Foamable Thermoplastic Implants With Variable Density for Bone Matching
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Solution Overview
Problem
Current orthopedic implants lack patient specificity and biological interaction, often resulting in issues such as stress shielding, bone resorption, and poor osseointegration due to mismatched modulus of elasticity, and require subsequent surgical procedures for removal.
Innovation Solution
A method for producing variable density 3D printed components using a foamable thermoplastic composition comprising biodegradable polymers and bioactive agents, adjusted through temperature control during 3D printing to match patient-specific bone density and structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional orthopedic implants are used, then structural support is provided, but stress shielding and bone resorption occur due to mismatched modulus of elasticity
Solution Approach 1:
The patent applies parameter changes by varying the density of the 3D printed implant across different regions to match the modulus of elasticity with surrounding bone tissue. By controlling printing parameters such as infill density and layer thickness, the implant achieves a graded modulus of elasticity that prevents stress shielding while maintaining structural support.
Solution Approach 2:
The patent implements local quality by creating regions of varying density within the implant structure. Different portions of the implant have different material densities tailored to match the specific mechanical properties required at each location, allowing the implant to interact harmoniously with surrounding bone tissue and prevent stress shielding.
2Strength
If conventional orthopedic implants are used, then structural support is provided, but poor osseointegration occurs
Solution Approach 1:
The patent employs porous materials by incorporating a controlled pore structure within the 3D printed implant. This porosity allows bone ingrowth and enhances osseointegration while maintaining adequate structural support. The pore size and distribution are optimized to facilitate bone cell attachment and proliferation.
Solution Approach 2:
The patent utilizes composite materials by combining different polymer components or adding reinforcement phases to the base material. This creates a multi-phase structure that simultaneously provides structural support and promotes biological interaction, improving osseointegration while maintaining mechanical strength.
3Ease of manufacture
If uniform density 3D printing is used, then manufacturing is simplified, but patient specificity and biological interaction are reduced
Solution Approach 1:
The patent applies dynamics by implementing variable density control during the 3D printing process. The printing parameters such as infill density, layer height, and printing speed are dynamically adjusted based on the specific patient anatomy and required mechanical properties, allowing customization while maintaining manufacturing feasibility.
4Duration of action of stationary object
If biodegradable polymers are used, then subsequent removal surgeries are eliminated, but control over degradation rate and mechanical properties becomes more difficult
Solution Approach 1:
The patent uses composite materials by combining biodegradable polymers with varying degradation rates or adding non-biodegradable reinforcement phases. This allows control over the overall degradation profile and mechanical properties, eliminating removal surgery while managing the complexity of material behavior through careful composition design.
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 method enables patient-specific implants with improved biological interaction and reduced negative impacts on surrounding tissues by mirroring bone density and structure, eliminating the need for subsequent surgeries.
Implementation Method 1
adding a chemical foaming agent... heating and cooling elements cooperate to heat the thermoplastic polymer composition to the temperature that corresponds to the desired density... decomposition temperature of the chemical foaming agent
Implementation Method 2
heating and cooling elements cooperate to heat the thermoplastic polymer composition to the temperature that corresponds to the desired density
Implementation Method 3
heating and cooling elements cooperate to heat the thermoplastic polymer composition to the temperature that corresponds to the desired density
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A method for 3D printing a patient-specific bone implant having variable density, in various aspects, comprises: (1) providing a thermoplastic polymer composition comprising: (A) between about 20% and about 50% bioactive agent by weight; (B) between about 0.5% and about 10% chemical foaming agent by weight; and (C) balance structural polymer by weight; (2) receiving, by computing hardware, a scan of a bone, the scan comprising at least a 3D image of the bone and radiodensity data for the bone; and (3) causing, by the computing hardware, a 3D printer to form the patient-specific bone implant from the 3D image using the thermoplastic polymer by modifying a 3D printing temperature of the 3D printer during printing of the patient-specific bone implant such that each portion of the patient-specific bone implant is produced at a temperature that corresponds to a desired density defined by the radiodensity data for the bone.