Unitary PEEK Intramedullary Stem for CMC Joint Implants
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Solution Overview
Problem
Metal-on-metal joint implants generate excessive metallic debris, leading to inflammatory reactions, and existing designs often require complex assembly and multiple components, increasing the risk of manufacturing errors and surgical complications.
Innovation Solution
A unitary intramedullary stem with a polymer body, specifically made of PEEK or CF-PEEK, featuring a integral ball-and-socket articulation and a titanium plasma coating for enhanced osteointegration, which eliminates the need for separate components and reduces the risk of debris generation and assembly errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If metal-on-metal bearing surfaces are used, then rigidity and strength are improved, but excessive metallic debris is generated causing inflammatory reactions
Solution Approach 1:
The patent merges the stem and liner into a single unitary component made of polymer material, eliminating the metal-on-metal interface that generates harmful debris. The unitary construction maintains structural integrity while using polymer throughout to prevent metallic particle generation.
Solution Approach 2:
The patent changes the material parameter from metal to polymer for the stem and liner components. This material substitution eliminates the harmful metallic debris generation while maintaining the necessary mechanical properties through careful polymer selection and design.
2Adaptability or versatility
If multiple separate components are used, then flexibility in assembly is improved, but device complexity and risk of manufacturing errors increase
Solution Approach 1:
The patent combines the stem and liner into a single unitary component, reducing the number of parts from two separate components to one. This simplification eliminates assembly errors while maintaining the necessary functional flexibility through integrated design features.
Solution Approach 2:
The unitary stem incorporates multiple functions within a single component: the proximal end provides articulation features, the mid-portion provides structural support, and the distal end provides bone engagement. This multi-functionality maintains versatility while reducing component count.
3Object-generated harmful factors
If polymer material is used for the stem, then debris generation is reduced, but structural strength may be compromised
Solution Approach 1:
The patent employs advanced polymer materials with reinforced structures to achieve the necessary structural strength without using metal. The composite polymer construction provides both the debris-free benefit and the required mechanical properties for load-bearing applications.
Solution Approach 2:
The patent optimizes polymer material parameters including density, cross-linking, and reinforcement to achieve sufficient structural strength. By carefully selecting and engineering polymer properties, the material can replace metal while maintaining load-bearing capacity and eliminating metallic debris.
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 provides a simpler, more reliable implant with reduced risk of debris-related inflammation, easier manufacturing and sterilization, and improved osteointegration, allowing for a single-piece removal during revision surgeries and flexible socket placement for optimized biomechanics.
Implementation Method 1
the stem comprises a coating on an external bone-contacting surface of said integral body... the coating comprises titanium plasma material, preferably CPTi
Data Source
AI summary
An intramedullary stem (1) is for a CMC joint implant. It has a distal bone-engagement end (10) and a proximal end (11) for engaging an articulation component such as a ball to complete a ball-and-socket coupling to a trapezium-contacting platform. The stem has an integral body (2) of material with an external surface for engaging a bone and with an aperture (3) leading to a socket (4) in the proximal end for engaging an articulation component ball or the like. The stem comprises a proximally extending projecting portion 5) which partly surrounds the socket. It is of PEEK material, which provides the desired strength and bone-contacting properties. The stem may have a coating over an elongate portion (203) of the surface extending distally and also in a ring (204) around the proximal end, to achieve optimum adhesion without excessive difficulty in extraction during revision surgery.