Polymer Surgical Implant With Stiff Bone Interface Layer
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Solution Overview
Problem
Existing surgical implants, particularly femoral implants, suffer from dimensional inaccuracies due to thermal deformation during cooling post-injection molding, leading to inconsistent interference fits and potential loosening, and lack mechanical compatibility with bone, causing stress shielding and bone loss.
Innovation Solution
A surgical implant with a bone interface layer comprising a polymer barrier layer at least 0.5 mm thick, providing stiffness to resist deformation, and optionally porous layers for bone ingrowth, is manufactured using insert molding to maintain accurate dimensions and improve fixation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a surgical implant is made of a single material, then the manufacturing process is simple, but the implant cannot provide both mechanical strength and bone regeneration capability
Solution Approach 1:
The surgical implant is divided into a first portion made of a first material and a second portion made of a second material, allowing each portion to provide different functions. The first material provides mechanical strength while the second material promotes bone regeneration, resolving the contradiction between manufacturing simplicity and functional versatility.
Solution Approach 2:
The implant uses composite construction with a first material and a second material, where the first material provides mechanical strength and the second material provides bone regeneration capability. This composite approach enables the implant to achieve multiple functions that a single material cannot provide.
2Adaptability or versatility
If the implant has complex multi-material construction, then functional versatility is achieved, but the manufacturing process becomes complex
Solution Approach 1:
The implant is segmented into distinct first and second portions that can be manufactured separately and then joined, simplifying the overall manufacturing process while maintaining functional versatility. Each portion can be optimized for its specific function without requiring complex integration.
Solution Approach 2:
The implant includes a junction portion that allows for relative movement between the first and second portions, enabling dynamic adaptation during surgery. This dynamic feature simplifies manufacturing by allowing flexible assembly while maintaining the functional benefits of multi-material construction.
3Stability of the object's composition
If rigid fixation is used to secure the implant, then stability is improved, but the ability to allow relative movement between portions is reduced
Solution Approach 1:
The junction portion is designed to allow relative movement between the first and second portions while maintaining overall implant stability. This dynamic design enables the implant to adapt to different anatomical conditions and surgical requirements without compromising stability.
Solution Approach 2:
The junction portion can change its mechanical parameters (such as flexibility and movement allowance) based on the specific surgical application. This parameter change capability enables the implant to provide rigid fixation when needed while allowing relative movement when beneficial, resolving the contradiction between stability and adaptability.
Data Source
Figure 1
Figure 2(a)~2(c)
Figure 3(a)~3(b)
AI summary
A surgical implant (10) comprising an implant body (12) and a bone interface layer (18). The implant body comprises a polymer material and has a bone-facing surface (14). The bone interface layer is provided over at least a portion of the bone-facing surface. The bone interface layer is formed of a material having a higher stiffness than the polymer material. The bone interface layer includes a polymer barrier layer (40) at least 0.5 mm thick across a majority of the surface area of the bone interface layer, the polymer barrier layer being impermeable to the polymer material. A method of manufacturing the surgical implant comprises over moulding the polymer material over the bone interface layer to form the implant body.