainless steel, then mechanical strength and impact resistance are improved, but manufacturing cost increases and mass becomes excessive
Solution Approach 1:
The impactor body combines a metal frame (providing mechanical strength and impact resistance) with a polymer envelope (reducing mass and manufacturing cost). This composite structure allows each material to contribute its advantageous properties while mitigating their individual disadvantages.
Solution Approach 2:
The metal frame is strategically positioned only where mechanical strength is critical (handle, striking zone, cup support), while the polymer envelope covers areas where lower strength is acceptable but weight reduction is beneficial. This localized application of materials optimizes the strength-to-weight ratio.
2Strength
If the impactor body is made of stainless steel, then mechanical strength is improved, but mass increases making it unwieldy
Solution Approach 1:
The hybrid metal-polymer construction reduces overall mass compared to a fully metal impactor while maintaining necessary strength through the metal frame skeleton. The polymer envelope acts as a lightweight protective covering.
Solution Approach 2:
Metal is applied only in localized areas requiring high strength (frame structure), while the majority of the body volume is occupied by lightweight polymer, significantly reducing total mass.
3Strength
If the impactor body is machined from stainless steel, then mechanical strength is ensured, but design freedom is limited
Solution Approach 1:
The polymer envelope can be molded into complex geometries that would be difficult or expensive to machine from metal, providing design freedom for ergonomic handles, integrated features, and customized shapes while the metal frame maintains structural integrity.
Solution Approach 2:
Different materials are used in different zones to optimize both strength and design freedom - the metal frame provides structural constraints where needed, while the polymer envelope offers molding freedom for ergonomic and functional features.
4Manufacturing precision
If a complex kinematic chain guidance system is added, then cup positioning precision is improved, but cleaning and sterilization difficulty increases
Solution Approach 1:
The kinematic chain guidance features are extracted from the traditional metal impactor body and integrated into the polymer envelope through molded-in channels and geometric features. This separation allows the guidance system to be formed as part of the envelope rather than requiring separate metal components with complex joints.
Solution Approach 2:
The polymer envelope incorporates the kinematic guidance geometry directly into its molded structure, creating smooth, continuous surfaces that are easier to clean and sterilize compared to machined metal components with tight tolerances and multiple assembly interfaces.
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
The solution results in a lightweight, cost-effective, and ergonomic impactor that is easy to clean and sterilize, offering improved mechanical performance and reduced mass, with options for reusability or disposability based on polymer resistance to steam sterilization.
Implementation Method 1
the armature is then placed in an injection mold into which the polymer shell is injected. The casing is therefore molded over the frame.
Implementation Method 2
The latter has a U-shaped chute the same width as the driveline. This chute, combined with the material of which the casing is made, has a bearing effect and makes it possible to guide the kinematic chain, with a minimum of friction
Data Source
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AI summary
The invention relates to a surgical impactor body and to a production method for making said body. The impactor body comprises an impact head (12), a handle (20a), a cup abutment (13, 20c) and a long element (20) containing a conduit (20d) designed to house a kinematic chain (30), characterised in that said long element (20) is at least partially formed by an envelope (20).